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[IN STOCK] Eurorack: Discrete State-Variable VCF v1.4
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author [IN STOCK] Eurorack: Discrete State-Variable VCF v1.4
negativspace
There is a long and helpful thread on the filter itself HERE. I'll re-post the critical stuff:

This filter started life as the SVF design (based on the J. Haible discrete 2040 gain cell) which Scott Stites posted over at electro-music in April. I'd been wanting to work with another filter for a while and this one looked interesting, so I started playing with it. I lopped off the audio input section and grafted on the CP3 mixer (moar transistors!) Eventually I made a few other changes - I got it self-oscillating, added a 1v/oct CV input with scale trim, and did some work in the resonance circuit - and the end result of all of that is the filter heard here:

[s]http://soundcloud.com/negativspace/discrete-svf-test-01[/s]

Ignore the photo in the Soundcloud clip, that's a different project using the same circuit. The panel for this one is 14hp, and depth is in the ~40mm range with the two PCBs stacked parallel to the panel. I'll get better photos of the panel and update this post ASAP.



Scott has given his blessing on both a DIY run and a retail release of this filter - so with my deepest thanks to him for the lion's share of this circuit I declare game on.
negativspace
Prices
Eurorack Panel + Bare PCB set: $45/ea
Bare Filter PCB: $20/ea
Shipping: $3/USA, $10/Canada, $15/Overseas
The Paypal address for payment is jcoates42@gmail.com

BOM
Resistors
[1] 1M R45
[1] 390k R13* (* = change to alter signal level from mixer to filter section. Suggested range is ~270-470k.)
[1] 240k R33
[2] 200k R36,R41
[1] 180k R19
[1] 110k R47
[5] 100k R15,R17,R38,R39,R40
[1] 62k R42
[1] 47k R10
[1] 39k R16
[4] 22k R1,R2,R3,R35
[3] 15k R5,R7,R43
[7] 10k R18,R27,R28,R29,R30,R31,R32
[3] 6.8k R8,R14,R46
[3] 1k R21,R22,R44
[2] 560R R9,R11
[3] 470R R20,R34,R37
[1] 240R R48
[4] 220R R23,R24,R25,R26
[1] 200R R6
[2] 100R R4,R12

Capacitors
[1] 3.3nF Film, C5
[1] 2.7nF Film, C13
[2] 1nF Polystyrene/Polypropylene *main timing caps in VCF
[2] 10-100uF Electrolytic *power decoupling caps, value noncritical
[3] 220pF MLCC, C7,C11,C12
[1] 150pF MLCC, C6
[5] 10uF Electrolytic, Q8,Q9,Q10 = audio path. The other two are for decoupling the +5 and -6V rails.
[2] 0.1uF MLCC

Transistors/Diodes
[11] 2N3904/Other NPN [PN100A] Q1,Q4,Q5,Q8,Q9,Q10,Q11,Q14,Q15,Q16,Q19
[2] 2N3904 Q17,Q18
[6] 2N3906/Other PNP [PN5138] Q2,Q3,Q6,Q7,Q12,Q13
[2] 1N4001

ICs/Sockets
[3] TL072 *or other standard pinout dual opamp.
[1] LM337LZ, TO-92
[1] LM78L05 *silkscreen on v1.2 PCB is reversed; TO-92
[3] 8P DIP socket (optional)

MISC
[1] 20k Trimpot (v/oct)
[1] 2k Trimpot (-6V)
[1] 100r Trimpot (null)
[2] Ferrite Bead
[1] 16P Header (power)
[2] 12P Header + socket (board to board interconnections)
[4] 7/16" Nylon standoff + 3/4" #4-40 screw + hex nut set. (Use 12mm standoff if metric)

Panel Controls
[3] A20-25k Pots (lugs) - audio inputs
[4] B100k Pots (pins) - CV inputs, cutoff frequency
[1] B10k pot (pins) - notch balance
[1] B10k Dual-ganged Pot (pins/lugs - BYOC, Banzai, or Small Bear) - resonance
[12] 3.5mm Jack (Erthenvar-style preferred, 16PJ138 in a pinch)
[6] 1900H or clone
[1] Davies 1913BW
[1] Davies 1910CS

Surface Mount Parts:
[2] 0.1uF 0805 ceramic, install on back of main PCB
[2] 0.1uF 0805 ceramic, control board
[2] 22pF 0805 ceramic, control board
[4] 47k resistor, 0805, control board
[2] 330R resistor, 0805, control board
[1] TL072, SOIC, control board

Instructions for trimming
the -6V and null trimpots:

Quote:
No cables in the module. No inputs, no outputs. Use the test points on the board.

1) The grounded test pad is over by the lower screw hole on the left-hand side of the PCB.

2) Adjust -6V trimpot until the test point "-6V" reads -6.00V. This test point is down by the LM337. Once you set this, for fuck's sake leave that trimpot alone!

3) Measure the test point labelled "-". This incorrectly corresponds to the jack labelled 'mix +' on the front panel. It should read somewhere between 55 and 110mV, give or take. The null trimpot won't effect this measurement, so just note the voltage. It may bounce around a bit. Just... ballpark it.

4) Measure the test point labelled "+". The null trimpot will effect this voltage so you now have two choices:
4a) Recall the voltage from Step 6 and adjust the null trim until the voltage at TP "+" reads the inverse.
4b) Forget Step 6 and adjust the null trim until the voltage at TP "+" is ~0.00V.

5) You're done with the mixer.



PCB v1.2
- note reversed power regulators & resistor lead jumper in bottom left corner. Not necessary on v1.4 PCBs:


Method for connecting the audio input pots - use the same technique for dual-ganged pots with lugs if you're going that route:





Here is a photo guide for the surface-mount section on v1.4 boards:




Here is the pinout diagram for the headers, if you're wiring them up the old-fashioned way:

negativspace
Schematic, sans SMT section:

[/quote]
sammy123
Full set with panel please.
lintfresh
In for one set! Been waiting eagerly for this one.
spneca
One full set, please.
qp
Add me for 1 set + Panel!
dropmotif
One PCB set for me. No panel.
rosch
1 full set pcb+panel for me please!
3M-10
Please put me down for 2 full sets of PCB's + Panels.

thanks!
sduck
negativspace wrote:
BOM

Resistors:
[0] 100k
******


Now this is my kind of BOM!
skyshaver
I am interested in a pcb and panel set.
lodsb
I am interested as well, 2x (pcbs + panel) please!
thetwlo
2 sets: PCBs + Panel, please.

Beautiful work! Thanks!!!!
Barcode
One PCB set for me. No panel needed. I've been waiting for this one for a while now. thumbs up
mikecameron
I'm in for one.
mDang
Sound great ! And it can do stereo smile
One full set for me please !
Rigo
One full set for me please ... makes my backlog happy hihi
regenbot
one set for me thumbs up
qfactor
Me too, negativspace!
I set (pcb/panel) for me!
mcop
I'm in for a pcb & panel set
apophis93
Take my money already! hyper

one set.

- Daniel
mxmxmx
1 x pcbs + panel, please.
negativspace
mxmxmx wrote:
1 x pcbs + panel, please.


Finally I can ship your CP3. It's still sitting here with a note "Wait for SVVCF" hihi Dead Banana
Monobass
1 PCB + panel please
medbot
PCB and panel for me too. Could you explain what the + and - outputs output, or how they differ from the lp/hp/bp outs? seriously, i just don't get it
Isaiah
I think we established in the other thread that the input/output spacing wouldn't accomodate banana sockets, right?
That's a shame.

What are the PCB dimensions?
What are the co-ordinates of the mounting holes on the PCB?
Thanks.
gbiz
Oh yes. 2 PCB/panel sets for me please.
robot909
Looks and sounds interesting.

Is there a BOM?

I'm about to order a bunch of shit from Mouser.
Jarno
1x full set please (PCB's and panel)

thumbs up
gwaidan
1 full pcb plus panel set for me!
diablojoy
4 x pcb only sets please
I like to do my own panels
thorncore
2x pcb only please thumbs up
pre55ure
jumping on the bandwagon. 1 pcb and panel set for me please!
mush
1 full set, please.

Thanks!
mothertongue
1x PCB and Panel set please!
astroschnautzer
one set here
latigid on
Keen for PCBs + panel. What are the hard-to-get components?
Reality Checkpoint
The first 15 seconds of the soundcloud demo (lopass) had me drooling, the rest is just icing on the cake!

All good things are worth waiting for!

2 complete sets please (PCBs and panels) shipped to the UK.

Thank you!
woodster
Yay!
One set of PCB's and Panel please.
mangros
I've built a stripboard version of this from the original schematic. It's great, but self-oscillation would make it even better.

1 PCB set, no panel please!
mangros
latigid on wrote:
Keen for PCBs + panel. What are the hard-to-get components?


Not sure what the revised version is exactly like but the original schematic had some matched PNPs and matched NPNs. I used two THAT340Ps but negativspace might have gone for a THAT300P and a THAT320P. Otherwise hand matched transistors would do.
nikmis
2 pcbs no panels for me, please. I think that one of that pcbs is just for the panel mounting, right? Well I don't need those because not eurorack. So whatever I can get to build two filters.
jgb
Four sets of panel+pcbs for me please! smile
lessavyfav
1 set for me please!
oberkorn
checking with local wigglers here, might be in for up to 4 PCB/panel sets
frozenkore
One set please!
dreamtraveler
1 PCB/Panel set for me, please.
Sorcerer
Please count me in for 1 set (panel+pcb) thumbs up
cleahy
In for a panel and PCB please!
M-Circus
Don't even own a case at the moment, but what the hell:

One set of PCBs and panel for me, pretty please.
sgnelson
I'll take 1 set of PCB's and a Panel please.
Mindarp
I would like 2 complete sets please, including panels. Cheers very much.
Stinktier86
what is the estimate bom sum price? just checking whether to go nuts or not. love
ablearcher
1 set (panel + pcb) here please!
hsimonis
Two complete sets (PCBs plus panels) please!

Thanks
KNYST
YES! w00t

2x PCB sets + panels

[edited/updated amount]
sicpaul
2 PCB sets please (no panel)
negativspace
Holycrapsixpages... I'll work on compiling the orderlist tonight so I don't get too far behind. eek!

Those of you not interested in a panel, please be aware that this thing is not a multi-format PCB like I usually offer. It's made to integrate with the Euro panel and one of the PCBs has no other purpose than to hold the panel controls. So you'll only need the one board if you're working in a non-Euro format. (Bonus for you.)

If you want a control board with which to do your own panel using the same control layout I'll send you a blank FPE file with only the hole locations so you can roll your own. thumbs up

You can still build it in other formats, there are mounting holes for standoffs, but you'll need to solve the power on your own (Euro header only) and you'll also have to wire it up using the pads for the inter-board headers. It's not a big deal, it'll work perfectly, but I wanted you all to know what's what. Those pads are not marked on the PCB but I'll trace 'em out and make a JPG for this thread once the final layout is verified.
negativspace
latigid on wrote:
What are the hard-to-get components?


There are none. It's all discrete. I couldn't justify $6 for 4 transistors - x4 per board - when 2N390x at $0.02/ea work and sound just as nice. As far as matching goes, I've built them with matched and unmatched transistors and couldn't really tell any difference. I recommend loosely matching them as a matter of best practice but it's not something you should worry about. (And certainly not something worth spending an extra $23 per module on.)

I even found that I liked it better with TL072s as the output buffers vs. expensive audio opamps, so I wouldn't even recommend reaching on those.

The only "specal" parts I use are the styrene timing caps (Mouser) and the particular transistors I prefer. (PN100/PN5138) The design works well with 2N390x as I said above, though, and should work with any general-purpose small signal transistors. The PCB has the pinouts marked for all transistors (EBC) so substituting your own, no matter the pinout, should be straightforward.
negativspace
sduck wrote:

Now this is my kind of BOM!


Talk about something for nothing... hihi

I'm hesitant to post the final BOM as I still have a tweak or two to make to the design. Once it's nailed down I'll post it. (It's probably not going to change from where it is now, I'm just being pedantic. There's only a resistor value or two left to play with.)
magneticstripper
I would love 1 full set please
Phetus
screaming goo yo SlayerBadger! screaming goo yo SlayerBadger! screaming goo yo
I ffull set for me please!!! How do I add myself to the list?
Phetus
is this actually the paypal address? xxxxxxxx@gmail.com
Cat-A-Tonic
The demo sounds fantastic!

I don't really feel like I need more filters in my backlog at the moment, but... you make it hard to resist.

Nice job. thumbs up
nigel
This one has been on my list for a while. 1 panel + PCB set.
Rigo
Phetus wrote:
screaming goo yo SlayerBadger! screaming goo yo SlayerBadger! screaming goo yo
I ffull set for me please!!! How do I add myself to the list?

You just did ...
Phetus wrote:
is this actually the paypal address? xxxxxxxx@gmail.com

No ... since the exact price isn't known yet there is no need for putting the correct address. Though you could easily find it out by looking at any of the other order threads from Negativspace hihi
latigid on
negativspace wrote:
latigid on wrote:
What are the hard-to-get components?


There are none. It's all discrete. I couldn't justify $6 for 4 transistors - x4 per board - when 2N390x at $0.02/ea work and sound just as nice. As far as matching goes, I've built them with matched and unmatched transistors and couldn't really tell any difference. I recommend loosely matching them as a matter of best practice but it's not something you should worry about. (And certainly not something worth spending an extra $23 per module on.)

I even found that I liked it better with TL072s as the output buffers vs. expensive audio opamps, so I wouldn't even recommend reaching on those.

The only "specal" parts I use are the styrene timing caps (Mouser) and the particular transistors I prefer. (PN100/PN5138) The design works well with 2N390x as I said above, though, and should work with any general-purpose small signal transistors. The PCB has the pinouts marked for all transistors (EBC) so substituting your own, no matter the pinout, should be straightforward.


Cool, 2x 1 nF polystyrenes? I'm contemplating an order from musikding.
nikmis
negativspace wrote:

Those of you not interested in a panel, please be aware that this thing is not a multi-format PCB like I usually offer. It's made to integrate with the Euro panel and one of the PCBs has no other purpose than to hold the panel controls. So you'll only need the one board if you're working in a non-Euro format. (Bonus for you.)


Thanks! so two of those main circuit PCBs for me
windspirit
im in for a full set. this thing sounds really smooth
4285407da1d2a63820a3007c1
One full set for me, sounds great!
Delta T
I'll take two complete PCB sets (no front panels) and when you have a chance I would like a copy of the FPE layout as well.

Thank you so much for doing this!
Stinktier86
negativspace, regarding what you wrote in this thread https://www.muffwiggler.com/forum/viewtopic.php?t=110487

and since the CP3 circuit is essentialy the same - would i be able to add a couple of more channel ins to this one too, and thereby hit two birds with a rock?

bonus question: would i be able to tap the mixed signal, pre-filter, to a separate extra output jack?
Skaput
w00t iam not missing this party, 1 set for me please
duff
I'm interested in a full set, and possibly some single boards as well.
MindSnared
Write me down for a full set! (panel + 2 pcbs)
adnauseam
I'd like a full set
2xPCB + panel
Isaiah
I'm trying to avoid adding anything to my backlog that is superfluous to my End Game Strategy.
But, I do like discrete transistor designs and the sound of this filter.
However, all my modular filters (built and planned) are 2-pole already.
Hmmm...
apertureburn
I'd be in for a full set.
euromorcego
one full set: pcb and panel for me ...
rockwoofstone
Full 2 PCB + panel set please.
ringstone
2 PCB sets + panels please
bsmith
3 sets here please (3x panel's, 3x pcb's)

(edit for count revise)
davidschwan1
1 panel with PCB set.
Randy
1 panel and PCB set for me too.

Randy
L-1
One full set for me! thumbs up
stellvia
2 full sets please! thumbs up
Valleyroad
2 full sets for me, thanks.
analogdigital
2 PCB + Panel sets for me please.
negativspace
Hey wigglers... internet snafu has me stuck on my phone until Monday. I'm not man enough to do the order list on my phone so I won't get to it until they come hook me back up. I'm still checking in though if there are any questions.
bugfight
2 pcb/panel sets please
cane creek
1 x Eurorack Panel + PCB set please 😃
vtl5c3
It's 2 poles per PCB, right? I'll take 2 if that's the case.
onthelees
1 PCB + Panel please.
fluffybeard
1 PCB and one panel. Pleeeeeease.
Jop
Hi Jason,

Please one main PCB for me (no panel or control PCB).

Is it correct that the Mix + & Mix - only carriers the mixer outputs for standalone use (without filter)?

How do the 4 filter outputs interact with the Lp-Noth-Hp knob?

Thanks thumbs up
Morbid
Finally nanners .
One full set for me please.
g0lem
1 set of eurorack stuff.
thanks a ton, j!
negativspace
YAY! My idiot cable company came today and hooked my house back up to the grid... they'd come on Friday and disconnected me based on an errant work order. (They had the wrong address on file.)

So here's my attempt to catch up in this thread:

vtl5c3 wrote:
It's 2 poles per PCB, right? I'll take 2 if that's the case.


Yes, each PCB has one mixer + 1 2-pole VCF onboard.

Jop wrote:

Is it correct that the Mix + & Mix - only carriers the mixer outputs for standalone use (without filter)?

How do the 4 filter outputs interact with the Lp-Noth-Hp knob?


Yes, the +/- outs are for the mixed, pre-filter signal. If you want the mixer but not the filter, you're covered. (Or you can take the mix from one and go through 2 in parallel for stereo use, etc.)

The LP/BP/HP outs are sovereign. The NOTCH out obeys the panel knob.

Stinktier86 wrote:
and since the CP3 circuit is essentialy the same - would i be able to add a couple of more channel ins to this one too, and thereby hit two birds with a rock?

bonus question: would i be able to tap the mixed signal, pre-filter, to a separate extra output jack?


Yes, you'll just need to add extra input resistors that sum at the same junction as the ones onboard. I'll try to work an extra pad into the layout to make that simple.

Bonus answer: see my first answer above! There's already a pre-filter mix out.

latigid on wrote:
Cool, 2x 1 nF polystyrenes? I'm contemplating an order from musikding.


Yes, I went with styrenes and probably will for the commercial version as well. Polypropylene is another good option, whichever you personally prefer will work great.
Stinktier86
Top service! Hope you find the needed space for the extra lead. I'm certainly buying at least one (pcb set + panel +(!!!) a single cp3mixer panel for the expansion if they're still available), but may possibly buy up to four kits all in all after i've compared the bom pricing with my income and other less exciting expences. Can't tell right now though.
ym2612
One full Euro set for me, please!
Maco
1 Main Circuit PCB for me
c1t1zen
2 full sets please.

applause
Dego
One set pcb plus panel pls
LoveBot
congrats on getting this out! I'm in the Peruvian Amazon now for a year, but look forward to picking up a production model in 2015 once I'm reunited with my kit! Time to load a photo image onto modulargrid, no?! thumbs up
negativspace
The orderlist is updated. If you notice something incorrect next to your name, please let me know! I'm betting I screwed up at least one. 8_)
woodster
Hey Jason,

I'm missing from the list, as per previous post on page 4, please put me down for a full set. thumbs up
mig27
Two full sets for me please!
zamp
The demo sounds awesome!

Quote:
Two PCB sets for me, no panels.


Please change that to two main PCBs and no control PCBs or panels.
twospartans
i'll take 1 panel+pcb set!

i'll also take two cp3 panels! applause
Cheradenine
I'll take 2 mainboards only, please
bartleby
1 full set + panel for me, please.
pulse_divider
4 full pcb/panel sets for me, please!
dropmotif
I'd like to change my order to:

2 main boards
no control boards or panels

thanks!
latigid on
Tentative full set for me, I would like to see the final costs, build docs etc.
zamp
dropmotif wrote:

no control boards or panels
thanks!


I've edited my original post to not include control boards or panels. I didn't realize we could get main PCBs without control PCBs.
Dego
Does it run on 9 volt?
negativspace
It should work on 9V, likely with some resistor tweaks. But I've certainly never tried. seriously, i just don't get it
lodsb
hey negativespace!

I'll also like to change my order (sorry for the inconvenience):
instead of 2x(boards+panels) i'd like 4x(boards+panels) - i'd guess with some extra VC mixer that would make an interesting "filterbank".

thanks! + apologies!

edit: thanks + <3 !
Paradigm X
two filter circuit pcbs only please, if this is possible!

Cheers
bne
Synthsense
One full set of PCBs + Panel, please, Cheers! Guinness ftw!
tds
I would like one full set + panel, please. Thank you!
kwaidan
One full set of PCBs + Panel. Thanks!
extinguish
One full set of PCBs and Panel please. Thanks!
baloo
one full set of PCBs and panel for me too please.
Zergon
One full set of PCBs + panel, please. smile
negativspace
I put together the second prototype using my chosen transistors this time. There is definitely mojo in the transistor choice! It works perfectly well with 2N3904 and 2N3906. If you're on a budget and want to spend $0.38 total on the transistors for this build, do it! It'll be very nice. But if you track down PN100A and PN5138 you won't be disappointed. 8_)

I'm going to have to try one with 2N5089/5087, maybe one with 2SC945/2SA733... zombie

There is one resistor that needs to be tweaked depending on your transistor choice. I'll be sure to note that in the first post as it becomes a compilation of tips, notes, corrections, etc.

BOM is mostly set now, I need to proofread myself tomorrow and then I'll update that post.
bartleby
interesting.
would it make sense to socket those transistors/resistor to try different combinations?
negativspace
Wouldn't do any harm. You'd probably want to socket that resistor, too.
Randy
Mouser has the PN100A

http://ca.mouser.com/ProductDetail/Fairchild-Semiconductor/PN100A/?qs= UMEuL5FsraCM8j0fFDnVxg==

One version of the PN5138 is obsolete but there is this:

http://ca.mouser.com/ProductDetail/Central-Semiconductor/PN5138-LEADFR EE/?qs=sGAEpiMZZMshyDBzk1%2fWi3tqAXZbtg%2fNwEAxJavIXQ8%3d

Not currently in stock 'though.


Randy
udbhav
I'll take 1 full set (both PCBs + panel). Thanks, really looking forward to it!
negativspace
Yep, Mouser just restocked the PN100A this Monday so that's easy.

The PN5138 looks like it's available to special order with a minimum quantity of 3050. That sounds intimidating but it's only $604... I could (and probably should) order that for my production run. (The CP3s will use 'em too.)

I just submitted a quote request to Mouser, hopefully they get back to me tomorrow with an estimated delivery date. I'll keep you posted. If I buy a giant pack of these I'll gladly sell them on. Maybe I can convince Mouser to keep a few hundred on hand as well.

Another option is futurlec, I believe they still have them in stock.
mcop
How many (if any) of the transistors need to be matched in this circuit?

Also will this design work at 12 and 15 volts?
negativspace
It should work fine on 15V, there are a couple of things which won't be ideal but a few resistor swaps should help out there. In truth those are somewhat academic - it'll run and do what it's supposed to do just fine, only a little differently.

As for matching transistors, none of them "need" to be matched. There are a few pairs that "should" be matched but IMO it's somewhat academic as well. I've tested it out with matched pairs everywhere and with blind parts pulls and it seems to perform no differently either way.
Stinktier86
Please edit my order to 4 complete pcb sets + panels. And 2 cp3 panels for expansion purposes thumbs up
withakay
I don't seem to have anytime for DIY at the moment, but what the hell..... put me down for 2 full sets!
Royalston
One full set please!
mcop
Thanks. My synth is at 15V at the moment but I have so much stuff I want to build I'm intending to build a 12V system too. I'll just build this as is and worry about modifications if needed. I'm guessing like your other boards you're going to keep some stock of these so if I wanted more at a later date I could come back for more.

negativspace wrote:
It should work fine on 15V, there are a couple of things which won't be ideal but a few resistor swaps should help out there. In truth those are somewhat academic - it'll run and do what it's supposed to do just fine, only a little differently.

As for matching transistors, none of them "need" to be matched. There are a few pairs that "should" be matched but IMO it's somewhat academic as well. I've tested it out with matched pairs everywhere and with blind parts pulls and it seems to perform no differently either way.
negativspace
Yeah, these aren't going anywhere. The price for this group buy will probably be a little lower than the retail price for future runs but not by enough to make a real difference. (I'm just not likely to be ordering in this quantity ever again...)
Magicpockets
1 Full Set to the Uk please
Jop
Hi Jason,

Are you ready to reveal the B.O.M. ?

Thanks!
negativspace
Um... yes. I will do that this evening when I'm back home.
alessioit2809
2 full sets please. I'm located in italy
bennelong.bicyclist
1 full set of PCBs please, no panel.
paulstone
please 2 full set of PCBs , no panel ( i make my own for 5U)

thanks
Paolo
paulstone
paulstone wrote:
please 2 full set of PCBs , no panel ( i make my own for 5U)

thanks
Paolo


i will update my order with 4 full set PCB (no panel)
thanks
sammy123
For the first time ever I proudly declare I will take two panel/PCBs sets.

Jason can you update me to two full sets please?

Thank you.
negativspace
Updated. w00t

BOM needs a little work, I have the parts count set up but now I have to add the legending so you know which is which. SlayerBadger!
keninverse
Jason...
will you please put me down for at least 2 sets of panels and PCBs? I may be interested in more depending on timing.

Thanks!
Barcode
Will you please add a panel to my order? That would make it 1 PCB set and 1 panel! Thank you!
negativspace
Updated the BOM post, I still haven't decoded the resistors but I thought I may as well put up the parts list anyway. This is subject to a couple of resistor value tweaks, but I do think I'm done with that. Maybe one more...
stellvia
Hi Jason,

After having looked at the BOM, I think I better just wait till the built version comes out. Could you take my name of the list please?

Apologies.
qfactor
Does it matter of the LM337 is not with the prefix "LZ"?
Coz Tayda has a LM337T regulator chip. Is that the same?
Thanks
negativspace
What you need is one in the TO-92 package, which is necessary for this build. Other packages won't fit, and the pinouts are probably not the same.
yan6
One full set please
Jop
Thanks Jason for the BOM!
rosch
16mm pots?
so it's not similar to the MVP build control pcb wise?
grilojoe
I'd like 2 x main circuit board, no control boards or panels (if you're willing to sell them that way). thanks!
negativspace
rosch wrote:
16mm pots?
so it's not similar to the MVP build control pcb wise?


It is, but with 16mm pots rather than 9s. It's exactly like the MA35 if you've ever had hands on one of those.
mcop
So we're talking about this type of pot are we?



http://www.smallbearelec.com/servlet/Detail?no=692
negativspace
Alright wigglers, orders have slowed down to the point that I set prices on the sets. We're way past where we need to be to get down to my usual pricing. SlayerBadger!

As always, payment is now open but not required. I will send PMs asking for payment in a few weeks, once all of the prepaid orders have been shipped.
grilojoe
I went ahead and sent payment for my boards. Thanks!
Randy
Me too.

Randy
Stinktier86
Paid! Wrote specifics in the transfer note since my order also included panels from another of your projects.
cane creek
Payment sent thumbs up
zamp
Sent payment for 2 bare filter PCBs plus shipping to US.

Thanks!
rosch
of course smallbear carry the dual right angled long pin 10K pot only in Audio.
(if that's the right kind of pot)

please could you post a pic of the backside? right now i'm getting the idea it might be easier to just mount it perpendicular and wire the controls to the boards than finding those special pots at normal suppliers.
but i don't know, haven't seen it yet.
negativspace
I added a link to the correct part in the BOM post. thumbs up

I don't have a photo of the backside and I don't have one on the current revision PCB to photograph. Another panel should be delivered Monday, I'll build that one and get photos of it ASAP.
rosch
cool, thanks!!!!
and the supplier says paypal accepted, alrighty thumbs up Guinness ftw!

edit:
WTF are they nuts? don't deliver to germany?
strange..... i'll check banzai & co maybe more lucky
rosch
yup banzai have dual B10K just regular pins and solderlugs - which is good enough for only one pot.... those few wires hihi
negativspace
Regular-pin is all you need, the long pins are WAY too long. (Banzai to the rescue again! Love that shop.)
potpourri
One PCB set for me. No panel.

Potpourri
iL
One set of PCB & Panel please.
polyot
I'll take a set, PCB and Panel. Payment coming momentarily.
woodster
Paid
Have high hopes for this one!
MY ASS IS BLEEDING
qfactor
headbang PAID!!
far gon
2 full sets PCBs + Panels please

Thanks!
M-Circus
Just had a look at the BOM. Care to elaborate a bit on the optional tempco as well as whether choice of electrolytic caps within the stated range have any effect on the end result?
livefreela
please put me down for 2 full sets please...

thx...
paulstone
Paid this morning for 4 pcb set .

Paolo
synchromesh
I've just paid for 2 panel & PCB sets, including postage to the UK. Glad I spotted this in time! This is fun!

Thanks for putting this together, it looks great! SlayerBadger!
euromorcego
also just paid: one full set and shipping overseas. Looking forward to building it ...
bartleby
negativspace wrote:

[1] B10k Dual-ganged Pot (16mm Alpha, pins)

unfortunately, the source you linked to seems to have a rather bizarre shipping policy according to their faq:
Quote:
Q: Do you ship direct outside of the U.S.?
A: Yes, but only to certain countries - Australia, New Zealand, Brazil, and Israel.

any idea where these can be purchased from europe?

banzai and musikding here in germany only carry versions with straight pcb mount pins and with solder lugs. :(
could either of those somehow be modified to fit this design?
Stinktier86
Struggling with the same problem as bartleby here. confused
euromorcego
Quote:
[1] B10k Dual-ganged Pot (16mm Alpha, pins)

hum, if they are difficult to get in europe, maybe there is a way to include one in the full set?
negativspace
Check Banzai Music, rosch just said they carry them in solder-lug form. That'll work fine for this build, you're going to have to run a few leads on the audio input pots anyway. The dual pot will be the exact same procedure, just more of the same. thumbs up

(For those of you who've built one of NV's Klee kits, remember having to use resistor-lead clippings on the 12mm pots? You'll be doing the same thing for this one.)
negativspace
M-Circus wrote:
Just had a look at the BOM. Care to elaborate a bit on the optional tempco as well as whether choice of electrolytic caps within the stated range have any effect on the end result?


The caps are for supply decoupling - meaning their value is noncritical. Use what you have. Anything in the given range (or higher, really) will work. (edit: I use 22uF for almost all of my production modules, so I buy them cheap in huge quantity. That's what I use.)

The tempco is optional, if you don't want to use it then you need to substitute a regular 0805 1k resistor. Don't leave it off entirely.
ym2612
Just paid up for my full set!
KNYST
Paid Guinness ftw!
bens
Please put me down for one full set. Thanks!
oberkorn
please put me down for 3 full sets (PCBs + Panel). thanks
davidschwan1
Mark me as paid for panel and pcb set (email davidsch@)
jgb
Paid! smile
ChrisR
I'd like one bare filter PCB please. thumbs up
Jarno
Paid!
treseja
One full set for me, thanks.
treseja
Paid. thumbs up
ablearcher
moneeeeeeeeee sent! MY ASS IS BLEEDING
woodster
Is this the correct Polystyrene Cap ?

http://uk.mouser.com/ProductDetail/Xicon/23PW210/?qs=sGAEpiMZZMv1cc3yd rPrF9hNhJC57Qe1buQXMSCZa7M%3d
astroschnautzer
can I change my order to 2 x pcb + panel sets?
negativspace
woodster wrote:
Is this the correct Polystyrene Cap ?

http://uk.mouser.com/ProductDetail/Xicon/23PW210/?qs=sGAEpiMZZMv1cc3yd rPrF9hNhJC57Qe1buQXMSCZa7M%3d


Yes.
woodster
Many thanks thumbs up
I'm just trying to get a Mouser order together.

Any other suggested upgrades ?
EG, are the [5] 10uF Electrolytic in the audio path, so worth upgrading to Elna Silmic like the ones suggested in the VCA ?

Is the 1k Tempco (optional) the same SMT part as per the VCA ?

[2] 12P Header + socket (b-2-b)... I know I'll quickly get lost in a world of pain trying to search and find these at Mouser, any tips ?

I'm Very excited about this Filter.
negativspace
The tempco in this one is currently a through-hole part... but now that you mention it I may as well put a pad for the 0805 on there as well. So by the time these are ready it'll be optional - either will work! Take your pick.

IIRC 3 of the electros are in the audio path.. given that Silmics are inexpensive there's very little reason not to use them there if you feel like it. Even if they do no good you're only out ~$0.20/ea vs. inexpensive all-purpose caps.

For the standoffs, I bought a bag of 4300 recently because it cost about 10% more than it would've to buy 1000... so I have a lot of them. I can always send some. But any 12mm or 7/16" standoff will work. Doesn't have to be nylon. Likewise the hardware doesn't have to be #4-40, you can use M2.5 or M3. Local hardware shops are probably the best bet for that stuff. I source mine from the same company that supplies the local Ace and True Value stores. (Fastenal)

The 12P headers are just like Euro power headers, only 12 pins instead of 10 or 16. (2 rows of 6 pins in this case.) The accompanying sockets I actually source @ Pololu, they had a much better price than any of my usual suppliers when I went looking for the MA35s.
polyot
If one of you guys would be so kind as to share a mouser cart at some point I'd be ever grateful. I have soldering experience, but still pretty beginner as far as the buying parts thing goes. Just want to make sure I don't screw up. If I get a cart going before then I'll run it by here to get the seal of approval. This is fun!
InfraXpert
Can PCBs still be ordered for this project?
negativspace
Yes!
InfraXpert
Paid you for 2 bare filter PCBs and shipping
Stinktier86
negativspace wrote:

For the standoffs, I bought a bag of 4300 recently because it cost about 10% more than it would've to buy 1000... so I have a lot of them. I can always send some.


Can you please do this with my order (four kits)? Already paid but pm me whatever extra i should transfer. It would really save me some effort (mouser newbie here - hardware parts are still a bit tricky to get right for me).
arrmcbain
Just squeezing in at the last minute...
1 set PCBs + panel please

Edit: added an 's' for pedantry Mr. Green oh and money sent
designator
I'd like to order

4x
Eurorack Panel + Bare PCB sets
Shipping: Overseas - Germany

I wonder what the timeline is, I'm absent for ten days end of june and would like to avoid that the PCBs+ Panels are delivered then.
oberkorn
just paid for 3 PCB/Panel sets
from Greenland, on contract work north of the polar circle,
no wigglers here but there is internets at least
qp
payment sent! Moar build!
nangu
I'd like 6 PCB/panel sets.

Thanks!
tuukka.j
Still possible to order? If yes, then one full kit plz!
latigid on
Okay, in for one full set please 8_)
regenbot
Jason put one more full set for me, please. So 2 full set in total.
M-Circus
If anyone has gotten as far as compiling a Mouser BOM for this, sharing is caring. hihi

(If not, I'll get on it later…)
regenbot
Make that 4 sets in total, please. Already payed for two sets. Will pay the two more in a bit.
regenbot
payed for two more sets. does the 10$ post still apply?
sicpaul
Payed for 1 Panel/PCB set and 1 bare filter pcb just a minute ago.
tuukka.j
Just paid the Panel + PCB! Thanks!
alessioit2809
M-Circus wrote:
If anyone has gotten as far as compiling a Mouser BOM for this, sharing is caring. hihi

(If not, I'll get on it later…)


+1
we're not worthy
Phetus
Is a full Thonk kit happening?
Nordcore
Please put me in for a full set with panel.
Zergon
Paid for panel + pcb.
chocolatyshatner
I'm in for a pcb + panel set please
Royalston
Is shipping the same for two sets?
apophis93
Paid for can't wait…
negativspace
Royalston wrote:
Is shipping the same for two sets?


Yes, shipping is charged per order rather than per unit. thumbs up
gwaidan
Just now sent payment for 1xCP3 panel and 2x CP3 boards bits to bundle with the order. Thanks for this!
Reality Checkpoint
Payment sent.

Orbitals yesterday, this today. I'm going to be busy!
Barcode
Paid for 1 set. Thanks!
mcop
Payment sent.

Also, what footprint is needed for the trim pots?
negativspace
I use the Bourns 3296-style pots, so any similar part will work fine. The pinout is set up to take either staggered or inline.
Jop
Just paid, do you already have the core pcb dimensions? I'm designing my own front panel right now and dimensions would be really nice to have.

Thanks.
Royalston
Paid for 2 sets (Panel & PCB)
Sorcerer
I just sent my payment for 1 set.
Morbid
Sorry if this question came up early but
is this the right header for the PCB's?
Header

hmmm.....
mcop
Thanks
negativspace wrote:
I use the Bourns 3296-style pots, so any similar part will work fine. The pinout is set up to take either staggered or inline.
duff
What is the footprint of the trimmers? - or does trim pot suggest a particular style of trimmer - if so which one?.
mcop
[/img]
negativspace
Morbid wrote:
Sorry if this question came up early but
is this the right header for the PCB's?
Header


Looks correct to me. thumbs up
windspirit
hey so im trying to figure this out is the mix section an input or is it the output of the state variable filter? Which output is the one that state knob effects? Im guessing that there is no CV control on that knob.
diablojoy
lol my new job sucks ! turn around for 5 minutes and so much happens
here , paid for 4 today thanks thumbs up
onthelees
Paid for 1 panel board set
Royalston
Ive assembled a Mouser BOM with most components...I'm having trouble working out these:

[2] 12P Header + socket (b-2-b)
[4] 7/16" Nylon standoff + 3/4" #4-40 screw + hex nut set.

Any ideas?

is there cabling required between the 12p headers?

And these weren't at mouser but i think that has come up in an earlier post:
-Tempco resistor
-[1] B10k Dual-ganged Pot (16mm Alpha, pins)

I'm happy to share the mouser bom if anyone wants it. You would want to check it as I'm pretty new to this...
InfraXpert
Please share, it would be a great help.
Thanks :0)
mcop
Looking at Scott's original circuit for this, would I be right in thinking the 0.1uF capacitors are for decoupling around the op-amps? And if so should there be 6 as there are 3 TL072's?
negativspace
There are 2 sets of pads on the back side of the PCB for 0805 decoupling caps @IC1 and IC3 if necessary. IC2 is so close to the input decoupling components that it should be covered. I have not found the caps necessary given that none of my prototypes have used them. But I did include the pads just in case...
negativspace
windspirit wrote:
hey so im trying to figure this out is the mix section an input or is it the output of the state variable filter? Which output is the one that state knob effects? Im guessing that there is no CV control on that knob.


Royalston wrote:
Ive assembled a Mouser BOM with most components...I'm having trouble working out these:


Each one of those things has been addressed in the thread already.
windspirit
sigh time to start diggin then
tholos
"the +/- outs are for the mixed, pre-filter signal."
mcop
Thanks, for the reply. Makes sense. Got a load of 0805 caps I could pop on if I find I need to.
negativspace wrote:
There are 2 sets of pads on the back side of the PCB for 0805 decoupling caps @IC1 and IC3 if necessary. IC2 is so close to the input decoupling components that it should be covered. I have not found the caps necessary given that none of my prototypes have used them. But I did include the pads just in case...
negativspace
Ack. Now that I look at your address, Royalston, I realize we may not have covered the dual-ganged pot for Australians. (BYOC is best in the US, Banzai in Europe.) Small Bear has the solder-lug version, same as Banzai. They should ship to anywhere on the planet. They supplied the parts I've used in prototyping so I can say for certain that their pots will work!
Royalston
Any chance you could clarify a mouser part numbers/ more detail on these :

[2] 12P Header + socket (b-2-b)

I spent 4 hours making a BOM I can share but these are missing and I'm out of my depth a little! (I have read the thread many times..)

Also I'm assuming you are using the American Pot taper 'standard'. So A=Audio B=Linear? This simple stuff is confusing for a newb like me and I can't afford to get the shipment from mouser to Australia wrong!

Cheers!
Royalston
May I order 2 sets of of the Nylon standoffs and nuts with my 2 pcb sets?
windspirit
just buy some breakaway headers and pins. then you can break/ cut off the amount that you need. Just search "breakaway header."
Royalston
thanks windspirit!
diablojoy
Quote:
I realize we may not have covered the dual-ganged pot for Australians. (BYOC is best in the US, Banzai in Europe.) Small Bear has the solder-lug version, same as Banzai. They should ship to anywhere on the planet. They supplied the parts I've used in prototyping so I can say for certain that their pots will work!



Yeah both banzai and smallbear will ship to OZ ,
I have ordered from both in the past.
Stollmeister
Frak!!

I kept watching that other thread and I missed this one. Is this still open for orders?
negativspace
Yes, there's still time. thumbs up
negativspace
Royalston wrote:
Also I'm assuming you are using the American Pot taper 'standard'. So A=Audio B=Linear? This simple stuff is confusing for a newb like me and I can't afford to get the shipment from mouser to Australia wrong!


Correct. The 20k audio pots are the input pots for the audio mixer section. The rest is all linear.

As for the standoffs... that's a totally noncritical part. You can use nylon, aluminum, stainless steel, brass, hex, round, whatever. The important thing is 7/16" height as that matches the pin headers perfectly. You can go slightly bigger with no problem - 1/2" will work. 12mm will also work. Whatever you can get. Likewise the holes involved are plenty big enough for M3 hardware. Again, whatever you can get wherever you are.

I can get this stuff locally at any one of 4 different stores. I don't know what is customarily stocked in hardware stores outside the US but I can't imagine it's much different. Mouser most certainly has nylon and aluminum standoffs, although I don't get my bulk supply from them so I don't have any #s handy.

If you really need to get them from me I can do it for $3/set.
qfactor
Is it alright if you don't use these stand offs too? seriously, i just don't get it
negativspace
It'll hold together reasonably well if you never move your rig around... it's a pretty big board to support with 24 pins' worth of header. I'd definitely use the standoffs.
polyot
Royalston wrote:
I spent 4 hours making a BOM I can share but these are missing and I'm out of my depth a little! (I have read the thread many times..)


Definitely interested in this if you've got it ready nanners
negativspace
Royalston wrote:
Any chance you could clarify a mouser part numbers/ more detail on these :

[2] 12P Header + socket (b-2-b)


Here's a Mouser search tip:

I'm assuming you have the power header sorted... if so then you basically have the board-to-board headers done as well. Go to the page for the 2x8 power header and click on the "PDF Catalog Page" link. (Hopefully it has one - most parts @ Mouser do.) That'll download a PDF page with the whole product line that the 2x8-pin header is in. The 2x6s will be right there.

This is good for any parts search - found a nice 150pF cap and need a 300pF to go with it? Or maybe you need 5 differently-valued trimpots in the same pinout/package? Click the catalog page. The PDF pages are active, too, so you can simply click on the part you need in the list and a browser tab will open with it.

I've found many a tricky part using the catalog pages over the years. thumbs up
Royalston
Thanks Negativspace! Too late for my order but here is my attempt at the BOM:

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=1c6a7 53551

I'm hoping this link works.

Disclaimer: Please check through this list if you're going to use it - I'm new to this and I may have wrong parts in there. There are also extra Transistors in there - so edit them out if you don't want extras. Also: Let me know where I went wrong so I know what parts I have to re-buy confused

This list does not include any panel controls or standoffs.
negativspace
Ok, so on the PN5138 transistors... I'm going to order a few thousand through Mouser. I've asked them if they would stock a couple thousand themselves while we're at it. We'll see what they say.

Hopefully they say "yes" and in 4-6 weeks they'll be in stock. That would all but solve the availability problem for most of us.
kcr
If there is time to sneak in I'd be in for two board and panel sets? please?
*sad look*
negativspace
Yes, I'm still waiting for the proofs to come back on the panels. There's time. SlayerBadger!
Bakeneko
negativspace wrote:
Yes, I'm still waiting for the proofs to come back on the panels. There's time. SlayerBadger!


I only just got the heads up on this, but please add me to the list too for 1 PCB and 1 panel.

Many thanks
Sittidae
Does anyone know if the Thonk kits are happening?
negativspace
Yes, but not immediately. I think Steve wants to build one first and get a feel for what needs to be done.
Sittidae
Thanks Jason. I just needed to know I wasn't missing the boat with this by being under-confident about BOMs.
negativspace
Royalston wrote:
Thanks Negativspace! Too late for my order but here is my attempt at the BOM:

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=1c6a7 53551

I'm hoping this link works.

Disclaimer: Please check through this list...


A few things - please note that I didn't check for accuracy of the BOM, only suitability of the parts chosen:

The resistors are all carbon comp - fine if you're doing that intentionally for a "vintage" feel, but not recommended unless you know exactly why you're choosing to do it that way. I would (and do) use 1% metal film resistors for the whole thing. That's super-easy - the part code is 271-XXX-RC where 'XXX' is the value - so 271-4.7k-RC to get 4.7k, 271-100-RC to get 100R, etc. I've experimented with CC resistors vs. MF in a couple of guitar pedals. I can say for certain the CC resistors make for a mildly-noisier circuit. I'm less convinced that they add any "tone."

The single-row pin strip you selected is non-stocked. There are plenty which aren't if you want to substitute one. Personally I'm going to recommend that you get your breakaway pin strips from Tayda - they have the best price I've found. Buy 20 of their 40-pin strips for a couple bucks and be set for years! (I have a huge bag in my desk drawer...)

You can also pick up your TL07x ICs from Tayda as well as 1N4001s, 4148s. They have great prices on this stuff - ~25c/ea for TL072 vs. 70c @ Mouser, for example.

The first trimpot you selected is perfect, the proper Bourns part. Try the T93YA series instead, though - same size, equal quality, 25% less expensive. (Just type T93YA into the search and select your value from the resulting list.) If you want offset pinout for whatever reason, those are T93YB. Or... use the inexpensive version Tayda sells. They're off-brand but quality, I've used them for years. I think they carry all 3 values at ~$0.40/ea. Don't use the other two box trimmers, I don't think they'll fit. It's a pretty tight layout. (Select all 3 from either the T93YA series or from Tayda IMO.)

Transistors - I recommend saving yourself some money (slightly) by using 2x 2N3904 on the CV side along with 11x PN100A in the audio path. I'm going to be building ~200 of these which will be sold at a profit, so for me it makes a difference. For a single module it'll save you ~$0.35 so maybe not a big deal. (I'll change the BOM to reflect this advice.) Tayda has 2N390x for $0.02/ea if you want to add that to your pin strip order. 8_)

Dual-row male headers - shrouded for power is OK but I cannot promise that it'll fit. I don't use shrouded headers, I think they're nothing more than a disaster waiting to happen, so I've never tested one. I use FCI 2-row headers in that position, Mouser carries them. The part# is 67996-416HLF. Tip for 12p headers - replace the '16' with '12'. thumbs up

^ For the 12p female headers I ended up going to Pololu. They have all kinds of MTA100 bits, mostly well-priced.

Styrene caps - those are currently out of stock, but don't worry about it. They expect 3000 of them on June 4, at which point the PCBs/panels will still be in manufacturing. You can substitute the axial-lead version, it might be in stock, but the radial leads make for a more elegant install. Not a huge difference one way or the other.

Don't get hung up on trying to source the entire BOM from Mouser. I use about 10 suppliers for my parts, whether it's for supply or price reasons. This module was designed from my parts bin so I used stuff which was sourced from several of those places. You may end up going there for your parts as well - specifically Tayda, as you're probably guessing at this point. hihi
Royalston
Thanks Negativspace. I knew I'd probably got some wrong parts/ more expensive parts in there. I copied the carbon resistor choice from someone's CP3 bom (of which I just ordered two of). I had hoped not to do another order but I guess I also knew that would be unavoidable! (Unfortunately it costs Australian's $40 in shipping.)
negativspace
Ugh... another perk of using Tayda - I just pretended I lived in Melbourne and filled out their shipping form for a few hundred transistors and some TL072s. Estimated @ $4 regular post, $14 w/ DHL. w00t

Anything Mouser stocks you can always try to find at a more local site - cut the manufacturer part# (not the Mouser part#) from the Mouser page and enter that into the search box at your preferred site. Should pop right up if they carry it.
Royalston
negativspace wrote:
Ugh... another perk of using Tayda - I just pretended I lived in Melbourne and filled out their shipping form for a few hundred transistors and some TL072s. Estimated @ $4 regular post, $14 w/ DHL. w00t.


I guess I'll be using tayda for those replacement trimmer resistors then! I actually spent ages looking for ones similar in shape to what I'd seen you use on other projects... I have much to learn. confused
negativspace
Sourcing parts can be a pain! I learned the hard way too. I still make mistakes. (Anyone need some 2x8 female headers? I bought 200 last week. Needed 2x6s.)

Who is the go-to macro seller in your region, MCM/Element14/etc? I honestly don't know...
Royalston
I dont know who the macro seller in Sydney is (I should have probably done some extra research)... As far as retail shops we only have 'Jaycar' and their parts sections seems to shrink every year.
yan6
If there is still time, can i up my order to 2?
skyshaver
You can take me off the list. I'm way too busy to source parts. sad banana
gwaidan
negativspace wrote:
Sourcing parts can be a pain! I learned the hard way too. I still make mistakes. (Anyone need some 2x8 female headers? I bought 200 last week. Needed 2x6s.)

Who is the go-to macro seller in your region, MCM/Element14/etc? I honestly don't know...


Element 14 first with RS components for the odd thing element14 doesn't sell. If you buy stuff in reasonable quantities and use parameter searching to get the cheapest option Element 14 can actually be in Mouser's price ballpark for a lot of things (or even better for some ICs and resistors), plus their service is awesome.

Second the opinion of Jaycar, glad they exist but...just had grief with a CVPal build cos the 3.6V zeners they are selling in York St Sydney are dodgy and test more like 1.5V...
negativspace
Element14 or whatever they call themselves in the N. American market (Newark?) is good. I've sourced a few odds and ends through them over the years. SlayerBadger!
polyot
Royalston wrote:
Thanks Negativspace. I knew I'd probably got some wrong parts/ more expensive parts in there. I copied the carbon resistor choice from someone's CP3 bom (of which I just ordered two of). I had hoped not to do another order but I guess I also knew that would be unavoidable! (Unfortunately it costs Australian's $40 in shipping.)


Whoops. I let the excitement get the better of me and ordered your BOM as soon as I saw it. I went ahead and already reordered Metal Film resistors(except for the 560R which they were out of), and believe I have breakaway pin strips leftover from my Arduinome days. Still greatly appreciated your efforts though. nanners
alessioit2809
When the pcb+panel will be shipping? I check the list everyday but my order is still pending....
negativspace
These will ship in about 4 weeks. It takes time to have panels and PCBs manufactured.
Bakeneko
negativspace
Hi Jason , my error, I'm after a set of PCBs and Panel , I didn't realise it was two pcbs. Please could you amend my order.
Sorry about that.

cheers and regards

Paul
negativspace
You're already down for one full set. thumbs up
onlyHzwhenI...
Jason, if it's still hitting, I'd like to get two panel + PCB sets.
Sorry to wait so long, lost track of... something!
Thanks!

~jt
negativspace
Yep, still haven't had the artwork come back. thumbs up
onlyHzwhenI...
I meant 2 full sets, the dual PBC x2 and the panel x2, enough to build 2 modules, complete. You put me down for 1 set.
Put it this way: I'd rather give you $90 than $45. I can't believe I said that!

These multi-board projects confuse the flux outta me!

Thanks!

~JT
MatMillion
If there is still time, I'd be in for a set.
Skaput
I may have left my wallet in my other pants, in an alternate universe hihi
negativspace
Alright, finally! The artwork's in and these are underway. I'm officially closing the last-minute squeeze-ins and putting this one to rest.

ETA on the panels is 3-4 weeks. Anyone who hasn't paid when they arrive will receive a PM from me within a week or two of that date. In the meantime I'll work on fleshing out the BOM and putting up some photos to document a couple of special steps in the construction process.

Thanks, everyone! SlayerBadger!
sammy123
Thank you man.
Randy
Fantastic news, thanks!

Randy
grilojoe
I'm really looking forward to this one. Thanks! SlayerBadger!
ablearcher
Pretty psyched about this. Pretty much all my patches lately have my cp3 feeding a pittsburgh filter as one of the final stages in one voice. Whether its drums or a bunch of different waveforms from the same oscillator I find the transistor distortion/compression of the cp3 really glues a voice together. I also have the mix which I was initially excited about due to the higher fidelity being used less or at a later stage since it lacks this property. Anyway, might as well hardwire something you keep patched all the time right? It'll be nice to free those two up as well.
thumbs up
bsmith
Negativspace are the film caps and such all 5mm lead spacing?
wired
Looking forward to wiggle this one Rockin' Banana!
negativspace
bsmith wrote:
Negativspace are the film caps and such all 5mm lead spacing?


Um... basically yes. The timing caps (styrenes) are 7.5mm and then there's C6, I think that's the 150pF, which is 2.5mm.
woodster
I'm also mad keen on fast tracking this one to the top of the pile.
Have already started getting the BOM bits together in anticipation.
paulstone
personally i prefer to see the pcb and even the schematic before buy bom stuff , so i wait for it smile
Jop
Hi Jason,

Wondering if you have an update for us already....

Hope they can ship soon.

Thanks
negativspace
Still waiting to receive both panels and PCBs. I'm in the queue, I'll get them when they're ready. Shouldn't be too long, but panels at least are a little slower than usual right now.
nikmis
I just realized I still haven't paid for mine yet!
Jop
Thanks Jason for the update.
Jarno
This topic sunk to the bottom a little bit, any news?
negativspace
I had to make a tiny change to the panel graphics and I haven't heard back from MPC about it at all. I presumed the holiday last week was part of the problem... I just sent an email to them about 10 minutes ago asking where we are - I'll let you know what they tell me.

Those of you with mainboard-only orders will be a bit ahead of the game, I may be able to start shipping those next week.
negativspace
I have my answer... they're shipping tomorrow. screaming goo yo screaming goo yo
bsmith
w00t w00t
Jarno
SlayerBadger!
regenbot
w00t
woodster
Does anybody have a source of the Linear (B)10k 16mm Dual Gang Right Angle PCB Mount Pots ?
BYOC won't ship them to the UK, and I've had no response as of yet from the UK BYOC distributor (who doesn't actually list them on their site anyway).
Smallbear don't have them, couldn't see them on the Rapid or Mouser sites...
medbot
woodster wrote:
Does anybody have a source of the Linear (B)10k 16mm Dual Gang Right Angle PCB Mount Pots ?
BYOC won't ship them to the UK, and I've had no response as of yet from the UK BYOC distributor (who doesn't actually list them on their site anyway).
Smallbear don't have them, couldn't see them on the Rapid or Mouser sites...


Jason said earlier in the thread that solder lug style pots would work fine, you'll just have to run wires or use resistor legs or whatever. I grabbed one like that from Small Bear with another order so here's hoping.
qfactor
woodster wrote:
Does anybody have a source of the Linear (B)10k 16mm Dual Gang Right Angle PCB Mount Pots ?
BYOC won't ship them to the UK, and I've had no response as of yet from the UK BYOC distributor (who doesn't actually list them on their site anyway).
Smallbear don't have them, couldn't see them on the Rapid or Mouser sites...


Would this, from Tayda, do? hmmm.....
http://www.taydaelectronics.com/10k-ohm-linear-dual-taper-potentiomete r.html

Only 80cts each! thumbs up
negativspace
No, those are straight-pin. You want the right angle leads. Those would work if you use wire, but if you're doing that the lug version is way easier to work with.
Skaput
[quote="qfactor"]
woodster wrote:
Does anybody have a source of the Linear (B)10k 16mm Dual Gang Right Angle PCB Mount Pots ?
BYOC won't ship them to the UK, and I've had no response as of yet from the UK BYOC distributor (who doesn't actually list them on their site anyway).
Smallbear don't have them, couldn't see them on the Rapid or Mouser sites...


These look like the ones you want, though i have no experience with this particular seller

10 K dual gang linear pot
woodster
thumbs up
negativspace
That one looks correct. The default knobs would prefer round-shaft pots, but that's up to you as the builder to decide.
negativspace
Re-fixed the link to the Soundcloud demo now that embedding is working again. w00t
negativspace
Panels are IN. They look excellent! Now just waiting on the PCBs... won't be long. 8_)
Phetus
My names on the list, I was just wondering if it's too late to pay and get the set? Has that boat sailed?
horstronic
Will you have some spare sets for the people who missed it?
negativspace
1) Yes, I do have spares. Not many this time, but there will be a round two once they run out. The price may increase marginally for subsequent rounds since I will not be able to order in this quantity again.

2) Of course it's not too late to pay! If you're on the list there's a PCB set with your name on it. I'll send out PMs to those who haven't paid once the boards are also here.

Those of you who've been holding off payment until something tangible happens, well, now is a good time. thumbs up
horstronic
negativspace wrote:
Yes, I do have spares. Not many this time, but there will be a round two once they run out. The price may increase marginally for subsequent rounds since I will not be able to order in this quantity again.


thumbs up It's peanut butter jelly time!
Crashlander42
I would be interested in a spare board as well.
Phetus
Paid smile
negativspace
PCBs arrived on my doorstep about 3 minutes ago. I'm going to build one up for verification and then I will get this show on the road. The control board is still a few days away so the first to go out will be the PCB-only orders.
4285407da1d2a63820a3007c1
Would it be possible to combine my order with a friend (we're both on the list already) and save on the postage? How much would the worldwide postage option be for 2 sets of PCBs and panels?
negativspace
Yeah, I'm happy to do that... two sets won't cost any more than one set, so you save $10.
woodster
Bear in mind though, In my own experience it can often be a false economy trying to combine shipping on multiple orders.
PCB's on their own are VAT free, but the Panels are not.

1 set will sail through UK customs, 2 sets is likely to be beyond the import price cut off value, so you can often get stung for VAT, plus the £8 parcelfarce "handling fee"
So it is often more expensive, and I'd rather give my money to Jason and it be part of his turnover, as opposed to Royal Mail getting a tenner (or more) out of me, for doing nothing but deliver a service that was already paid for by the sender.
4285407da1d2a63820a3007c1
That's a good point woodster, hadn't considered that two sets would take it over the customs threshold. So irritating when the £8 fee ends up being a hefty percentage of the total cost! Plus the added delays...

Will just stick with the separate orders then.
Cheradenine
Questions for panel design...
What's the actual size of the filter PCB ?
And the spacing for its mounting holes ?
negativspace
The board itself is 2.714" wide and 3.550" tall. (~70mm x 90mm)

The mounting holes at the top of the board are centered .125" from both top and side edge. The lower pair is .125" from the side and 2.90" from the top pair. (0.65" up from the bottom edge.)
iL
finaly payed today!

we're not worthy
Cheradenine
Thanks !

negativspace wrote:
The board itself is 2.714" wide and 3.550" tall. (~70mm x 90mm)

The mounting holes at the top of the board are centered .125" from both top and side edge. The lower pair is .125" from the side and 2.90" from the top pair. (0.65" up from the bottom edge.)
LektroiD
Paid (as agreed via PM).

Many thanks for allowing me to grab one of the spare sets, since I was late to the party.

thumbs up
LektroiD
It appears Banzai only carry 10K log duals. Anyone know where I can get a linear version in the UK, or will the log be ok?

http://www.banzaimusic.com/Alpha-16mm-Stereo-PC-Angled/
Jop
Banzai carries the regular pin and soldelug variant. If i'm correct this was discussed earlier and no problem to use, only a little bit more work...
Nordcore
Can you buy these pots (right angled pcb-pins, 16mm alpha, dual 10k lin, with 6.3mm round shaft) anywhere on the planet?
cane creek
Nordcore wrote:
Can you buy these pots (right angled pcb-pins, 16mm alpha, dual 10k lin, with 6.3mm round shaft) anywhere on the planet?


NO, you'll have to catch a rocket to planet Ebay , you'll have to forget about the right angled pins though waah .
Nordcore
I need them for another project (about 30...50 pieces, so shipping is not that much of a problem), but the PIN-DIY is not acceptable there.

(For my build of this filter I'll just take the solder lug version and fit wires to it. )
bartleby
cane creek wrote:
NO, you'll have to catch a rocket to planet Ebay

hey thanks for that ebay link! this is actually the first eu source i saw for those pots!

@nordcore: are you getting some from there? would your order one for me, too, and combine it with my (upcoming) order for a bunch of ssmcv pcb and chips, and we share the shipping cost from the uk?
Nordcore
UK-Elektronik (in Germany) has the knurled shaft types with straight legs in a wide selection:
http://uk-electronic.de/onlineshop/index.php?cPath=367_38_152

What I'm looking for is this:
in 10k lin.
bartleby
ah i see, you're right. turns out that ebay links wasn't all that helfpul, after all. :(

so if anybody does know of e source for these in the eu (or willing to ship to eu), do let us know.
4285407da1d2a63820a3007c1
Does the site that negativspace but in the BOM (http://buildyourownclone.com/parts/pot16mmdgpc.html) not ship to the EU at all or will they just have stupidly expensive postage?
bartleby
4285407da1d2a63820a3007c1 wrote:
Does the site that negativspace but in the BOM (http://buildyourownclone.com/parts/pot16mmdgpc.html) not ship to the EU at all or will they just have stupidly expensive postage?

no, they don't. they seem to have a rather strange shipping policy. from their faq section:
Quote:
Q: Do you ship direct outside of the U.S.?
A: Yes, but only to certain countries - Australia, New Zealand, Brazil, and Israel.
LektroiD
What is the application of this elusive pot?

Any chance of a silkscreen or photo of the PCBs so we can see the placement of such components? At the moment it's all blind guess work as to how we can kludge another type of pot to fit.

I can imagine this project will be sitting in a lot of people's backlog drawer, since it requires such a hard to find part.
latigid on
If it's the only weird one then the remaining pots can be used to hang the panel. Nordcore's suggestion of flying leads or even bending/soldering cut resistor legs to a PCB mount version should work okay.

Further: perhaps they won't ship to the EU based on RoHS rules? A kind state-side wiggler (or even negativspace himself) could run a bulk for the rest of us.
woodster
It is strange that BYOC refuse to ship to the UK.
I've asked them why, but they don't give any reason, just say they don't do it.
I've asked Vibe-o-tronic (UK based BYOC dealer) if they can get them, and linked to this thread to illustrate the demand.
He said he'd look into it, but I've not heard anything back beyond that.
That was about a month ago.
I also asked bitsbox, but he said he couldn't find them in the catalog.

A groupbuy really would be the way forward!
LektroiD
woodster wrote:
It is strange that BYOC refuse to ship to the UK.
I've asked them why, but they don't give any reason, just say they don't do it.
I've asked Vibe-o-tronic (UK based BYOC dealer) if they can get them, and linked to this thread to illustrate the demand.
He said he'd look into it, but I've not heard anything back beyond that.
That was about a month ago.
I also asked bitsbox, but he said he couldn't find them in the catalog.


Just speculation, but maybe there have been problems in the past with unexpected customs fees.

woodster wrote:
A groupbuy really would be the way forward!


Count me in if it goes ahead. Any US friends who would kindly help us UK folk out with this?

I ordered a dual from evilBay, but not entirely happy about kludging it in. Would much prefer to use the intended part.
woodster
LektroiD wrote:


Count me in if it goes ahead. Any US friends who would kindly help us Brits out with this?

I ordered a dual from evilBay, but not entirely happy about kludging it in. Would much prefer to use the intended part.


^+1
Exactly, Flying wires isn't hard, and certainly won't deter me from building one (or two) of these beasts.
I'd much rather use the pcb pot though.
4285407da1d2a63820a3007c1
Would need to get sent to a single person in the UK and distributed from there to make sense I suppose.

An alternative option could be for negativspace to get a bunch and pack one with the PCB for an extra few dollars, though it would be entirely understandable if he'd rather not spend his time doing that. I also don't know how much the shipping costs depend on it being a flat package, my experience with Royal Mail over here suggests it could easily push it into some sort of more expensive package category.
LektroiD
Thonk would probably be the best hub for this in the UK.

Hopefully if he gets these VCFs in as kits, he may order a few extra 10KB duals for us in need (nudge nudge, wink wink)...
Reality Checkpoint
Count me in for a couple if a group buy goes ahead.

I am willing to kludge if necessary but would rather not.

Maybe a kind US wiggler will notice our plight!!
negativspace
If Steve does do kits - and I'm sure he will - I'll be sure to hook him up with the appropriate pots. BYOC sells them here in the US so they're easy for me (and other US builders) to get. They don't seem flexible with their international shipping options, though.

Carsten, if you need a bulk quantity let me know and I will do the same for you.

The pot in question is in the resonance circuit, one half is the resonance pot itself and the other half is used in the drive circuitry to correct for some inelegance in that area of the design. There are more details in the original Home Cookin' thread.

It's not a hard pot to get ahold of, the solder-lug version will work fine and Banzai sells those. Thonk will eventually have the PCB-mount version as will Synthcube. Don't panic! hihi
duff
I bought these as a stop gap until I could find somewhere local selling the alphas and/or required some other bits I could combine with them to make postage acceptable from further afield.

The action appears to be ok and according to the shop page
Quote:
Our products will enhance your experience to unparalleled inspiration

So even though they are 5 for only £1.69 - including shipping from the other side of the world - my hopes are high....

(I might hit up that eBay link though, just in case)
negativspace
I've built the tester... it's drying now after its final wash so I won't be able to test it for at least a few hours. Can't wait! w00t
Bakeneko
negativspace wrote:
I've built the tester... it's drying now after its final wash so I won't be able to test it for at least a few hours. Can't wait! w00t


Good stuff...

cheers and regards
LektroiD
negativspace wrote:
I've built the tester... it's drying now after its final wash so I won't be able to test it for at least a few hours. Can't wait! w00t


Any chance we can get photos of the boards, both populated and un-populated?

Can't wait to hear how good this sounds...
negativspace
Yes, I have those and others to post as well as a verified BOM.
negativspace
Alright, it's working! w00t

There are a couple of small errors in the silkscreen. The only problematic one is that the LM78L05 is reversed, but I'll make note of it in the BOM and that should sort the issue. The + and - mixer test point labels are swapped, but that's not really relevant unless you need to troubleshoot a nonworking build. The front panel outputs are labelled correctly.

At the last second I changed the trimpot footprints to accommodate both inline and offset pinouts - unfortunately one pad in the -6V trimpot which should have been grounded did not get connected to the ground plane. That's what I get for trying to be nice...

sad banana

Easy fix, though, and one which if not addressed will not ruin anything. The -6V rail will be stuck at -7.6V, which only impacts the mixer circuit and will not cause it to malfunction. (The clipping point on the negative swing of your input signals will be 1.6V less asymmetrical. In practice it's a very small change, the clipping is still asymmetrical which is what we're going for.) I'll post a photo of the recommended fix along with the other build photos.
negativspace
First batch is out as of an hour from now - writing customs forms and then I'm off to the post office.

I've worked out a few tweaks in the BOM, just a resistor value here and there to perfect a few little details. I'm going to build a fresh one using only the BOM as a guide and then post it pending correction if necessary.
grilojoe
negativspace wrote:
First batch is out as of an hour from now - writing customs forms and then I'm off to the post office.

I've worked out a few tweaks in the BOM, just a resistor value here and there to perfect a few little details. I'm going to build a fresh one using only the BOM as a guide and then post it pending correction if necessary.


It's peanut butter jelly time! w00t screaming goo yo
medbot
*runs to check mailbox*
duff
You posted earlier in the thread that there were transistors choice that could be made to enhance/change the sound - have I overlooked the update on that one somewhere or will your verified BOM highlight the possibilities?
negativspace
It will.
grilojoe
My boards showed up today safe & sound. Thanks! hyper
negativspace
Crap, I'd better get that tester done. eek!
medbot
Everything works great, forget I said anything oops
onlyHzwhenI...
Since folks are already getting theirs in the mail I'd better pay up. Thanks for all you've done on these!
~JT
spneca
Got mine today. Thanks!
onthelees
Woo Hoo! Boards are here - thanks
negativspace
Quick update, folks... I'm going to be working out the last of the BOM today, the tester build is the only thing left on my agenda. (Spent the morning packing more so I could ship before the post office closed. hihi )

I'll have photos of the control board construction which should help with any fitment issues you might experience.

Also, for those of you waiting on CP3s along with your filter order, I'm out of CP3 boards. I'm going to order more over the weekend and they will be here in roughly 2 weeks.
sammy123
Got my boards today. Thank you.
qp
Boards arrived!
negativspace
Now that I've got my head above water on the shipping front I've sent out PMs for payment to everyone still listed in black. thumbs up
Stinktier86
negativspace, sorry to bother you, but did you get my pm regarding my change of adress? I'm getting a little bit nervous oops
negativspace
Yes I did - you're still on hold while I restock the CP3 boards, so it hasn't gone out yet. thumbs up
bartleby
medbot wrote:
I was also poking around with the continuity tester on my multimeter and just about everything has continuity with almost everything else on my panel board. Like the audio inputs are all apparently connected to each other, to each other's grounds, to the CV jacks, to legs 1 and 3 of all pots but frequency and resonance, to several of the pins of the headers, etc. That doesn't seem normal, does it?

hm, that doesn't sound too good. has this been resolved in any way? is there really something wrong with the panel boards in this run?
medbot
No, I think it's something I did on my end. I was having trouble fitting the pots (shoulda waited for the guide I guess confused ) and the pcb may have gotten bent a degree or two during the process.
thetwlo
thanks! received mine, on Sunday? hmmm.....
They weren't with yesterday's mail, odd.
4285407da1d2a63820a3007c1
Just paid! Is the BOM finalised now or might there be a few more changes?
regenbot
couple of questinons regerding the BOM

can i get away with 25k trimpot?
What package is the lm7805? (don't have the pcb's yet)
negativspace
The LM78L05 is in the TO-92 package. I'm about to post the BOM, so here in about 12 seconds you can just check the top of the thread. w00t
negativspace
Ok, the BOM is updated with the correct parts, proper placement, and any notes I could think of. That should get you up and running! I'm testing the module I built over the weekend right now and there are no problems.

I want to get photos of the front and back side of the completed PCB and then I will add the build pics to the BOM post.
Delta T
Boards arrived today! smile Thanks for all of your hard work!
4285407da1d2a63820a3007c1
So is this pot from Banzai the best plan for us European people? I saw a mention of Thonk getting some but I'm not sure when that's happening.
negativspace
I'd use the solder-lug version rather than that straight-pin version, simply because it'll be easier to physically solder the wires to it. Electrically speaking that one will work.
sammy123
I started populating the board last night. Woohoo!
4285407da1d2a63820a3007c1
negativspace wrote:
I'd use the solder-lug version rather than that straight-pin version, simply because it'll be easier to physically solder the wires to it. Electrically speaking that one will work.


Oh yeah just went back a few pages to the last time we discussed this. It's the right-angled pins one that we really but Banzai don't have them. Damn. I'll either get the solder lug one or wait for Thonk.
ym2612
Got my boards and panel yesterday! I just finished ordering parts. Can't wait!
Randy
Got mine today, thanks! With the luck I've been having getting stuff working lately 'though I might just look at the boards and panel for a few weeks.

Randy
negativspace
bartleby wrote:
hm, that doesn't sound too good. has this been resolved in any way? is there really something wrong with the panel boards in this run?


No, there's nothing wrong with them. All of the input jacks are normalled to ground, so with no cables plugged in everything is sort of connected to everything.
livefreela
just got mine - hitting the bench now!
Randy
Is there any chance someone could take a few photos as they're building these for those of us who have consistently bitten off more than they are ready to chew by jumping in on projects that might be a bit more difficult than they are ready for. Not that I know anyone like that of course...

Randy
livefreela
is the 337 silkscreen reversed too? - looks like it -or am i reading this wrong - been a long day wink
livefreela
yep - kludged up regulator and missing ground jumper installed and she's up and singing - very cool filter, great job negativespace. any advice on the null trim?[/img]
negativspace
Photos added to the BOM page - that should illustrate the necessary wiring for the pots as well as the fix for the ungrounded trimpot pin. thumbs up
MindSnared
Got my package yesterday, looking great! Now for some BOM hunting It's peanut butter jelly time!
Randy
negativspace wrote:
Photos added to the BOM page - that should illustrate the necessary wiring for the pots as well as the fix for the ungrounded trimpot pin. thumbs up


Cool, thanks!

Randy
medbot
I don't have the right pots for the mixer section, but since it's just an attenuator I should be able to use other values, right? Or am I wrong thinking that? If I'm not, should I go up or down in value? I have 10k and 100k to choose from.
4285407da1d2a63820a3007c1
More pot questions I'm afraid, trying to order them before my board arrives so I'm using the photos at the beginning of the thread. The BOM says 3 audio lugs and 4 audio pins, but the photos seem to show all of them being right-angled pins? Will I be ok with these two?

http://www.banzaimusic.com/Alpha-16-PC-ANG-100k-lin.html
http://www.banzaimusic.com/Alpha-16-PC-ANG-25k-log.html

Already got the rest of the BOM ordered so if I can sort these out then I'll be good to go when the boards come in. Cheers.
medbot
The 3 audio lug pots aren't actual right angle pots, they have resistor legs or whatever soldered into the lug. The regular right angle pins like you linked are too big to fit in that spot.
sammy123
[5] 10uF Electrolytic, Q8,Q9,Q10 = audio path. The other two are for decoupling the +5 and -6V rails. 

Should I be using some fancy electros these 3?
negativspace
You don't have to, but I though I'd note that in case you want to. I use Elna Silmic caps in mine, available at Mouser and not expensive by any stretch.
sammy123
negativspace wrote:
You don't have to, but I though I'd note that in case you want to. I use Elna Silmic caps in mine, available at Mouser and not expensive by any stretch.


Cool. I am going to build it with what I have and upgrade when I build the second one. I did have the alternate tranasistors though. I ordered those months ago thumbs up
negativspace
medbot wrote:
The 3 audio lug pots aren't actual right angle pots, they have resistor legs or whatever soldered into the lug. The regular right angle pins like you linked are too big to fit in that spot.


This. You need to build your own pot, basically, since Alpha makes the angled-pin parts take up unnecessary space for whatever reason. seriously, i just don't get it

I've built about 230 MA35s this same way and for me it's a really quick process. You may find it a bit fiddly at first (I did) but try to jam the resistor clippings into the gap between the plastic element and the crook of the lug. That should hold it well enough while you solder it.
grilojoe
Did I miss the pinout for the two headers to the control board?
4285407da1d2a63820a3007c1
Thanks for the replies medbot and negativspace, I'll stop trying to be clever and just follow the BOM. The resistor clippings technique looks pretty straightforward.
Bakeneko
PCBs and panel landed in the UK - thanks!
ym2612
Looks like I bought little 1/8 watt resistors, whereas the board is designed for 1/4 watt. Should I reorder, or would I be safe with 1/8W?
nigel
PCBs and panel arrived safely in Australia. I know what I'll be doing this weekend!
sammy123
Jason, I finished mine the other day and I gotta say this filter is really nice. Everything I run through it sounds great. The resonance is great, all outputs sound really nice and the self oscillation of the resonance is also nice and controllable. Excellent work.
thumbs up
negativspace
Thank you! I did a little polishing at the end but I think Scott deserves most of the credit.
sammy123
negativspace wrote:
Thank you! I did a little polishing at the end but I think Scott deserves most of the credit.


Thanks Scott. Guinness ftw!
qfactor
Ok mine finally arrived at the "other side of the world" in Singapore! nanners
Thanks Jason! thumbs up
qfactor
eek!
Arranging all the parts I need to get started, I suddenly realized that I don't have the schematics! d'oh!
Can someone help me with the link to where I can get the schematics and all?! help
Thankie... sad banana
Bakeneko
ignore - I just saw the photos... ;-)

cheers
bens
Wow, what a terrific module! I just finished mine, and it sounds great. I haven't touched the trimmers, and I don't think I need to.

This is the fifth module I've built (others are MA CP3, MA CVP, Barton VCA/Mix, and Turing Machine with expanders), and I thought I'd make a couple of observations on DIY for people new(er) to this kind of project. This is something like notes to self, but maybe it'll be helpful for someone.

One point is that there's often more than one way to skin a cat, though it may be an unpopular phrase around here. I ordered my parts from Mouser and Tayda before the BOM was finalized, so didn't realize there were surface-mount parts (could have looked more carefully at the PCB! more on that in a sec.) Although I'd have been thrilled to make my first foray into SMT, I was impatient to get going, so I used a through-hole 1K, as mentioned in the BOM, and then kind of dabbed two through-hole MLCC caps on the back of the PCB, lying along the board. (I can post a picture of this if anyone's interested.) I also had missed the 62K resistor when I ordered, so glommed together a 63K from two resistors in series. (And I suppose I could have used some other value with no problem.)

(Along similar lines is the method above for constructing the pots with PCB pins from lugged pots and resistor leads. Also, though I can't find it right now, there's the bit about constructing the two-row inter-board headers from one-row header.)

Another point is that you necessarily become more familiar with the layout of a PCB as you stuff and solder it, but it would be better to read it over carefully before you start, for BOM ordering, for not making mistakes, and for understanding the general arrangement of the circuit. Maybe I'll take this advice myself someday.
sammy123
Nice work. I had to stack two resistors for the 240r and I used a 9mm pcb mount pot for the notch control. First time for everything.
bens
Here's a picture of the 0.1uF caps dabbed on to the back of the main PCB instead of the 0805 surface-mount devices. I taped the body down and then the legs, leaving the leads over the pads exposed, then pressed each lead down to its pad with the iron and added solder.

Also note the wire jumper at bottom right. Also note that I put the male headers on this board instead of the other way around, as in the BOM post -- I'm sure it doesn't make any difference.

negativspace
Nice to see some of these come into being! A few quick notes:

That's perfectly normal @ the caps. Any with 2.5mm lead spacing can be installed like that quite easily.

Which header goes on which board is irrelevant. For me in a production environment it matters, I need to be able to replace a broken mainboard and not worry about connector placement. For one-off DIY builds, though...

There is no 240K resistor - it's 240R. Doublecheck that. hihi EDIT: now there is a 240K in addition to the 240R. If you're reading this in 2015 or later, please don't get confused. cool

I will post the schematics when I get home from my trip.
sammy123
Yeah I meant 240R. hihi
qfactor
negativspace wrote:
Nice to see some of these come into being! A few quick notes:

That's perfectly normal @ the caps. Any with 2.5mm lead spacing can be installed like that quite easily.

Which header goes on which board is irrelevant. For me in a production environment it matters, I need to be able to replace a broken mainboard and not worry about connector placement. For one-off DIY builds, though...

There is no 240K resistor - it's 240R. Doublecheck that. hihi

I will post the schematics when I get home from my trip.


What about the value of the 62k resistor? Must it be exactly that value? hmmm.....
negativspace
No, that was a tweak-to-taste value I settled on if I recall correctly. It's not critical. I'd have to peek at the schematic to give more detail.
negativspace
Guinness ftw!
qfactor
negativspace wrote:
No, that was a tweak-to-taste value I settled on if I recall correctly. It's not critical. I'd have to peek at the schematic to give more detail.


Ok, good to hear, coz I think I've got a 63k or something near that value only thumbs up
Thanks!
thresholdpeople
Totally missed this... any chance for another run of this board in the future?
negativspace
I have many spares.
khakifridge
negativspace wrote:
I have many spares.


Boards and panels?
negativspace
Yep. thumbs up
khakifridge
I'll be in for a set then, please! It's peanut butter jelly time! nanners It's peanut butter jelly time! nanners

PP in its way... smile

Edit: done!
4285407da1d2a63820a3007c1
PCBs have arrived. Time to discover which components I forgot to order.
thresholdpeople
negativspace - did you get my PM?
Morbid
PCB`s and panel were in the mail today.
Under 2 weeks USA > Europe, not bad. thumbs up
mush


Surprised to have a few quirks to iron out. (I've had a long run of quirk free builds, and most been a lot more complex than this...) Anyway - most of it works as expected and especially the bandpass on this thing is amazing!

Thanks!
cane creek
I've just noticed some of the resistors I have are the smaller looking 0.4w rather than the usual 0.25w
Are the smaller 0.4w ok to use on this build ?
negativspace
They should be... even 1/8W resistors are fine in most synth circuits. Watch the mixer section, though, it gets a bit warm even with 0.25W parts.
negativspace
mush wrote:

Surprised to have a few quirks to iron out. (I've had a long run of quirk free builds, and most been a lot more complex than this...) Anyway - most of it works as expected and especially the bandpass on this thing is amazing!

Thanks!


Nice work! Looks great. Let me know if you need any assistance with the quirks, as usual.
Reality Checkpoint
Just collected mine. They had been sitting in customs for a week. I don't mind paying duty and VAT etc but it annoys me that I have to pay £8 to the Royal Mail for them to do basically nothing. Absolute rip off.
4285407da1d2a63820a3007c1
Two sets seems to take it over the customs threshold, as someone on here helpfully warned me before I got my order sent. Slightly cheaper (and much less infuriating) to get them sent as two packages. Ridiculous isn't it?
onlyHzwhenI...
Got mine too, thanks!
-JT
Randy
I've started mine but it will take me months to finish it. I tend to install stuff from my stash until I run out of stuff, and then order more stuff.

Randy
qfactor
Question: for the R44 1k thermistor, should it be in "contact" with any component on the PCB for it to temperature compensate? hmmm.....

Thanks!
mcop
Mine has arrived It's peanut butter jelly time!
Phetus
Have any of the German crew got theirs? Maybe I'm just being impatient...
synchromesh
My two-sets-in-one-package turned up yesterday, with no customs duty/VAT to pay. Just lucky, I guess... This is fun!

Thanks Jason (and Scott & Jürgen [RIP]) for putting this together for us! we're not worthy
khakifridge
synchromesh wrote:
My two-sets-in-one-package turned up yesterday, with no customs duty/VAT to pay. Just lucky, I guess... This is fun!


While it may technically go "over the limit", there's a buffer zone where HMRC won't bother to chase you for the money. I guess it works out too expensive for them to cover their costs. @Reality Checkpoint may have been unlucky. sad And yes, £8 is a bit steep for nowt.
gbiz
I didn't have to pay duty for 2 sets either. Mine arrived on tuesday.

The £8 handling fee is to cover their costs.

As i was told it in the local post office one time when having to pay import duty etc. For post items that are in that buffer zone/grey area, they should collect it, but it's down to how busy the office is & also whether they can be bothered. They don't have the staff/time to charge everything they have to handle in that zone.
Jop
Received yesterday without customs duty and vat nanners (including two complete mvp's sets).
Guess I was lucky and to me it looks like customs picks randomly on a sample basis (been charged for smaller orders before)

Since i do not use the panel and associated pcb I'm looking now how to wire it manually. Jason, is there a diagram available or schematic?

Thanks
Skaput
Just getting my Bill of materials together almost there, but would some kind soul let me know if these trim pots from mouser will do the job

http://uk.mouser.com/ProductDetail/Bourns/3296W-1-203LF/?qs=sGAEpiMZZM vygUB3GLcD7sSg8po3Zpo3tckTNAsM5eY%3d

Id hate to order the wrong ones as they are not exactly cheap.

What about these they are a little bit cheaper http://uk.mouser.com/ProductDetail/Murata-Electronics/PV36W203C01B00/? qs=sGAEpiMZZMvygUB3GLcD7u3z%252bNHL9M9LmVBh6Z80G7o%3d

This is a visual representation of me after working on the BOM Dead Banana

Is there anyone out there that actually enjoys getting the BOM together!
Randy
I ordered these:

http://www.ebay.com/itm/251118498866?_trksid=p2060778.m2749.l2649&ssPa geName=STRK%3AMEBIDX%3AIT

No idea if they are the "correct" trimpots but they seem to match what was mentioned in the BOM.

I've given up trying to get everything on one BOM from one vendor. Now I just look around on eBay and order what I can, pick up a few things locally and sometimes need to look for specialized bits, like the dual-ganged pot in this case. It takes longer (can take a month to get stuff from China to Canada) but I'm not in a hurry.

Randy
Skaput
Thanks for the reply Randy, these are definitely better priced.

I actually looked at these on the Tayda Website but dismissed them because i thought they had four leads but on closer inspection its just a shadow on the photograph, that must be BOM fatigue d'oh!
sammy123
I use Tayda trims on all builds including this one. They work fine.
Skaput
sammy123 wrote:
I use Tayda trims on all builds including this one. They work fine.


Thanks Sammy123, good to know. Tayda order it is then. thumbs up
pulse_divider
Would this work for the 1k tempco? It's 1/6 W

http://www.thonk.co.uk/shop/tempco-resistor-anakeohm-1-3300ppm-x3/
sammy123
http://www.digikey.com/product-detail/en/ERA-S33J102V/P1.0KCDCT-ND/526 980

I am not as familiar with tempcos. I used the smd part. I would check with Jason though. I had this part from another project so I used it. I have not verified how well it is working.

Edit:

It doesn't look like Digikey stock any SMT versions that are more than 1/10th watt. I don't know how critical that is. Here are my search results.

http://www.digikey.com/product-search/en?pv1=2358&FV=fff40001%2Cfff804 d0%2C2dc1b2a&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm =0&fid=0&pageSize=25
Skaput
pulse_divider wrote:
Would this work for the 1k tempco? It's 1/6 W

http://www.thonk.co.uk/shop/tempco-resistor-anakeohm-1-3300ppm-x3/


That part is the one i was going to order, should be fine. I used this online ohms law calculator to work it out.

Ohms law calculator
Morbid
Did someone calibrate it already.
I have a strange problem, the 2k trimmer for the -6 volt does nothing.
No matter how often i turn it around.
The multimeter reads -7,55 volt on the test pad.
So I replaced the trimmer and test it.
I also replaced the LM337.
I checked all solder points and all parts around the voltage regulator
But nothing.
If I turn the "Null" trimmer the voltage jumps to -7,30volt.

seriously, i just don't get it

Any suggestions?
windspirit
Did you chEck continuity on the pins to power? It could be a bad trace, havent built it yet but id wager this is a voltage divider of power
Morbid
Sorry guys.
I read about that bug on page 38 and see the fix on the first page. d'oh!
Nordcore
Received my boards + panel yesterday, thanks negativspace. This is fun!
Plus no hassle with customs, just a green "passed" sticker on it It's peanut butter jelly time!
Morbid
It works now. w00t
And omg this thing is a beast.
This is one of the best sounding filters I ever heard.
I think I need another one for my second case.

Just one last thing.
If I use the notch output and turn the knob is it normal that it makes a small jump between LP and HP?
qfactor
Still stuffing and soldering mine.
Question: do I only need to socket Q17 and Q18 to do the trannie swaps (PNxxx etc)? hmmm.....
Thanks!
oberkorn
really looking forward to this.
hope mine will be shipped soon help
ym2612
Finished!

[s]http://soundcloud.com/ym2612/discrete-svvcf-test[/s]

It went together really easily and worked the first time I powered it up. I made all my mistakes in the part-sourcing process and fixed those by the time I started soldering. I trimmed it 1v/oct and got the sine tracking roughly with my Furthrrrr Generator.

Do I need to spend time trimming the other pots? What will those help me adjust?
qfactor
Bump up my Question: do I only need to socket Q17 and Q18 to do the trannie swaps (PNxxx etc)?
Anyone can help me with this? help

Also, I suddenly found myself out of TL072s eek!
Would I be able to use the NE5532, which I have access of? They look the same, pinout-wise. seriously, i just don't get it
Stinktier86
Went to get my parcel yesterday, everything looking great - and no added duty for the four kits and two cp3 panels. w00t
khakifridge
qfactor wrote:
Would I be able to use the NE5532, which I have access of? They look the same, pinout-wise. seriously, i just don't get it


The pinouts are indeed the same (as you'll find for most - if not all - dual opamps). The characteristics of each are slightly different. The 072 has high-impedance JFET inputs, the 5532 is lower and bipolar. The 5532 draws more current than the 072, but has less noise and a faster slew rate. (And there are other differences.) These may or may not matter.

The worst you can do is to try it. All other things being equal, nothing's gonna blow up. grin
cane creek
Skaput wrote:
Just getting my Bill of materials together almost there, but would some kind soul let me know if these trim pots from mouser will do the job


I always get my trimmers from Bitsbox , much cheaper and do the job perfectly well thumbs up
Royalston
Anyone got theirs in Australia yet? I ordered and paid a long while ago...worried it's been lost.
nigel
Royalston wrote:
Anyone got theirs in Australia yet? I ordered and paid a long while ago...worried it's been lost.

Mine arrived back on the 8th., so yeah, I would expect it by now (if they were mailed at the some time).
Stinktier86
What resistor do i have to tweak if i want to use the aforementioned PN100A and PN5138 instead? Couldn't find any info on it in this thread. seriously, i just don't get it
sammy123
Stinktier86 wrote:
What resistor do i have to tweak if i want to use the aforementioned PN100A and PN5138 instead? Couldn't find any info on it in this thread. seriously, i just don't get it


I don't recall reading anything about resistor tweaking. I used those and didnt tweak anything. I would be interested to know as well if necessary.
regenbot
when will mine be sent? oops
qfactor
sammy123 wrote:
Stinktier86 wrote:
What resistor do i have to tweak if i want to use the aforementioned PN100A and PN5138 instead? Couldn't find any info on it in this thread. seriously, i just don't get it


I don't recall reading anything about resistor tweaking. I used those and didnt tweak anything. I would be interested to know as well if necessary.


I had a question too about whether the transistors that need to be swapped are Q17 and Q18 only or all of them?? seriously, i just don't get it
sammy123
I did all. I know that doesnt help...but it works and sounds awesome.
qfactor
sammy123 wrote:
I did all. I know that doesnt help...but it works and sounds awesome.


Wow!! eek!
Sounds tempting! Possible to have a comparison soundcloud demo to hear the difference? seriously, i just don't get it
sammy123
I dont have anything to compare it to as I have not built a second. I just saw the early comments by Jason and ordered these parts instead of the normal transistors. But I have been using it pretty much in all my recent Sound Cloud and Instagram tests (mostly with the Orgone Accumulator) if your interested.


Instagram

Sound Cloud
Skaput
cane creek wrote:
Skaput wrote:
Just getting my Bill of materials together almost there, but would some kind soul let me know if these trim pots from mouser will do the job


I always get my trimmers from Bitsbox , much cheaper and do the job perfectly well thumbs up


Hi Cane Creek, thanks for the Bitsbox link. Ive not come across that supplier before so will now be bookmarking it. It's peanut butter jelly time!
Morbid
Did someone noticed that there is a signal bleed even if the filter is fully closed?
It get's really loud if you move into subaudio territory.
Is that normal or can I tweak it with some other resistor values?
sammy123
I have not noticed....ill check though.
negativspace
If you want to play with the transistors it'd be all of them. The 2 I've marked as 3904s are on the CV side and probably don't make a huge difference in sound.

I haven't noticed any bleed but I'm still 600 miles from my modular so I can't really do much with that right now.
Stab Frenzy
If there's another run of these or if there's any left over from people changing their minds I'll take 1 PCB and panel. Guinness ftw!
sammy123
Morbid wrote:
Did someone noticed that there is a signal bleed even if the filter is fully closed?
It get's really loud if you move into subaudio territory.
Is that normal or can I tweak it with some other resistor values?


I tested lp and notch with a 555 saw at different tunings and did not have any bleed.
4285407da1d2a63820a3007c1
cane creek wrote:
I always get my trimmers from Bitsbox , much cheaper and do the job perfectly well thumbs up


Half the price and only £1.75 postage! Thanks for the tip.
Morbid
sammy123 wrote:
Morbid wrote:
Did someone noticed that there is a signal bleed even if the filter is fully closed?
It get's really loud if you move into subaudio territory.
Is that normal or can I tweak it with some other resistor values?


I tested lp and notch with a 555 saw at different tunings and did not have any bleed.


Thank you.
After I read my posting again it occurred to me that you get me wrong.
Bleed is not the right word.
So if I turne the cutoff knob fully left in LP mod there is still a signal coming thru.
So it dont close complete.
That is really curious. seriously, i just don't get it
sammy123
Mine closes completely in LP mode...no signal is coming through. Did you check all your resistors to make sure nothing is misplaced?
Morbid
I would but it's a bit hard because the silkscreen is covered with parts. hmmm.....
Maybe a hint where I have to do a closer look
The other thing that came to my mind is that my system draws too much current.
It's a doepfer LC9 and it's full with small modules.
Many are diy an some are dual.
sammy123
I don't have the knowledge to guide you to a particular part, but verifying the resistors by looking up the color codes is a good place to start. Then move on to the other parts. Just google resistor codes for the type you used.
negativspace
I have a second report of bleed, so it's definitely something I want to check out. I just can't from where I am right now... power draw is one of my leading suspects, though. As far as I know I have had none in any of my builds, but the second report concerns a unit I built and shipped away so something is going on.
LektroiD
negativspace wrote:
I have a second report of bleed, so it's definitely something I want to check out. I just can't from where I am right now... power draw is one of my leading suspects, though. As far as I know I have had none in any of my builds, but the second report concerns a unit I built and shipped away so something is going on.


Is it possible to subsitute any of the TL072's for TL062's? That would decrease the overall power draw.

I can't understand the benefit of a tempco on this board; it's not thermally coupled to anything. Care to elaborate?

hmmm.....
negativspace
It's coupled to the ambient environment in whatever enclosure it ends up housed in, but I get what you're saying. It is there as an option. I'm not sure it really does much.
diablojoy
Hi Jason
I keep trying to pm you but don't think they are getting through ?
have a slight problem .
negativspace
They're getting through but I have 987456903465 PMs to deal with right now and it's way past my bedtime... Dead Banana
crc
finished mine. sounds super, but i think the resonance self oscillating is a bit loud. any ways to tame it down a notch? it starts oscillating at 12 o'clock. does that sound right?

also the phase of the waveform comes out flipped after the filter, only the "MIX -" outputs the waves in the right phase.

oh any advice on how to calibrate the -6 and null trimmers correctly?
Jop
Check the cp3 thread for the -6 and null trimmers.

https://www.muffwiggler.com/forum/viewtopic.php?t=91461&highlight=cp3
LektroiD
Been through the whole thread, but can't find any info on calibration for this. Turning the Null & -6V trims (they seem to interact with each other) changes the output on the pads from -2.7V to +1V, I set it to 0V... Just a guess this is what's meant to be there without any calibration notes. I have no idea what to trim the mixer to though.

Anyone? seriously, i just don't get it
gbiz
Jason, is there any chance you could post schematics for this please ?. I've built two of these & both have an identical problem. Schematics would be really useful.

With no audio or cv input I'm seeing a low frequency (5-15Hz) oscillation on all three outputs, from about halfway into the resonance pot's travel. Amplitude of this waveform increases as the frequency pot is wound up. The filter still resonates as expected from about 2pm on the pot.

All the resistors & caps match the ones on your images above. I used 3904/3906 throughout & didn't bother matching them. I'm thinking about matching the set on one board to see if that fixes it.
bsmith
These things sound wicked!

So - I set the -6v trim so the -6v pad was at -6v, and the null to chase away the offset on the mix + out. Yeah?
Jop
I can't power mine yet cause I still have some components missing. I assume the calibration of the mixer is the same as the CP3:

Quote:
2) Adjust the 2k trimpot until the output of the LM337 is -6.0V.
3) Adjust the 100R trimpot until the output has no DC offset.


Don't expect them to behave too "normally" until the -6V rail is trimmed. For that one you'll want the black probe on ground, red probe on the output of the LM337. (You'll see the appropriate trace on the back side, it's thick and leads to the square pad of the 10U cap and then up to 3 resistors.) Once you have that sorted, trim the 2k pot until you read at or very close to -6.00V

Once that's done you should get a mixer that behaves as you expect it to.

Having verified this, remove all inputs and set the output pot to 12:00. Black probe to ground, red to the tip of the output jack. Adjust the 100R trimmer to get 0V.
LektroiD
bsmith wrote:
So - I set the -6v trim so the -6v pad was at -6v, and the null to chase away the offset on the mix + out. Yeah?


Where did you get your calibration notes?

Mine only goes to -2.7V at maximum, which is why I guessed 0V was what we are looking for.

Also mine bleeds in the high pass. No trimmimg seems to get rid of it. Low pass is fine though.
negativspace
Now that I'm back home with my gear I can answer this a bit more...

Mine does not have any output with no input. There is nothing on the scope as I add resonance until it begins to oscillate. Since I am not experiencing the issue with this unit and have not yet experienced the issue with any previous builds I'm afraid I can't offer much insight. My test unit, BTW, is the prototype I built with 2N390x transistors.

FWIW I don't match the transistors in my builds either - I tested it both ways, couldn't find any observable difference - so I'm not certain that's the answer.

For the "bleed" in the HP mode, it's true that it doesn't cut off to complete silence at full-CW on the cutoff knob. If that's what you mean by "bleed" then that's normal. If not then something is up, because I don't hear anything I'd consider "bleed" in mine.

For calibration (and I'll add this to the build page) you definitely want to set the -6V rail up properly first, so do the little fix and then set the trimmer. There's a test pad onboard as well as a spare ground pad for the black probe so calibration should be pretty simple.

Once that's done you can set the null. This was a really useful trimmer in the standalone CP3 with the bipolar output as it could be used to zero out any offset at zero-output. (12:00) I learned in making this version, though, that the trimmer only effects the +OUT. So you have 2 options:

1) Trim as you would in a single-output situation and make the +OUT 0V
2) Trim as you would the standalone version and match the absolute value of the offset present on the -OUT. (Memory fails but I think it's roughly -70mV on the -OUT, so you'd want +70mV on the +OUT)
gbiz
I just replaced the six pairs of transistors in the filter section with matched ones & that's fixed it on both. nanners
negativspace
Good to know. Maybe I should do that myself, just in case... but I really haven't had it come up yet!

Either way I'm glad you have it working. w00t
gbiz
Just looking at hFE on the transistors i pulled, they're all over the place. No wonder they didn't work.

Whilst i had the soldering iron out, i swapped the styrene timing caps on one with polypropylenes. With the polys, the resonance is far more pronounced, especially at the upper end of the pot's travel. It also osciallates without any input, whilst the one with the styrenes doesn't. But the one with the styrenes sounds cleaner. I'm not sure which i prefer. Think i'll leave them as one of each.

As the others have said, this is a great sounding filter Guinness ftw!
negativspace
Interesting, mine built with styrenes will oscillate quite nicely on their own. In general I've noticed exactly what you say in many filters, though - polypropylene especially gives a much more robust resonance compared to styrene.
nigel
Can someone confirm the orientation of the LM337LZ? The data sheet shows pin 1 Adjust, pin 2 VOut, pin 3 VIn, but the silkscreen shows -12 going to pin 1.
gbiz
nigel the silk screen is correct for the lm337lz. The flat side faces the outside of the board.

The orientation of the 78l05 *is* incorrect on the silkscreen.
nigel
Then I am officially confused. The data sheet shows pin 3 (the rightmost pin, looking at the flat side) as voltage in, not pin 1. Any explanation for this?
Nordcore
mixed up top and bottom view?
nigel
Nordcore wrote:
mixed up top and bottom view?


I don't think so. Here's the pinout clipped from the NS datasheet:



and here it is superimposed over the PCB from the front page, viewed from the bottom, flat side to the outside of the board, showing the -12V rail connected to the Adj pin:



What am I missing?
gbiz
Can't argue with that. That looks right.

I just tried swapping one of mine around & it'll adjust to -6V with that orientation too.
negativspace
Weird that it works either way. I guess just install it whichever the fuck way you feel like. seriously, i just don't get it

(For the record you guys did way better in this thread than the CP3 mixer thread. Nobody's noticed the regulator backwards in those yet and it's been out way longer...)
crc
i also noticed that bleed when the filter is fully closed. you can hear the unfiltered signal bleeding trough silently.
nigel
gbiz wrote:
I just tried swapping one of mine around & it'll adjust to -6V with that orientation too.

OK, looks like I'm not delusional after all. It's peanut butter jelly time! I only started checking the PCB because I don't have a TO-92 package on hand, so I was thinking of temporarily wiring in a TO-220 LM337, which has a different pinout! very frustrating
Thanks for the replies.
qfactor
nigel wrote:
gbiz wrote:
I just tried swapping one of mine around & it'll adjust to -6V with that orientation too.

OK, looks like I'm not delusional after all. It's peanut butter jelly time! I only started checking the PCB because I don't have a TO-92 package on hand, so I was thinking of temporarily wiring in a TO-220 LM337, which has a different pinout! very frustrating
Thanks for the replies.


Wait a minute! I'm confused now d'oh! (noob alert!)
So does this mean LM337 could go in either orientation?? woah
Wouldn't a -12v into Adjust damage the regulator, in the long run??
So do I just go ahead with the orientation as per the PCB silkscreen?

In your case, nigel, how did you end up orientating your TO-220 337? Coz I may have to go that route if I can't get to an LZ version soon! sad banana
nigel
qfactor wrote:
Wait a minute! I'm confused now d'oh! (noob alert!)
So does this mean LM337 could go in either orientation?? woah
Wouldn't a -12v into Adjust damage the regulator, in the long run??


Well, that's a very good question! I'm not sure what's happening. Maybe someone who knows more about the internals of the regulator can help out.

qfactor wrote:
In your case, nigel, how did you end up orientating your TO-220 337? Coz I may have to go that route if I can't get to an LZ version soon! sad banana


Right now, it's still sitting on my workbench. That part of the PCB uses the standard circuit for the 337 regulator, so I'll just wire it according to that. The hole nearest the bottom of the card goes to -12 (easy to see), the top hole goes to the 240 ohm / trimmer circuit. (Through the jumper - don't forget to add the jumper!)
negativspace
The TO220 version has a different pinout such that it won't be "reversible" as the TO92 seems to be. Pin 2 (Vout) is not the middle pin in the larger package.

As for which way to install the TO92, empirically it seems to make no difference whatsoever in this circuit based on the fact that it spits out -6V in either orientation and the mixer behaves as expected either way. In spite of that, though, I would recommend you install it correctly which means the reverse of the silkscreen on the PCB. It may well make no difference whatsoever but it's still best to do it properly. As Khew says, there may be long-term repercussions to having it backwards - although my earliest prototypes have been running for many months with reversed regulators that still supply a solid -6V. Ask me again in 3 years...

If you've installed it backwards and trimmed it to -6V I would leave it as it is until it develops some fault, which may well never occur.
talfred
Hey Negativspace, you don't happen to have a set with panel and pcbs left? Or will it be available later?

If you do, I'd like a set now.
LektroiD
negativspace wrote:
For the "bleed" in the HP mode, it's true that it doesn't cut off to complete silence at full-CW on the cutoff knob. If that's what you mean by "bleed" then that's normal. If not then something is up, because I don't hear anything I'd consider "bleed" in mine.


Yes, exactly what I meant by bleed...

My understanding for high pass filters is that a lowpass output and an inverted version of the source signal are mixed together. As I found on other Low Pass Filters, attenuating the level of the inverted signal reduces the High Pass bleed. So I'm wondering, which resistor regulates the gain of the inverted source signal? I would like to play around fine tuning that to hopefully remove the bleed...
medbot
I don't know that I've ever used a high pass filter that closed all the way, but I've only got a handful to test right now (ssvcf, sem, minibrute).
medbot
Also, while I have the floor I'll take a minute to say how just bad ass this filter is. I honestly wasn't super sold based on the lone demo on the first page but figured I'd build it anyway since MA has yet to disappoint me, and I'm really glad I did. Combining the filter with the transistor mixer was an inspired idea, and I already wish I had another one or two in my rack. This thing would kill in a polysynth.

It's motherfucking bacon yo
LektroiD
medbot wrote:
I don't know that I've ever used a high pass filter that closed all the way, but I've only got a handful to test right now (ssvcf, sem, minibrute).


I've made a quick video to illustrate how to get rid of the bleed at the top end of the cutoff on a hipass filter.

I just need to know which resistor adjusts the level of the inverted signal of this filter so I can fine tune it. Any schematics available for this?

mcop
Not sure if this helps, but here's a link to Scott Stites original thread where he presented his schematics.

http://electro-music.com/forum/viewtopic.php?t=57575&postorder=asc
paulstone
pcb's arrived today thumbs up
LektroiD
negativspace wrote:
For calibration (and I'll add this to the build page) you definitely want to set the -6V rail up properly first, so do the little fix and then set the trimmer. There's a test pad onboard as well as a spare ground pad for the black probe so calibration should be pretty simple.



I couldn't find the ground test pad, only +/- pads, so I hooked up my probe to the chassis.

Quote:
Once that's done you can set the null. This was a really useful trimmer in the standalone CP3 with the bipolar output as it could be used to zero out any offset at zero-output. (12:00) I learned in making this version, though, that the trimmer only effects the +OUT. So you have 2 options:


What do you mean by zero output? Nothing plugged into the filter?

I have nothing plugged in.

Quote:
1) Trim as you would in a single-output situation and make the +OUT 0V


This makes even less sense "single output situation???" It's a filter, nothing plugged in, do I plug something into one of the outputs?

Quote:
2) Trim as you would the standalone version and match the absolute value of the offset present on the -OUT. (Memory fails but I think it's roughly -70mV on the -OUT, so you'd want +70mV on the +OUT)


Now I'm really flummoxed... "standalone version"? You made other versions of this filter? How do I know which one I have?

Furthermore, trimming will not get these results, the two trimmers interract with each other, so turning one makes the other completely wrong output. I simply can not get 70mv out of both at the same time, no matter what I do.

I get 70mv out of the +, then the - is messed up, and vice versa. This thing is impossible. Am I supposed to be rotating the mixer trim too? That seems to do nothing.

Should I use a scope, or a multimeter?

I have absolutely no idea what those instructions mean. If anyone has worked it out, could you please translate to plain English.

& I've still not worked out how to reduce that hipass bleed, it's unusable as a hipass like that.
woodster
Hey LektroiD,

I think Jason is referring to the CP-3 Mixer when talking about a standalone version.
As he says, his 4hp Euro CP-3 offering only has a single output which is a sweepable bi-polar output, as opposed to the dual separate + and - implementation as used as part of this Filter build.

"What do you mean by zero output?"
Again, this refers to the CP-3 with the single bi-polar output, Zero output is the output knob positioned at 12 o'clock (Like an Attenuverter).

I'll have to dig out my SVVCF PCB's to see if I can locate the test point for you...

I had a problem trimming the -6v on one of the three CP-3's I built.
It was related to a chip in the solder mask right next to a pad, and the inevitable solder finding it...
Do you have any decent PCB pic's ?
gbiz
LektroiD, the calibration method for the -6V & NULL pots is exactly the same as you would for a standalone CP3 mixer. Once you have the -6V calibrated, with nothng present at the inputs, adjust the NULL pot so OUT+ of the mixer section is at 0V.

The ground test pad is the one marked "G" adjacent to Q14.
LektroiD
I don't understand why Jason would be referring to a different module which requires different callibration techniques, as there is nothing that zeroes at 12:00 on this, just makes it all the more confusing.

gbiz wrote:
LektroiD, the calibration method for the -6V & NULL pots is exactly the same as you would for a standalone CP3 mixer. Once you have the -6V calibrated, with nothng present at the inputs, adjust the NULL pot so OUT+ of the mixer section is at 0V.

The ground test pad is the one marked "G" adjacent to Q14.


Now I'm even more confused... So what does Jason mean when he says "-70mV on the -OUT, so you'd want +70mV on the +OUT"?

I can't even get mine to go as far as -6V.

I'm even more confused now...
windspirit
The point is that the cp3 mixer circuit is the same as the summing section on the filter, i believe for the CV inputs. Therefore it uses the same calibration procedure.
LektroiD
windspirit wrote:
The point is that the cp3 mixer circuit is the same as the summing section on the filter, i believe for the CV inputs. Therefore it uses the same calibration procedure.


We're just going round in circles here... It IS different... There is no zero point at 12:00 on ANY of the pots, no Standalone, no "single output situation". It makes NO SENSE!.

Where are the notes about the mixer trim, which appears to do absolutely nothing?

This clearly requires a different calibration method to the CP3, which I am not even familiar with.

Still not resolved that awful HP bleed either
medbot
Dead Banana
ym2612
From the CP3 thread:

Quote:
Adjust the 2k trimpot [labeled -6v] until the output of the LM337 is -6.0V.
Adjust the 100R trimpot [labeled null] until the output has no DC offset.


That's all there is to it.
LektroiD
Quote:
Adjust the 100R trimpot [labeled null] until the output has no DC offset.


Which output? Hipass, Bandpass, or Lopass?

And what is Jason talking about when he mentions -70/+70mV on the +/-?

If I trim for -6V, these settings go all over the place.

And... What is the MIXER trim for?
nikmis
1. -6 volt trimpot

First you should turn the -6v trimpot until the output pin of the lm337 is -6volts. After that, you are finished with that trimpot, don't touch it


2. DC offset trimpot, null on the pcb,
Quote:
Which output? Hipass, Bandpass, or Lopass?

You would measure using the mixer output, mix+ on the panel, I believe. So before it ever gets to the filter section. Try to get it to 0 volts in reference to ground.

3. 1v/o trimpot

Quote:
And... What is the MIXER trim for?

It's not a mixer trim, its a volt per octave trimmer. The word mixer is just close to it. Set it to self-oscillating and try to get as close as possible to 1 volt per octave. Use the low pass output


I wish I could help you with the highpass bleed, I haven't built mine yet
gbiz
Quote:
Adjust the 100R trimpot [labeled null] until the output has no DC offset.


Quote:
Which output? Hipass, Bandpass, or Lopass?


None. The (pre-filter) OUT+ output from the mixer section.

Quote:
And what is Jason talking about when he mentions -70/+70mV on the +/-?


You have two options for calibrating the pre-filter mixer stage. With no input signal, either (1) simply adjust the NULL pot until you see 0V on the OUT+, or (2) adjust the NULL pot so the offset at the OUT+ matches whatever the offset is at OUT-, which will likely be in the order of +/- 70mV. There's no adjustment for OUT-. FWIW, i used (1) on mine, & with 0V at OUT+ i see 125mV at OUT- on one & 135mV on the other.

As Jason mentioned way back in this thread, the Mix+ & Mix- test point labels on the PCB are reversed, so be aware of that. The outputs on the panel are correctly labelled.

Quote:
If I trim for -6V, these settings go all over the place.


I'm not going to suggest this is the cause, but have you tried reversing the 337, as Nigel picked up a few pages back ?. Might be worth a try. -6V doesn't vary here on both of mine.
negativspace
Holy crap, this isn't hard. d'oh!

No cables in the module. No inputs, no outputs. Use the testpoints on the board.

1) As mentioned, the ground pad is over by the lower screw hole on the left-hand side of the PCB.

2) Adjust -6V trimpot until the test point "-6V" reads -6.00V. This test point is down by the LM337. Once you set this, for fuck's sake leave that trimpot alone!

3) Forget everything else I've said about the CP3 circuit in this thread.

4) Seriously, just take a deep breath and forget all of it. I'll give you a moment.

5) ...

6) Measure the test point labelled "-". This incorrectly corresponds to the jack labelled 'mix +' on the front panel. It should read somewhere between 55 and 110mV, give or take. The null trimpot won't effect this measurement, so just note the voltage. It may bounce around a bit. Just... ballpark it.

7) Measure the test point labelled "+". The null trimpot will effect this voltage so you now have two choices:
7a) Recall the voltage from Step 6 and adjust the null trim until the voltage at TP "+" reads the inverse.
7b) Forget Step 6 and adjust the null trim until the voltage at TP "+" is ~0.00V.

8) You're done with the mixer.
negativspace
Added the pinout diagram to the build page for you non-control-board builders.

It is double-checked but not verified!
paulstone
negativspace wrote:
Added the pinout diagram to the build page for you non-control-board builders.

It is double-checked but not verified!


thanks for the picture , i will chek soon thumbs up
Jop
Just finished wiring it the old fashioned way. I can confirm the pinouts are correct SlayerBadger!

Also trimming was easy due to the testpoints and clear instructions!

Great filter, now time to explore all the possibilities.
LektroiD
Thanks for the detailed calibration guide. thumbs up

Anyone else have a quiet spot in the middle of the notch pot? I wonder if a lower value pot might sort it? I have 100K's in as per the BOM. Moving the mixer trim doesn't do anything to help (I still have no idea what that trim is for).
Stinktier86
I happen to have a clip of LM337 of the TO-220 variety. While these are flat-pinned and wont fit through the holes without adaption, the dimensions are basically the same. Is the input/putput/variable pinout the same as the TO-92 also?

Or maybe i should just order a bunch of modern LM337s?
nigel
Stinktier86 wrote:
I happen to have a clip of LM337 of the TO-220 variety. While these are flat-pinned and wont fit through the holes without adaption, the dimensions are basically the same. Is the input/putput/variable pinout the same as the TO-92 also?


NO, the pinout on the LM337L TO-92 and the LM337 TO-220 packages are different. The TO-92 is Adj / Out / In, the TO-220 is Adj / In / Out.
qfactor
Also remember the silkscreen on the PCB of the Lm337 is reversed too! thumbs up
designator
Fetched boards and panels from the customs yesterday. Great stuff! It's peanut butter jelly time!
Thank you very much!
bsmith
qfactor wrote:
Also remember the silkscreen on the PCB of the Lm337 is reversed too! thumbs up

Mine are working fine with the lm337 oriented as shown on the screen.
Stinktier86
bsmith wrote:
qfactor wrote:
Also remember the silkscreen on the PCB of the Lm337 is reversed too! thumbs up

Mine are working fine with the lm337 oriented as shown on the screen.


Huh.. huh? and there's a stable -6v coming out?
Since the emitter is in the middle, that won't change, and you would get a voltage into the adjuster either way, but.. it shouldn't be possible to control via the trimpot.
negativspace
Odd, right? It does work either way. That's why I never noticed the reversed silkscreen. seriously, i just don't get it
woodster
I should have 5 of the obscure unobtainable 10k dual gang pots spare.
Hopefully getting the delivery next week.
If anybody in the UK needs one, PM me.
They cost me £1.60 each, add £1 for 1st class postage.
Stinktier86
negativspace wrote:
Odd, right? It does work either way. That's why I never noticed the reversed silkscreen. seriously, i just don't get it


My best layman guess is that it works because the (untrimmable) adjuster voltage simply divides (or subtracts, i'm unsure) the input voltage. In other words, the division/subtraction is fixed but the voltage to be divided/subtracted is variable by trim. Even if the sources are mixed up, the emitter point of the LM337 wouldn't know the difference. But then i haven't looked at the circuit or its diagram (or the component's diagram).

Anyhow, i'd swap around even if it 'works', the risk being the only reason for the emitter reading a stable -6v is because of the stability of the source (ie. the power supply on the prototyping desk or the synth's internal PSU). If the source proves unstable at some point, chances are the regulator won't really regulate. Just a guess, but i'd be cautious.
Morbid
gbiz wrote:
I just replaced the six pairs of transistors in the filter section with matched ones & that's fixed it on both. nanners


So this fixed the bleed problem?
qfactor
Ok, I just finished my build and also found that the filter (in LP mode) doesn't close completely at its minimum knob position. What I'd assume one poster described his as "bleed"?
Also, when I do a filter sweep, the effect is most effective from minimum up to 12 o'clock poisition of the Cutoff Freq knob.
Beyond this, it's high frequency all the way (Rufus, my Scottie would probably "appreciate" this portion, more! seriously, i just don't get it ) hyper

These are all with NE5532 op-amps plugged in (as I mentioned in an earlier post that I have a lot of these). Maybe, I should test it again with TL072s?
But if some of the others are also facing this issue, any suggestions as to where to look at in the circuit to expand the effective range of the sweeps? I know some of you got yours "just right", so what did you do differently?! hmmm.....

Also, is there a trim for the V/O input as, in self-osc mode, with a keyboard plugged in, I'm getting a major scale by playing chromatically from C-G(!!) d'oh!

Any suggestions would be most appreciated! thumbs up
negativspace
Sounds to me like those opamps are not suitable for this application. I'd try swapping in some TL072s before you dig too deeply into the circuit.
qfactor
negativspace wrote:
Sounds to me like those opamps are not suitable for this application. I'd try swapping in some TL072s before you dig too deeply into the circuit.


You know what? Popped in the 3 TL072s and *presto* it woirks!! nanners Rockin' Banana! It's peanut butter jelly time! It's motherfucking bacon yo
Sweeps all through and Fc set at minimum makes no sound! applause

So now we know that NE5532s won't work.... d'oh!
crc
the "bleeding" i'm experiencing with this filter is not that the cutoff pot's range wouldn't be enough, but when the filter cutoff is at zero, there is a silent unfiltered signal bleeding to be heard. (i have TL072's) i think the same happens in HP mode but that is not so easy to spot.
the bleeding is not loud and you can not hear it in the mix, but it's there and you can hear it quite clearly especially with headphones.
negativspace
qfactor wrote:

You know what? Popped in the 3 TL072s and *presto* it woirks!! nanners Rockin' Banana! It's peanut butter jelly time! It's motherfucking bacon yo
Sweeps all through and Fc set at minimum makes no sound! applause


That's what I thought would happen. SlayerBadger!

The 5532s could probably be used if you tack on some stabilizing capacitors, but swapping to the TLs is much more elegant solution. Also it must be said that I tried this thing with many "better" opamps and I ended up going with the TL072s on purpose.
Jarno
Do you think the FET input of the TL07*'s could help? Maybe that's also a reason for the filter working with TL072's but not with NE5532.
Morbid
I think I found a fix (kind a) for the bleed problem.
I spend the whole morning replacing all transitors with matched one's.
But that made no difference Dead Banana .
I used the trimmer for 1V/O to get it fully closed.
So maybe I used a wrong resistor somewhere.

@Negativspace
Maybe you can add a picture of the silkscreen on the first page.
That makes it easier for troubleshooting.
Reality Checkpoint
Hello,

Whilst doing the final troubleshooting on these boards I realised that I completely neglected the SMD caps!

I have looked online but you have to buy a 100 or more, and I certainly do not want that many! So, does anyone in the UK have 8 x SMD 0805 0.1uF capacitors they could let me have? I have plenty of chips (see my post in the parts trading thread) that I could give you in return.

I actually only need 4 but having never done any SMD soldering I am bound to burn the little gits!

Cheers,

Simon.
gbiz
Simon, i've got some you can have. I just PM'd you.
Reality Checkpoint
gbiz wrote:
Simon, i've got some you can have. I just PM'd you.


....... And replied, thank you!
Randy
Can't you just solder a normal cap carefully in place of the SMD?

Randy
crc
SMD parts where really easy to solder. i didn't have any problem with mine, and i'm not a pro by any means. just add a little solder to both pads before you put the SMD part in. then put the component in place and carefully heat the solder pads from the side so that the part sinks into place. really easy!
Reality Checkpoint
crc wrote:
SMD parts where really easy to solder. i didn't have any problem with mine, and i'm not a pro by any means. just add a little solder to both pads before you put the SMD part in. then put the component in place and carefully heat the solder pads from the side so that the part sinks into place. really easy!


Many thanks, I shall give this method a go!
Reality Checkpoint
Randy wrote:
Can't you just solder a normal cap carefully in place of the SMD?

Randy


I suppose I could, but I really ought to face the inevitability that is SMD!

I suppose it is all a question of confidence really, as it wasn't until just a few months ago that I had ever picked up a soldering iron!
Randy
I used regular caps. In my case it wasn't confidence (I have soldered a bit of SMD) but availability.

Randy
qfactor
Me too. I just soldered a couple of normal ceramic 0.1 caps in there. Due to the pads with no through hole, I guess it's pretty much doing the same to the normal caps, ie, put as little solder on the pads, secure the cap legs to the solder and melt it away!

One other thing when doing the SMDs is to have a pair of tweezers around! With the size of those SMDs, handling them with fingers is almost too clumsy!! seriously, i just don't get it
polyot
Finished this bad boy up last night. The filter is a beauty, but something is up with my mixer section and I could use some help trying to track down what.

- I used the instructions a few pages back for trimming. The -6v trim went just fine. No problem.

- Measured the test point "-" (+) on the board which Jason said should hover around "55 and 110mV". I was getting something like 2.12V. Then I tested "+" (-) on the board and got something like .15V. The null trimpot had no affect on it at all.

- So while I might have a bad trimpot, I'm also wondering why the "-" test point was so high. Anything else I can look at? Would it be possible to get a photo/rendering of the board unpopulated so that I can recheck my resistors?

Functionally, it works, though I have to have the resulting input volume cranked up all the way to use the filter. As a result of this, Mix - and Mix + output very loud. Very odd.

I've had great luck building modules thus far, but am a bit of a noob when it comes to diagnostics and troubleshooting.

Still, awesome filter. Rockin' Banana!
windspirit
qfactor wrote:
Me too. I just soldered a couple of normal ceramic 0.1 caps in there. Due to the pads with no through hole, I guess it's pretty much doing the same to the normal caps, ie, put as little solder on the pads, secure the cap legs to the solder and melt it away!

One other thing when doing the SMDs is to have a pair of tweezers around! With the size of those SMDs, handling them with fingers is almost too clumsy!! seriously, i just don't get it


I use a tiny piece of poster tack to keep smd parts still while i solder.
Randy
Got mine built and calibrated tonight, wow, that's quite a filter! Resonance goes nuts with the input cranked, lots of fun.

I also get a bit of signal in LP mode with the resonance at minimum, but only if the input is cranked to the max. Not sure if this is normal, I'm not going to worry about it 'though. If there's an easy fix, someone let me know, but it might be just some loose tolerances in the various components.

Thanks to everyone involved in the design of this.

Randy
lessavyfav
I'm gonna order the few bits I need for this build and am getting the old itch about "best" parts- who is using the spendy transistors? I want to not sweat it and get the available/cheaper ones but need affirmation ;-)
diablojoy
Quote:
I use a tiny piece of poster tack to keep smd parts still while i solder.


now I am not the only one- yay lol
Stinktier86
lessavyfav wrote:
I'm gonna order the few bits I need for this build and am getting the old itch about "best" parts- who is using the spendy transistors? I want to not sweat it and get the available/cheaper ones but need affirmation ;-)


Wondering this too - got my parts drawer full of the 'regular' ones but i'm still hesitating over soldering them in.
Randy
I used the regular stuff. Would it sound "better" with the fancy stuff? Who knows, define better. How does the better stuff interact with the tolerances in all of the passive components?

I think you would need to build a version with sockets for the fancy stuff. Then you could compare directly without worrying about differences in tolerances in other components changing the sound.

Or, you could just build it with what you have and actually be using it.

Randy
polyot
On further testing re: my above post, the null trimpot actually affects the '-' measurement, but not the '+'. Is is possible I have something in backwards somewhere?
sammy123
I built a fancy one. Maybe if I build my second one I'll go non fancy and do a comparison. But that probably won't be for a while since I have a queue of filters in my backlog.
Randy
polylot, the + and - labels are reversed on the PCB.

Randy
lessavyfav
Randy wrote:
I used the regular stuff. Would it sound "better" with the fancy stuff? Who knows, define better. How does the better stuff interact with the tolerances in all of the passive components?

I think you would need to build a version with sockets for the fancy stuff. Then you could compare directly without worrying about differences in tolerances in other components changing the sound.

Or, you could just build it with what you have and actually be using it.

Randy


Thanks! Neurosis averted!
Randy
Whew, that was close. Now I just need to do something about my own Neurosis.

Randy
polyot
Randy wrote:
polylot, the + and - labels are reversed on the PCB.

Randy


No I know that. But following Jason's instructions from page 55:

Quote:
6) Measure the test point labelled "-". This incorrectly corresponds to the jack labelled 'mix +' on the front panel. It should read somewhere between 55 and 110mV, give or take. The null trimpot won't effect this measurement, so just note the voltage. It may bounce around a bit. Just... ballpark it.

7) Measure the test point labelled "+". The null trimpot will effect this voltage so you now have two choices:


The trimpot on mine affects the '-' measurement (mix +) but not the '+' (mix -). So I've goofed somewhere.
Randy
Oh, sorry. Those instructions are a bit confusing, at least for me. I just put the common probe from my multimeter on the G pad and the positive probe on the - pad (that's supposed to be +) and adjusted the NULL trim until the reading was 0.

So, I did this:

1) As mentioned, the ground pad is over by the lower screw hole on the left-hand side of the PCB.
2) Adjust -6V trimpot until the test point "-6V" reads -6.00V. This test point is down by the LM337.
7b) Forget Step 6 and adjust the null trim until the voltage at TP "+" is ~0.00V.
8) You're done with the mixer.

Then I adjusted the v/oct until the filter opened (using the LP out) just as I turned the Frequency control. To be honest, I have no idea if it sounds "right" but I like it.

If that's not working for you, check obvious stuff, like potential solder bridges, diodes in the wrong way, ICs inserted backwards, that sort of thing.

Randy
bsmith
Try flipping the lm337 too...
polyot
Randy wrote:
Oh, sorry. Those instructions are a bit confusing, at least for me. I just put the common probe from my multimeter on the G pad and the positive probe on the - pad (that's supposed to be +) and adjusted the NULL trim until the reading was 0.

So, I did this:

1) As mentioned, the ground pad is over by the lower screw hole on the left-hand side of the PCB.
2) Adjust -6V trimpot until the test point "-6V" reads -6.00V. This test point is down by the LM337.
7b) Forget Step 6 and adjust the null trim until the voltage at TP "+" is ~0.00V.
8) You're done with the mixer.

Then I adjusted the v/oct until the filter opened (using the LP out) just as I turned the Frequency control. To be honest, I have no idea if it sounds "right" but I like it.

If that's not working for you, check obvious stuff, like potential solder bridges, diodes in the wrong way, ICs inserted backwards, that sort of thing.

Randy


Interesting. I'll just go with how you did it there. Haven't touched the v/oct yet, that'll be next so this is a great help. Thanks!

I will give some thought to the LM337 as well bsmith. I had already soldered it 'correctly' before it came up that reversing it might be a good idea.
bsmith
Bizarrely, the first one I built I had the 337 aligned as the screen showed and I was able to trim that + mix - the next two I needed to flip that to get trimming going on to chase the offset away...
polyot
bsmith wrote:
Bizarrely, the first one I built I had the 337 aligned as the screen showed and I was able to trim that + mix - the next two I needed to flip that to get trimming going on to chase the offset away...


This sounds like it might be the ticket then. thumbs up I'll probably put it off for a bit, but will give it a try.
ym2612
Well, even after I thought I'd trimmed mine in correctly and reversed the 337 as per the notes, the mix output is much louder than the other outputs. Also, the frequency dial doesn't really start to kick in until around 12-1:00. I guess either I've got a weird value of pot or I've got an incorrect resistor value in there somewhere. I'll debug it some weekend when I've got time to kill.
Stinktier86
On the other hand, 100pcs of PN100A is the cost of your standard hangover pizza. Well enough to complete my four pcbs and have extras for future projects. *Neurosis reinstated* *dangerous thinking*
polyot
Could anyone that did not start building their filter put up a photo of the main board, unpopulated? Would definitely help with debugging and double checking everything.

Although, my audio interface just bit the dust so I'm not testing much of anything for a little while. Dead Banana
thetwlo
polyot wrote:
Could anyone that did not start building their filter put up a photo of the main board, unpopulated? Would definitely help with debugging and double checking everything.


here ya go:
Picture file
polyot
thetwlo wrote:
polyot wrote:
Could anyone that did not start building their filter put up a photo of the main board, unpopulated? Would definitely help with debugging and double checking everything.


here ya go:
Picture file


You are awesome, thank you applause
Nordcore
thetwlo wrote:
polyot wrote:
Could anyone that did not start building their filter put up a photo of the main board, unpopulated? Would definitely help with debugging and double checking everything.


here ya go:
Picture file


And some derived work:

Top overlay with component values:


Resistors checked against image from the completed board from the second posting in this thread.

Exclamation marks:
Both regulators flipped to original board silk screen. (78L05 as noted in the build documentation, LM337 double checked by traces & data sheet. )

390k might get sockets (pins from an IC socket or so) so it could be changed easily.

As stated in the build docu:
Put only one "1k Ohm TC" in, either the thru hole on top or the SMD one on bottom. You can use a standard 1k Resistor here, the "Tempco" is only needed für temperature compensated octave tracking of the resonance frequency. As these 12dB Filter are pretty unstable in self oscillation anyway using a temp compensating resistor here is somewhat of a luxury thing.
thetwlo
Nordcore wrote:


And some derived work:

Top overlay with component values:


THANKS!!!! that is very helpful/time saving. SlayerBadger! SlayerBadger! SlayerBadger!
jgb
PCB:s and panels arrived last week, time to order parts! smile
Zergon
would there be a problem if i solder 1,1k smd resistor?

edit: ok got it, didn't see Nordcore's post. d'oh!
Randy
Nordcore, nice! Wish I had that before I built mine.

Randy
Royalston
Does anybody have any idea how to adjust this circuit - I have almost no notch sound - from 9 oclock to 3 o clock on the 'notch -lp-hp' knob I just get a volume drop (taken from the notch out).

I feel like my high pass should go a lot higher too.

Great filter sound though!
qfactor
Couple of questions:

1) why is this known as a "state variable"? Which "state" is it variable in? hmmm..... as compared to a straight off, VCF?
2) how many pole is this filter?
Thanks! thumbs up
Randy
1. Ohio only apparently.
2. No Poles, just Italians I think.

1. High pass, band pass, low pass - multiple filter "states" from one input.
2. Usually 2 for this kind of filter but I could be wrong.

Randy
qfactor
Randy wrote:
1. Ohio only apparently.
2. No Poles, just Italians I think.

Randy


Yeah, re-reading my 1st message after I sent it off to this forum, I was kinda expecting those answers!! d'oh!
hihi
mcop
Got my build working and I'm having loads of fun with it. Thanks

Only issue I had with the build was purely mechanical and easily resolved. I thought I'd mention it though for anyone about to build.

I used Tayda pots with dust covers on the mixer inputs and discovered you couldn't get the bolt through to bolt the boards together without removing the dust covers on the pots for input 1 & 3.
Randy
qfactor wrote:
Randy wrote:
1. Ohio only apparently.
2. No Poles, just Italians I think.

Randy


Yeah, re-reading my 1st message after I sent it off to this forum, I was kinda expecting those answers!! d'oh!
hihi


Sorry, I couldn't resist. At least I followed up with real answers.

Randy
bartleby
Nordcore wrote:
390k might get sockets (pins from an IC socket or so) so it could be changed easily.

what's that one about, again? why would you want to be able to change that particular resistor?
Nordcore
BOM says 390k (* = change to alter signal level from mixer to filter section. Suggested range is ~270-470k.)
negativspace
Trimming instructions added to the BOM post.
designator
Quote:
Couple of questions:

1) why is this known as a "state variable"? Which "state" is it variable in? hmmm..... as compared to a straight off, VCF?
2) how many pole is this filter?


Circuits like these are used in analog computers. It models ( and is ) a second order dynamical system (i.e. it contains two energy storing elements - integrators). It is used to compute variables - the "state variables" of the system. The value of those state variables are measured (as a voltage) at the outputs HP, BP, LP). For a mechanical system (spring-mass system for example) the state variables are the mass's

1: acceleration - HP output
2: velocity - BP output
3: position/displacement - LP output

The number of poles is related to the order of the system.
windspirit
Hmmm your explanation sounds a lot smarter than mine but I always thought that they were called state variable because you can smoothly transition between lowpass and highpass "states" ?
designator
'State variable' is a technical/scientific term meaning a 'variable that describes a state', instead of 'state that is variable', so the name is there for historical reasons. For audio (you can see this kind of filter often in parametric equalizers) and synthesis purposes the state variable itself is of no importance so the original meaning got lost and was reinterpreted.
designator
Sorry, double post...
duff
I have an issue that I think must be due to a mistake somewhere, but I am not sure where.

I can dial in -6V easily enough on the relevant trimmer, but whatever value I see here is also exactly what I see on both the - and + pads. Adjusting null has no discernible effect on the - pad at all.

Anyone else seen this or can provide any pointers as to my error?
negativspace
I just built one with the exact same issue... I haven't really had any luck finding the problem, though. Are you getting any audio out of the mixer section at all? (Mine passes only the -6V, no audio. The filter section works fine insofar as the self-oscillation is functioning.)
duff
I found my issue . The PCB had sat mostly stuffed as I had run out of 62K and 200R resistors. These were duly ordered and received, but not actually soldered in d'oh!

Not sure how I missed that when I was looking over the board last night but unsurprisingly with these added it works a lot better lol
NekoNeko
Gutted i missed this one! Perfect filter for me and built in mixer is nice!

If anyone's got spare pcb's and panels please let me know.
negativspace
I have spare sets available, order at will! thumbs up
negativspace
duff wrote:
I found my issue . The PCB had sat mostly stuffed as I had run out of 62K and 200R resistors. These were duly ordered and received, but not actually soldered in d'oh!


Ha, that'll definitely help! hihi

Mine, I'm afraid, is not going to be that easy. All my parts are correctly picked and placed and it still passes only 6V. Even with the transistors and half the resistors in the mixer section lifted. I suspect a PCB error, probably a short somewhere, but damned if I can find it. d'oh!
NekoNeko
negativspace wrote:
I have spare sets available, order at will! thumbs up


Amazing!!

Can I order 2 x pcb and panel sets with shipping to the uk please.

New to ordering from muffwiggler so what's the plan? Paypal ok?
negativspace
Yes, there are payment details for Paypal at the very beginning of the thread and those are valid as long as I have stock. thumbs up
Sittidae
Could I order 2 x SVVCF panel & PCB please

Plus any 1 each of any E.A.S Miss10 front panels you have (VCO, LFO, HADSR, Mindreader)

+ UK shipping
NekoNeko
negativspace wrote:
Yes, there are payment details for Paypal at the very beginning of the thread and those are valid as long as I have stock. thumbs up


Cheers, missed that in my sleep deprived state. Payment sent. Whats the shipping time like to the UK, I know how long is a piece of string question but has varied so much for me in the last year.

Very excited to receive these.
gbiz
Cool. I was wondering if there were any more of these available. I just pp'd you for another two Jason. Loving the sound of this filter.
negativspace
Glad to hear!
Zergon
Can I use 2,7nF ceramic cap?

Anyone tried "Kobiconn" jack sockets?
negativspace
Kobiconn #16PJ138 sockets will need to be grounded but they should work aside from that. Grounding them is easy; I've used them in a prototype or two.

A 2.7nF cap is a 2.7nF cap, if you have ceramic that'll work.
negativspace
Doublepost gremlins got me! MY ASS IS BLEEDING
drip.feed
Just finished my first build. Jason, this filter sounds superb. What a beauty.

My mix + & - outputs are a lot louder than the filter outs...is that normal?
chito
negativspace wrote:
I have spare sets available, order at will! thumbs up


Any chance I can still get one of these pcbs and panels?
drip.feed
I have build a 2nd one of these and there is almost no resonance when I turn the res pot. And it only self-oscillates for the first quarter turn of the Freq pot, then the sine wave disappears.

Could it be the weird Res pot? I bought two identical from Banzai, and the first one is working fine in my first build, but if the pot was defective would it cause the symptoms I'm seeing? waah
Dogma
Please tell me Im not to late to get a kit? I just heard this filter and must have it.
negativspace
Not too late at all. thumbs up
Dogma
It seems I might need to order a few things from you..... HOw do I go about it?
negativspace
PM'd
seepaxton
Hey there! I was wondering if I could order a pcb set and panel??

Cheers

Conor
iL
mine -6v allways gives me -10.4v the -6v trim does nothing.

i allready change two times the lm337 and one time the 2k trim

no change. also tride different orientation of the lm337.
is the orientation important?
Dogma
Ordered! How did you guys find the build? Theres no wiring is there?
sammy123
I found the build to be pretty simple. There is some work extend the jack legs, but it is simple. I made it harder by using 9mm Alphas.
iL
i found it also straight forward. i will see how much the debugging will take.
Dogma
iL wrote:
i found it also straight forward. i will see how much the debugging will take.


What do you mean - you found the build simple but youve not calibrated it?
negativspace
iL wrote:
mine -6v allways gives me -10.4v the -6v trim does nothing.

i allready change two times the lm337 and one time the 2k trim


Don't forget the fix posted in the first few posts. You won't get -6V trimmed unless you do. If you still have trouble after adding the jumper, let me know and we'll sort you out. thumbs up


[Edit: added more detail when not posting on phone.]
iL
yet not. hope i going to find the problem so i can calibrate it. hihi
iL
the little wire bridge seems to done the trick.
negativspace
w00t
iL
yeah.

but next: audio seems not to pass throu to the filter.

i only got audio thru the + mix out. everything else nothing or really
quite. filter is running and sweeps nice.

negativespace: didnt you got some similar problem? any hints?

how to measure the 0v thing on the +/- part? i can measure there something like -6.01v (-) and -5.93v (+)
salih03
hi,
please one panel and pcb !
thanks
negativspace
I had the same thing, 6V on the + and - test points. It turned out to be - as I suspected - a short on the PCB. The location of the short was along the trace that leads from Q1 into the resistors, along the edge of the board there. I cut it free from the ground pad and it's working - it's making sound right next to me as I type this, matter of fact.

Inspect that trace, test for continuity between that and ground, etc. and see if that's the culprit. I hope it's that simple.
iL
e of Q1 seems to go to ground. is this the bad one? can you point me were do you made the cut?
negativspace
Yep, that's the bad one. w00t

There's a thinnnnnn bit of the ground plane that runs between that trace and the edge of the board. I bet that sliver of grounded copper has been dragged into the trace that leads from the emitter of Q1 there. I just cut that whole thin bit of copper loose from the ground plane at both ends, one tiny cut at each corner there where it gets thin should do it.

I thought I'd lined it up so there was no copper there, fearing this exact problem, but... seriously, i just don't get it
iL
so i guess you mean this, the short passage on the edge going from Q1 emitter to R(whatever). that looks quite risky on the microcam.


negativspace
Exactly that... mine looked nearly identical. Mind the little squiggle there that appears to connect to the plane there between B and E of Q2.
iL
that made my day. thanks negativspace.

for everyone else if you just got no audio on the filter this fix it. cut the red marked pieces out to free up Q1 e is drains away to ground plate.


negativspace
I love it when the first guess is right. Glad you have it working! w00t
ChrisR
FWIW, i just checked my (still unbuilt meh ) PCB and it has the same thin piece of copper touching the trace to Q1.

Thanks for the info! thumbs up
dropmotif
negativspace wrote:
BOM
Here is the pinout diagram for the headers, if you're wiring them up the old-fashioned way:


Wiring the old fashioned way.

Where it says "NOTCH: LP to CCW, HP to CW, WIPER to NOTCH JACK TIP"

Does this mean the LP and HP jack TIPs, or the switch connections?
drip.feed
drip.feed wrote:
I have build a 2nd one of these and there is almost no resonance when I turn the res pot. And it only self-oscillates for the first quarter turn of the Freq pot, then the sine wave disappears.

Could it be the weird Res pot? I bought two identical from Banzai, and the first one is working fine in my first build, but if the pot was defective would it cause the symptoms I'm seeing? waah


Found the problem. I used the wrong cap value for C6. very frustrating

It's amazing what a few nights sleep can do.

This filter is in my top 5 list now. It should be given to people as wedding presents.
Peake
Missed out on this and would love to pick up a few of the bare PCBs if anyone is willing to part with them. Thanks!
negativspace
Mike, I have plenty left... you're welcome to as many as you'd like.
negativspace
dropmotif wrote:
Does this mean the LP and HP jack TIPs, or the switch connections?


The LP and HP pins or jack tip lugs are good places to tap the signal.

drip.feed wrote:
Found the problem. I used the wrong cap value for C6. very frustrating

It's amazing what a few nights sleep can do.

This filter is in my top 5 list now. It should be given to people as wedding presents.


Glad you got it working!

Also glad you're loving 'em. SlayerBadger!
crc
i have to ask since my filter self oscillation is really really loud, and starts at around 11o'clock and is at full whistle at 12, if that could be a C6 cap issue too.
i checked the cap i have there bit i was not able to confirm the actual value of the cap i have there. thanks!
iL
great filter!

but i also have some bleed on hipass. its not that the filter cuts all hi freq away.

here is a freq band with a square wace full ccw:


and another with full cw:


you can see the bleed in the second one. the hp filter effect is audible, but on the end you have still some original sound in the background.

can this be eleminated by the MIXER trim?
negativspace
That's the v/oct (CV scale) trim. There is no "mixer" trim.

I've chased down that extra signal in the HP for literally weeks... can't get rid of it. It's present all the way back to my first prototype build.
iL
ok. would be cool if it could tracked down and when there is a fix for it. the hipass in the circuit sounds really great and quirky. its allready useable for the little quirky sounds but could to better. i guess the notch and bandpass would then also have a more push then.

did not scaled the v/oct yet. is there a way how to do it right? i did not installed the tempco 1k cause i did not had one by hand in smd. maybe later...


negativspace wrote:
That's the v/oct (CV scale) trim. There is no "mixer" trim.

I've chased down that extra signal in the HP for literally weeks... can't get rid of it. It's present all the way back to my first prototype build.
101010oxo
And this can be bought (fully assembled) where, please? seriously, i just don't get it
Spip
@negativspace : PM'ed

A little bit late to the party... w00t

Would it be possible to order 2 sets of PCB (for making 2 modules) without panels ?

Thanks in advance
negativspace
101010oxo wrote:
And this can be bought (fully assembled) where, please? seriously, i just don't get it


Any retailer who carries my stuff should have them in the next few weeks.

You're in Germany... Schneidersbuero will have them soon, less than 2 weeks. Their order is the one on my bench right now.
101010oxo
negativspace wrote:
101010oxo wrote:
And this can be bought (fully assembled) where, please? seriously, i just don't get it


You're in Germany... Schneidersbuero will have them soon, less than 2 weeks. Their order is the one on my bench right now.


Great news, thanks! thumbs up
memorygardens
Looking for 3 of these bad boys if anyone is willing to part with them?!
wired
Looking forward receiving mine Rockin' Banana!
pulse_divider
I built 4 of these together and 3 work fine but the fourth is having problems with the mixer section. The filter seems to be working fine in self-oscillation, I just can't get any input into it.

I trimmed the -6v and am now measuring the same -6v at the - pad and around 100mv at the + pad. The null trimpot does not change the -6V at the - pad during the second calibration step. I'm getting 4.92v at the 5v test point.

After checking all my solder joints, parts polarities and board interconnects I replaced the trimpot and it didn't fix anything. I then took the brute force approach and replaced Q1-4 and the lower TL072 and that didn't fix it.

Any suggestions?
Thanks.
Randy
Potentially stupid question time, but can someone tell me what the -mix and +mix outs should be used for? Using this as a "normal" filter works fine, send it some input, grab some output from one of the dedicated outs and things happen as expected.

But, if I send a signal into In 1 and then try use one of the Mix outs instead of, for example, the LP out, and then turn the Frequency pot, nothing happens. I get lots of output, but it is as if it bypasses the filter.

Thanks

Randy
windspirit
It's the output of the mixer section (mix - is inverted). It has a CP3 discrete mixer built in as a bonus.
Randy
So it acts only as a mixer, passing in 1, in 2 and in 3 direct to the output without going through the filter?

Cool, thanks. Not sure what I would use that for but at least I know it's working properly.

Randy
negativspace
The mixer circuit on the front end is a bit of an effect. If you want that effect in a patch but prefer another filter, you have the option. Can also make stereo patching easier.
Randy
Thanks for the reply. I'll need to fool around with it a bit more.

Randy
ppccdd
Finished building this one tonight, after about 1 hour of fooling around with it, i just had to come and say, thank you! I´m in love with it already.
pulse_divider
pulse_divider wrote:
I built 4 of these together and 3 work fine but the fourth is having problems with the mixer section. The filter seems to be working fine in self-oscillation, I just can't get any input into it.

I trimmed the -6v and am now measuring the same -6v at the - pad and around 100mv at the + pad. The null trimpot does not change the -6V at the - pad during the second calibration step. I'm getting 4.92v at the 5v test point.

After checking all my solder joints, parts polarities and board interconnects I replaced the trimpot and it didn't fix anything. I then took the brute force approach and replaced Q1-4 and the lower TL072 and that didn't fix it.

Any suggestions?
Thanks.


Anyone? Is there a schematic somewhere that I'm not seeing?
Thanks.
yan6
Hi there, I have a few of these and was wondering if I could put 10Kohm resistor across the outer two lugs on each layer in order to use it?
crc
i have to ask AGAIN. my filter self oscillation is really really loud, and starts at around 11o'clock and is at full whistle at 12. is that normal?
Jop
[list=]i have to ask AGAIN. my filter self oscillation is really really loud, and starts at around 11o'clock and is at full whistle at 12. is that normal?[/list]

Mine starts around 2 and is at full amplitude around 3. What kind of caps did you use for the 1nF's (mine are polystyrene)?

I have recorded some audio to compare. First with no input signal followed by a 555 saw. Levels not changed during recording.
crc
thanks for the repy and comparison clip.

i have used 1nF polystyrene caps. i had polypropylene caps first but just because of this i changed them to polystyrene. it helped but just a bit.
here is a clip of a saw wave from z3000 to the filter with a saw lfo modulating it at full. the first resonance sweep is from 11 to 1, and the second one is from 11 to 5.

https://dl.dropboxusercontent.com/u/3543499/svvf-filter.mp3

sounds a bit too harsh, don'y you think?
Jop
Yes, indeed. Especially the second sweep.

I'm afraid I cannot help you further besides double checking the obvious things (correct parts & values on the correct location and orientation).

BTW, I have used PN100A & PN5138 transistors.
trololoff
Built mine the other day.. did get a sense of the filter's character but the resonance is less pronounced than I'd want it to be and turning resonance past 10 o'clock causes weird feedback-like blips at some point before going into self-oscillation. Maybe its because I'm feeding it a loud bass signal all maxed out in the mixer? Will experiment.

Can anyone with a good build suggest what the knob position for the CP3 mixer on a standard saw to get a good filter sweep.

Not sure if its my build error or choice of components. Will double and triple check. Also - what are the poly caps known to be good for the build?

Many thanks!
trololoff
Can't get that nice squelch as in the filter demo by Jason no matter what.

Having double checked everything it's probably down to the wrong capacitor material type - I used Kemet PHE 450 film/polypropylene thinking it would work.. I understand polysterene is a must?

I am using PN100A/PN5138 as well.
trololoff
Found my issue! The dual-gang pot was not soldered properly - one of the leg extensions on the lugs went loose. Discovered by taking the panel off and wiggling the pots one by one. Once resoldered we are in business! It's motherfucking bacon yo

This is a great filter (thanks Jason!). Super excited to have it! applause
negativspace
I like it when it's a mechanical issue... usually pretty easy to find. Glad you got it going! SlayerBadger!
drip.feed
I'm taking this filter to Vegas to renew our vows.
NekoNeko
so received my pcbs a week or so ago, really quick thanks!

built two of them and both sound great but have issues with "bleed" mentioned earlier in the thread. When using high pass or band pass the original unmodified signal can clearly be heard even with the filter cutoff fully closed. or CW.

Read through the thread but unless i missed it no solution posted. looked at the schem's and the only point i could see where the unfiltered signal is present is the resonance pot or the input of U1 pin 6 for the actual HP.

Any ideas?
windspirit
I think it was mentioned that matching the transistors took care of a lot of bleed but like many HP filters the input signal will not be completely attenutated.
SkoPe
Maybe someone can help me here.. Yesterday received all the parts to build this great filter.

But it seems that i've ordered the wrong 1nF polystyrene caps...
got the Xicon 23PW series instead of 23PS... The only difference its on the terminal type, PW being Radial and PS Axial. d'oh!

http://www.mouser.com/ds/2/449/23p-341148.pdf


This will fit with some leg bending? I´m trying to avoid making another Mouser order. hmmm.....

Thanks guys.
horstronic
SkoPe wrote:
Maybe someone can help me here.. Yesterday received all the parts to build this great filter.

But it seems that i've ordered the wrong 1nF polystyrene caps...
got the Xicon 23PW series instead of 23PS... The only difference its on the terminal type, PW being Radial and PS Axial. d'oh!

http://www.mouser.com/ds/2/449/23p-341148.pdf


This will fit with some leg bending? I´m trying to avoid making another Mouser order. hmmm.....

Thanks guys.


I don't know why it shouldn't work.
Just try it out!
sammy123
Bending the legs won't be an issue. I have done that many times.
negativspace
They'll fit fine with some leg-bending. My first prototype board is sitting right next to me on the desk and guess which capacitors I used? 8_)
mcop
I used them too as Mouser where out of the other type at the time.
iL
so is there a verified testing that matched transistor will get away the bleed in HP?

as i looked checked the threat there where differnt results on this. also would be great if so it should be marked in the BOM which transistors should take care of matching.

just wanted to know befor i buy a bunch of these:
http://www.mouser.de/ProductDetail/Analog-Devices/MAT12AHZ/?qs=sGAEpiM ZZMv9Q1JI0Mo%2ftQd1ICN3SH2P

razz Mr. Green
just joking! but would be nice to know before i try to order a large batch of PN100As.
negativspace
No, the bleed has nothing to do with the transistors. I'm working on that one, give me a couple of days.

I also have a few resistor changes to recommend in the resonance and output amplifier areas of the circuit which will help those of you with extra-strong resonance to tame that a bit. (Not necessarily recommended for everyone - one of my prototypes does not need the fix but the production run I'm doing does.)
crc
negativspace wrote:
No, the bleed has nothing to do with the transistors. I'm working on that one, give me a couple of days.

I also have a few resistor changes to recommend in the resonance and output amplifier areas of the circuit which will help those of you with extra-strong resonance to tame that a bit. (Not necessarily recommended for everyone - one of my prototypes does not need the fix but the production run I'm doing does.)


Good news! This is fun!
NekoNeko
negativspace wrote:
No, the bleed has nothing to do with the transistors. I'm working on that one, give me a couple of days.

I also have a few resistor changes to recommend in the resonance and output amplifier areas of the circuit which will help those of you with extra-strong resonance to tame that a bit. (Not necessarily recommended for everyone - one of my prototypes does not need the fix but the production run I'm doing does.)


Good news in regards to the bleed, I decided to try matched trannies and got the same results, still bled and no real difference to the circuit.
negativspace
The bleed in HP mode will never go away entirely, it's inherent to the core of the filter. But with a couple of tweaks it can be mitigated a bit. thumbs up
crc
I just need to know how to tame down the
resonance bit
livefreela
hey jason, what would be those resistor swaps. i love my filter as it is, but the resonance is a tad strong; especially relative to the overall audio output (usually relatively low in loudness compared to my other filters, but the res screams easily highter than the rest). might those swaps be of some use, or have i fucked something up elsewhere hmmm.....
Kunfuz
I've now wasted two days at work reading all 47 pages of this and my conclusion is I need this filter badly Mr. Green

PM'd for a set of pcbs and a panel!
negativspace
livefreela wrote:
hey jason, what would be those resistor swaps. i love my filter as it is, but the resonance is a tad strong; especially relative to the overall audio output (usually relatively low in loudness compared to my other filters, but the res screams easily highter than the rest). might those swaps be of some use, or have i fucked something up elsewhere hmmm.....


No, I think that's fairly normal. I've got most of the kinks worked out, hopefully by this afternoon I'll have the whole suite of swaps. These signals all interrelate so when you change the balance in one place, 3 other balances get upset. Lots of trial and error to get everything into its sweet spot, or to get the compromise between two conflicting goals *just right*...
rosch
Alright should I get the 3300ppm or 3500ppm tempco from Thonk? Does it matter at all?
livefreela
negativspace wrote:
livefreela wrote:
hey jason, what would be those resistor swaps. i love my filter as it is, but the resonance is a tad strong; especially relative to the overall audio output (usually relatively low in loudness compared to my other filters, but the res screams easily highter than the rest). might those swaps be of some use, or have i fucked something up elsewhere hmmm.....


No, I think that's fairly normal. I've got most of the kinks worked out, hopefully by this afternoon I'll have the whole suite of swaps. These signals all interrelate so when you change the balance in one place, 3 other balances get upset. Lots of trial and error to get everything into its sweet spot, or to get the compromise between two conflicting goals *just right*...
than i shall leave well enough alone seeing that as it is now its one hell of a filter Mr. Green
mcop
rosch wrote:
Alright should I get the 3300ppm or 3500ppm tempco from Thonk? Does it matter at all?


I used the 3300ppm, think the bigger KRL tempco might be a bit of a tight fit anyway.
qfactor
mcop wrote:
rosch wrote:
Alright should I get the 3300ppm or 3500ppm tempco from Thonk? Does it matter at all?


I used the 3300ppm, think the bigger KRL tempco might be a bit of a tight fit anyway.


My question about this is, as this is not in contact (or at least, it doesn't have to be) with any other components, then what is it basing its temperature on, to change its resistance to?!! seriously, i just don't get it
Crashlander42
I really want to build this one. Does anyone have a board they want to get rid of, or is Synthcube going to pick this up at some point?
nikmis
I built two behind one panel. One of them works perfectly, the other works great too but doesn't self-oscillate. It has like half resonance. Does anybody have advice on what components to check? besides the resonance pot of course
drip.feed
nikmis wrote:
I built two behind one panel. One of them works perfectly, the other works great too but doesn't self-oscillate. It has like half resonance. Does anybody have advice on what components to check? besides the resonance pot of course

Check your C6 value. And check your R13 value.
nikmis
thanks, but those are correct. I figured out what area to look in, at least. The fact that the resonance control works, just not enough, made me think that is the resistor value between the resonance amount pot and the mixer input, where it feeds back in.
NekoNeko
Hate to nag I know your busy but i really need a fix on the bleed issues. I'll have to record a sample as I get the impression it's worst than other builds on mine, it doesn't seem to bother others too much.

Any chance you could point me to which part of the circuit to debug?
yan6
Guys, I built two of these both with the same resonance; and both just squeal in self oscillation. Any suggestions where to look for misplaced components.
nikmis
yan6, the first place I would look is the wiring of the dual resonance pot. I guess if you built the full eurorack assembly that isn't an issue

after that, check these component values and check for solder problems around them. after that, there are probably other places to check


but I am the wrong person to answer this because I still have only one of my filters performing correctly.
nikmis
Well, I fixed my problem. I reduced the 33k (r16) to 22k and it works just perfectly. The same as its twin which still has a 33k.

At first I tried changing the 10k near C6. That made the filter self-oscillate but made the filter sound like garbage.

I think that is what negativespace was talking about in the older thread
Quote:
The dual-gang pot, BTW, is for the resonance control. I tinkered with the circuit and found that it never seemed to go down to 'zero' resonance. I played with R7 from Scott's schematics and found that higher values gave a lower minimum resonance but in doing so it lost that lovely 'bite' that it has at high resonance. My solution is a 10k dual pot; one side is the resonance pot as drawn and the other side goes in series with R7. As you reduce resonance you increase the resistance of the pot so that at '0' you have 20k in that slot.


Now thats fixed, I too have the bleed that nekoneko is talking about. You can hear the low pass very well in the highpass output. That's the next task
nikmis
Quote:
You can hear the low pass very well in the highpass output. That's the next task

oh sorry, its not the lowpass that you can hear in the highpass output, its the original signal.
crc
nikmis wrote:
Well, I fixed my problem. I reduced the 33k (r16) to 22k and it works just perfectly. The same as its twin which still has a 33k.


i tried this and replaced the 33k to 22k and i think my "resonance too loud" problem just got worse. to be more clear it sounded more distorted and "broken" for the lack of a better word. :(
negativspace
^ That's normal. That is the summing resistor for the resonance signal. Higher value = less amplitude.
crc
negativspace wrote:
^ That's normal. That is the summing resistor for the resonance signal. Higher value = less amplitude.


ok should i try it with a bigger value then?
other than that, a coulple of my friends have this filter too and their resonance starts self oscillating at 2-3 o´clock, where mine starts at 11 o´clock in a really loud way. saying that the pot travel there from no self oscillation to full is from 11 to 1 or something like that.
negativspace
Yikes... with the 33k mine have all kicked in at around 2-3 o'clock as you say. I've never built one that comes in so early! You can try larger values in that spot to try and cure the symptom, but I'd also doublecheck resistor values elsewhere too. What's in R13, 390k?
crc
negativspace wrote:
Yikes... with the 33k mine have all kicked in at around 2-3 o'clock as you say. I've never built one that comes in so early! You can try larger values in that spot to try and cure the symptom, but I'd also doublecheck resistor values elsewhere too. What's in R13, 390k?


i tried different values in r13 without any effect on the resonance.
i think it's something like 300k at the moment.
crc
ok i replaced the 33k restistor with a 50k one (closest i had in that ballpark little over 33k) and R13 with a 390K, and i have to say i'm quite happy with the results now. self oscillation isn't over the top loud and self oscillation happens after 2 o'clock > ... Guinness ftw!

Edit: self oscillation with oher audio still sounds quite distorted rather than liquid/squelchy. should i still try a different resistor in r13? higher or lower value?
L-1
I've assembled but made some changes:

- I wanted louder and choosen R13 120K

- I changed opamps to OPA2604. It made the sound much nicer.

- Frequency knob opened the filter not from beginning therefore I connected CCW pin through 300K to V- and changed wiper's resistor R47 to 160K.

- Changed HP mode 82K resistor to 62K. It made HP loudness equal to LP.

- HP or BP sound was heard where the filter was closed in LP. I normalled BP and NOTCH jacks to ground. It made this bleed much quiter near noisefloor.

- Input sound is heard in HP mode. Can't do nothing with that because of the filter schematic. I tried to connect reso loop, feedback loop, inputs to + and - inputs of the opamp in different combinations with no success.

This is a record. I turn FREQUENCY knob twice in LP, then BP, then HP, then NOTCH, then selfoscillation.

Wave - saw from the new L-1 Basic VCO.

Please download the file because Soundcload distorted it much.

[soundcloud url="https://api.soundcloud.com/tracks/180607611" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]
jgb
Hi everyone!

I am finally getting around to building this filter, but feel quite unsure as to what pots I should order. I would prefer to order from as few suppliers as possible (freight to Sweden is not always that cheap when ordering from outside of Europe).

All components will be ordered from Mouser (as part of a much larger order), so if any suitable pots can be found there I would be really happy. I am also planning to order from Banzai Music, but if some other supplier has all pots needed I would gladly order from them.

Could someone please help a newbie when it comes to ordering pots? smile
drip.feed
You will need to buy the resonance pot from Banzai or Musikding. I don't think Mouser has them. The only places I could find that pot were Banzai and Musikding (Germany) and SmallBear (USA).

But I think I remember Mouser having everything else.
sammy123
That's interesting. Thanks for sharing. I should build up my second one and compare.

L-1 wrote:
I've assembled but made some changes:

- I wanted louder and choosen R13 120K

- I changed opamps to OPA2604. It made the sound much nicer.

- Frequency knob opened the filter not from beginning therefore I connected CCW pin through 300K to V- and changed wiper's resistor R47 to 160K.

- Changed HP mode 82K resistor to 62K. It made HP loudness equal to LP.

- HP or BP sound was heard where the filter was closed in LP. I normalled BP and NOTCH jacks to ground. It made this bleed much quiter near noisefloor.

- Input sound is heard in HP mode. Can't do nothing with that because of the filter schematic. I tried to connect reso loop, feedback loop, inputs to + and - inputs of the opamp in different combinations with no success.

This is a record. I turn FREQUENCY knob twice in LP, then BP, then HP, then NOTCH, then selfoscillation.

Wave - saw from the new L-1 Basic VCO.

Please download the file because Soundcload distorted it much.

[soundcloud url="https://api.soundcloud.com/tracks/180607611" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]
jgb
drip.feed wrote:
You will need to buy the resonance pot from Banzai or Musikding. I don't think Mouser has them. The only places I could find that pot were Banzai and Musikding (Germany) and SmallBear (USA).

But I think I remember Mouser having everything else.


Thanks! I digged a bit further on Banzai and found everything needed, assuming that 16mm pots will do in all places. smile
4floorsofwhores
2x just pcb please
crc
tried a few of these "mods" L-1 posted about.
didn't notice any difference with opa2604 opamps. maybe i wasn't listening hard enough. razz

L-1 wrote:
I've assembled but made some changes:
- HP or BP sound was heard where the filter was closed in LP. I normalled BP and NOTCH jacks to ground. It made this bleed much quiter near noisefloor.


all this did was make the LP output ALOT quieter. Maybe i did something wrong here. care to take a picture of the groud wiring?
negativspace
If you keep the notch balance pot centered that works. if you have it toward either end, you'll lose volume and eventually short LP or HP out to ground. The real solution there is to buffer the notch output, which should be do-able but will require a board revision.

As luck would have it I'm down to about 8 of these left, though, so the iron is hot for striking.

All of the other changes I've settled on for my version can be done to the existing hardware. I'll post those when it's not 5:30 in the morning and I haven't been working for 15 hours. zombie
L-1
Quote:
all this did was make the LP output ALOT quieter. Maybe i did something wrong here. care to take a picture of the groud wiring?


This happens if NOTCH pot is full LP, turn it closer to center and LP out will sounds loud.

Quote:
didn't notice any difference with opa2604 opamps. maybe i wasn't listening hard enough.


I have OPA2604 in my final mixer and everywhere in my system. I was with friend when changed opamps and we both noticed big difference in good direction.
sammy123
Hey Jason, thanks for including all the safety measures into these modules. I was in a hurry for my first rehearsal last night with a new group and had to throw together a portable setup in less than a hour. I was running around like a mad man and could not figure out my issue. I had a reversed power cable going to the SVVCF. No damage. thumbs up
negativspace
SlayerBadger!
Logite
are there any kits around? if not i'll take a panel+pcb smile
Monobass
I'll have Panels and PCBs at Thonk soon.
Kunfuz
Got my SVVCF and VCA last week Jason, thanks a lot hyper
onthelees
Sorry to be such a noob, but I am trying to order the BOM for this on Mouser and there seem to be a million choices for everything. Is 2.54mm the correct spacing for the headers? will any 16 pin 2 row w/ 2.54mm spacing work? same for the 12 pin?. The pots. Should Audio input be log taper, and everything else linear? or does it matter in this case?

Thanks,

Brian
negativspace
^ Correct on all counts - basically any 16 or 12 pin, 2-row header on 2.54mm (0.1") spacing will work. Some have oddball pin lengths so it's not entirely fool-proof. I use part #s 649-67996-416HLF and 412HLF... you can probably guess which is which.

Female headers I get @ Pololu so can't help with Mouser numbers on that.

A25k input pots for the audio channels, linear everywhere else.
rosch
One word about the stereo pot for those who haven't ordered theirs yet. I have the dual pot with solder lugs from Banzai. The lugs get so close to the pcb that i had to bend the lower 3 back in order to fit it in there. That means had I bought the solder pins version I could just have bent the lower row down and only wire the upper row.
Of course that may vary depending on which headers people use (I've used regular stuff from Reichelt.de) It was no problem with the lugs either, just looks more kludged (only if you look very close hehe)
tweakfilter
did you mean like this to bend? its a narrow space;)

woodster
I've still got a few of the hard to find specified PCB pin versions if anybody in the UK needs any.
They cost me £1.60 each, add £1 for 1st class postage.
ablearcher
I had gotten the impression negativspace was going to post some final resistor substitutions/mods. The semester just ended so I have time to dig in to my backlog a little, should I be waiting for those or just build it up?
Logite
Mind posting a pic of the pcb unpopulated without the values? I kinda put a 10K somewhere on the board I shouldn't have..
thetwlo
Logite wrote:
Mind posting a pic of the pcb unpopulated without the values? I kinda put a 10K somewhere on the board I shouldn't have..


go back a few pages, I posted it on Sept. 11
vtl5c3
Alex,

Thank you for posting your mods Which transistors did you use for your filter?

L-1 wrote:
I've assembled but made some changes:

- I wanted louder and choosen R13 120K

- I changed opamps to OPA2604. It made the sound much nicer.

- Frequency knob opened the filter not from beginning therefore I connected CCW pin through 300K to V- and changed wiper's resistor R47 to 160K.

- Changed HP mode 82K resistor to 62K. It made HP loudness equal to LP.

- HP or BP sound was heard where the filter was closed in LP. I normalled BP and NOTCH jacks to ground. It made this bleed much quiter near noisefloor.

- Input sound is heard in HP mode. Can't do nothing with that because of the filter schematic. I tried to connect reso loop, feedback loop, inputs to + and - inputs of the opamp in different combinations with no success.

This is a record. I turn FREQUENCY knob twice in LP, then BP, then HP, then NOTCH, then selfoscillation.

Wave - saw from the new L-1 Basic VCO.

Please download the file because Soundcload distorted it much.

[soundcloud url="https://api.soundcloud.com/tracks/180607611" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]
L-1
I used 2N3904 / 2N3906
rosch
tweakfilter wrote:
did you mean like this to bend? its a narrow space;)


I did it in the other direction, yours looks like less trouble. I also bought the long pin angled version for the others, the lower row was a PITA to bend, not recommended. (left)

Btw I read earlier in the thread that the LM337 has to be flipped too, but didn't see any confirmation by the designer.
So what's the deal, silkscreen correct or not?

edit: Works with orientation according to silkscreen
khakifridge
negativspace wrote:
There are a few pairs that "should" be matched . . .


If I were to match transistors, which ones should I be looking at? I'm guessing at the twelve snuggled up down the LHS of the board (Q8/5, Q7/6, Q10/9, Q13/12, Q16/15, Q14/11). What about the two in the Mixer side of the board (Q2/3)? Had a bit of a match-o-thon and thought it would be nice to use the fruits of my labours. hihi
negativspace
The pairs in the mixer can be matched, I match them within ~3% or so, but honestly I've tried the standalone CP3 mixer circuit with both matched and totally unmatched transistors and haven't been able to observe any difference at all.
khakifridge
Thanks Jason: might give that a go. Got a CP3 on "the list" too - could try matched/unmatched. Were the filter-side pairings right that I listed?

(Seriously, matching transistors beats Christmas telly...)
Lachlan C.
Just a quick note to say I have received my pcb/panel set - Many thanks Jason. Pumped to be building this up soon
Phetus
Does anyone have the BOM etc.? Been trying to get on for ages, but couldn't find anything anywhere. Would be very grateful if anyone could post it.
negativspace
Quickie for now:

** PLEASE NOTE THAT THIS LIST CONTAINS PREVIOUSLY UNPUBLISHED (but long-promised) RESISTOR SUBSTITUTIONS.

Resistors
[1] 1M R45
[1] 390k R13* (* = change to alter signal strength from mixer to filter section. Try ~270-470k.)
[1] 240k R33
[2] 200k R41,R36
[1] 180k R19
[1] 110k R47
[5] 100k R15,R17,R38,R39,R40
[1] 62k R42
[1] 47k R10
[1] 39k R16
[4] 22k R1,R2,R3,R35
[3] 15k R5,R7,R43
[8] 10k R18,R27,R28,R29,R30,R31,R32
[3] 6.8k R8,R14,R46
[2] 1k R21,R22
[2] 560R R9,R11
[3] 470R R20,R34,R37
[1] 240R R48
[4] 220R R23,R24,R25,R26
[1] 200R R6
[2] 100R R4,R12
[1] 1k Tempco R44* (* = optional, replace with standard 1k if temp. compensation not desired. Install either SMT or through-hole, not both.)

Capacitors
[1] 3.3nF Film C5
[1] 2.7nF Film C13
[2] 1nF Polystyrene/Polypropylene *main timing caps in VCF
[2] 22-100uF Electrolytic *decoupling caps, value noncritical
[3] 220pF MLCC C7,C11,C12
[1] 150pF MLCC C6
[5] 10uF Electrolytic Q8,Q9,Q10 = audio, the other two are for decoupling
[2] 0.1uF MLCC
[2] 0.1uF 0805 *install on back of PCB

Transistors/Diodes
[11] 2N3904/Other NPN [PN100A] Q1,Q4,Q5,Q8,Q9,Q10,Q11,Q14,Q15,Q16,Q19
[2] 2N3904 Q17,Q18
[6] 2N3906/Other PNP [PN5138] Q2,Q3,Q6,Q7,Q12,Q13
[2] 1N4001

ICs/Sockets
[3] TL072
[1] LM337LZ
[1] LM78L05 *silkscreen on v1.2 PCB is reversed
[3] 8P DIP socket (optional)

Miscellaneous
[1] 20k Trimpot (v/oct)
[1] 2k Trimpot (-6V)
[1] 100r Trimpot (null)
[2] Ferrite Bead
[1] 16P Header (power)
[2] 12P Header + socket (b-2-b)
[4] 7/16" Nylon standoff + 3/4" #4-40 screw + hex nut set. (M3x20mm also works.)

Panel Controls
[3] A20-25k Pots (lugs) audio inputs
[4] B100k Pots (pins) CV inputs, notch balance, frequency
[1] B10k Dual-ganged Pot (pins/lugs - BYOC, Banzai, Small Bear) resonance
[12] 3.5mm Jack (Erthenvar-style)
[6] 1900H or clone
[1] Davies 1913BW
[1] Davies 1910CS
Phetus
Lotsa Love Thankyou!!! My weekend has been saved/consumed wink
negativspace
Are you good on the procedure for the panel pots with solder lugs?
mcop
windspirit wrote:
hey so im trying to figure this out is the mix section an input or is it the output of the state variable filter? Which output is the one that state knob effects? Im guessing that there is no CV control on that knob.


'- mix +' is the outputs from the CP3 mixer pre-filter.
thetwlo
negativspace wrote:
Are you good on the procedure for the panel pots with solder lugs?


Would like to see this again, finally about to start mine.
Would be great.
THANKS!!!!
negativspace
Here are the original images:



Also don't forget to install the wire jumper... which is only necessary on boards purchased before this date. I sold my last Rev 1 PCB this afternoon. w00t

M-Circus
If anyone decides to go ahead and compile a Mouser cart for this revised BOM, I'd be grateful to have it.

Cheers
Mr. Lazy thumbs up
Flux302
^co-sign that!
woodster
Many thanks for the updates Jason.
I just finished building one of these a few days ago.
What will the resistor changes do ?
windspirit
I would appreciate a reminds of where to probe for calibrating the "null" pot. I believe it is the +/- points?
thetwlo
much appreciated! THANKS!!!!!
negativspace
windspirit wrote:
I would appreciate a reminds of where to probe for calibrating the "null" pot. I believe it is the +/- points?


Specifically the '-' point. thumbs up
negativspace
woodster wrote:
Many thanks for the updates Jason.
I just finished building one of these a few days ago.
What will the resistor changes do ?


Balance out the relative volumes of the LP/HP/BP outputs while allowing as hot a signal from each as possible without overdriving and clipping the output buffers. And tweak the resonance strength a bit. (Lowering it, which allows more headroom for the input signal.)

Nothing that totally changes the module, or that you'd likely even notice in casual use.
windspirit
negativspace wrote:
windspirit wrote:
I would appreciate a reminds of where to probe for calibrating the "null" pot. I believe it is the +/- points?


Specifically the '-' point. thumbs up


Thanks!
crc
since the original posts are somewhere in limbo, could you tell me the resistors that you changed only? .. don't have a list to compare.

negativspace wrote:
woodster wrote:
Many thanks for the updates Jason.
I just finished building one of these a few days ago.
What will the resistor changes do ?


Balance out the relative volumes of the LP/HP/BP outputs while allowing as hot a signal from each as possible without overdriving and clipping the output buffers. And tweak the resonance strength a bit. (Lowering it, which allows more headroom for the input signal.)

Nothing that totally changes the module, or that you'd likely even notice in casual use.
apoisontree
Hi negativspace,

could you please do the same for your THAT2180 VCA (with the bug fixes for v1.2), I don't even have the BOM and the page is completely gone. Many thanks!
negativspace
In light of the ongoing recovery attempts I'm not going to prioritize rebuilding my threads just yet. Let's let this play out a bit before sinking hours into a fruitless task...

Of course the instant it proves necessary, if it does, I'll be all over it. thumbs up
Phetus
Am I right in thinking there are only 7 10k? Or did something get lost in translation?

To what accuracy should the transistors be matched?

Also, I'm guessing it's ok to use PN100As for Q17 & Q18?
woodster
[quote=crc]since the original posts are somewhere in limbo, could you tell me the resistors that you changed only? .. don't have a list to compare.
[/quote]

For reference, here is the OLD BillOfMaterials, the resistor value changes are listed in brackets next to the resistor that needs changing -
The quantity numbers in brackets are now obviously wrong, so disregard.
Older SVVCF BOM

Resistors
[1] 1M R45
[1] 390k R13* (* = change to alter signal level from mixer to filter section. Suggested range is ~270-470k.)
[1] 200k R41
[9] 100k R15,R19-(change to 180k),R33- (change to 240k),R36-(change to 200k),R38,R39,R40,R47-(change to 110k)
[1] 82k R17-(change to 100k)
[1] 62k R42
[1] 47k R10
[1] 33k R16-(change to 39k)
[4] 22k R1,R2,R3,R35
[3] 15k R5,R7,R43
[8] 10k R14-(change to 6.8k),R18,R27,R28,R29,R30,R31,R32
[2] 6.8k R8,R46
[2] 1k R21,R22
[2] 560R R9,R11
[3] 470R R20,R34,R37
[1] 240R R48
[4] 220R R23,R24,R25,R26
[1] 200R R6
[2] 100R R4,R12
[1] 1k Tempco R44* (* = optional; replace with standard 1k if temp. compensation is not desired. Install either SMT or through-hole, not both.)

Capacitors
[1] 3.3nF Film, C5
[1] 2.7nF Film, C13
[2] 1nF Polystyrene/Polypropylene *main timing caps in VCF
[2] 10-100uF Electrolytic *power decoupling caps, value noncritical
[3] 220pF MLCC, C7,C11,C12
[1] 150pF MLCC, C6
[5] 10uF Electrolytic, Q8,Q9,Q10 = audio path. The other two are for decoupling the +5 and -6V rails.
[2] 0.1uF MLCC
[2] 0.1uF 0805 ceramic, install on back of PCB

Transistors/Diodes
[11] 2N3904/Other NPN [PN100A] Q1,Q4,Q5,Q8,Q9,Q10,Q11,Q14,Q15,Q16,Q19
[2] 2N3904 Q17,Q18
[6] 2N3906/Other PNP [PN5138] Q2,Q3,Q6,Q7,Q12,Q13
[2] 1N4001

ICs/Sockets
[3] TL072 *or other standard pinout dual opamp.
[1] LM337LZ, TO-92
[1] LM78L05 *silkscreen on v1.2 PCB is reversed; TO-92
[3] 8P DIP socket (optional)

MISC
[1] 20k Trimpot (v/oct)
[1] 2k Trimpot (-6V)
[1] 100r Trimpot (null)
[2] Ferrite Bead
[1] 16P Header (power)
[2] 12P Header + socket (board to board interconnections)
[4] 7/16 Nylon standoff + 3/4" #4-40 screw + hex nut set. (Use 12mm standoff if metric)
crc
so the list of resistor changes is somehting like this?

100k R19- change to 180k
200k R33- change to 240k
100k R36- change to 200k
100k R47- change to 110k
33k R16- change to 39k
10k R14- change to 6.8k
STOJ
Hi
I just finished building this filter and then I realised that BOM has been updated. I would like to make suggested resistor changes but it is difficult to find resistors on populated PCB. Is there anybody that can post picture of bare PCB and calibration procedure?
Thank you!
negativspace
Calibration:

Use probes + the test pads provided on PCB.

1) Trim -6V rail using 2k trimpot. (-6.00V)
2) Trim '-' mixer output's DC offset using 100R trimpot. (~-5 to +5mV, roughly)
3) Trim 1v/oct response if desired using 20k trimpot. I use 0V and 3V, alternating until I get 100Hz @ 0V and 800Hz @ 3V.
woodster
Here you go STOJ -

STOJ
Thank you!
Stinktier86
There's nothing stopping me from soldering a 5x2 pin connector for the +/-/gnd connection, right?
Phetus
Thats what ive done, the other cv pin isnt connected to anything it seems.
Randy
Is it worth the trouble to change the resistors on a built and working filter? Do the changes make enough of a difference?

Randy
Spip
@negativespace: check your PM. I sent you the old thread in pdf.
Benjamin AM
I was not able to get the -6v trimmer to work and realized that the pad was not connected to the ground plane on my PCB. It was a simple fix with a jumper cable. I was curious if anyone else expirenced this.
negativspace
Yes, you have to do that. (I made note of it two pages back when I reposted the pot images.)
Stinktier86
Seems like the new BOM got lost in the restoration process, but YAY, the thread is back from the dead! zombie
negativspace
Fortunately it's a lot easier to fix that than the other way around. (The text file is sitting on my desktop, so...)
Stinktier86
Quick question: Do the standoffs/spacers have to be nylon? And would a m2.5 or m3 screw fit through just aswell as a 4-40? (looking at what i've already got in my drawer)
rosch
No and yes! I use metal standoffs with M3 screws, no problem (see pic a few posts above)
STOJ
Hi
I finished building this filter and I have one problem that I can't solve by myself. I have sound going through in LP mode even when filter is fully closed. I have have tried to change all TL072's, I checked connections between boards. I also calibrated -6v and Null trimmers. Is there anything else I can do?
Stinktier86
Out of curiosity (and partly, precarity if that's a word) what are the 0805 caps doing and how are they connected (in the feedback loop, perhaps?)? Just realized i mounted them without looking up dielectric properties but i think the ones i chose unknowingly should be fine. Either way i'm trying to understand the circuit as i build it.
negativspace
They're just decoupling caps, nothing special required. thumbs up
Stinktier86
Quote:

Btw I read earlier in the thread that the LM337 has to be flipped too, but didn't see any confirmation by the designer.
So what's the deal, silkscreen correct or not?

edit: Works with orientation according to silkscreen



i suspect it works only insofar as the voltage source is stable. A quick look at its schematic shows diffences between the 'source' and 'trim' inputs' corresponding signal paths (this holds true for both regulators and explains the thermal development). Other than that it "doesn't" matter which incoming signal is what as long as one is trimmable and thus is able to program the correct output voltage. However, if the PSU is unstable then the regulator probably won't function the way it is supposed to, is my guess.



EDIT: edited out some desinformation as corrected.
rosch
I did it with the LM337 as on the board, and the other one flipped around. I also installed the jumper wire and trimming worked too. For me the only difference was that the (+) and (-) testpoints were swapped compared to the description (could change the other one by turning trimmer).

During the forum downtime there was a post where someone showed all recommended resistor swaps in one post, which has disappeared again. Does anyone have the info?
M-Circus
negativspace wrote:
Fortunately it's a lot easier to fix that than the other way around. (The text file is sitting on my desktop, so...)


Care to post this again? Figured I was gonna try to place a Tayda order tonight.
STOJ
seriously, i just don't get it
STOJ wrote:
Hi
I finished building this filter and I have one problem that I can't solve by myself. I have sound going through in LP mode even when filter is fully closed. I have have tried to change all TL072's, I checked connections between boards. I also calibrated -6v and Null trimmers. Is there anything else I can do?
negativspace
LM337 is incorrect in the silkscreen - should be flipped. Stable -6V is attainable either way, but I strongly recommend you do the "proper" thing and reverse it relative to the printed orientation. It gets warm if you don't, so clearly it's not as happy as it could be.
Zergon
I'm facing some difficulties here... I can't set the -6V! LM337 is flipped as stated, and as I turn the trimmer in either way, voltage meter reads -9,90V., it goes nowhere. I also replaced one LM337 already.
And the resistors next to -6V trimmer (R4, R9, R8, R11 and R12) get a warm after a while
What to do next?
negativspace
Make sure you've installed the jumper. (See photos in the OP.)
Zergon
I already installed it.

EDIT: Yaaay, did ti!! Apparently I wasn't rough enough to the trimmer smile
negativspace
SlayerBadger!
cleaninglady
Can anyone point me at a link for the 1k Tempco ? I use Farnell/Element14 but a Mouser number is fine too.
cleaninglady
Would this be OK for the Tempco ? Have asked same question on the VCA thread , sorry double post.

http://au.element14.com/panasonic-electronic-components/era6aeb102v/re sistor-thin-film-1k-0-125w-0/dp/1577659
rosch
it has 25ppm temperture coefficient. You want 3300. So this looks like a normal smt resistor. I got mine from Thonk (through hole) but not sure if it's terribly importnt, as I haven't matched the transistors anyway
ablearcher
hey jason, could you post again the changed resistor values? (including what they replace, I'm about 3/4 through stuffing the board, might as well swap em out from the originals now)

the "new" thread from the great muffwiggler outage of 2015 does not seem to be around

thanks! Guinness ftw!
spacedog
I would also like to buy 1 PCB and panel.
Are they still available?
negativspace
These are temporarily out of stock while I wait for a new batch.
negativspace
ablearcher wrote:
hey jason, could you post again the changed resistor values? (including what they replace, I'm about 3/4 through stuffing the board, might as well swap em out from the originals now)

the "new" thread from the great muffwiggler outage of 2015 does not seem to be around

thanks! Guinness ftw!


Ok, the changes are as follows (old values in parentheses):

R14: 6.8k (10k)
R17: 100k (82k)
R47: 110k (100k)
R16: 39k (33k)
R19: 180k (100k)
R33: 240k (100k)
R36: 200k (100k)
rosch
Does anyone happen to have a pic of an untouched board so i can see locations? I somehow failed to take pics for reference, or just can't find them anymore.
I've done 2 of L-1's mods, the 120K for loudness and higher HP gain but wasn't sure about the rest of the values.
I've had it playing the whole evening today, it's a great filter. And I'm curious to see how the changes will be after these resistor changes here.
thanks Jason!
diablojoy
built 2 so far, number one worked like a charm
build 2 had an issue neg rail was grounded turned out to be a faulty trace
on the panel board. one of the extra traces on the freq pot ( pin 3 ?) had no clearance to the ground plane at one point at the header pin this was under the solder mask so not a solder whisker , pretty rare sort of fault these days.

cleaninglady - re 1K tempco , I built mine with thru hole versions sourced from thonk simply because I had them, I dont think it should be in contact with anything in particular considering the SMT pad positions for it are on the other side of the board .
I think it's unlikely to be make that much of a difference , so you could probably just throw in a standard 1K MF and call it done but hey I could be wrong .
If you really feel the need to use a tempco I can pop a couple in the post
for you.
you are really going to like this filter thumbs up
grilojoe
rosch wrote:
Does anyone happen to have a pic of an untouched board so i can see locations? I somehow failed to take pics for reference, or just can't find them anymore.


This what you're looking for?

negativspace
Yeah, the tempco is really just there as an option because option. Given that many cases are not ventilated, it can have some effect in the sense that it is coupled to the ambient environment inside the case. If the ambient temperature inside the case rises 20 degrees above baseline after 2 hours of use, the tempco should help keep things stable. But it's not like a VCO where the response is calibrated to high degree of precision and the tempco mates to the expo converter to all but entirely keep it from moving.

To be perfectly honest, I don't bother. I use regular 1k metal films.
cleaninglady
I have one tempco on the way from a friend , if i was to choose would i be best to keep it for the SVVCF or the VCA ?

Just fishing for an opinion here.
negativspace
I'm not really sure... I use tempcos in the VCA because the THAT datasheet told me to and I believed it. I'm not sure what the consequence would be if you didn't, but I assume it would be hard to perceive.
cleaninglady
Thanks again for your help, Jason. Across both threads. Cant wait to finish these ! SlayerBadger! SlayerBadger! SlayerBadger!
negativspace
My pleasure! I think you'll like them both... and they work well together.
yan6
Has anyone confirmed the replacement resistor values. I changed them as specified and seemed to have broken my filter confused I should have paid more attention to the old values (in parenthesis) and probably would have noticed before hand; there seems to be a discrepancy with R48, the original value should be 240ohm. This in turn makes me question the replacement value.

Anyways I changed the values and got nothing out of my lowpass, bandpass seemed ok and I received sound, but no change as I swept the frequency dial from the notch. Also the resonance was a weird zipper kind of sound. After changing back to the original values I still have the same issues, so Im guessing I fried something hmmm.....

Any ideas where I should start looking for broken bits seriously, i just don't get it
negativspace
d'oh! That was a typo... should be R47, not R48.

I also forgot to add R33, so that's there now as well.
yan6
Hmmm, any clues as to what I might have blown up by putting 110k in R48
negativspace
That's the 240 ohm? That'll be part of the -6V rail, in the LM337's part of the circuit. The only active component directly impacted by this resistor would be the LM337 itself.

Beyond that, the -6V rail is only used for the mixer section so you're unlikely to have damaged anything else beyond Q1-Q4.

(In other words it should be a $0.10 fix, hopefully!)
Randy
yan6 wrote:
Has anyone confirmed the replacement resistor values. I changed them as specified and seemed to have broken my filter confused I should have paid more attention to the old values (in parenthesis) and probably would have noticed before hand; there seems to be a discrepancy with R48, the original value should be 240ohm. This in turn makes me question the replacement value.

Anyways I changed the values and got nothing out of my lowpass, bandpass seemed ok and I received sound, but no change as I swept the frequency dial from the notch. Also the resonance was a weird zipper kind of sound. After changing back to the original values I still have the same issues, so Im guessing I fried something hmmm.....

Any ideas where I should start looking for broken bits seriously, i just don't get it


yan6, you accidentally answered my question from a few pages ago regarding modifying an already built filter to change the resistors. I think I'll just leave mine alone for now.

Randy
negativspace
If you don't follow my incorrect instructions - which are no longer posted - you'll be fine! oops

Every retail build I do uses the new values. I've verified it 40 times over by now. Works great. (Of course the original values are also fine, so... salt to taste, if you will.)
windspirit
Ok finally built this and I have quite a few problems:

1) LPF output is very very quiet

2) Self oscillation does not happen even with resonance control set at full

3) Not sure how highpass is achieved but usually it is done by subtracting the LP output from the input. The highpass output sounds like the low pass output is being added to the input, as in with the filter all the way down I head a completely unaffected signal and when I sweep up I hear a filter sweep that sounds identical to the lowpass filter sweep. The HP output is however at normal volume level.

4) When I sweep to a low frequency on the LPF I get a loud "thud" which sounds like DC voltage getting to the output, possibly a cap dumping all of it's charge.

Anyways I installed the lm337 backwards and added the jumper. The circuit is calibrated to within .001V (except for the 1v/o trimmer, which I can't calibrate since I hear no self oscillation.) I used the PN100A and PN5138 transistors and tried both a set of TL072s and LM358s to see if the chips were bad but I had the exact same results. I also cut that one stray trace on the side of the board which connected one of the transistors to the ground plane just in case.

I will be checking out the schematic soon but if anyone has suggestions as to where to poke around please let me know.
negativspace
Hmm... #3 is normal and unavoidable due to the core design of the filter, so no worries there. Occasionally I build one and find the resonance to be off a bit like #2, so while rare that's not unheard of. I solve it by tweaking the 39k resistor until it oscillates @ 10-12VPP, but in light of #1 and #4 I'd hold off on that until you find the source of your other issues.

-6V only applies to the mixer section, so forget about all that.

Did you also install the LM78L05 backwards relative to the silkscreen?
windspirit
Lol no was I supposed to do that one backwards too? I used the picture in the first post as a reference.
negativspace
Yep - doublecheck the first post, both the photo and written BOM indicate that. Definitely won't work with it backwards, so I'd take this as a hopeful sign.
windspirit
Ah, I think that I just saw that only one regulator was backwards in the picture and I assumed that it was the lm337 although I can see now that it is on the other side. Ill fix this tomorrow and follow up with a report, thank you!
negativspace
My pleasure. I think you'll be sorted when you flip the other regulator, I've done that before (two or three times) and I kinda remember symptoms similar to yours.
windspirit
Ok flipping the 5v reg fixed the filter, so glad that this didn't become another "debug later" project, this thing sounds soooooooo good!

Thanks again for helping me out, I hate being the guy who didn't read things carefully and asked the question that was already answered (in the OP no less.)

Very excited to finally have this filter. I sold my m303 hoping that this would be my new squelchy filter for my "bass skiff". I just does so much more than squelch!
negativspace
Excellent! I'm glad it was the easy fix. w00t

We all read things wrong sometimes so don't sweat it. I got the regulator footprints backwards in the first place because I didn't read the part of the pinout diagram that said "BOTTOM VIEW" and assumed it was a top view like every other datasheet out there. hihi
lessavyfav
Hey Y'all, finally getting on this build after a long solder break.

The dual gang pot was bugging me out but finally I sorted the part number I think. Looks like Mouser actually does carry it. Am I wrong?

RV24BF-10-15R1-B10K
http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV24BF-10-15R1-B10K/? qs=Lvq%2FhcVrBjO9Zp87U9%252bDGw%3D%3D
woodster
Right value, but you'll need to run flying wires to the PCB, as it should be the PCB pin version as opposed to solder lug.
No big deal as you need to run flying wires from the 3 inputs anyway...
lessavyfav
Argg! I think I just did something idiotic! Is the BOM in the post at the top of this page totally different from the final BOM I see referenced way down here after the outage?

Barf. Soldered in a buncha of wrong resistors that means...


My bad for not reading the damn thread carefully but maybe an ALL CAPS note at the top mentioning that the BOM there is not accurate
negativspace
Both versions of the BOM are accurate and will result in a working, lovely-sounding filter. There are 6 or 7 resistors different between the two, nothing more, and mostly they are just to balance output levels a bit.
lessavyfav
negativspace wrote:
Both versions of the BOM are accurate and will result in a working, lovely-sounding filter. There are 6 or 7 resistors different between the two, nothing more, and mostly they are just to balance output levels a bit.


Thanks man! You please me!
negativspace
Glad to help! There's a list of all 7 changed resistors on the last page, toward the top, posted by me. New values are listed along with old values in parentheses.
qfactor
negativspace wrote:
Glad to help! There's a list of all 7 changed resistors on the last page, toward the top, posted by me. New values are listed along with old values in parentheses.


Mine's got all weird on me!! sad banana
I did the new values expecting things to be more balanced, but instead, after changing to the new resistor values (stated in your list) the cutoff now only works from 12 o'clock onwards. Closes up way too much and too fast from the left half (CCW) of the cutoff knob! eek!

Also, now, the resonance doesn't self oscillate, with the new values. The old values did all that better but I can't tell if it's more balanced with these changes now d'oh!

Which are the resistors that controls cutoff and resonance in your list? hmmm.....
cleaninglady
Hi Jason , I just got a grab bag of styrene caps. It has plenty of 3.3nF and a few 2.49nF.

Would it improve anything sound or response wise if I swapped the two film caps (3.3 and 2.7nF) for styrenes ? Would the 2.49nF be an OK drop in replacement for the 2.7nF ?
negativspace
No, neither of those two caps will benefit from being styrene. Value isn't critical on either, so 2.49n will work fine.

@qfactor I'm not sure what's up with the cutoff knob... Doublecheck your 110k but look for collateral issues because resistor value changes should not cause that.

The 33/39k controls resonance amplitude. Resonance behavior isn't always the same from unit to unit, so don't worry about the value of that resistor if it's not what it's "supposed to be." Try to find a value that gets you 10-12VPP at maximum level. I had one the other day that was super-strong and needed a 43k to behave properly.
cleaninglady
Thanks Jason , I haven't trimmed it yet but it worked first time i plugged it in and sounds great ! Another great module from MA , congrats !! It's motherfucking bacon yo
Stinktier86
Almost finished with my four. Though, i have been hesitating over the timing caps and waited popping them in. I've got a bunch of PP:s @ 2,5% tolerance but i'm almost sure i want PS (got a lot of filters with very pronounced resonance already).

Then i found soviet made 1% tolerance PS caps on the net. They have 0.8mm leads. Will they fit through?
talfred
Hello,

does nybody here have a working mouser cart for this project?
I have too little experience to find all the stuff myself. There's too much to choose from..
negativspace
cleaninglady wrote:
Thanks Jason , I haven't trimmed it yet but it worked first time i plugged it in and sounds great ! Another great module from MA , congrats !! It's motherfucking bacon yo


You're really putting a dent in the backlog this week. lol

Glad to hear you're loving the modules.
lilakmonoke
jason are those back in stock?

i already bought one from schneidersladen and like it so much that i want to put a few into a polyphonic synth im designing at the moment with digital oscillators from a raspberry, analog filters/vcas.

also is there a way to just use the filter without the mixer? i use one for each voice and probably do the mixing digitally.

thanks from berlin!
rosch
Here's a pic with the official mods i just made for myself for easy reference. Gonna try them tonight.
lilakmonoke
what are these mods for?
negativspace
Decrease resonance amplitude. (39k)

Tweak the LP feedback path to decrease HP bleed somewhat. (6.8k)

Increase + balance the HP/BP/LP output levels. (180k/200k/240k)

Tweak the range of the front panel frequency pot for more usable range in HP mode. (110k)
negativspace
lilakmonoke wrote:
jason are those back in stock?

i already bought one from schneidersladen and like it so much that i want to put a few into a polyphonic synth im designing at the moment with digital oscillators from a raspberry, analog filters/vcas.

also is there a way to just use the filter without the mixer? i use one for each voice and probably do the mixing digitally.

thanks from berlin!


They're not, but they will be again in early March. Schneiders is due for 8 more as of right now. Control just got my last 9.

It is easy to omit the mixer section, simply pull R13 and plug an audio signal into the VCF-side pad. Are you planning to build these or to modify finished units?
lilakmonoke
negativspace wrote:
It is easy to omit the mixer section, simply pull R13 and plug an audio signal into the VCF-side pad. Are you planning to build these or to modify finished units?


great! actually the cp3 is cool because you can get lots of gain dependent colors out of it. i just dont need 3 inputs.

i think i will build them from scratch, make all the necessary mods and integrate the controls into the synth.

what would be great if there was an easy way to graft on a transistor based vca. ... then thats all the analog processing i need for one voice in one unit.
lilakmonoke
just to give you an idea what i think this will be finally:

sine -> phase distortion + 2 sine X phase modulation / ringmodulation = one digital voice ..... -> analog saturation (cp3 / fet preamp etc.) -> SVVCF -> discrete vca - > xfade with clean digital voice ... this x 4 voices

this is the synth that casio never made ;-) .. point is i need an attenuator/saturator before the filter and a 2 channel mixer/xfader after so i can blend a heavily processed analog signal with a clean digital one.

maybe i can split the cp3 in 2+1 parts?
crc
did the mods, and while i now have all the outs in better balance, i think the LPF bleed got alot louder. should i undo some of the mods (6.8k for example) to try to get the bleed a bit more quiet?
crc
did the mods, and while i now have all the outs in better balance, i think the LPF bleed got alot louder. should i undo some of the mods (6.8k for example) to try to get the bleed a bit more quiet?
lilakmonoke
just finished a test track for my synth: http://tindeck.com/listen/kylqs

this is a home made phase distortion osc run through the SVVCF and then mixed with the digital signal. whats especially pleasing to my ears is the contrast between zero resonance precision filtering (phase distortion) and the unpredictable chaotic resonance of the filter.
thermionicjunky
lilakmonoke wrote:

what would be great if there was an easy way to graft on a transistor based vca. ... then thats all the analog processing i need for one voice in one unit.


http://www.oakleysound.com/vinvca.htm
lilakmonoke
thermionicjunky wrote:
lilakmonoke wrote:

what would be great if there was an easy way to graft on a transistor based vca. ... then thats all the analog processing i need for one voice in one unit.


http://www.oakleysound.com/vinvca.htm


i have that one, it sounds great. it has too many features for my purposes, i can control the gain voltage through software so something like the STG .vca fits better. i need four of them so i wish i could find something even simpler and discrete.
negativspace
If you pay a little closer attention to the photo in the soundcloud preview of the filter you may see a VCA section, which may or may not be a Minimoog VCA clone, which may or may not be my next release. Ninja

(And of course you'll hear said VCA in the clip... not in the first part, when only the mixer and VCF were populated, but in the second section.)
lilakmonoke
jason ... after some hard squinting there is indeed an input called "acv" in the top right of the module. pair this module with a 30$ microprocessor based digital soundsource + cv and you have the equivalent of a poor mans dsi pro2 synth. just saying ...

also, all kinds of interesting things happen when you mix the source with the filtered signal so while you are at it, lose one mixer input and add a xfader ... analog eq!
Waz
BOM says 9 x 100k resistors, but only 8 listed places for them.
Waz
Which 2 capacitors placements call for 10-100 electrolytics? I ask because I have 2x100s.
Waz
Bumping with another question. I have 2 104 c5k capacitors for the .1uf. Is this ok? I dont know what c5k means... It measures in roughly at .1uf so.... it SHOULD work. hmmm.....
Waz
bump.
negativspace
Waz wrote:
Which 2 capacitors placements call for 10-100 electrolytics? I ask because I have 2x100s.


That's for the 2 main power input decoupling electros. The two attached to the regulators should stay 10uF as marked.

Your ~100nF caps should also work, those are also decouplers. (All .1uF caps in the module are for that; through-hole or SMT.)
Waz
negativspace wrote:
Waz wrote:
Which 2 capacitors placements call for 10-100 electrolytics? I ask because I have 2x100s.


That's for the 2 main power input decoupling electros. The two attached to the regulators should stay 10uF as marked.

Your ~100nF caps should also work, those are also decouplers. (All .1uF caps in the module are for that; through-hole or SMT.)



I'm having a hard time "seeing" where this is. The 2 next to the 1n4001s? They can be 100uf? I see the traces lead from the 8x2 pin header to 2 caps.

C8,9,10 have to be 10uf?
Waz
bump
negativspace
Correct, the two caps in question are the ones closest to the power header along the bottom of the board. C8-10 are part of the filter circuit.
Waz
negativspace wrote:
Correct, the two caps in question are the ones closest to the power header along the bottom of the board. C8-10 are part of the filter circuit.


Thanks for the help!
Waz
Is there another run of these happening anytime soon? I built one for someone and was so impressed with it that I think I want one for myself... Dead Banana
negativspace
Any day now... I've ordered the new boards, simply waiting for them to be manufactured and delivered. w00t


[Edit] I just got notice 20 seconds ago that they've shipped, so should have them in by the middle of next week.
FingerTappin
Does this filter need/benefit from matched transistor pairs?
fluffybeard
Finished mine yesterday. With some issues :(

The resonance sound clear when no input is present, but as soon as I add an oscillator to the input resonance starts to gets some irregularities. Squeeling, dithering kinds of sound. Also there seems to be some resonance even with resonance pot turned set to zero and popping noises with fast envelopes. I changed the 33k resistor to a 39k, but no luck. Any guesses? very frustrating
fluffybeard
fluffybeard wrote:
Finished mine yesterday. With some issues :(

The resonance sound clear when no input is present, but as soon as I add an oscillator to the input resonance starts to gets some irregularities. Squeeling, dithering kinds of sound. Also there seems to be some resonance even with resonance pot turned set to zero and popping noises with fast envelopes. I changed the 33k resistor to a 39k, but no luck. Any guesses? very frustrating


Never mind. Just some distortion I guess. The resonance is still quite loud even after switching to the 39k resistor. But it sounds sweet if I don't bring up the resonance too high. Great sounding filter!
woodster
Glad to hear these will be appearing again soon.
I have the BOM all ready to build a second hyper
ym2612
I did the official resistor mods last week on my DIY build, and all of the operational quirks are gone. thumbs up Very happy with this guy now.
yan6
I'm trying to recover from having blown mine up with the initially wrong resistors posted for the mod. I replaced the LM337 and can measure -6V & +5V. from Gnd to the '-' test pad I am getting -3.45v and ~120mv on the '+' test pad.

In audio testing it:

BP - seems to work
LP - no sound at all
HP - sound but no change when sweeping frequency dial
Notch - sound only on HP side
Resonance - slow and bubbly sounding

I have the updated resistors in place as per Rosch's picture. I tried swapping all the TL072's with no results

Anybody have some suggestions or test points to help me trouble shoot this
negativspace
Blowing up the LM337 would result in, at worst, a local apocalypse within the mixer circuit. The -6V rail is limited to that part of the module - it feeds through R8, R9 and R11 into the transistors and nothing else. Anything in the filter core should be, by my reckoning anyway, totally unrelated.

Nevertheless... try to see if the LP signal is present at pin 6 of U2, the TL072 nearest the power header and go from there. That's the input pin for the LP output buffer.
cane creek
Its odd all the resistor changes are not on the front page.

I populated my board yesterday going by the BOM on first page, now i find i need to change resistors d'oh!
negativspace
Shit, it was the version of the thread during The Great Outage that got the new BOM on the front. d'oh!

Will sort that, maybe after this weekend as I'm super pressed for time.
yan6
No signal present at pin 6, should I be looking at replacing the row of transistors then?
negativspace
I get ~similar symptoms when I put a pair of PNPs where NPNs shoud go or vice-versa, so definitely double-check that all your transistors are in the right spots before you go too much farther.
yan6
Found the problem, In changing the resistor values my soldering iron must have touch C15 very frustrating very frustrating and had melted the top of the timing cap. I'm surprised it affected the internals of it, but as soon as I changed it out the filter came back to life.

I have to say in a side-by-side comparison of one with original resistor values and with the new resistor values. The new values sound much better, especially the BP, it is much fuller sounding
negativspace
Fantastic, I love it when it turns out to be something easy like that. w00t

I've never melted through a cap box either, and I've gone pretty deep into a few over the years.
cane creek
Finally got around to finishing this today, sounds awesome Mr. Green



woodster
It really is a phenomenal Filter!
I've put together a second BOM in anticipation of another future run.
I was chatting to a fellow wiggler a fer days ago, and he mentioned the wide variety of sound and responses he got using different trannies.
He said he favored the 3904/3906 combo over the PN100/5138, which surprised me.
More raspy and 303 esque apparently

My build uses the PN100/5138 combo, and the second BOM I've made up uses them too, maybe I need to build three of them hihi

@ CaneCreek I reversed the LM337 on my build, as it was highlighted way back when in the thread.
I noticed in your pic it is orientated as per the silkscreen, wondering if there is now a definitive answer as to the correct orientation of that part ?
cane creek
woodster wrote:


@ CaneCreek I reversed the LM337 on my build, as it was highlighted way back when in the thread.
I noticed in your pic it is orientated as per the silkscreen, wondering if there is now a definitive answer as to the correct orientation of that part ?


I hope not, i was led to believe it was the LM78l05 you put in backwards ?
woodster
Yeah the LM78l05 defo goes in backwards, but there was also a picture and talk of the LM337 going in backwards too on page 21.
Edit: Nordcore also posted a picture on page 24 of the PCB with an overlay of component values, and suggested mods which I downloaded prior to building, and just blindly followed
I wouldn't really worry though Mr Creek if you've managed to trim yours successfully. The LM337 appears to work both ways, and only a few people had troubles calibrating, which was fixed by flipping it...
gbiz
woodster wrote:
It really is a phenomenal Filter!
I've put together a second BOM in anticipation of another future run.
I was chatting to a fellow wiggler a fer days ago, and he mentioned the wide variety of sound and responses he got using different trannies.
He said he favored the 3904/3906 combo over the PN100/5138, which surprised me.
More raspy and 303 esque apparently


/me waves

The buzziest sounding one is the one with the 390[46] & Wima Polyester caps. The caps make a big difference too.
woodster
gbiz wrote:


/me waves

The buzziest sounding one is the one with the 390[46] & Wima Polyester caps. The caps make a big difference too.


applause

I put wima's in mine too, as I had them on hand, might try something different on one of the others I'll get in the future...
Michiel
negativspace wrote:
Any day now... I've ordered the new boards, simply waiting for them to be manufactured and delivered. w00t

[Edit] I just got notice 20 seconds ago that they've shipped, so should have them in by the middle of next week.


Eagerly awaiting a new run and these reports of successful builds only make me want one more. Noticed the above posted 3.5 weeks ago. Any news on when there will be more... PCBs + Panels in my case... or even complete modules.
gbiz
Definitely give Styrenes a go. Rush online have some nice small ones that are a good physical fit.
woodster
Oh, yeah I put Styrenes in the .001uF spots specified.
Gotta love Rush on line, uber oldschool site but good accurate stock info thumbs up
gbiz
woodster wrote:
Oh, yeah I put Styrenes in the .001uF spots specified.
thumbs up


Those are the two that i meant put polyesters in for a buzzier sound.

I've been meaning to try it with something like a pair of C0G in there.
jackmattson
What to get some knobs in this style for my filter.
https://www.sparkfun.com/products/10001

But can't find the right ones.

Can anyone help?
Old Man Euro Module
livefreela
i have some of these in a variety of sizes - got em on eBay - search "aluminum knurled knob:" or "aluminum hi-fi knob"

jackmattson wrote:
What to get some knobs in this style for my filter.
https://www.sparkfun.com/products/10001

But can't find the right ones.

Can anyone help?
Old Man Euro Module
jackmattson
livefreela wrote:
i have some of these in a variety of sizes - got em on eBay - search "aluminum knurled knob:" or "aluminum hi-fi knob"

jackmattson wrote:
What to get some knobs in this style for my filter.
https://www.sparkfun.com/products/10001

But can't find the right ones.

Can anyone help?
Old Man Euro Module


And they fit a normal D shaft poti or do I need to order a special poti?
negativspace
The knobs in the sparkfun link are for knurled shafts, so you'd need to get pots that match that description. Fortunately it's easy to find 16mm Alpha pots with knurled shafts. The only tricky one might be the dual-ganged 10k.
dsf
Hi!, will this be restocked anytime soon??
jackmattson
Anyone have a link to the specific pots and jacks are using for this project preferably at mouser or segor ? I'm kind a new to this and want to make sure that I get the right angle and shaft size etc.
negativspace
The jacks you need come from Erthenvar or Thonk, probably the latter in your case. For the dual-ganged pots you can also go through Thonk (soon, I'll be shipping him some next week)

The other pots are standard Alpha 16mm, try Banzai Music.

BTW the LM337 does need to be reversed. See, I made myself a little "cheat sheet" JPG with all of my commonly-used transistor and regulator pinouts on it. Super handy, I just open one file and bam, like 15 pinouts... the problem is that when I cut the LM337 diagram out of its datasheet I forgot to include the note that it was a bottom view. Since that's completely counter-intuitive to me I never once suspected it was a bottom view, and thus I laid out the CP3 and SVVCF boards as if it were the top view. Since the resulting arrangement gave a pretty stable -6V I never thought to explore it further until someone caught the mistake. (Thanks!)

d'oh! oops

Will be fixed going forward; all incorrect boards have been built or sold and the new ones are corrected. Version # is updated on the new ones so you won't ever have to guess which is which.
ablearcher
fiiiiinally finished building this filter (using original resistor values, did those mmonths ago and then it sat for too long), anyway, it sounds awesome!

...it doesn't self-oscillate though, should I lower that 33k? switch to the updated resistor values? or could there be a totally different issue?
negativspace
Hmm, I've never had one fail to self-oscillate although I have had a couple of oddballs that needed drastically different values for that 33/39k resistor in order to perform as the others. (oscillating with a max ~10VPP sine)

The old resistor values won't have much effect on that, although obviously you don't want to raise the 33k if it's already too high. Is the resonance working, just not quite enough to break into song?
ablearcher
Quote:
The old resistor values won't have much effect on that, although obviously you don't want to raise the 33k if it's already too high. Is the resonance working, just not quite enough to break into song?


Yeah, as far as I can tell. It's got a nice sweep on the resonance knob from clean/no resonance to a pretty serious resonant growl at full CW but it's not quite screaming and it definitely not singing (self-oscillating).
negativspace
In that case you may just have an "oddball"... try a 27k, 24k, or 22k in place of the 33/39k. I've only had them go the other way (one needed a 43k, the other a 51k) but like I said, it does seem to happen now and again. Transistors... meh
jackmattson
Anyone know a single place to get these parts I can't find at Tayda:

- Lm337LZ TO92
- Lm7805 TO92
- the Davies big and medium caps 1913BW & 1910CS

Some nice to haves:
- Erthenvar type vertical pc mount 3.5" jacks
- b10k dual gang with pins
- PN100A & PN5138 (how much do these influence the sound? Anyone AB test it?)
- CA3046 chips
- female 12 pin sockets
- Ferrites
- nylon spacers
- love, pride and good service
- located in Germany or the EU
livefreela
thonk will have the jacks and knobs. for the rest, reichelt maybe?
crc
what are the power consumption specs for this one?
ablearcher
Tried 22k and still no oscillation, 15k and it screams!

So yeah, it works now, crazy distorted screaming beast. Maybe if I build another ill match the transistors and it won't need such a low value to self oscillate? seriously, i just don't get it

Anyway. Rad filter Guinness ftw!
negativspace
I'm not sure why the oddballs are odd... haven't chased it down as it's very uncommon. Prototypes built with non-matched transistors did not show this behavior, though. seriously, i just don't get it

Remember there are 18k and 20k resistors if you want to hone the response a bit further. It "should" oscillate beginning at about 3:00 on the resonance knob, give or take a sliver.
ablearcher
Huh. yeah, I didn't have anything between 15 and 22k in my box, but I'll pick up some in my next parts order.

Wiggling with it more seemed like with 15k there was some resonance going on even when the resonance was fully ccw, I think it sounded more full open with the 22k. It does self oscillate at about 3 o clock though. Maybe something in the 18k range will do the trick.

screaming goo yo
cane creek
Have you got a "Bare Filter PCB" for sale ? , i fairy smoked my last one after reversing the transistor.
jackmattson
@Negativespace

I got all the parts to build 3 of these (3 people). Is it worth the effort to sort our transistors (got the PN type) in an effort to pseudo match them?

(We haven't made a tranny testing board yet.)

How much "better" is it going to sound. Or more scientifically, what will the difference be between matched and non-matched transistors.

Hoping the answer is, don't worry about it.
woodster
I REALLY want to build a few more of these, so do hope they get another run.

@ jackmattson No matching required according to negativespace earlier in this thread.

What Transistors you choose to use will have a big effect though.
negativspace
I still have never been able to tell a difference between matched and nonmatched transistors in this particular circuit. I match my pairs anyway just to be pedantic, but early prototypes with 19 random pulls from the bag work just as well.

More boards are coming soon... had a fresh shipment last week but Thonk got them all. More are being manufactured now. You'll need to break out your SMT skills for this one, but in exchange the notch output is done properly.
woodster
Great news Jason w00t
I'll hassle Steve when they are due to land.
Any BOM additions/changes you can outline ?
negativspace
No changes to the main body of the filter... the SMT parts will be added to the BOM and the notch pot is B10k now vs. B100k.
flab
great news applause
cane creek
negativspace wrote:


More boards are coming soon... had a fresh shipment last week but Thonk got them all.


Cool ill grab one from Thonk thumbs up
jackmattson
Cool!!

I have a PCB sent from Jason with some SMT work done, around April 10th. Says v1.4 on the board.

Ok in the middle of the build now and down to the Lm337 and 78L05

The Bom clearly says that LM78L05 is reversed on 1.2... I'm assuming that all is good here on 1.4

negativspace
Yes, everything is correct on v1.4. No jumpers needed, no silkscreen errors.
sammy123
Jason, did you ever try with the 2N5089/5087 or 2SC945/2SA733? I used the pn100a/5158 and it was amazing. Now it's time to build my second.
FingerTappin
negativspace

I don't know what the issue was with the old notch output, but is the adjustment something I could do on my v1.2 board/stripboard? I haven't populated it yet
jackmattson
Everything works great on mine!!
390k (or whatever the suggested was) Resonant resistor worked fine. normal 1k instead of tempco. Haven't tuned it to the v/oct yet but haven't needed to touch the trimmers or anything else to get great sound. Thanks! SlayerBadger!

Will give it a hard run through when I get back to the (very cool) office (that has a studio and soldering station).

The notch output was all LP or HP but after some jiggling and touch-up joints it just worked ...

===
But does someone have sound examples of their notch with some different settings to compare? It's a little weaker than I was expecting against that nice overdriven input.
negativspace
sammy123 wrote:
Jason, did you ever try with the 2N5089/5087 or 2SC945/2SA733? I used the pn100a/5158 and it was amazing. Now it's time to build my second.


No, but it's certainly worth a try! I have the 945/733s here and also a giant pile of 5089s (and also of 5088s) but I haven't given them a go in this circuit yet. I'm interested in your results if you do. cool

As for the notch output in v1.4, it's been converted from a passive control to an active control. You can certainly retrofit an older board with such a circuit, but you'll have to whip it up from scratch (either dead-bug an opamp on the control board or make something on perf.) A new control board with the SMT circuitry can also be made to work with a trace cut and a jumper on one of the interboard headers.

I can give instructions and pointers for doing so to anyone interested. Just be aware that it's not a beginner-level task.
sammy123
I am really going to have to order another pcb/panel set at some point so I can do the side by side I intended from the start.
negativspace
I'll have more soon... I have the updated control boards in now but the main boards are down to just a handful. (And I need those for my retailers' orders.) More are already being made, though.
FingerTappin
I am interested in the retrofit. I would probably perf, but could dead-bug also.
NS4W
This filter has a lovely vintage sound thumbs up
negativspace
Alright, finally some good news! The new boards shipped this morning. I do have a handful (~15) left so I may as well open up orders again.

Fire away!
NS4W
1 pcb + panel please!
negativspace
All of the ordering information in the first post is still valid, and if you do it in the next ~30 minutes I'll even get it out today. (Headed to the post office shortly.)

I owe you all an updated BOM to include the SMT parts, I'll also get that done this weekend - before anyone gets the new boards for sure.
sammy123
Ahhh payment/pm sent!!
NS4W
Payment sent!
Dogma
Wicked! Im going to do another one as this was an issue on mine. I like this filter waaay more than the E440 and I got rid of the 440 for this reason. I cant wait for this!
herringson
I build my one of the three @JackMattson got yesterday.
All working and sounds amazing!

The only problem I'm having is the cutoff frequency control has a very limited useful range, somewhere between 1-2 o'clock sweeps frequency, everywhere else is dead range.

The CV inputs are also overly sensitive and barely opening up the CV pot causes massive sweeps.

I've tried trimming the V/oct but that didn't help.
Does the 1.4 PCB have the correct LM337 orientation?
Anyone have other ideas about obvious things I could have done wrong?

I didn't see where I could find a schematic to try and troubleshoot, if there's a link please let me know.
Thanks!
gianni
I would like one PCB + panel set please!
herringson
So I swapped out the op amps just to make sure ones between the CV inputs/Freq pot and the filter weren't causing the problem and this hasn't changed anything.

I'm assuming I've got an incorrect resistor somewhere in the the frequency control circuit as it's currently way too sensitive.

I'm looking here http://electro-music.com/forum/phpbb-files/2040_svvcf_rev100_1_386.jpg

In this I guess that if one of
R34
R36
R4
R27
R32
R6/R5

Was wrong then the voltage feeding the circuit would be wrong.
Is there an equivalent schematic for the manhattan board?
I'm not sure what the part number correlations are so this would really help.

Let me know if anyone has ideas.
Thanks
negativspace
Definitely something amiss... here's a schematic which has everything on it except for the new SMT section on the control board. (Have not updated it for that yet.)

Michiel
1 PCB set and a panel for me too please.

Slightly nervous about the SMT stuff, and this is my first project sourcing the parts myself, but the filter sounds so good, I'm going to give it a try.
herringson
Thanks for the schematic! I'll look into it tonight and see if I can get this bad boy behaving =)

Already making some great noises I just have to go very easy on the frequency control.

Will post back once I work out what the issue was.
appliancide
I would like a PCB for this and one of the mixer as well. Will the shipping come to $4 still?
negativspace
Yep, especially for domestic orders you pay for the envelope once and then I stuff whatever I can fit into it. hihi

Internationally the price may increase given that the scale slides rapidly with weight, but there will still only be one shipping charge per order, no matter what it is.
mxmxmx
negativspace wrote:

I can give instructions and pointers for doing so to anyone interested. Just be aware that it's not a beginner-level task.


as i still have to build mine (1.2) .. i guess i'd be interested, too.

i haven't been following this thread all that closely -- so i'd just need to buffer said signal? are +/- 12v available on the control board? or is it going to be messy? in which case ... are the new control boards available separately? thanks ( + sorry if that's been covered).
gbiz
negativspace wrote:
I can give instructions and pointers for doing so to anyone interested. Just be aware that it's not a beginner-level task.


I'd be interested in this too
negativspace
Alright, for those of you for whom this will be a beginner-level task I will whip up a little instruction. A quick schematic + instructions for either retrofitting the old boards or using a new control board should do nicely. Just let me get this order for Control out the door first...
leterell
so i know it's prob been asked to death and for all i know my pcb's are still to leave the states. but i'd like to set up a mouser project cart with the updated parts, which was promised in an earlier message so i could fire away lightning fast with the order when necessary hihi

is the first page BOM up to date?
negativspace
No, the forum outage derailed a few of my plans. I'll get on it ASAP.
Michiel
A couple of questions after trying to find the parts for this at Banzai.

1) I can't find 2.7nF film caps anywhere. How critical are these? Will either 2.2 or 3.3nF do?

2) trimpots - similar problem. 2.2k and 22k but not 2k and 20k. I can't imagine that's a problem, right?

3) Any reason not to use angled 16mm 25k log pots for the audio inputs? I know the build shows the version with lugs and wires. Do the pins not fit? Looking at the panel pcb, it looks as though it should.

4) Can I use an LM 337 T instead of an LM337LZ. Difference is that it has TO-220 rather than TO-92, so I'd need to figure out what the right orientation is.

Thanks,
Michiel
negativspace
1) I believe you'll be fine with either as a substitute.

2) Definitely no problem there.

3) Yes, they won't fit physically. Believe me, if I didn't have to manually wire 3 pots per unit I wouldn't design it that way. I have to build hundreds of these. hihi

4) I wouldn't. It's huge, for one, and the pinout is also different. Strictly speaking if you sorted those two issues it would work fine, though.

I don't know where you're sourcing parts, but Mouser at least has the -LZ readily available for like $0.40/ea. (Edit: You said Banzai, derp. Checking the other large stores, Farnell has them for $0.79. Digikey $0.83. I guess my Mouser price is in bulk...)
Michiel
Thanks Jason.

Just found most of the stuff I couldn't get at Banzai (SMD parts, PIN headers, LM337LZ) at a local electronics store.

Still difficult finding the 1nF timing caps. I've ordered ones that are 12mm in length, but not ones that are ~7.5mm, which is about the space that's available. I'll see whether I can make the larger ones fit anyway. Don't really want to try Mouser, Farnell for just a few parts and be hit by the shipping costs.
NS4W
Is there a valid BOM for PCB v1.4 anywhere?
Michiel
Second post of this thread contains an updated BOM. Last edited 5 days ago with the SMT parts. This is the list I'm using.
Crashlander42
These are currently in stock? Do I need to PM you or just Paypal the money?
negativspace
They are. Either way works!
negativspace
Michiel wrote:
Second post of this thread contains an updated BOM. Last edited 5 days ago with the SMT parts. This is the list I'm using.


^ Exactly this. I forgot to post a note that I'd updated it. d'oh!

I still need to add some photos of the completed SMT section which should be all the "build notes" necessary to complete it. I'm starting on another batch of these soon and I will photograph one of them for the thread.
leterell
ahh superb, finally i can fill a mouser cart. also wasnt smart enough to check the BOM post for edits.
NS4W
leterell wrote:
ahh superb, finally i can fill a mouser cart. also wasnt smart enough to check the BOM post for edits.


Please share the BOM here when you're done SlayerBadger!
leterell
EDIT: please note, this link is after all to my project of a dual SVVCF so almost all parts are there twice!!!


Quote:
Please share the BOM here when you're done


https://fi.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ebb8 2e18c

here's a go at a cart. probably freely editable by all so please click 'order project' first before editing and updating, so that you edit your shopping basket instead of this particular project. there are some extra resistors to accommodate some resistor changes recommended in this thread. today i still went through the 2nd post BOM by negativespace and all that's there should be here. but please, before you order, DO double check. i have ended up with apples instead of oranges on occasion. the tempco may not really be a tempco. at least it's 5% tolerance.

no panel hardware, just a switch that i need for my build since it will be a dual unit with a custom panel so please omit.

and please feel free to comment the choices, i find filling these mouser carts challenging, especially making them as cheap as possible (ok not including 1% resistors) and i'm doing alot of it lately...
NS4W
Thanks a lot for the Mouser BOM!

About the updated BOM in the thread, this has not the resistor changes right?
antf4rm
Got my panel and boards for v1.4 today. smile

Looking forward to a build guide for the SMT components on the control board.

Happy to see this filter is available again.
negativspace
NS4W wrote:
Thanks a lot for the Mouser BOM!

About the updated BOM in the thread, this has not the resistor changes right?


d'oh! It does now.

I posted the corrected values a while back but I think that was in the sandbox version of this thread that we had just after the attack in January.
leterell
i'm toying with the idea of omitting simultaneous outputs for lowpass, bandpass and highpass. the inspiration is the picture of the black panel shown with the soundcloud demo of the filter. somehow i just like the idea of being able to switch the filter mode without re-patching

that would however call for a smallish rotary switch, which i've been looking for, but so far no luck (the nomenclature is also somewhat new to me). can anyone point me to a nice one? hmmm..... my understanding is that toggle switches wont accommodate such three-way connections easily, and i'd prefer rotary...

or would this fit my bill?
http://fi.mouser.com/ProductDetail/ALPS/SRBM131300/?qs=sGAEpiMZZMvNbjZ 2WlReYsJPkGOdzUkSomtl5KsbJNE%3d

i realize that such a switch will sometimes cause cracks and pops in the output, but since i perform to myself mostly that's not a huge issue...
negativspace
The switch works nicely... that panel was intended to be one section of an ~80hp standalone monosynth module to go into a Super37 case, so no need for individual outs.

The one used in the prototype is made by Alpha and should be pretty easy to dig up @ Mouser, but I can probably find it in my order history and give you a part# if you don't have any luck.

Small Bear also stocks some Alpha 9mm rotary switches but I don't know if they have a 3-pos.
donpachi
leterell wrote:


that would however call for a smallish rotary switch, which i've been looking for, but so far no luck (the nomenclature is also somewhat new to me). can anyone point me to a nice one? hmmm..... my understanding is that toggle switches wont accommodate such three-way connections easily, and i'd prefer rotary...


http://uk-electronic.de/onlineshop/product_info.php?cPath=39_102&produ cts_id=2551&osCsid=d18eee249ba9515e531746b7400f6e5b
leterell
Quote:
http://uk-electronic.de/onlineshop/product_info.php?cPath=39_102&produ cts_id=2551&osCsid=d18eee249ba9515e531746b7400f6e5b


superb, that seems to be the one i need. and it seems to be the same type i posted earlier from mouser, but mouser wants 6,50 whereas this is 2,30. and what's cool about that switch, omitting the individual jacks i can now instead wire up indicator LED's for filter mode with the second set of pins nanners

Quote:
The switch works nicely...


good to know.

thx for the assistance!
antf4rm
I would love to know where the smt components are supposed to go on the control board.

Please. hmmm.....

is this correct?
C = .1uf
15 = 22pf
3 = 330r resistor
4 = 47k resistor

negativspace
I took some photos of the last batch I built (yesterday) ... a friend from out of town is coming by here in like 10 minutes but I'll get them together for you later on tonight.
sromanel
leterell wrote:
EDIT: please note, this link is after all to my project of a dual SVVCF so almost all parts are there twice!!!


Quote:
Please share the BOM here when you're done


https://fi.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ebb8 2e18c

here's a go at a cart. probably freely editable by all so please click 'order project' first before editing and updating, so that you edit your shopping basket instead of this particular project. there are some extra resistors to accommodate some resistor changes recommended in this thread. today i still went through the 2nd post BOM by negativespace and all that's there should be here. but please, before you order, DO double check. i have ended up with apples instead of oranges on occasion. the tempco may not really be a tempco. at least it's 5% tolerance.

no panel hardware, just a switch that i need for my build since it will be a dual unit with a custom panel so please omit.

and please feel free to comment the choices, i find filling these mouser carts challenging, especially making them as cheap as possible (ok not including 1% resistors) and i'm doing alot of it lately...


So, is this BOM 100% correct? If I order what'sin here, just half the quantity, will I be good?
sromanel
Oh, I see it uses a 16 pin power connector instead of the "regular" 10 pin one. Does this mean tha I have to modify my bus board in order to suit the +5V needed?
leterell
Quote:
So, is this BOM 100% correct? If I order what'sin here, just half the quantity, will I be good?


hey, i can give a definite answer only in 2-3 weeks, since i'm working too much atm to build, and only with a built working unit can i vouch for the BOM being correct

Quote:
Oh, I see it uses a 16 pin power connector instead of the "regular" 10 pin one. Does this mean tha I have to modify my bus board in order to suit the +5V needed?


only in case your bus board/PSU dont produce 5v, AND the module needs 5v. i am not sure if the design needs 5v, negativspace will prob chime in on that
sromanel
leterell wrote:
Quote:
So, is this BOM 100% correct? If I order what'sin here, just half the quantity, will I be good?


hey, i can give a definite answer only in 2-3 weeks, since i'm working too much atm to build, and only with a built working unit can i vouch for the BOM being correct

Quote:
Oh, I see it uses a 16 pin power connector instead of the "regular" 10 pin one. Does this mean tha I have to modify my bus board in order to suit the +5V needed?


only in case your bus board/PSU dont produce 5v, AND the module needs 5v. i am not sure if the design needs 5v, negativspace will prob chime in on that


Well let's hope negativespace will give us feedback then hihi Oh btw, I made my attempted BOM using your as a reference, I added and swapped a few things

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=dee8d a3c73

If anyone wants to check or use it, go ahead please
negativspace
Answer in the form of a quiz: what is the purpose of the LM78L05?
sromanel
negativspace wrote:
Answer in the form of a quiz: what is the purpose of the LM78L05?


I don't know, I know almost nothing about transistors hihi
negativspace
Between goggling the part number and checking the schematic I posted a few pages back it should be pretty clear. cool
revel8or
Voltage regulator
leterell
Quote:
Between goggling the part number and checking the schematic I posted a few pages back it should be pretty clear.


thanks. i was also pretty sure looking at the schematic, but then again i've never designed a PCB and i'm only learning to read those things razz
sromanel
negativspace wrote:
Between goggling the part number and checking the schematic I posted a few pages back it should be pretty clear. cool


I see. Another thing, will I need to match the transistors?
leterell
Quote:
I see. Another thing, will I need to match the transistors?


that was discussed a few times in this thread. IIRC negativspace mentioned that it's not a necessity. i think you can delve into the thread íf you want some details on the sonic consequences, but FWIW i'm not going to
sromanel
leterell wrote:
Quote:
I see. Another thing, will I need to match the transistors?


that was discussed a few times in this thread. IIRC negativspace mentioned that it's not a necessity. i think you can delve into the thread íf you want some details on the sonic consequences, but FWIW i'm not going to


Yeah I gave the thread a brief read but they're almost 40 pages hihi However I suppose I won't match them either
antf4rm
NO! You don't need to modify your bus board.
You can just put a 10 pin header on this module between the +12 and -12 markings.
If you look closely, you'll see that the other 6 positions are not connected to anything. So no need for all 16 pins.
There is a 7805 on the module to provide a 5v power rail. That's what they do. It is a voltage regulator.

About that SMT section on the control baord? wink
Is this legend correct?
C = .1uf
15 = 22pf
3 = 330r resistor
4 = 47k resistor

Sorry to keep buggin you about this. I'm just excited to hear this thing.
sromanel
antf4rm wrote:
NO! You don't need to modify your bus board.
You can just put a 10 pin header on this module between the +12 and -12 markings.
If you look closely, you'll see that the other 6 positions are not connected to anything. So no need for all 16 pins.
There is a 7805 on the module to provide a 5v power rail. That's what they do. It is a voltage regulator.

About that SMT section on the control baord? wink
Is this legend correct?
C = .1uf
15 = 22pf
3 = 330r resistor
4 = 47k resistor

Sorry to keep buggin you about this. I'm just excited to hear this thing.


I'm curious about that, too
negativspace
antf4rm wrote:
NO! You don't need to modify your bus board.
You can just put a 10 pin header on this module between the +12 and -12 markings.
If you look closely, you'll see that the other 6 positions are not connected to anything. So no need for all 16 pins.


DO NOT do this. It defeats the reverse power protection scheme. Very bad idea.
sromanel
negativspace wrote:
antf4rm wrote:
NO! You don't need to modify your bus board.
You can just put a 10 pin header on this module between the +12 and -12 markings.
If you look closely, you'll see that the other 6 positions are not connected to anything. So no need for all 16 pins.


DO NOT do this. It defeats the reverse power protection scheme. Very bad idea.


Di not do what? Use a 10 pin header? Modify my bus board? hmmm.....
sammy123
I think Jason means just use the proper power headers and cables, which is good advice for any build.
antf4rm
I suppose hooking up a 16pin header backwards is safer in this case because it sends the +12 and the - 12 to pins that are not connected. That's pretty slick. wink

On that note what would happen to a 5v rail suppliedby the bus board?
If properly connected it would just be not connected..that is good.
If reversed the 5v would go to ground...not good.

The best thing to do is just hook it up the right way!


Do the 1n4001's also protect against reverse power?

Anyone finish a v1.4 that wants to post some photos?
antf4rm
Stinktier86 wrote:
There's nothing stopping me from soldering a 5x2 pin connector for the +/-/gnd connection, right?


Phetus wrote:
Thats what ive done, the other cv pin isnt connected to anything it seems.


I knew got that idea from somewhere earlier in this thread. wink
negativspace
antf4rm wrote:
I suppose hooking up a 16pin header backwards is safer in this case because it sends the +12 and the - 12 to pins that are not connected. That's pretty slick. wink


Thanks. I've always thought so. cool

I suppose I did come on a bit strong there... technically speaking you do still have the 1N4001s to protect you if you choose to use a 10-pin header. You won't burn down your studio or anything.

But if you reverse the 10p cable end you'll short both rails, and while they're diode protected the shorting of both to ground could potentially cause problems with other modules on the bus or with the power supply itself. That's why I use PTC resettable fuses on my modules with 10p headers. (Not only does the 10p scheme protect the module from shorts, but also your other modules and your power supply.)

As for +5V, you are all correct that the +5V is handled on-board. Also that if your bus supplies it it will simply end up on floating pins of the power header. Electrically speaking it remains unconnected.

antf4rm wrote:

If reversed the 5v would go to ground...not good.


Also correct. Can't win 'em all. d'oh!

The saving grace there is that most 5V adapters I'm aware of use LM7805 or LM78L05 and those are internally protected from overcurrent and short-circuit conditions.
antf4rm
right on!


wink

Thanks for explaining that. It makes perfect sense. Again that 16p scheme is slick. Did you come up with that neat little trick? If so.. Nice one!
negativspace
Yeah, it was one of the first design decisions I made when I started MA. Back then reverse protection was kind of a big deal so I wanted to sort that right at the start. Erthenvar, my power cable supplier, only had 16p cables in those days so I started with a 16p header as a given and worked it out from there. The tradeoff is a 1/3-smaller ground connection back to the bus but I don't think it's a big deal.

I did mean the 10p scheme in that quote - the 10p scheme employs the fuses to protect the PSU and other modules since the only possible result of a backwards cable is a double-short. This is the more ideal solution, obviously, but I didn't start building modules this way until Erthenvar started carrying the 10p cables as well. hihi

Meanwhile the 16p scheme has worked so well that I haven't bothered to change. I've still never seen a single report of a MA module failing in the field due to reverse-power.
antf4rm
Almost there! Need more chip sockets, jacks, and polystyrene caps. d'oh!

Detail on my solution for the dual pot. Clipped off the solder lugs and inserted pins into the part left behind. It mates well with the board.



SMT on back side. Soon I'll be cleaning up that flux.
negativspace
Nice! I'll get those photos of the SMT section doctored up in photoshop and posted soon... working on the very last bits of a big order right now, then I'm free to do that.
antf4rm
negativspace
SMT guide incoming; check the OP in about 2 minutes.

Edit: it doesn't cost extra to post it here in addition:

antf4rm
yay! hihi hyper applause
damn i need to leave the house now.... d'oh!
antf4rm
they work they work!!
great sounding filter!
Super nice in low and band pass modes!
totally distinct and different sounding than my other filters.

yes hi pass has some bleed but it doesn't matter because the low pass sounds soooo awesome...

thanks for the great project and the great sounding filter!
Jop
Hi Jason,

Can you post the schematic for the SMD part so first version builders can make there own on stripboard?

Thanks.
BARE BONES
what is the smd part that sits vertically on the back of the main board with the 2 capacitors?
is it a resistor? it looks like 33k in ant4rm's pic above, but in the initial build pics at the start of the thread it doesnt look like you have a part there at all
negativspace
That's an optional pad for a 1k 0805 tempco.
lilakmonoke
we are doing a group build in berlin soon. i have an xtra pcb/panel set so if somebody wants to join the fun, mail me.

SMT? damn, that wasnt part of the deal ;-)
appliancide
Jop wrote:
Hi Jason,

Can you post the schematic for the SMD part so first version builders can make there own on stripboard?

Thanks.


Looking at the pictures, it looks like the TL072 is set up as a pair of inverting buffers fed by the HP and LP, the outputs of which go to the outer lugs of the notch pot, making the wiper the notch output.

If I'm right, Jason has to mail me a cookie. hihi

Is the pinout diagram on page one still correct for the 1.4 boards?
lilakmonoke
again, i have 2 xtra sets of pcbs/panels in berlin. we are doing a group build so we will order parts together and then meet and build soon. it should be fun so if somebody wants to join, please mail to lilakmonokeätgmaildötcom.
BARE BONES
is the silkscreen for 78L05 correct on the v1.4 pcb or does it still need to be reversed?
negativspace
Everything is correct in v1.4

@appliancide I owe you a cookie. hihi

Pinout on the headers is the same across versions, I just stuck a pair of inverted buffers in between the header and the notch balance pot.

I'll get that schematic up ASAP, but I'm having a reunion/party with some very old friends this weekend and I may not have time until Monday.
leterell
done!

negativspace
Beautiful! love

Reading my last post I still have a schematic to revise... lemme finish up this order on my desk right now and then I'll do all my schematic work for this + the CVP.
sromanel
Does anyone have the product code for the Alpha pots? Or at least the dimensions?
sromanel
sromanel wrote:
Does anyone have the product code for the Alpha pots? Or at least the dimensions?


No one?
FingerTappin
sromanel
Not sure if this is what you are looking for but they are your regular old 16mm Alpha pots with 1/4 inch shaft that you find all over the internet. However, the type of pin termination in this application is important. See the first page of the values and type of termination.

Also, note that if you have the new boards, the value for the notch pot may have changed. Negativspace will have to comment on that part.

I got my single gang pins and lugs from here
http://www.mammothelectronics.com/category-s/50.htm
http://www.mammothelectronics.com/category-s/101.htm
The dual gang I got from Small Bear Electronics

You should probably be able to get most, if not all, of them from Banzai or Build Your Own Clone since you are in Europe.



On another note. Negativspace, thank you for drawing up and posting the schmatics to retrofit the older board with the mod. Kind of excited as this will be my first time using stripboard.
sromanel
FingerTappin wrote:
sromanel
Not sure if this is what you are looking for but they are your regular old 16mm Alpha pots with 1/4 inch shaft that you find all over the internet. However, the type of pin termination in this application is important. See the first page of the values and type of termination.

Also, note that if you have the new boards, the value for the notch pot may have changed. Negativspace will have to comment on that part.

I got my single gang pins and lugs from here
http://www.mammothelectronics.com/category-s/50.htm
http://www.mammothelectronics.com/category-s/101.htm
The dual gang I got from Small Bear Electronics

You should probably be able to get most, if not all, of them from Banzai or Build Your Own Clone since you are in Europe.



On another note. Negativspace, thank you for drawing up and posting the schmatics to retrofit the older board with the mod. Kind of excited as this will be my first time using stripboard.


Yep, I was particularly looking for the shaft lenght. Thanks.
FingerTappin
sromanel
I don't think either of those numbers are shaft length.
16mm is the footprint size (diameter of the pot base) I believe, where as 1/4 inch is the shaft diameter. Of all the Alpha ones I have gotten of that type, they all have the same shaft length... about 5/8 inch including the bushing (just measured). Shaft length is arbitrary since these are panel mounted, so long as you have a knob that will fit the depth of the shaft nicely.
sromanel
FingerTappin wrote:
sromanel
I don't think either of those numbers are shaft length.
16mm is the footprint size (diameter of the pot base) I believe, where as 1/4 inch is the shaft diameter. Of all the Alpha ones I have gotten of that type, they all have the same shaft length... about 5/8 inch including the bushing (just measured). Shaft length is arbitrary since these are panel mounted, so long as you have a knob that will fit the depth of the shaft nicely.


Yes, I know, but I would like for mine to be as close as possible to the one that's sold assembled. Let's wait for negativespace then
negativspace
Yeah, the desired shaft length is "standard" which is almost never listed by sellers... there are long and short-shaft versions of these pots out there but you kinda have to hunt for them. Order the standard stuff from the usual suppliers and you shouldn't have problems. (Tayda, Small Bear, Banzai, Thonk etc. will all have the right pots.)

I tend not to order pots from Mouser because their prices are not competitive with the more specialized vendors mentioned above. If you're curious, every 16mm pot I use in production comes from Small Bear. (Except the dual-ganged 10k.)
sromanel
negativspace wrote:
Yeah, the desired shaft length is "standard" which is almost never listed by sellers... there are long and short-shaft versions of these pots out there but you kinda have to hunt for them. Order the standard stuff from the usual suppliers and you shouldn't have problems. (Tayda, Small Bear, Banzai, Thonk etc. will all have the right pots.)

I tend not to order pots from Mouser because their prices are not competitive with the more specialized vendors mentioned above. If you're curious, every 16mm pot I use in production comes from Small Bear. (Except the dual-ganged 10k.)


Are they stocked from Mouser? I can't find them anywhere. It would be quite a stroke of luck for me if they were, since I'm just a few € away from having free shipping
negativspace
Should be, lemme have a go.

Edit:

From my order history, here are the A25k for the 3 mixer inputs. The shafts do have a screwdriver slot at the end but are otherwise identical to other 1/4" round-shaft pots.

I don't see any of the vertical PCB-mount style in their catalog, which you'll need for the rest of the positions.
sromanel
negativspace wrote:
Should be, lemme have a go.


You'd do me a huge favour, I've always hated sorting things parts out
NS4W
Are these the correct pin pots?

http://smallbear-electronics.mybigcommerce.com/alpha-single-gang-16mm- right-angle-pc-mount/
leterell
Quote:

negativspace wrote:
Should be, lemme have a go.


You'd do me a huge favour, I've always hated sorting things parts out


sonce you're in italy, i'd recommend looking into ordering from http://www.musikding.de/
in germany
they had the dual ganged 10k pots in stock, and most other necessary pot types for various projects now. it really made more sense for me to shop for resistors caps diodes op amps at mouser and get the pots from there...

EDIT:
but of course not the ones with pins i think. i forget since i wired it all up instead of the easy nice panel mounting option Dead Banana
negativspace
NS4W wrote:
Are these the correct pin pots?

http://smallbear-electronics.mybigcommerce.com/alpha-single-gang-16mm- right-angle-pc-mount/


Yes.
sromanel
leterell wrote:
Quote:

negativspace wrote:
Should be, lemme have a go.


You'd do me a huge favour, I've always hated sorting things parts out


sonce you're in italy, i'd recommend looking into ordering from http://www.musikding.de/
in germany
they had the dual ganged 10k pots in stock, and most other necessary pot types for various projects now. it really made more sense for me to shop for resistors caps diodes op amps at mouser and get the pots from there...

EDIT:
but of course not the ones with pins i think. i forget since i wired it all up instead of the easy nice panel mounting option Dead Banana


Point is, I always hate having to pay shipment almost as much as the product's cost, so if they were available from mouser it'd be great. I'll have a look at musikding tho
sromanel
I think I found em. Are they these ones? http://www.op-electronics.com/it/potenziometri/38-potenziometro-16mm.h tml#/taper-lineare/resistenza_potenziometro-100k
negativspace
Those look right... also I did link the A25k @ mouser up above.
sromanel
negativspace wrote:
Those look right... also I did link the A25k @ mouser up above.


Huge thanks, one last thing: do the potentiometers valies change on the last version of the PCB or are they the same as previous versions?
revel8or
negativspace wrote:
That's an optional pad for a 1k 0805 tempco.


Should this be a 3300ppm? That's what I ordered...
sromanel
Please, that's the only thing keeping me from clicking on that "Place order" button hihi
sromanel
PCB just arrived, I must say I'm very impressed by its quality. Big props negativspace!
negativspace
Cheers, glad you approve!

Sorry I didn't get anything posted this weekend, Sat. was a holiday here in the States and Sun. was the world cup final. I've been reworking the MVP schematic a bit this morning so I'll be able to kick out the notch buffer this evening.
sromanel
negativspace wrote:
Cheers, glad you approve!

Sorry I didn't get anything posted this weekend, Sat. was a holiday here in the States and Sun. was the world cup final. I've been reworking the MVP schematic a bit this morning so I'll be able to kick out the notch buffer this evening.


Well, to catch things up, is the notch pot value correct for v1.4?
negativspace
The BOM posted at the start of this thread has been updated for 1.4. (Notch pot is now 10k; no other changes to the pot values.)
sromanel
negativspace wrote:
The BOM posted at the start of this thread has been updated for 1.4. (Notch pot is now 10k; no other changes to the pot values.)


Glad to hear that since I already ordered it :^) Welp, time to get this done
NS4W
Please explain where the SMD resistors go on the control board, it is hard to read their tiny markings on your photo guide.
negativspace
The two marked "3" are the 330R, the others (4 and 15) are 47k.

If you're curious, those are R3, R4, and R15 in an unrelated circuit from which I cut and pasted the buffer layout. (Twice, obviously.)
FingerTappin
I was wondering what the status was on the schematic to retrofit the old pcbs? I got all my parts and stripboard today applause
jgb
As a proud owner of unbuilt PCBs from the first run I wonder if there is a "how to build a 1.X version" of this somewhere? Including details of components to change direction, resistors to swap et.c.

If someone has made such a thing I would be grateful, wading through 42 pages (this far) in this thread takes some time. smile
latigid on
jgb wrote:
As a proud owner of unbuilt PCBs from the first run I wonder if there is a "how to build a 1.X version" of this somewhere? Including details of components to change direction, resistors to swap et.c.

If someone has made such a thing I would be grateful, wading through 42 pages (this far) in this thread takes some time. smile


+1, just thinking this!
negativspace
Build is the same, just ignore the SMT section. Instructions to fix the pcb errors are still in the OP.
Conjure
I guess I'm dumb. I've sourced all the parts I need except for the nylon 7/16" standoffs with screws and nuts. Does Mouser have something I can grab from them?
NS4W
Conjure wrote:
I guess I'm dumb. I've sourced all the parts I need except for the nylon 7/16" standoffs with screws and nuts. Does Mouser have something I can grab from them?


You could also do without them, the connectors will keep things together. Not as bombproof though.
negativspace
11 or 12mm should also work.
cold_fashioned
What if I were anxious and decided to install a 330k resistor, since I saw the "33" and thought "what the hell?" Could I have damaged my filter? When I turned the filter on to perform the calibrations, I did notice a puff of smoke (first time seeing that since ELEC 105 in college) coming from the area near the transistors between the trimpots. I completed the calibration and ran a simple patch through the filter. Using LP mode, I get resonance, but the filter doesn't seem to clamp down all the way down when I sweep cutoff to the left. I had to run, so I couldn't fully test the other modes. Any advice you could give me is appreciated!

negativspace wrote:
That's an optional pad for a 1k 0805 tempco.
Conjure
I bought a v1.2 PCB. Are the only differences the silk screen error and the resistor lead jumper? Sorry, I'd do a more in-depth search but I'm confined to my phone tonight. Regardless, I bought the entire BOM and can't wait to put this together.
sromanel
Almost finished it. One last thing I didn't get: could I use a 10p ribbon cable (hooked up between +12V and -12V marks) or must I absolutely use a 16p one?
Monobass
sromanel wrote:
Almost finished it. One last thing I didn't get: could I use a 10p ribbon cable (hooked up between +12V and -12V marks) or must I absolutely use a 16p one?


yes it will work, note that the reverse polarity protection kind of relies on using a 16p cable though. (negativspace wrote more above)
sromanel
Monobass wrote:
sromanel wrote:
Almost finished it. One last thing I didn't get: could I use a 10p ribbon cable (hooked up between +12V and -12V marks) or must I absolutely use a 16p one?


yes it will work, note that the reverse polarity protection kind of relies on using a 16p cable though. (negativspace wrote more above)


Well let's try not to mess things up then Mr. Green
negativspace
Let's just go with "not recommended but not forbidden" on that one. I wouldn't do it on my own build but if needs must...

Hell, you can put a 10p header in now, order another, and trim it to 6 when it arrives and fill the header out. Electrons won't know the difference.
negativspace
Conjure wrote:
I bought a v1.2 PCB. Are the only differences the silk screen error and the resistor lead jumper? Sorry, I'd do a more in-depth search but I'm confined to my phone tonight. Regardless, I bought the entire BOM and can't wait to put this together.


Basically correct aside from the new SMT section... if you have a 10k pot for notch balance then entirely correct. The revision fixed the errors in 1.2 and added a pair of buffers for the notch out. Nothing else. thumbs up
sromanel
negativspace wrote:
Let's just go with "not recommended but not forbidden" on that one. I wouldn't do it on my own build but if needs must...

Hell, you can put a 10p header in now, order another, and trim it to 6 when it arrives and fill the header out. Electrons won't know the difference.


Thing is, I have plenty of 10p to 16p cables, but no 16p to 16p, so I'd have to buy one and one only for this module, and I'd end up spending more than I'm willing to (shipment, taxes, etc - definitely not worth IMHO). So if I find the way to connect the remaining 6 pins to each other I'd be fine?
negativspace
Don't connect them to each other, either leave them empty or fill them with header pins. It really is better (and safer, for this module and your PSU and the rest of your expensive system) to use the 16P header & cable. But in a pinch - and only in a pinch - the 10P solution will work.

The risk is that you might damage your PSU in the event that you plug a 10P cable in backwards. Both power rails will be shorted to ground by the 4001 diodes, protecting the module but placing a lot of stress on the supply. Most supplies are protected from short circuits so this, in most cases, is not a big deal. But sometimes it is... and if you end up being one of those cases you'll regret not spending $5 on a 16p cable. (If your PSU goes, it can take other modules with it. It may not, but it can.)
negativspace
cold_fashioned wrote:
What if I were anxious and decided to install a 330k resistor, since I saw the "33" and thought "what the hell?" Could I have damaged my filter? When I turned the filter on to perform the calibrations, I did notice a puff of smoke (first time seeing that since ELEC 105 in college) coming from the area near the transistors between the trimpots. I completed the calibration and ran a simple patch through the filter. Using LP mode, I get resonance, but the filter doesn't seem to clamp down all the way down when I sweep cutoff to the left. I had to run, so I couldn't fully test the other modes. Any advice you could give me is appreciated!


I'm not clear on where the '33' you're speaking of is... so I'm unclear where the 330k may have been installed. Help me find my bearings a bit and I can offer much better advice. cool

The transistors in between the trimpots are in the mixer section, so an issue there shouldn't show up in the filter section necessarily. Do the two pre-filter mixer outputs work as expected?

How is your +5V rail? -6V rail?

Are all of your transistors correctly oriented?

One way or another we'll sort this... feel free to put up photos if that's helpful. Sometimes a second set of eyes will find the obvious stuff you've gone blind to. (Happens to all of us.)
FingerTappin
PM'ed instead
cold_fashioned
Thanks for the help! I installed the SMT resistor on the pads on the main board where you mentioned an optional 1k tempco could be installed. Another user posted a photo where I thought I saw "33..", so I assumed it was another 330k resistor. Actually - correction, it's a 330R SMT resistor, that I installed.

My -6V and 5V rails are good. I was able to calibrate things just fine as far as I can tell. I'm fairly certain that all the transistors are oriented correctly (I took my time when installing those). I'll double-check everything when I find out whether I have to remove that resistor, though I assume I do.

negativspace wrote:
cold_fashioned wrote:
What if I were anxious and decided to install a 330k resistor, since I saw the "33" and thought "what the hell?" Could I have damaged my filter? When I turned the filter on to perform the calibrations, I did notice a puff of smoke (first time seeing that since ELEC 105 in college) coming from the area near the transistors between the trimpots. I completed the calibration and ran a simple patch through the filter. Using LP mode, I get resonance, but the filter doesn't seem to clamp down all the way down when I sweep cutoff to the left. I had to run, so I couldn't fully test the other modes. Any advice you could give me is appreciated!


I'm not clear on where the '33' you're speaking of is... so I'm unclear where the 330k may have been installed. Help me find my bearings a bit and I can offer much better advice. cool

The transistors in between the trimpots are in the mixer section, so an issue there shouldn't show up in the filter section necessarily. Do the two pre-filter mixer outputs work as expected?

How is your +5V rail? -6V rail?

Are all of your transistors correctly oriented?

One way or another we'll sort this... feel free to put up photos if that's helpful. Sometimes a second set of eyes will find the obvious stuff you've gone blind to. (Happens to all of us.)
Conjure


These are the jacks I got from Erthenvar. Can I use these? I'm just a little confused with the pinout vs the pcb.

Thanks.
negativspace
Not the right jacks, although you could make them work in a pinch. You need the older "erthenvar style" jacks, the one shown is one of the "thonkiconn" style that I really would love to switch to, honestly. (If there's an American source now, I may.)
Conjure
Hmm, okay. How would I make those work? Something like this?



negativspace
No, those tabs sticking out the side are the ground tabs so definitely don't connect those to any of the other pins. You'll have to maybe clip them a bit short of the PCB, wire them to one another with some bare bus wire, and then connect that "matrix" to one of the unused side pads to ground the lot.

They may also be upside down, I'm not sure on the pinout. You want the tip lug (which carries the actual signal) to go into the top holes of each row, as viewed if the module were installed in a rack. (Check the traces on the PCB, you'll see where they go. Make sure it's the tip lug, not the N/C switch lug, that goes in the pads attached to the traces.)
sammy123
Not like that. The outside jack lug is the ground so you would not want that going to the same pad/hole as another lug. You would have to bend it around to one of the side holes, which it probably won't reach. If you have to use those jacks I would create a ground rail and to connect all jack ground lugs together and then connect that rail to one of the ground pads. The best option though is to get the right jacks.

Edit....yeah just listen to Jason. He knows best.
negativspace
Well, you just said the exact same thing I did with different words... so I guess listen to whichever one of us explained it better. hihi
Conjure
Yeah, that's what I thought. I've gone ahead and ordered the right jacks. Doh.
negativspace
Honestly I should switch over to those... I've stayed away from using them on major DIY (or retail) projects just because they could only be found at one shop. Since I sell to a globe full of builders I try to use parts that are more widely available. I don't like sending people hunting for parts or having to source them from one shop halfway around the world. (And who may or may not run out of them at an inopportune time.) Can't always be avoided (see: dual-ganged 10k pot) but when it can...

Now that these are a bit more common, they're a superior part IMO.
sromanel
negativspace wrote:
Honestly I should switch over to those... I've stayed away from using them on major DIY (or retail) projects just because they could only be found at one shop. Since I sell to a globe full of builders I try to use parts that are more widely available. I don't like sending people hunting for parts or having to source them from one shop halfway around the world. (And who may or may not run out of them at an inopportune time.) Can't always be avoided (see: dual-ganged 10k pot) but when it can...

Now that these are a bit more common, they're a superior part IMO.


Just to know, why do you consider them as a superior part? I mean, I built every DIY module I own using Thonkiconns, but I decided to use PJ301BMs for the SVVCF (I had a few leftovers from a kit and I prefer to stay as close as possible to what the module's meant to be). From what I see, PJs are simply Thonkiconns with a metal jacket and side ground lugs, so that means more stiffness and stability. Given so, the only reason I'd take Thonkiconns over PJs is because of their lined up lugs configuration - takes less space and needs a PCB hole less. But apart from that, I think PJs are a better choice.
negativspace
I like the PCB pins vs. lugs, for one, as you need smaller (and fewer) pads which require a lot less solder. I also like the lack of a jacket for weight reasons if nothing else. It adds up...

I also find that jacket clumsy to solder and lay out boards for. They don't fit neatly into a 2hp slot like the other styles do. And they never seem to sit quite flat for me either. Don't get me wrong, I've used thousands (tens of thousands?) of the PJ301-type and will probably continue to do so for a long time to come. They're fine jacks. But the thonkiconns are a lot easier to work with, all things considered.
cold_fashioned
Not trying to be a nuisance, but did you miss my comment on the previous page? Or did my comments not make sense? help
negativspace
negativspace
cold_fashioned wrote:
Not trying to be a nuisance, but did you miss my comment on the previous page? Or did my comments not make sense? help


I bet the "33" you remember was a reference to 3300ppm, which is a measure of the temperature sensitivity of a tempco resistor.

Did you install both the 1k through-hole and 330r SMT resistor? If so, just pull the 330 and give it a shot. Otherwise, pull the 330 and install the 1k, then go from there.
Jop
Thanks Jason for the schematic thumbs up
sromanel
negativspace wrote:
I like the PCB pins vs. lugs, for one, as you need smaller (and fewer) pads which require a lot less solder. I also like the lack of a jacket for weight reasons if nothing else. It adds up...

I also find that jacket clumsy to solder and lay out boards for. They don't fit neatly into a 2hp slot like the other styles do. And they never seem to sit quite flat for me either. Don't get me wrong, I've used thousands (tens of thousands?) of the PJ301-type and will probably continue to do so for a long time to come. They're fine jacks. But the thonkiconns are a lot easier to work with, all things considered.


Why no love for heavy modules? (jk, they're real troublemakers, unless you have a reeeeally deep case, which I do). However I see your point
cold_fashioned
I wrongly installed a regular resistor where the SMT tempco was to go. I'll knock it out and see what happens. Of course, I can't do this until I get home from work, so the hours will drag on slowly..! Thanks again for your help.

negativspace wrote:
I bet the "33" you remember was a reference to 3300ppm, which is a measure of the temperature sensitivity of a tempco resistor.

Did you install both the 1k through-hole and 330r SMT resistor? If so, just pull the 330 and give it a shot. Otherwise, pull the 330 and install the 1k, then go from there.
sromanel
So, I just finished assembling it - damn, it sounds AMAZING! On a second note, I'm facing two minor issues:
1)notch output's volume is waaaaaaay lower than other mode's out (no matter how I set the notch balance)
2)is there a way to offset the cutoff frequency? cause it seems to me it starts to cut frequencies later than it should (from fully ccw to h9:30 there's no difference whatsoever)

I've calibrated the mixer section (-6.00V on the -6V pad, 70mV on minus pad and 0.00V on plus pad), so does the second question find answer by properly calibrating V/Oct?
sromanel
sromanel wrote:
So, I just finished assembling it - damn, it sounds AMAZING! On a second note, I'm facing two minor issues:
1)notch output's volume is waaaaaaay lower than other mode's out (no matter how I set the notch balance)
2)is there a way to offset the cutoff frequency? cause it seems to me it starts to cut frequencies later than it should (from fully ccw to h9:30 there's no difference whatsoever)

I've calibrated the mixer section (-6.00V on the -6V pad, 70mV on minus pad and 0.00V on plus pad), so does the second question find answer by properly calibrating V/Oct?


UPDATE: notch out behaves like it's a weaker LP (the absence of HP may cause the volume drop)
cold_fashioned
I now have an amazingly awesome sounding filter! Except for the notch output - I have zero (or virtually zero) volume coming out of the notch output, no matter where I sweep the notch pot. Everything else seems to be right on. Resonance is killer, the cutoff works great, everything sounds great! I can't recall if there is any info on the notch stuff in this thread, but I'll take another look. Cheers!

edit: Does the notch output come off of the surface mount TL072? I thought I had it soldered well, but those legs are so small, it's hard to see.
Conjure
Sorted.
sromanel
cold_fashioned wrote:
I now have an amazingly awesome sounding filter! Except for the notch output - I have zero (or virtually zero) volume coming out of the notch output, no matter where I sweep the notch pot. Everything else seems to be right on. Resonance is killer, the cutoff works great, everything sounds great! I can't recall if there is any info on the notch stuff in this thread, but I'll take another look. Cheers!

edit: Does the notch output come off of the surface mount TL072? I thought I had it soldered well, but those legs are so small, it's hard to see.


It seems like we share a problem
Conjure
Still getting audio bleeding in at zero cutoff in LPF, on all inputs. Weird. I'm using TL072CN from Tayda. Mine sounds nothing like Divkid's video when he has cutoff at zero.

I love this filter, if I can get a nice sweep in LPF with no bleeding I'll be extremely happy.
Conjure
https://soundcloud.com/conjureofficial/zero-cutoff-signal-bleed-saw-lp f/s-hPW2c

Here's a quick demo of what I mean. Don't mind the clipping and white noise, my audio interface is fucked up at the moment. But with zero cutoff, I can still hear the saw coming through. It never fully closes.

PCB 1.2
negativspace
Ok, a few things to maybe get you guys started...

1) For the cutoff frequency thing, doublecheck the resistors around the topmost of the two interboard headers. Esp. the 110k and 62k. Also, if you haven't calibrated it to 1v/oct or at least close, do that first just to eliminate it as a variable.

2) If you're not getting anything out of the notch output but LP and HP outs both work, the issue is almost certainly in the SMT section. Definitely start there! While you're examining that area, make sure you don't have 100nF caps where the 22pF should be. 100nF for power decoupling, 22pF for stabilizing the opamp feedback loop.
sromanel
negativspace wrote:
Ok, a few things to maybe get you guys started...

1) For the cutoff frequency thing, doublecheck the resistors around the topmost of the two interboard headers. Esp. the 110k and 62k. Also, if you haven't calibrated it to 1v/oct or at least close, do that first just to eliminate it as a variable.

2) If you're not getting anything out of the notch output but LP and HP outs both work, the issue is almost certainly in the SMT section. Definitely start there! While you're examining that area, make sure you don't have 100nF caps where the 22pF should be. 100nF for power decoupling, 22pF for stabilizing the opamp feedback loop.


About V/Oct calibrating, I tried doing that, but I noticed that its pitch was constantly floating (±2-3 cent if i remember correctly), is that normal? Also, it's not like I get no output at all from notch out, it's just very very quieter than other outs. Also (2) what should I check for HP section? I think there's something not working properly
Conjure
negativspace wrote:
Ok, a few things to maybe get you guys started...

1) For the cutoff frequency thing, doublecheck the resistors around the topmost of the two interboard headers. Esp. the 110k and 62k. Also, if you haven't calibrated it to 1v/oct or at least close, do that first just to eliminate it as a variable.


v/oct calibrated. Even before calibration I swept through the trimpot to see if there was any point where the sound didn't bleed through. There wasn't.

I tested and replaced all the resistors in the R40's in that section. No dice.

Blah :(
Conjure
Quote:
the final production modules I got recently have pretty much zero bleed on the LPF. Maybe ask jason at Manhattan what he changed in the final versions? I had an earlier prototype version, and moaned at him about the lowpass bleed until he redesigned it to remove it. I then sent mine back to get the final production one in exchange. the lowpass mode is TONS better. The HP and BP still bleed loads, but that is an unavoidable side effect of the design, and bothers me much less to be honest
negativspace
If the notch output works but is too quiet, something must be amiss in the SMT section I would think. Again, the notch output is just a unity-gain buffered HP and LP signal copy spit out through a pot. If HP and LP out work fine and notch doesn't (no sound/low volume/loss of upper harmonics) there are only like 11 components that could possibly be involved. I'm happy to check out a photo of your SMT section if you're stumped.

As for the bleed, there is a (very) small amount of bleed in the LP in v1.2 modules and none in v1.4, so if you have LP bleeding in a 1.4 build that's a problem but not one I've ever experienced so I can't offer much insight offhand.

HP bleed (which appears in the BP as well) is inherent to the core design. I know where it comes from but eliminating it completely destabilizes the entire filter so I just mitigated it as much as I could without ruining everything. It's still present with the cutoff knob at full CW.
herringson
Hey Jason,

I'm still having this weird problem where I can only get the frequency to sweep between 1 and 2 o'clock on the knob, either side I get no sound.

I've replaced U3, Q19, checked the resistors values and everything looks ok, I can't figure it out.

If I measure between R45 and pin 6 on the TL072 I get 0 volts for most the of the frequency knobs movement, it quickly sweeps from 0->6V between 1-2 o'clock and then for the rest of the knobs range is stuck at 6V.

I guess something is being amplified too much somewhere in the control voltage circuit and then clamping either side but I can't figure out where this is happening.

Is there a good place in the frequency control circuit where I could for a known good voltage and work back from there?

#stumped

Thanks.
Dylan.
Conjure
negativspace wrote:

As for the bleed, there is a (very) small amount of bleed in the LP in v1.2 modules and none in v1.4, so if you have LP bleeding in a 1.4 build that's a problem but not one I've ever experienced so I can't offer much insight offhand.


It's a 1.2 -- Any way to fix?

Thanks for all of your help thus far too, by the way.
negativspace
The only way to kill the LP bleed in the 1.2 set is to retrofit it with the buffers from 1.4. That eliminates the path through which the bleed can flow. It also improves the notch output.

Good news is that it's a pretty simple process, you'll need 2 trace cuts + a dual opamp, 6 resistors and 4 caps. The bad news is that you'll need to assemble it on some perfboard or 'deadbug' the opamp chip on the control board. (Glue it down to the PCB w/ pins up, and then wire everything to those. Sounds sketchy but works well!)

The schematic for the buffers is posted just a few messages up.
negativspace
herringson wrote:
I'm still having this weird problem where I can only get the frequency to sweep between 1 and 2 o'clock on the knob, either side I get no sound.


That is a puzzler, never run into that one before. I've never even had occasion to probe the cutoff CV section of the circuit with a meter to determine its behavior so I'm afraid I can't offer much on that front...

Photos of the PCB may help - maybe I'll spot something? Happy to give it a shot.
Jop
Rev 1.2 here and just performed all resistor mods as advised and I must say I'm in love again smile Also planning to do the notch buffer, cause the output is now quite low compared to the HP and LP.

One thing I'm not sure about is when the frequency is fully open, the sound it passes is still a bit muffled / not sparkling compared to what is going in. Like there is still high frequency blocking. Is this normal behavior and inherent to the design or something that can be fixed?

Thanks.
FingerTappin
Aren't there supposed to be .1uf caps on the retrofit schematic?

Also, where do you suggest tapping -12v and ground? If from the power header, would it benefit to put protection diodes on my stripboard circuit also?

Thanks
negativspace
If you feel like using .1uF caps for decoupling the rails @ the IC, go ahead.

I'd tap the -12V rail from either the power header or maybe the backside of U3? (topmost chip.) No need for additional diodes here, it's already protected by the existing system.
Jop
Hi Jason,
can you comment on my question? I can post some sound clips if that's helping.

Thanks.

Quote:
One thing I'm not sure about is when the frequency is fully open, the sound it passes is still a bit muffled / not sparkling compared to what is going in. Like there is still high frequency blocking. Is this normal behavior and inherent to the design or something that can be fixed?
negativspace
The only time I've ever heard anything like that was when I made a mistake building the SMT notch out buffers and put 0.1uF caps where the 22pF should go. ( d'oh! )

Obviously that only effects the notch output in any case, so if you're hearing that from the LP out it's not something I've encountered.
Jop
Thanks Jason, problem is I not sure what I'm hearing is normal.... hihi

To give you a better idea I have recorded a short clip:

* First an unprocessed saw wave
* Followed by the same wave going trough the filter, zero resonance and frequency fully CW.
* Last two sweeps with the frequency from fully CCW to CW.

To me it sounds the same like the sweeps from ben_hex video.

https://www.youtube.com/watch?v=IKi3_4VuUsg
Jop
seriously, i just don't get it

Nobody have a similar experience or can check briefly?
sromanel
After installing a brand new SMT TL072 and redoing a few joints, the problem is still there (ie no change in sound from cutoff fully CCW to 12:00, weak outputs, all filter types behave like a different flavor of LP). I'll attach photos of my PCBs asap. Any help would be reeeeeeally appreciated
sromanel




Hope they're clear enough
cold_fashioned
Well, sromanel's photos up there pretty much confirm what I was going to post about my notch output being faulty. I am pretty sure I mounted my SMT TL072 in reverse / backward. I have the stripe facing the bottom of the board, instead of the top. I'll reverse it tonight and see if that helps. Can anyone tell me whether that TL072 could be damaged from being mounted in reverse?

Thanks!
sromanel
cold_fashioned wrote:
Well, sromanel's photos up there pretty much confirm what I was going to post about my notch output being faulty. I am pretty sure I mounted my SMT TL072 in reverse / backward. I have the stripe facing the bottom of the board, instead of the top. I'll reverse it tonight and see if that helps. Can anyone tell me whether that TL072 could be damaged from being mounted in reverse?

Thanks!


I guess it has reverse polarity protection, but I'm far from sure about that. In any case, that's why I bought 3 of them when ordering the BOM cool
sromanel
Double post
sromanel
Triple post
sromanel
Quadruple post (guys, if you have a Surface, wait a few months more before updating to Windows 10, otherwise stuff like this will happen)
Jack Gull
sromanel wrote:

I guess it has reverse polarity protection, but I'm far from sure about that. In any case, that's why I bought 3 of them when ordering the BOM cool

it does not
sromanel
Jack Gull wrote:
sromanel wrote:

I guess it has reverse polarity protection, but I'm far from sure about that. In any case, that's why I bought 3 of them when ordering the BOM cool

it does not


daje j
cold_fashioned
Oh rats. Good thing I spent all that time desoldering and resoldering last night. I guess I'll test it out and see if I got lucky. Otherwise, does anyone have a spare TL072 they can send me out of the kindness of their heart? MY ASS IS BLEEDING
negativspace
In my experience you have a 50-50 chance that it'll be ok. Sometimes they survive... I'd send you a fresh one off my reel but I just left on vacation. (Writing this at a gas station on the interstate.)
sromanel
negativspace wrote:
In my experience you have a 50-50 chance that it'll be ok. Sometimes they survive... I'd send you a fresh one off my reel but I just left on vacation. (Writing this at a gas station on the interstate.)


Dang, I guess I'll have to wait for my support hihi Enjoy your vacation
cold_fashioned
I concur - enjoy that vacation! This message will be here when you get back.

I did manage to test out the properly oriented TL072, and it appears to be a goner. The notch output still delivers nothing. The rest of the filter sounds soo cool - I love it. At this stage, I more want to get the notch output working, just to hear what it sounds like! I know I can just watch youtube videos to hear it.. but you know what I mean!
FingerTappin
So, I made an attempt at the retrofit circuit. I have one issue and that is my low pass output stopped working. I have checked over my stripboard layout ( seems good) and did some continuity testing (seems good).

I had not soldered in the notch pot before attempting the mod. So instead of cutting the traces, I tapped from the pads for the pot and then soldered to a solder lug pot. Could this be my problem?
Cablebasher
Hey Guys,

Im just starting to build the V.1.2 pcb board.

For the notch pot, should I use the orignal B100K pot or the newly mentioned B10K pot.

Was wondering if this change was related to the newer PCB (v.1.4, which I dont have).

Thanks, as always.
Rumblin_Cynth_Rampo
Just finished mine off last night. No real problems (except dufos put the 5v regulator arse about face DOH!).

My question what the best way to go about calibrating the V/octave trimmer?

I messed around for ages trying to get it to track but didn't get any thing like decent tracking. (or it may just have been because it was late o'clock this morning and i was screwing up due to the ZZZZZZ beam hitting me)
sromanel
Rumblin_Cynth_Rampo wrote:
Just finished mine off last night. No real problems (except dufos put the 5v regulator arse about face DOH!).

My question what the best way to go about calibrating the V/octave trimmer?

I messed around for ages trying to get it to track but didn't get any thing like decent tracking. (or it may just have been because it was late o'clock this morning and i was screwing up due to the ZZZZZZ beam hitting me)


I think this is the way to go: full res, tune it using cutoff freq to any note you prefer (do this while feeding nothing to the V/oct input). Once you've done this, plug in to the v/oct in any controller which gives a constant & known voltage (cv keyboard, midi/cv interface, anything like that). Feed it 1V, it should play the same note as before, just one octave up. If it does not so, adjust it using the trimmer. Unplug the keyboard, re-tune it to any desired note, re-plug the keyboard, re-check, re-adjust, and so on for quite a few octaves. Tune, plug, adjust, check, repeat Dead Banana
negativspace
That's about right... I have a 3.000V reference signal patched up on a particular knob of my Z8000 and I use that for calibration. I aim for 100Hz at 0.000V and 800Hz when I apply the 3V.

Try starting with the 3V signal, setting the cutoff knob to 800Hz, and then removing the signal and trimming the result to 100Hz. You'll probably need to repeat the process 2 or 3 times.

Definitely do this with the res pot maxed.
sromanel
negativspace wrote:
That's about right... I have a 3.000V reference signal patched up on a particular knob of my Z8000 and I use that for calibration. I aim for 100Hz at 0.000V and 800Hz when I apply the 3V.

Try starting with the 3V signal, setting the cutoff knob to 800Hz, and then removing the signal and trimming the result to 100Hz. You'll probably need to repeat the process 2 or 3 times.

Definitely do this with the res pot maxed.


So glad you're back Rockin' Banana! Please, could you help me with the issue I described above? I had this filter lying around for quite a few now, and I just can't wait to hear it sound as it should
sromanel
I've recorded a short clip which explains quite better the problem going on with my module, I think you'll be able to hear it yourself.

https://soundcloud.com/simone-romanello/ma-svvcf

Here are a few pics of the spectrum of the fully open filter (sound source is a saw wave at about 67 Hz)

LP, no res, fully open



HP, no res, fully open




BP, no res, fully open




Notch, frequency at 12:00, notch balance at 12:00, no res




I suppose there's something wrong going on
negativspace
Sorry guys, been mired in house/car stuff the last few days since coming back home - gotta wrangle the grass and the tomato garden back in and get the car ready for a trip to Knobcon in a couple weeks among other tasks. Spent most of yesterday pretending to be a plumber...

I honestly haven't even turned on the modular or the iron yet. Sromanel, I'll take a look at all this ASAP.
sromanel
negativspace wrote:
Sorry guys, been mired in house/car stuff the last few days since coming back home - gotta wrangle the grass and the tomato garden back in and get the car ready for a trip to Knobcon in a couple weeks among other tasks. Spent most of yesterday pretending to be a plumber...

I honestly haven't even turned on the modular or the iron yet. Sromanel, I'll take a look at all this ASAP.


Ok, thanks, I understand there are more important works a houseman's gotta do cool
negativspace
Gotta say it's nice not to have to turn the water on and off behind the washing machine every time I need to clean some clothes now... but I hate plumbing, especially in tight places. Dead Banana
sromanel
negativspace wrote:
Gotta say it's nice not to have to turn the water on and off behind the washing machine every time I need to clean some clothes now... but I hate plumbing, especially in tight places. Dead Banana


Man I just love plumbing, or let's say fixing stuff in general. In fact, I just can't help but being super glad when something gets broken in my house (except modules)
negativspace
I love building things but not so much repairing them... although I'm competent at it at least. hihi
sromanel
negativspace wrote:
I love building things but not so much repairing them... although I'm competent at it at least. hihi


100% agree with that
sromanel
Still no time to check it out? (just askin')
negativspace
Building up a fresh batch now, won't be long. May not get to it until after Knobcon... only a few days until I have to leave for that.
Crashlander42
This may be a stupid question, but I ordered the PN100 and PN5138 and they came loose in the bag rather than on a strip. Should I match these? I've seen a lot of people say they haven't bothered and had plenty of success, but I assume they were pulling the transistors off a strip. In my experience matching transistors for the TTSH they we're all pretty damn close, but I've never dealt with the PN100. Just wanted a second opinion before I soldered them to the board.

I am lazy and would obviously prefer not to match them...
sromanel
Crashlander42 wrote:
This may be a stupid question, but I ordered the PN100 and PN5138 and they came loose in the bag rather than on a strip. Should I match these? I've seen a lot of people say they haven't bothered and had plenty of success, but I assume they were pulling the transistors off a strip. In my experience matching transistors for the TTSH they we're all pretty damn close, but I've never dealt with the PN100. Just wanted a second opinion before I soldered them to the board.

I am lazy and would obviously prefer not to match them...


Transistor always come in a electrostatic shielding bag rather than a strip (at least, when I order them) Rockin' Banana! However, negativspace commented about this about halfway this thread IIRC
Crashlander42
Quote:
Transistor always come in a electrostatic shielding bag rather than a strip (at least, when I order them) Rockin' Banana! However, negativspace commented about this about halfway this thread IIRC


Maybe he term is ammo reel?

negativspace said earlier in the thread "I recommend loosely matching them as a matter of best practice but it's not something you should worry about."

I decided to check the important pairs, and they were all nearly perfect matches anyway. MY ASS IS BLEEDING
Crashlander42
It is alive and sounds awesome. SlayerBadger!
sromanel
Crashlander42 wrote:
It is alive and sounds awesome. SlayerBadger!


I envy you. A lot. waah
horstronic
I have a problem with one of the two SVVCFs I built.
I just can't get the resonance to work properly, it just doesn't self oscillate. Also the amplitude is pretty low on every output, even on the +- Mix outputs.

Here's what I checked so far:
- All resistors and caps do have the right value
- Checked both boards for cold solder joints and I'm pretty sure there aren't any
- voltage regulators are orientated in the right direction and +5V, -6V and supply voltage can be measured on all the points where they should be
- tried out different values for R16. Going down to 15k makes it better but still no self oscillation
- checked out resonance pot, it works and is properly connected


I also went through the whole thread but couldn't find anybody with the same problem. This thing is now lying around for weeks, I worked on it from time to time but to no avail, so now I'm running out of ideas what else I could check.
The last thing I can think of is replacing all the transistors, maybe I got a bad one (they're all from tayda so you never know...).

Does anybody have an idea?
Thanks in advance!
cold_fashioned
I hate to be a pest, but I think someone (maybe even negativespace himself) mentioned that they'd be willing to send me a spare SMT TL072? I'm pretty sure I fried mine because I mounted it backwards. Thus, my notch output doesn't work. Everything else seems to work fine though, and I love this filter!

Cheers,
C
horstronic
horstronic wrote:
I have a problem with one of the two SVVCFs I built.
I just can't get the resonance to work properly, it just doesn't self oscillate. Also the amplitude is pretty low on every output, even on the +- Mix outputs.

Here's what I checked so far:
- All resistors and caps do have the right value
- Checked both boards for cold solder joints and I'm pretty sure there aren't any
- voltage regulators are orientated in the right direction and +5V, -6V and supply voltage can be measured on all the points where they should be
- tried out different values for R16. Going down to 15k makes it better but still no self oscillation
- checked out resonance pot, it works and is properly connected


I also went through the whole thread but couldn't find anybody with the same problem. This thing is now lying around for weeks, I worked on it from time to time but to no avail, so now I'm running out of ideas what else I could check.
The last thing I can think of is replacing all the transistors, maybe I got a bad one (they're all from tayda so you never know...).

Does anybody have an idea?
Thanks in advance!


Update: I started replacing all transistors in little groups and after the second groups it finally works now It's peanut butter jelly time!
Seems like I really had a bad transistor. Never happened to me before but there's always a first time.

cold_fashioned wrote:

I hate to be a pest, but I think someone (maybe even negativespace himself) mentioned that they'd be willing to send me a spare SMT TL072? I'm pretty sure I fried mine because I mounted it backwards. Thus, my notch output doesn't work. Everything else seems to work fine though, and I love this filter!

Cheers,
C


You're in the states, right? I could send you one, but I don't know if it's worth the shipping costs...
cold_fashioned
Yep - in Southern California. No worries - I'll get my hands on a new chip sooner or later. I might actually be placing an order soon, not sure though. I'm glad to hear you got your filter working. It must have been tedious going through all that to find the bad transistor!
sromanel
horstronic wrote:
horstronic wrote:
I have a problem with one of the two SVVCFs I built.
I just can't get the resonance to work properly, it just doesn't self oscillate. Also the amplitude is pretty low on every output, even on the +- Mix outputs.

Here's what I checked so far:
- All resistors and caps do have the right value
- Checked both boards for cold solder joints and I'm pretty sure there aren't any
- voltage regulators are orientated in the right direction and +5V, -6V and supply voltage can be measured on all the points where they should be
- tried out different values for R16. Going down to 15k makes it better but still no self oscillation
- checked out resonance pot, it works and is properly connected


I also went through the whole thread but couldn't find anybody with the same problem. This thing is now lying around for weeks, I worked on it from time to time but to no avail, so now I'm running out of ideas what else I could check.
The last thing I can think of is replacing all the transistors, maybe I got a bad one (they're all from tayda so you never know...).

Does anybody have an idea?
Thanks in advance!


Update: I started replacing all transistors in little groups and after the second groups it finally works now It's peanut butter jelly time!
Seems like I really had a bad transistor. Never happened to me before but there's always a first time.

cold_fashioned wrote:

I hate to be a pest, but I think someone (maybe even negativespace himself) mentioned that they'd be willing to send me a spare SMT TL072? I'm pretty sure I fried mine because I mounted it backwards. Thus, my notch output doesn't work. Everything else seems to work fine though, and I love this filter!

Cheers,
C


You're in the states, right? I could send you one, but I don't know if it's worth the shipping costs...


I think I might do the same - as the butler is always the guilty in thriller novels, so are transistors in electronics
negativspace
cold_fashioned wrote:
I hate to be a pest, but I think someone (maybe even negativespace himself) mentioned that they'd be willing to send me a spare SMT TL072? I'm pretty sure I fried mine because I mounted it backwards. Thus, my notch output doesn't work. Everything else seems to work fine though, and I love this filter!


Yeah, I have a huge strip of 'em here... drop me a PM with your address.
sromanel
Does notch output depend on LP and HP (socketed TL072) or only on the SMT one?
negativspace
Both... the LP and HP outputs are split off into the SMT chip which acts as the buffer(s) for the notch output. So if the HP or LP out itself is messed up, the notch will also be messed up.

However if the HP and LP are good and the notch is messed up it can only be the SMT chip or its attendant passives, as that's the only part of the circuit unique to the notch output.
sromanel
negativspace wrote:
Both... the LP and HP outputs are split off into the SMT chip which acts as the buffer(s) for the notch output. So if the HP or LP out itself is messed up, the notch will also be messed up.

However if the HP and LP are good and the notch is messed up it can only be the SMT chip or its attendant passives, as that's the only part of the circuit unique to the notch output.


I think it's the HP's fault, but again, I'll wait for you whenever you'll have time to help me sort this out since I'm no expert
negativspace
I'll definitely have more time to look into it when Knobcon is over.
sromanel
negativspace wrote:
I'll definitely have more time to look into it when Knobcon is over.


All right, have fun Guinness ftw!
Shoggoth
I'm thinking of creating an expander for myself with the other two filter gain cells for 3-pole and 4-pole outputs. I also have the stand alone CP3 and love the output pot, so I was thinking of adding that, with an extra output jack. I would have the output pot also control how much of the mixer section is sent to the filter. This would allow the negative clipping distortion to be sent to the filter, and negate the need to play with the input resistor value to the filter section.

A few questions since the schematic isnt available:

Could I just tap the positive side of C10 to send to the other filter cells?

Is the output circuit on the Stites schem whats used for the LP output? 10uf>10K>TL072 with 220pf/100k in feedback path? Any reason I would need to change that for the LP3/LP4 outputs?

The + and - pads can go directly to the output pot, right? I think thats how the CP3 standalone works.

I would leave the resonance pulling from the LP2 output unless someone has a recommendation to change it.
sromanel
sromanel wrote:
I've recorded a short clip which explains quite better the problem going on with my module, I think you'll be able to hear it yourself.

https://soundcloud.com/simone-romanello/ma-svvcf

Here are a few pics of the spectrum of the fully open filter (sound source is a saw wave at about 67 Hz)

LP, no res, fully open



HP, no res, fully open




BP, no res, fully open




Notch, frequency at 12:00, notch balance at 12:00, no res




I suppose there's something wrong going on


EDIT: checked the whole control board & connectors between the two boards - everything's perfect there. Scratching my head so much I think I've actually reached the bone...
crexam
Hi,
does anyone have a part number for the ferrite beads? Can you substitute the ferrite bead with a resistor?
Thanks
enj_music
Is this DIY kit still available?
cold_fashioned
crexam wrote:
Hi,
does anyone have a part number for the ferrite beads? Can you substitute the ferrite bead with a resistor?
Thanks


After having no luck finding through-hole ferrite beads (hard to believe), I googled and found out that ferrites are basically just inductors. I picked out a pair of inductors that seemed to be in the right range voltage-wise, and so far , no issues. At least I don't think I have any issues from that.
negativspace
The part number I buy from Mouser is 623-2743001112LF .

(Was going to post that last night, but I need to order another batch of 1000 and I wanted to make sure there was sufficient stock before I started sharing. hihi )
crexam
Thank you for the part number.

Can this module power up and be tested with out the beads?
crexam
Also, Does anything go here?

Thanks for your help.[/img]
negativspace
You'll need to use a jumper wire or 10R resistor in place of the beads but yes, it can be done. And no, nothing goes there.
crexam
Thank you. I appreciate it.
Shoggoth
Holy crap, this filter sounds so good, and it worked from the first power up. DIY win!

I started messing around with the + and - pads going to the outer lugs of a B50k pot, and lug 2 going through a 300K resistor (R13) to the filter section. Pretty interesting as you can overdrive various parts of the circuit (I think).

If you chose a lower value for R13 - like 270/300k - you would overdrive the mixer circuit and the filter circuit at the same time. I like both results but I want to be able to control them separately, because they have different sounds. Adding the pot above lets you choose what you want to overdrive, and you can use the negative clipping 'flavor' of the mixer as well. This way you can slightly overdrive/warm an input with the mixer, but turn down how much goes into the filter so it still sounds clean. The filter distortion is much nastier than the mixer.

One unexpected result was letting both mixer and filter overdrive, and the signal is hot enough to overdrive the MA VCA as well. Sounds really nice.

I'm thinking for my expander I would breakout the two modules - an output for the mixer that disconnects it from the filter, and an input for the filter that bypasses the CP3 circuit.
negativspace
Nicely done!

That portion of the circuit is definitely ripe for experimentation, I've probably spent most of my tweaking and development time on R13. (And why I left it with an asterisk.) hihi

At 390k it's basically set so that the filter section barely clips with a single mixer input at max level + enough resonance to provoke oscillation. Any more signal through that area (lower value resistor) will give significant clipping in the filter section.

I like the idea of the drive pot + separate mixer input.
KNYST
Hi, got some questions here...

I have two v1.2 PCB sets here, and I haven't understood difference between v1.2 and 1.4.
The 1.4 has got SMD parts, but is that all?

Any reason for me to jump on a 1.4 instead of what I already have??

Are the resistor changes valid for both?
R14: 6.8k (10k)
R17: 100k (82k)
R47: 110k (100k)
R16: 39k (33k)
R19: 180k (100k)
R33: 240k (100k)
R36: 200k (100k)


I guess all this was already covered somewhere, but couldn't find it.

Thanks!
Shoggoth
1.4 buffers the LP and HP signals before sending them to the notch pot. Supposedly, when sweeping the pot to either end, signal cuts out otherwise. There's a post with the buffered circuit if you want to add it to the 1.2.

I think the resistor changes work for either board.
polyot
Man, I haven't been in this thread since building mine from the original wait list. Quick question for anyone, to save me from scouring 46 pages of this thread:

Would my original 1.2 board, built with the original BOM benefit from these resistor changes I keep seeing mentioned? And in what way? I'm already pretty happy with it, but if I have the new values around I might as well.
negativspace
The changed resistor values rebalance some signal levels in the filter core... and little else. They work for any version as the core has not changed since release. They definitely improve the filter but it's not drastic.

V1.4 fixes the improperly-implemented notch output from v1.2 which you can also do as a retrofit by building a twin opamp buffer either on perfboard or just deadbugged on the control board. No other changes between the versions.
polyot
negativspace wrote:
The changed resistor values rebalance some signal levels in the filter core... and little else. They work for any version as the core has not changed since release. They definitely improve the filter but it's not drastic.

V1.4 fixes the improperly-implemented notch output from v1.2 which you can also do as a retrofit by building a twin opamp buffer either on perfboard or just deadbugged on the control board. No other changes between the versions.


Thanks as always buddy. I'll probably give those changes a go, not too worried about the notch thing, seems "good enough" for my uses.
Shoggoth
Sharing this info in case it helps another builder:

I built this filter and it worked, then after lots of additional work/testing to add a daughterboard with the 3rd and 4th poles, it started behaving really strange. The frequency pot didn't open up like it should, and sweeping between 11 and 12 the filter actually would close before it hit 12 and then it all the sudden opened waaay up. Also, turning the resonance up, the frequency pot between 7 - 12 would result in a LFO-like clicking, and once again, hitting 12 it would return to a more normal oscillation.

I socketed all (yes, all) the transistors and after swapping some of the NPNs in the 2nd pole, the filter returned to normal. I think the sockets were actually the problem as I think one of the legs of the NPNs didn't have good contact.

I doubt many people will have that problem but hope this helps.
cold_fashioned
I received the SMT TL072 (Thanks Jason!) and installed it last night. Tested it today and I have notch output! Very cool! Thanks for your help and great work designing a fantastic filter! we're not worthy
enj_music
How does the whole PCB duo get attached to the front panel?
woodster
It's all done via the pots n jacks, check the photo's in the 2nd post of this thread...
TripJ
Excellent filter, negativspace, and the soundclip seems to do it justice.
I'm keeping this on my radar for a build down the road if PCBs become available again.
negativspace
Thanks guys... looking forward to taking better care of these threads now that my season of travel is past. (And my taxes are done!)

I have a few boards left, going to order more but I need to finish and bill another order before I can do that. If they go out of stock it will only be for a couple of weeks. thumbs up
enj_music
Just built the filter - it sounds beautiful, but like a lot of people, my notch output is very very quiet/not working...

The lowpass and highpass outputs work really nicely, so it must be the SMT section on the control board, but everything looks good there. Should I just assume I fried the dual opamp chip and get a new one?
shiftr
I'm about to start my build and I have two questions about the BOM:

Would it be ok to use A100k pots on the audio inputs?
I can't find the 2.7nF film cap at my regular suppliers Does anybody have reference for a that (preferably in EU).
negativspace
Yeah, that'll be ok on the pots although the closer you can get to 25k the better. (10k would be better than 50k which is better than 100k.) The higher the pot value in relationship to the input resistor (22k), the more exaggerated the 'log' curve will be. Other than that they're wired as voltage dividers so the value isn't terribly important.

I can give you the mouser # for the 2.7n cap if you can't find one closer to home.
enj_music
By any chance, do you have a Mouser part number for the spacer/screw/washer pair you use? The ones I got were too long and are unusable
negativspace
I use spacers from Fastenal, no idea on a Mouser number. They're 7/16" which is ~11.25mm so 11 or 12mm would work fine.
enj_music
While trying to fix the module, I stupidly put some needle nose pliers in between the two boards to grab a test component and probably shorted something out. The filter outputs are all at various levels, and no longer filter. The lowpass out is dead. The mixer still works. What did I most likely break?

I am losing so much sleep trying to figure this out we're not worthy
negativspace
Ugh, I hate it when I do that. (We all do that.) d'oh!

How's the 5V rail?
enj_music
negativspace wrote:
Ugh, I hate it when I do that. (We all do that.) d'oh!

How's the 5V rail?


5V rail measures in at 5.03V, -6 is still at a beautiful -6.01V. I tried swapping out the TL072s one at a time and that didn't seem to fix the problem, unless more than one of 'em died (unlikely). Q19 is probing a little suspiciously.
fragletrollet
Are both cv inputs wired to affect the filter? Is the state moduletable? (LP-Notch-HP)
negativspace
enj_music wrote:
5V rail measures in at 5.03V, -6 is still at a beautiful -6.01V. I tried swapping out the TL072s one at a time and that didn't seem to fix the problem, unless more than one of 'em died (unlikely). Q19 is probing a little suspiciously.


I'd try replacing Q19 then, esp. if that's the direction from which you entered with the pliers. With a working 5V rail the problem is most certainly in the core transistors, Q19 or any of the cluster on the left side of the board. (The 4 near the LM337 are in the mixer.)

FYI the opamps are there as output buffers for LP/BP/HP and also as a summing mixer on the CV side.

fragletrollet wrote:
Are both cv inputs wired to affect the filter? Is the state moduletable? (LP-Notch-HP)


Yes, CV1 and 2 + v/oct are all wired to cutoff freq. No, the notch is not CV-modulatable.
fragletrollet
Thanks! w00t
negativspace
You bet! SlayerBadger!
enj_music
negativspace wrote:
I'd try replacing Q19 then, esp. if that's the direction from which you entered with the pliers. With a working 5V rail the problem is most certainly in the core transistors, Q19 or any of the cluster on the left side of the board. (The 4 near the LM337 are in the mixer.)

FYI the opamps are there as output buffers for LP/BP/HP and also as a summing mixer on the CV side.


So the opamps aren't actually part of the filter core? Also, is there a resistor/capacitor wired up in parallel with the C/E pins of Q19? Just wanna make sure that my on-board diode test results were okay
negativspace
Correct, they're only there to provide a bit of a buffer and level adjustment on the way to the outside world. (And the CV mixer.) The filter itself is discrete, as advertised.

Schematic is posted a few pages up... I went ahead and stuck it in one of the posts on the first page of the thread to make it easy to find. Have at it. w00t
enj_music
Thank you so much for the schematic! It is a little overwhelming however. Is Q19 part of the CV section, and would a broken Q19 really cause the filter to completely stop filtering/have weird level discrepancies between channels?

Also, there are a couple points in the circuit where there's just a random BJT with the base shorted to ground. Is that just you exploiting the properties of these transistors for a sonic quality, or is it doing something else?
enj_music
Just finished repairing the filter - switched out all the transistors and it works again. However, I still am having a couple problems. First of all, the notch output is getting the highpass signal fine, but does not have the lowpass signal. Also, the filter range seems skewed. It does not open very far when the knob is fully clockwise, and the filter closes completely before even reaching 10 o'clock. It is calibrated to track 1v/oct, and the -6 and +5 rails look good.

With filter cutoff fully clockwise, no CV input, resonant peak occurs around 7kHz:



Here is a recording: (The comments talk about the bugs)

[s]http://soundcloud.com/enj_hoffman/svvcf-bugs[/s]

Also, is there a teensy schematic for the SMT section?
sromanel
Still haven't figured out the cause of the notch issue with mine... hmmm.....
james2098
yes please!
negativspace
sromanel wrote:
Still haven't figured out the cause of the notch issue with mine... hmmm.....


Based on your soundcloud clip, it still sounds to me like the HP signal simply isn't getting to the notch balance pot... unless I'm totally mis-hearing things.

If you like, PM me and I'll give you my shipping address. You can send it over (I know it's international, but...) and I'll take a look.
lilakmonoke
just want to announce that next week we are finally doing the 5-SVVCF group build in berlin with the pcbs/panels i got from jason. before i read through all the posts, is there anything that we have to change or look out for?
sromanel
negativspace wrote:
sromanel wrote:
Still haven't figured out the cause of the notch issue with mine... hmmm.....


Based on your soundcloud clip, it still sounds to me like the HP signal simply isn't getting to the notch balance pot... unless I'm totally mis-hearing things.

If you like, PM me and I'll give you my shipping address. You can send it over (I know it's international, but...) and I'll take a look.


I don't think it'll be worth the shipment price, we're talking about almost a hundred euros send+return. I've had it checked by a synth repairman, there was a faulty trimmer (6V IIRC) but that didn't change much. HP works just fine, the only problem is with notch out. He even changed all SMD components, but with no luck. Is there any measurements I should do in order to understand a little bit of what's wrong?
lilakmonoke
here is our lötsportgruppe berlin (soldering sport group, berlin chapter) after completion of 5x SVVCF. final result are: 3 units working, 1 unit missing the highpass and 1 unit still missing in action. not bad for the first time.

assembly is no problem at all, except maybe the pots being fumbly to connect. the adjustments via the trimpots are mysteriously confusing but good thing a filter sounds even without being correctly adjusted ... if its not outright broken call it a feature ;-)

thanks jason for such a good module!

ps: yes that image is large but i dont know how to resize it

negativspace
Nice work, guys! w00t

Calibration is not absolutely necessary, but also not difficult. It takes me about 2 minutes to calibrate each one now, but that's with a hundred or so builds under my belt.

Would be good to set the -6V rail correctly, though, as the clipping behavior of the CP3 stage depends on it.
negativspace
sromanel wrote:
I don't think it'll be worth the shipment price, we're talking about almost a hundred euros send+return. I've had it checked by a synth repairman, there was a faulty trimmer (6V IIRC) but that didn't change much. HP works just fine, the only problem is with notch out. He even changed all SMD components, but with no luck. Is there any measurements I should do in order to understand a little bit of what's wrong?


It's ~$15 to ship one of these things from here to Italy, I've done it more than once. Surely Italian airmail isn't $85 for a 12oz package.

Anyway... if you *do* have a HP out then there is only one possibility for the fault and that is somewhere in the SMT/notch balance pot/jack "subsystem." Try probing the CW and CCW pins of the balance pot with a patch cable just to see if there's a signal on either, and we can work backwards from there. A photo might also help, otherwise I'm just taking blind guesses. hihi

6V trimmer will only have an effect on the mixer section, that rail is not used on the filter side.
sromanel
negativspace wrote:
sromanel wrote:
I don't think it'll be worth the shipment price, we're talking about almost a hundred euros send+return. I've had it checked by a synth repairman, there was a faulty trimmer (6V IIRC) but that didn't change much. HP works just fine, the only problem is with notch out. He even changed all SMD components, but with no luck. Is there any measurements I should do in order to understand a little bit of what's wrong?


It's ~$15 to ship one of these things from here to Italy, I've done it more than once. Surely Italian airmail isn't $85 for a 12oz package.

Anyway... if you *do* have a HP out then there is only one possibility for the fault and that is somewhere in the SMT/notch balance pot/jack "subsystem." Try probing the CW and CCW pins of the balance pot with a patch cable just to see if there's a signal on either, and we can work backwards from there. A photo might also help, otherwise I'm just taking blind guesses. hihi

6V trimmer will only have an effect on the mixer section, that rail is not used on the filter side.


I know shipment itself doesn't cost that much, but believe me, customs clearance does (there's a 100% package stop rate from/to USA & Canada here, and they make you pay for the package inspection - seriously, fuck Italy). Back to technical stuff - if I got that right, I hadto feed a signal into the filter, attach one clamp of the oscilloscope to left & right pins of notch balance pot. Here's what I measured:

Sine in, fully CCW balance


Sine in, fully CW balance
sromanel
Here are pics of the boards






The board seems sticky & greasy because of isopropyl alcohol[/img]
negativspace
I guess I'm spoiled with the USPS... I think in my entire life I've had to pay import duty one time. d'oh!

I presume you have an 0805 1k resistor installed on the backside of the main board, since the through-hole alternative is missing from the front. (Wouldn't explain the issue you're having in any event.)

On the scope shots... fully CW is HP side, looks like that's the one that works correctly? If that's true then it's your LP side that's broken. Is that accurate? If so, start by checking the soldering on the 47k 0805 input resistor. Possibly a cold joint there in your pic.

On the sticky stuff... I had to wash my boards about 3 times with alcohol when I was using rosin-core solder. It's always a gummy mess after the first pass. hihi
Jop
With my build I experienced some slight HF rolloff (posted orginally on page 44 with some sound clips). Jason confimed this was also present on his builds and suggested to lower the three 220pF caps on the output buffers to 22pF.

That did the trick, all frequencies are there with the cutoff fully open!
Thanks Jason thumbs up

So if you experience this same behavior you know what to do. cool
sromanel
negativspace wrote:
I guess I'm spoiled with the USPS... I think in my entire life I've had to pay import duty one time. d'oh!

I presume you have an 0805 1k resistor installed on the backside of the main board, since the through-hole alternative is missing from the front. (Wouldn't explain the issue you're having in any event.)

On the scope shots... fully CW is HP side, looks like that's the one that works correctly? If that's true then it's your LP side that's broken. Is that accurate? If so, start by checking the soldering on the 47k 0805 input resistor. Possibly a cold joint there in your pic.

On the sticky stuff... I had to wash my boards about 3 times with alcohol when I was using rosin-core solder. It's always a gummy mess after the first pass. hihi


I guess I screwed something up on the last measurements. I checked again, now this is what i have both CW and CCW



while this is what input signal looks like



Regarding 0805 1k resistor, you're right, this is SMT section on the main board



I tried resoldering all of the SMT section, but nothing changed
sromanel
Just did full continuity test on the control board, everything seems just fine seriously, i just don't get it And listening more carefully, it is clear to me that notch works fine, it just comes out at half volume
negativspace
Yeah, I was sitting on it overnight giving it some thought but it's clear from your last photo that both sides of the notch output are working...

There are 4 caps on the SMT section, two on the power rails and one in the feedback loop of each buffer. It's really hard to tell in the photo, but are you certain that the 0.1uF are in the correct spot as are the 22pF (0.1 on the rails, 22pF in the buffers.)

If you put a .1uF in the feedback loop of the buffer, you'll get a muted and filtered output. (From experience.)

Looking very closely at your photo it looks like you have physically thinner caps on the power rails and physically thicker caps in the feedback loop - that could be the problem. (For me, anyway, the 22pF I use are thinner than the 0.1uF. Mine are also different colors which helps a lot.)
sromanel
negativspace wrote:
Yeah, I was sitting on it overnight giving it some thought but it's clear from your last photo that both sides of the notch output are working...

There are 4 caps on the SMT section, two on the power rails and one in the feedback loop of each buffer. It's really hard to tell in the photo, but are you certain that the 0.1uF are in the correct spot as are the 22pF (0.1 on the rails, 22pF in the buffers.)

If you put a .1uF in the feedback loop of the buffer, you'll get a muted and filtered output. (From experience.)

Looking very closely at your photo it looks like you have physically thinner caps on the power rails and physically thicker caps in the feedback loop - that could be the problem. (For me, anyway, the 22pF I use are thinner than the 0.1uF. Mine are also different colors which helps a lot.)


You know what? I'll drop by the electronics parts shop where I usually supply and see if they have those components in stock, and try switching one at the time until (hopefully) the problem will be gone. Do you think I should try replacing the SMT TL072 as well?
negativspace
If it's passing a clean sine like it should on both sides, no. Seems to be working fine.

You won't have done any damage to the caps if they're in the wrong spots, swapping them around should work. (If indeed that's the issue.)
sromanel
negativspace wrote:
If it's passing a clean sine like it should on both sides, no. Seems to be working fine.

You won't have done any damage to the caps if they're in the wrong spots, swapping them around should work. (If indeed that's the issue.)


Yeah, but SMT components are quite delicate, and I'm rather clumsy at unsoldering hihi I'll see what I can do
negativspace
True... in my experience the ceramic caps can take some rework. Hope yours survive. hihi
sromanel
negativspace wrote:
True... in my experience the ceramic caps can take some rework. Hope yours survive. hihi


After double checking, I can quite surely say that caps are correct (the ones "above" and "below" TL072 are 0.1 uF, while the ones left and right of it (IE the ones nest to "4") are 22 pF. I was wondering - gain is set by 47k resistors, right? Could they be the guilty ones? And what if I replace them with, say, 100k s? Should this solve the problem?
negativspace
Hmm... can you confirm that you used a 10k pot for the notch balance? I've had super-quiet notch issues twice since the SMT revision. Once was when I put 0.1uF caps in the feedback loops, once was when I used a 1M pot from the wrong pile.

A slight drop in the middle is normal but it should be full strength at both ends. (Full HP or full LP.)

Gain is set by the ratio between input and feedback resistors - all should be 47k, which means gain = 1, so it should all be operating at unity. You can change the feedback resistors to fix the levels but that'll be a band-aid masking the real issue. (Which is really starting to have me curious.)
sromanel
negativspace wrote:
Hmm... can you confirm that you used a 10k pot for the notch balance? I've had super-quiet notch issues twice since the SMT revision. Once was when I put 0.1uF caps in the feedback loops, once was when I used a 1M pot from the wrong pile.

A slight drop in the middle is normal but it should be full strength at both ends. (Full HP or full LP.)

Gain is set by the ratio between input and feedback resistors - all should be 47k, which means gain = 1, so it should all be operating at unity. You can change the feedback resistors to fix the levels but that'll be a band-aid masking the real issue. (Which is really starting to have me curious.)


I'm quite sure everything's fine, knobwise

negativspace
Yep, perfect as can be. Hmm.

Back to thinking while I calibrate this stack of 16 CP3s...
sromanel
negativspace wrote:
Yep, perfect as can be. Hmm.

Back to thinking while I calibrate this stack of 16 CP3s...


I'm wondering - what are the odds that the TL072 might be involved in the issue?
sromanel
Update:

After replacing all the 47k resistors (again), I found out one of them (parallel to 22 pF capacitor, pic related) keeps reading 29 kohms, no matter how many times I replace it, while every other resistor reads ~47 kohms. It may be a reading problem, but I suppose it's worth mentioning. Another thing: I decided to test the notch balance knob, and while one of the test points (left one, towards lp side) correctly sweeps from 0 to ~10 kohms, the other one (right, towards hp) has a rather strange behaviour. It starts at about 3kohms fully CCW, it keeps rising to about 6 kohms about halfwat, and then falls to 4.5/5 kohms fully CW. Furthermore, it reads various values as I turn the knob more or less quickly. Note that all the readings were done with the module unplugged

FingerTappin
Hey negativspace,

So, I made an attempt at the retrofit circuit. I have one issue and that is my low pass output stopped working. I have checked over my stripboard layout ( seems good) and did some continuity testing (seems good).

I had not soldered in the notch pot before attempting the mod. So instead of cutting the traces, I tapped from the pads for the pot and then soldered to a solder lug pot. Could this be my problem?


Been sitting on the bench for a few months and with the holidays coming up, figured I would get it going. Thanks in advance.
sromanel
Swapped the non parallel 47k to 22k, now signal reaches 8 Vpp for an incoming 10 Vpp signal. The resistor I talked of before still reads 26k though hmmm.....
medbot
Does anyone have any experience using silver mica caps instead of the styrenes? I just ordered some polypropylene caps to try out and saw that Mouser had 1nf mica caps as well, but I didn't want to fork out the $6 to try them. hihi They were recommended in Moogah's SEM filter thread, that's what got me thinking. Going the other way, has anyone stuck some cheapo ceramics in there? I've got styrenes in mine now but am going to have it on the bench soon for the resister swaps, maybe I'll socket the caps and test some different things.
Jop
Just finished my second unit and unfortunately there are some issue's very frustrating

Build:

* Rev 1.4 PCB
* Wima polypropylene timing caps
* Experiment with different transistors, SA733P & SC945P correctly bend to allow the different pin layout (ECB) and matched within 2mV.
* Carefully build the unit and washed the PCB after soldering.

Calibration:

* -6V TP was easily set with the trimmer
* between + 5.2 and 5.6V on the +5 TP, reading change a bit depending on the frequency pot position.
* +TP a reading between + 3.2V and +5.5V depending on the null trimmer.
* -TP a reading between -141 mV and 19mV depending on the null trimmer.

Issues:

* Only the HP out carriers a signal, all other outputs are silent. The mix out jacks do work, although the plus jacks is much lower in volume, probably related to the calibration issue from above.

Frequency and resonance pot don't do anything.

In1/2/3 pot and jacks work properly.

What I already did is:

* Triple checked all transistors if the correct one's (PNP / NPN) where installed and matching the silkscreen.
* Replaced the IC's.
* Checked for LP signal at pin 6 of U2 without result.

I have the feeling my issues could be related to the transistors used (not looking forward replacing them all...) but I'm missing the technical background. Could someone please direct my where to look at first?

Attached some pictures.

Many thanks!





Jop
In the end I replaced all the transistors for 3904 & 3906 and everything is good now!

The circuit came alive with the 733p's & 945p's but it was far from stable, some trannies need bending to one end to become active and all kind of artifacts could be heard. Strange things hmmm..... seriously, i just don't get it , I din't bother further and just replaced all of them.

It could have been that the leg bending caused some shorts, I did see that on the DMM when testing them in circuit (C& B connected)...

In the end all good SlayerBadger!
negativspace
Glad to hear! I like it when I sit down to read a troubleshooting question and it ends with "nevermind, I fixed it." hihi
Grumskiz
Hey, just wondering is the PCB set currently available? (Don't need a panel)
negativspace
Yep, I recently restocked and I have a ton of these on hand again. thumbs up

*goes back to building more*
james2098
*SMT tip for new builders* (like me)
Sorry if this was said already, I missed it...

A. Follow Jason's SMT guide - it works surprisingly well for a SMT beginner!

B. START with the TL072 - Why?
Because I did the resistors & caps first and painted myself into a corner.
I'm sure if you have a better soldering iron you'd stand a better chance but I found it tight tacking down the pins 5,6,7,8 (right side).

Hope that helps at least someone :-)
negativspace
That's excellent advice and exactly how I do it. thumbs up
FingerTappin
Finally got this on the bench and tried out the retrofit. Seems to work well. I made a few noob blunders as this was my first stripboard project. Going back over it, and with some help from negativspace, I got it up and running.

Figured I would throw up a picture. Hopefully there are no errors, haha.

pulsepsycle
Sorry for cross posting but are the panels and pcb's still available? I would like one set. (posted in https://www.muffwiggler.com/forum/viewtopic.php?t=88663&highlight= earlier)

Best regards,
Karel.
negativspace
Nice work, FingerTappin! Missed the post while I was away in PR I guess. oops

pulsepsycle - yes, plenty in stock! PM me and let me know what you need.

Now, back to building the last of a batch of 15 of these things for Schneidersbuero for me...
GryphonP3
Having some trouble figuring out what to use for

[2] 1nF Polystyrene/Polypropylene *main timing caps in VCF

I usually use Wima film caps when polyester is called for, but you specify polyester separate from he other film box caps, and it looks from the shots like there are some big silver caps there, and the lead spacing is pretty huge. Could you recommend some caps for use there, or give an example?

Cheers!
gbiz
Depends on how you want the filter to sound, what you put in there will have a noticable effect on the sound. If you're happy unsoldering components, i'd suggest getting a couple of each type & trying them. You don't need to fully solder them in to test them.

Those big* silver caps are styrenes. They give the filter a nice smooth sound. If you use something like a Wima FKP2 polypropylene, it'll have a slightly more raspy/buzzy sound. I've always meant to give FKS2's or even some C0G's a try. I assume they'd be even more buzzy.

I've got four of these filters all fitted out differently, two with the original component spec where the filter doesn't quite self oscillate & two that self oscillate. One of each type has styrene & one with propylene. I can never decide which is my favourite sounding one, if i really had to pick one it'd probably be the one that doesn't self oscillate, with the FKP2's, but the styrene one really does sound lovely.

* Those styrenes don't have to be big. I used Suflex SC-225 from Rush online (linky). They're 7mm length, 3mm dia, so basically the same size as the Wima propylene.
Shoggoth
Small bear has the styrenes and I believe Jason has said he uses the pots from there as well. I did my build with these components and love it.
synthcube
we're happy to report that we (finally) have full kits in stock for this awesome filter-- after a world-wide hunt for sources of the pots lol

this is one of the sharper-looking filters of its kind we have seen, and the changes that MA made to the circuit sound fantastic!

http://synthcube.com/cart/index.php?route=product/product&product_id=1 023
TechnoPrisoner
any chance we see the full kit in EU ?

thanks.
mantiwhore


Here's mine. Awesome module!
oootini
anyone have a SVVCF BOM in a sensible format? like a spreadsheet or something? Guinness ftw! Guinness ftw! Guinness ftw!
oootini
to save 30 min of someones life doing silly search and replace in text pad and csv, see attached for a mouser compatible BOM based on the pdf (why u no like xslx?) posted by synthcube.

rename the txt file as a csv and you should be good to go.

Guinness ftw!
mig27
Old post, I know.

But I had the same problem with my SVVCF.
My mistake was that I had installed a 1k SMD tempco on the rear AS WELL AS a 1k on position R44.
That's one too many.

Removing one of the two 1k's solved my problem..

Cheers


Michael

herringson wrote:
Hey Jason,

I'm still having this weird problem where I can only get the frequency to sweep between 1 and 2 o'clock on the knob, either side I get no sound.

I've replaced U3, Q19, checked the resistors values and everything looks ok, I can't figure it out.

If I measure between R45 and pin 6 on the TL072 I get 0 volts for most the of the frequency knobs movement, it quickly sweeps from 0->6V between 1-2 o'clock and then for the rest of the knobs range is stuck at 6V.

I guess something is being amplified too much somewhere in the control voltage circuit and then clamping either side but I can't figure out where this is happening.

Is there a good place in the frequency control circuit where I could for a known good voltage and work back from there?

#stumped

Thanks.
Dylan.
oootini
hi, just about finished this build, i've not powered up/calibrated yet.

Anyone have any thoughts on the 10uF capacitors in the VCF section? do part selections here make a difference to the overall sound at all?

I have bog standard 10uF 25V electrolytics in there.
303ish
I finished my build some days ago but unfortunately it doesn't work as expected. Then I found that the BOM and photos in the first post have different resistor values (and who knows what else). I spend my afternoon debugging and already got almost everything working, except for the v/oct tunning. When I increase the resonance to the max there is a pulsating distorted signal that comes and goes.
oootini
303ish wrote:
I finished my build some days ago but unfortunately it doesn't work as expected. Then I found that the BOM and photos in the first post have different resistor values (and who knows what else). I spend my afternoon debugging and already got almost everything working, except for the v/oct tunning. When I increase the resonance to the max there is a pulsating distorted signal that comes and goes.



Yeah I have the exact same issue. Built board 1.4. What values from the first post are incorrect?
303ish
oootini wrote:

Yeah I have the exact same issue. Built board 1.4. What values from the first post are incorrect?


I emailed negativspace and he confirmed the BOM values, they are ok. I was just a bit confused with all the discussion on this thread.

That said, the resonance still was too much distorted to me. With 330K on R13 I have a lot more control - increasing the signal drops the resonance level.
itsritual
My frequency range is only really effective past 12 O'clock. On lowpass, it's basically muted for the first half going clockwise, then the filter only starts opening up in the second half. Any one else with this issue?

fwiw my main board is v1.4, control board is v1.3
itsritual
After rereading the entire thread looks like there's a few people with similar, but no solution posted.

sromanel wrote:
After installing a brand new SMT TL072 and redoing a few joints, the problem is still there (ie no change in sound from cutoff fully CCW to 12:00, weak outputs, all filter types behave like a different flavor of LP). I'll attach photos of my PCBs asap. Any help would be reeeeeeally appreciated


qfactor wrote:

Mine's got all weird on me!! sad banana
I did the new values expecting things to be more balanced, but instead, after changing to the new resistor values (stated in your list) the cutoff now only works from 12 o'clock onwards. Closes up way too much and too fast from the left half (CCW) of the cutoff knob! eek!

Also, now, the resonance doesn't self oscillate, with the new values. The old values did all that better but I can't tell if it's more balanced with these changes now d'oh!

Which are the resistors that controls cutoff and resonance in your list? hmmm.....


herringson wrote:
I build my one of the three @JackMattson got yesterday.
All working and sounds amazing!

The only problem I'm having is the cutoff frequency control has a very limited useful range, somewhere between 1-2 o'clock sweeps frequency, everywhere else is dead range.

The CV inputs are also overly sensitive and barely opening up the CV pot causes massive sweeps.

I've tried trimming the V/oct but that didn't help.
Does the 1.4 PCB have the correct LM337 orientation?
Anyone have other ideas about obvious things I could have done wrong?

I didn't see where I could find a schematic to try and troubleshoot, if there's a link please let me know.
Thanks!


Pretty sure there were others, but couldn't find them again.

Any clues? Went over the board, and paid special attention to the CV section on the upper right, but found nothing.
oskary
Happy builder of a SVVCF here, though I kind of expected slightly better tracking of the filter. I get at best one octave with my build.

There is some info about using a tempco for R44 in this thread, but this is not documented in the BOM on the first page - it looks like it does not apply for the version 1.4 PCB?

So, my question is:

- Can I still replace R44 with an 1k tempco, either through-hole or SMT?
- What specs should I choose for a tempco?

Hope somebody can help! help
zorglub76
Just to make sure: are these Erthenvar jacks (PJ301BM), and do they go on PCB like this (without any modifications)
jimfowler
Did the limited frequency knob control range (and very sensitive cv inputs) ever get addressed? Filter sounds great but kinda not useful in its current state.

My frequency knob doesn't do much from full ccw to ~10 and then stops effecting around 3-4 o'clock to fully cw. As well, as I'm sweeping it the frequency knob it mutes the output momentarily...like it's muting the output while it figures out where the frequency range knob is now set.
Jumbuktu
I seem to have stuffed up my build. On power up, no other modules in the case come on. Fuse is not blown - remove svvcf and everything is Ok. Case is doepfer LC6U. Any ideas where to start?
khakifridge
Get your DMM out and check for shorts between the power rails and 0V.
Jumbuktu
khakifridge wrote:
Get your DMM out and check for shorts between the power rails and 0V.


Thanks! That is the kind of guidance I was hoping for.
donpachi
After several years, I finally built this filter. It sounds ace w00t

negativspace wrote:
sammy123 wrote:
Jason, did you ever try with the 2N5089/5087 or 2SC945/2SA733? I used the pn100a/5158 and it was amazing. Now it's time to build my second.


No, but it's certainly worth a try! I have the 945/733s here and also a giant pile of 5089s (and also of 5088s) but I haven't given them a go in this circuit yet. I'm interested in your results if you do. cool


Did anyone build this with transistors other than 2N3904&2N3906 (I used 2SC1815&2SA1015, which should be very similar) or PN100&PN5138? Have another main PCB and would like to try something different. I think Jop reported that there were some problems with the behavior of the circuit with 2SA733&2SC945 in his build, possibly due to bending of the legs to fit the pinout, but cannot find the post.
Thanks thumbs up
Jumbuktu
khakifridge wrote:
Get your DMM out and check for shorts between the power rails and 0V.


I checked this. No shorts between Gnd and either +12v or -12v on the power header pins. However, +12v is shorted to -12v? Not sure what is causing it though.
khakifridge
Jumbuktu wrote:
I checked this. No shorts between Gnd and either +12v or -12v on the power header pins. However, +12v is shorted to -12v? Not sure what is causing it though.


Do these apparent shorts and not-shorts register no matter which way round you have the DMM test leads? The circuit is protected with diodes which will conduct in one direction.

If you do still have a real short between +12V and -12V, get out a magnifying glass and go hunting. It'll be a whisker of solder or a stray wire strand...
negativspace
Double-check the upper header, the top 2 pins bring + and -12V to the SMT circuit on the control board. Also don't forget to check the SMT section itself.
Jumbuktu
negativspace wrote:
Double-check the upper header, the top 2 pins bring + and -12V to the SMT circuit on the control board. Also don't forget to check the SMT section itself.


I separated the boards and got the same issue.

I am wondering if my soldering of one of the SMT caps on the back of the main board might have bridged the pads?
negativspace
Definitely not impossible. hihi

(I've done that once or twice...)
Jumbuktu
negativspace wrote:
Definitely not impossible. hihi

(I've done that once or twice...)


Ok, I lost most of the last week with an emergency visit to hospital to have my gall bladder removed. Back home now and I was able to sort this out today.

I had to remove both of the SMT capacitors from the back of the main board to get it to power up with no dramas. However, with the control board attached, I still had power problems - but some modules were now getting enough power to light some LEDs.

Suspecting a pattern here, I removed both of the 0.1uF SMT capacitors from the control board, and the module powered up Ok. After some calibration, I had a fully-functioning filter. The resonance is a bit ratty, but I am not sure the missing caps are affecting it much.

I can't believe I bridged the solder pads on EVERY 0.1uF cap (and still managed to solder the other SMT components properly). I must have mistakely been given or picked up a pack of resistors instead of caps.

Now my question is - what do the caps do? And does it matter if I don't replace them? I am relieved that I now have a working module, but I would like to finish the whole build off properly.
negativspace
Ugh, sorry to hear about that one. I had emergency surgery to remove my necrotic gall bladder a little more than a decade ago, so... been there. Not fun. Dead Banana

Those caps are all for decoupling. The module should work ok without them, but to be on the safe side I'd get some replacements with your next parts order and install them when you can.
GregorSmith
Hi Jason,
I purchased and built the 1.4 version and I've got a couple issues that hopefully you can help get to the bottom of. The filter section plays at extremely low volumes and the resonance is not working properly either. The mixer works just fine though. I'm including a few pictures and an audio file so maybe that will make it easier to troubleshoot. It seems when I close the cutoff frq I get some pops towards the bottom(closed) position on the way down from opened. Ive triple checked all trans and they are in the right position and with the proper value. I used red wima caps for the 10u instead of the silver ones in case I screwed up doing that and that might be an issue as well. On the posted soundcloud link I started with the lp with no resonance and then moved the res all the way up. I then moved to the BP, HP, and finally notch with the res maxed. At the end I switch to the mixer which works fine so you can hear the volume difference. Thanks!

i was playing with the resonance knob a little some during the middle of that sample.
Edit:
[s]https://soundcloud.com/djgregorsmith/6-15-18a/s-Dpb0a [/s]
Jumbuktu
GregorSmith wrote:
Hi Jason,
I purchased and built the 1.4 version and I've got a couple issues that hopefully you can help get to the bottom of. The filter section plays at extremely low volumes and the resonance is not working properly either. The mixer works just fine though. I'm including a few pictures and an audio file so maybe that will make it easier to troubleshoot. It seems when I close the cutoff frq I get some pops towards the bottom(closed) position on the way down from opened. Ive triple checked all trans and they are in the right position and with the proper value. I used red wima caps for the 10u instead of the silver ones in case I screwed up doing that and that might be an issue as well. On the posted soundcloud link I started with the lp with no resonance and then moved the res all the way up. I then moved to the BP, HP, and finally notch with the res maxed. At the end I switch to the mixer which works fine so you can hear the volume difference. Thanks!

[s]https://soundcloud.com/djgregorsmith/6-15-18a/s-Dpb0a [/s]


Hi, did you calibrate the voltages as per the build guide? Mine didn't work properly until I got that right.

PS the red box caps look like the same ones I used. Should be fine.
GregorSmith
Thanks for the reply. Everything is calibrated nicely. I adjusted until I got 6 volts then moved on to the + and -. The first one was the minus and I think it was + .10v so I adjusted the other to match at -.10v. The 5v is right on at 5v.
Jumbuktu
GregorSmith wrote:
Thanks for the reply. Everything is calibrated nicely. I adjusted until I got 6 volts then moved on to the + and -. The first one was the minus and I think it was + .10v so I adjusted the other to match at -.10v. The 5v is right on at 5v.


OK rules that out then.
Jumbuktu
GregorSmith wrote:
Thanks for the reply. Everything is calibrated nicely. I adjusted until I got 6 volts then moved on to the + and -. The first one was the minus and I think it was + .10v so I adjusted the other to match at -.10v. The 5v is right on at 5v.


Since no one else is chiming in, let me add a few obvious checks. I don't know much about electronics, but having just completed a build with problems, I feel your pain and I have been through some of the troubleshooting processes myself.

The images you posted are a bit fuzzy and perhaps too close up - parts of the boards are cropped off at the edges. So it's pretty difficult for me to check component values, IC orientation etc. Things i would check:

- The values of the capacitors on the main board. As you probably discovered, the BOM has the resistors coded R1, R2 etc, but for some reason it doesn't say which capacitors are which. I had to refer back to the schematic to work out a few of them. You might just check you have them in the correct place.

- Obvious things: correct orientation for diodes, electrolytics, transistors and ICs.

- The two regulators - are they in the right places? I was confused about the one on the left at first - the thread said that it was solk-screened the wrong way round, but in later boards (like mine) it was correct.

- Correct values for pots. It's easy to mix them up.

- Correct orientation of the SMT IC (although I don't think this would create the issue you are getting, since I think the SMT section just handles the notch behaviour).

Hopefully someone with a bit more knowledge will have a look at your build.
jgb
Also, double check the resistor values, sometimes I mess up due to misreading values.
GregorSmith
Thanks for the reply guys, I’ve checked all the basics already and most likely need to wait until Jason sees my post as he knows this circuit in and out. He most likely has had this symptom show up once during the many. Many builds he’s made.
Jumbuktu
GregorSmith wrote:
Thanks for the reply guys, I’ve checked all the basics already and most likely need to wait until Jason sees my post as he knows this circuit in and out. He most likely has had this symptom show up once during the many. Many builds he’s made.


Did you pm him? Good luck anyway!
GregorSmith
Thanks man and I really appreciate the help and input. I tried to PM hi but for some reason it didn’t go through. I’m new to posting here at Muff after years of lurking so maybe it’s my post count or something.
Jumbuktu
GregorSmith wrote:
Thanks man and I really appreciate the help and input. I tried to PM hi but for some reason it didn’t go through. I’m new to posting here at Muff after years of lurking so maybe it’s my post count or something.


One other thing you should try is swapping out the ICs. I had a similar problem with a Kotelnikov VCO I built last year. It all worked fine, except that the output distorted at a certain point when sweeping the wavetables. Turned out to be a faulty TL074. It's something easy to check, and would at least rule that possibility out.
GregorSmith
Good idea man. I haven’t tried swapping the ic’s so it’s definitely worth a shot. Thanks man I’ll let you know what happened.
GregorSmith
Yea I just checked and unfortunately it’s still the same. I hit Jason up with a PM. It went through this time I think.
jimfowler
DISCLAIMER: I don't know what the hell I'm doing.

That having been said, I was able to get rid of a lot of the odd behavior (which, for me, was thumping and clicking when moving the cutoff knob quickly and/or controlling it with cv AND no audio out if the cutoff knob was below ~40%) by changing R47 to 220k. It would appear that I've sacrificed a little resonance (no longer self-resonates) but that's ok with me. I might pop a 180k in there and see what happens.

- Jim
GregorSmith
Jim, thanks so much for the reply man. Really appreciate the lead. I’m definitely down for trying that but Jason sent me a PM and before I start desoldering I just wanna wait until he chimes in. I’ll be honest it’s very tempting to do it right now but with my luck something else will happen...lol.. thanks again
jimfowler
Let us know how you make out. Seems like a small group of folks are experiencing somewhat similar misbehavior despite correct assembly.
GregorSmith
Jim, wow that personally makes me feel a little better after hearing that though I don’t want anyone else to come into or deal with any issues obviously. I was on quite a good run of builds with
out a single issue. I might go over every resistor value again tomorrow. The thing that really makes it hard for me is that it’s calibrated perfect and I’ve checked everything that I thought of with the multimeter. I’m still drooling though because everyone who has this filter working perfectly just raves about the sound. I’ll definitely let you know what happens either way and thanks for checking in man.
JanneI
I just finished my trio in custom 5U format. Works fine and sound great! I needed to build the notch buffers on veroboard, so here's a pic if someone is about to do the same thing. I used the 3x2 pin header ("LP-HP-GRD" with 2 pins removed) to mount the little veroboard to the main pcb.


elmegil
I"m trying to troubleshoot one of these.

Does anyone have:

a schematic for 1.4?

a schematic with designators instead of values (aside from the transistors)?

Thanks....
negativspace
I don't think I've posted one with designators... made up a quick PDF for you, though.
elmegil
Awesome, thank you very much!
2thick4uni
Reviving an old thread - I've had the pcb and panel for this great filter for a while now and am just getting back into SDIY so have finally starting to build it.

I had a glance at the schematic and the 220p capacitors in the feedback loops of the LP and BP output amplifiers looked way too large and can cause a considerable LP filtering effect in their own right. I've modelled this in LTSpice and in the case of the LP output amp, assuming 10v p/p output levels the frequency response is -12dB at 10kHz, and -18dB at 20kHz; so even with the filter fully open there is quite a bit of LP filtering going on here at the output stage which will dull the sound. This could be a design choice though, perhaps it sounds better that way?

This capacitor is usually installed to prevent instability which manifests as unwanted resonance at higher gains (the gain on the LP amplifier is x27), and a large value is needed here because the TL072 is not good in high gain applictions, it quickly becomes unstable and resonates. The solution is to use an opamp that is more stable at higher gain factors, so that a much smaller LP feedback loop capacitor can be used. Most of my experience is with SMD opamps, and the OPA1678 is very useful for this, I'll try some DIP op-amps and find a suitable part that will work with a much smaller feedback cap. Just swapping out the op-amp will have no effect unless the capacitor value is reduced too. If a 22p cap is used insted of 220p then the frequency responce will only be -1dB at 10kHz and -2dB at 20kHz.

I've attached a graph showing the cutoff effect of the LP amplifier (purple trace) and the BP amplifier (yellow trace). The frequency responce of the bandpass amplifier is slightly better due to it having a lower gain factor of x9, but would still benefit from better opamp and LP capacitor an order of magnitude or two smaller.

When I get it built I'll try different opamps and capacitors and report back on my findings.
zer0point
2thick4uni wrote:
Reviving an old thread - I've had the pcb and panel for this great filter for a while now and am just getting back into SDIY so have finally starting to build it.

I had a glance at the schematic and the 220p capacitors in the feedback loops of the LP and BP output amplifiers looked way too large and can cause a considerable LP filtering effect in their own right. I've modelled this in LTSpice and in the case of the LP output amp, assuming 10v p/p output levels the frequency response is -12dB at 10kHz, and -18dB at 20kHz; so even with the filter fully open there is quite a bit of LP filtering going on here at the output stage which will dull the sound. This could be a design choice though, perhaps it sounds better that way?

This capacitor is usually installed to prevent instability which manifests as unwanted resonance at higher gains (the gain on the LP amplifier is x27), and a large value is needed here because the TL072 is not good in high gain applictions, it quickly becomes unstable and resonates. The solution is to use an opamp that is more stable at higher gain factors, so that a much smaller LP feedback loop capacitor can be used. Most of my experience is with SMD opamps, and the OPA1678 is very useful for this, I'll try some DIP op-amps and find a suitable part that will work with a much smaller feedback cap. Just swapping out the op-amp will have no effect unless the capacitor value is reduced too. If a 22p cap is used insted of 220p then the frequency responce will only be -1dB at 10kHz and -2dB at 20kHz.

I've attached a graph showing the cutoff effect of the LP amplifier (purple trace) and the BP amplifier (yellow trace). The frequency responce of the bandpass amplifier is slightly better due to it having a lower gain factor of x9, but would still benefit from better opamp and LP capacitor an order of magnitude or two smaller.

When I get it built I'll try different opamps and capacitors and report back on my findings.


I'd be interested to hear how it sounds with these mods...I wonder if the extra high-end roll off is what gives this filter its "vintagey" character.

Maybe related - one issue with my unit is that at high input gain and resonance over 50% certain frequencies resonate in a harsh way that sounds like the microphonic feedback you get with certain guitar pickups - could that be the opamps?
2thick4uni
Quote:
I'd be interested to hear how it sounds with these mods...I wonder if the extra high-end roll off is what gives this filter its "vintagey" character.

Maybe related - one issue with my unit is that at high input gain and resonance over 50% certain frequencies resonate in a harsh way that sounds like the microphonic feedback you get with certain guitar pickups - could that be the opamps?


Not sure it will have much effect on the overall character of the filter itself as its only a first order (6db/oct) roll off, I'd have thought it would only really be noticeable as the filter gets towards fully open.

I don't think the microphonic feedback you've described is down to the output amps, the TL072 should be rock solid with 220p across it, however you can easily test it by soldering another 220p in parallel (which will increase the capacitance to 440p) and then check if this behaviour diminishes. This isn't a fix as it further reduces the bandwidth, just a test to see if it is the problem.
elmegil
Normally stability caps in feedback loops are 10p, 20p range....
cygmu
2thick4uni wrote:

This capacitor is usually installed to prevent instability which manifests as unwanted resonance at higher gains (the gain on the LP amplifier is x27), and a large value is needed here because the TL072 is not good in high gain applictions, it quickly becomes unstable and resonates.


Is that right? My beginner-level understanding of stability is that higher closed loop gain configurations are more stable rather than less -- hence the datasheets proudly claiming that an op amp is "unity gain stable", because low gains are harder to stabilise.

Have I misunderstood something? Or is there something special about the TL072?
elmegil
cygmu wrote:
2thick4uni wrote:

This capacitor is usually installed to prevent instability which manifests as unwanted resonance at higher gains (the gain on the LP amplifier is x27), and a large value is needed here because the TL072 is not good in high gain applictions, it quickly becomes unstable and resonates.


Is that right? My beginner-level understanding of stability is that higher closed loop gain configurations are more stable rather than less -- hence the datasheets proudly claiming that an op amp is "unity gain stable", because low gains are harder to stabilise.

Have I misunderstood something? Or is there something special about the TL072?


I would think that they'd be boasting about harder things being stable rather than easier things?

But rather than speculate, here is what Analog Dialogue has to say about stability:

https://www.analog.com/en/analog-dialogue/articles/techniques-to-avoid -instability-capacitive-loading.html

Looks to me like it's a combination of capacitive load and unity gain itself rather than the total gain? But I just skimmed the article.
cygmu
elmegil wrote:

I would think that they'd be boasting about harder things being stable rather than easier things?

That was my point -- hence "unity gain stable" is a boast and "gain of 1000 stable" is not.

Quote:

Looks to me like it's a combination of capacitive load and unity gain itself rather than the total gain? But I just skimmed the article.


Right. The situation you want to avoid is where the negative feedback becomes positive feedback. This happens when there is 180 degrees of phase shift at a certain frequency.
Frequency-dependent phase shift comes from the op amp itself and from capacitance and inductance so e.g. a capacitive load will introduce some, as will capacitance at the op amp inputs, etc.

It causes a problem if the loop gain at that frequency, i.e. the amount of signal that is fed back, is at least 1. But as the frequency goes up, the op amp's open loop gain goes down. The configuration will be stable if the op amp can't produce enough gain to feed back the whole signal at the 180 degree frequency.

Higher closed-loop gains (like the x27 in this circuit) come from delivering less feedback (1/28 of the signal in this case). So they tend to be more stable, because the op amp runs out of open loop gain at a lower frequency, before 180 degrees of phase shift arises.

Or so I believe! I would be happy to be corrected.

In practice for this circuit, those 220pF caps do seem to be too large, and it is really odd that the LP output has the output resistor inside the loop while the other outputs have it outside the loop. It's not wrong, but strange that they differ, and in the loop resistors are bad for stability, because when connecting to a capacitive load they give you an RC network which introduces the dreaded phase shift. Outside the loop, they separate the op amp from the capacitive load and stabilise things.
2thick4uni
Putting a capacitor in the feedback loop of an op-amp forms an RC filter with a LP function. The cut off frequency reduces as the as the capacitance increases, and the cut off frequency also reduces as the op-amp gain increases - if you have a look at the simulation I posted earlier it shows the difference in bandwidth between x9 and 27x gain - both are with a 220p loop capacitor. This is why we usually see small 10 to 22p caps in parallel with the feedback resistor, as it keeps the LP filtering effect above 20kHz which is considered the top of the audio range. Larger caps and higher gains can bring this down into the audio range, which is what I am seeing in my Spice simulation and in practice.

If an opamp that is unity gain stable becomes even more stable as the gain increases then these capacitors would be not necessary at all, but in practice this rarely seems to be the case. I think it depends upon the internal compensation and phase margin of the particular op-amp used and the capacitive loading on the circuit. I've found that the TL07x require considerable compensation in higher gain circuits, but this is based purely on practical experience. Also, a circuit may be quite stable without anything patched to the output, but if a long patch cable (i.e. a capacitor) is connected to it then it will go into oscillation and require more compensation.

As I say I only know the practical side of it - it will be interesting to have some comments from those with a better grasp of the theory.
cygmu
2thick4uni wrote:
f an opamp that is unity gain stable becomes even more stable as the gain increases then these capacitors would be not necessary at all, but in practice this rarely seems to be the case. I think it depends upon the internal compensation and phase margin of the particular op-amp used and the capacitive loading on the circuit. I've found that the TL07x require considerable compensation in higher gain circuits, but this is based purely on practical experience. Also, a circuit may be quite stable without anything patched to the output, but if a long patch cable (i.e. a capacitor) is connected to it then it will go into oscillation and require more compensation.


Stability definitely depends on the op amp's phase response and the capacitive loading etc. Those are the two main sources of phase shift around the loop. A third one, which might be important here, is the capacitance at the input of the op amp, which forms an RC network with the feedback resistor. I wonder if the problems you've seen with higher gain circuits come not from the gain as such but from the high value resistors? There's about 8pF capacitance at the inverting input of a TL072. Together with a 270k resistor that gives you 45 degrees of phase shift at 73kHz. This will not help.

The more I read and think the more I believe that higher gain makes things more stable. E.g. there's this quote from p19 of TI's article "Stability Analysis of Voltage Feedback Op Amps" https://www.ti.com/lit/an/sloa020a/sloa020a.pdf

Quote:

The original loop-gain curve for a closed-loop gain of one is shown in Figure 17,and it is or comes very close to being unstable. If the closed-loop noninverting gain is changed to 9, then K changes from K/2 to K/10. The loop-gain intercept on the Bode plot (see Figure 17) moves down 14 dB, and the circuit is stabilized.


I did some Spice sims to experiment, using the idea in TI "SPICEing op amp stability"

https://e2e.ti.com/blogs_/archives/b/thesignal/archive/2012/09/10/spic eing-op-amp-stability

The idea is just to apply a transient to the configuration and see how much it overshoots and rings. Anything over 20% overshoot is asking for trouble.

Here's what happens with a TL072 set up for unity (inverting) gain, no cap in the feedback, 470R in the loop, and a capacitive load of 200pF. I'm applying a 1mV transient so we are looking for -1mV output.



30% overshoot and a couple of rings.
Now here it is with gain of 27:

It's a bit slow to get there but no overshoot or ringing. So I do think that the increased gain stabilises things. I don't know if my model of the TL072 models the input capacitance, though.

Back to the unity gain case, with a 47pF cap added to the feedback:

Obviously much better than the first example

And finally, with the 470R outside the feedback loop, unity gain and no feedback cap:

which again is pretty good although it never reaches the target value because of the voltage drop across the 470R.

Quite enough from me! Apologies if you don't find this interesting -- I am totally drawn in by this kind of thing.
2thick4uni
Thats very interesting - I'm still waiting for some parts to finish the filter build, but I'll check this out when it arrives - looks like the first thing to try is removing the 220p caps completely with TL072's on the output amplifiers...
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