[IN STOCK] Eurorack 4hp THAT2180-based Audio VCA

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
modular-synth.org
Learning to Wiggle
Posts: 4
Joined: Sun Jun 15, 2014 12:54 am

Post by modular-synth.org » Tue Dec 09, 2014 7:50 am

I have found an ingenious solution: Ultimate Hi Performance Feedback !! <3
Attachments
ultra short feedback
ultra short feedback
UltimateHiPerformanceFeedback800x600.jpg (162.17 KiB) Viewed 533 times

modular-synth.org
Learning to Wiggle
Posts: 4
Joined: Sun Jun 15, 2014 12:54 am

Post by modular-synth.org » Wed Dec 10, 2014 4:19 pm

we should see the schematics, to understand how to operate this VCA... for example I am aware that the output buffer would appear inverted. according to the datasheet, GND must go on pin 3 & the input/feedback to the second pin.

there would be a reason for this inversion?

Jarno
Super Deluxe Wiggler
Posts: 2820
Joined: Mon Nov 15, 2010 6:34 am
Location: Rosmalen, NL

Post by Jarno » Fri Dec 12, 2014 2:44 am

Did you do that discrete opamp yourself? Interested to see how it looks.

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Tue Jan 27, 2015 9:04 pm


User avatar
Thonk Support
aka Monobass
Posts: 8830
Joined: Fri May 29, 2009 5:39 pm
Location: Brighton, UK

Post by Thonk Support » Wed Jan 28, 2015 3:50 am

cleaninglady wrote:Will this be OK for the Tempco ?

http://au.element14.com/panasonic-elect ... dp/1577659
well it'll work, but it won't act as a tempo at only 25ppm,

this is the part Negativspace recommends - 3300ppm (no Eu stock at Farnell though)

I mean also he did say who's going to notice if a VCA isn't temperature compensated :)

http://au.element14.com/panasonic-elect ... t=S33J102V

http://uk.mouser.com/ProductDetail/Pana ... HlKg%3d%3d
Thonk - CLICK HERE - Modular Synth DIY + Eurorack Accessories Store

AS of October 2020 this account which used to go by the name of Monobass is now manned by various staff at Thonk.

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Wed Jan 28, 2015 6:24 am

Totally missed the 3300ppm not being there , found at Digikey AU.

http://www.digikey.com.au/product-detai ... -ND/578717

If its not so necessary in the VCA do you thinks its even less necessary in the SVVCF ?

User avatar
Thonk Support
aka Monobass
Posts: 8830
Joined: Fri May 29, 2009 5:39 pm
Location: Brighton, UK

Post by Thonk Support » Wed Jan 28, 2015 6:29 am

cleaninglady wrote:If its not so necessary in the VCA do you thinks its even less necessary in the SVVCF ?
No I wouldn't... but it would be interested to hear what Jason says, in a VCA a change in temperature I'm guessing might affect the level of the noise floor or quite small changes in the overall voltage of the output?

But in a filter it would affect the tracking and frequency response, it seems to me that your ear would be a lot more likely to notice that, even if you're not trying to tune it 1v/oct.

Total conjecture though :)
Thonk - CLICK HERE - Modular Synth DIY + Eurorack Accessories Store

AS of October 2020 this account which used to go by the name of Monobass is now manned by various staff at Thonk.

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Wed Jan 28, 2015 7:14 am

I've been thinking of going with through hole for the SVVCF but i'd like to know what the tempco needs to be in contact with. :hmm:

Dogma
Super Deluxe Wiggler
Posts: 4166
Joined: Wed Aug 28, 2013 10:46 pm

Post by Dogma » Thu Jan 29, 2015 10:28 am

does anyone have a BOM for this fine VCA? Im sure there was one in this thread...
look up!

User avatar
Thonk Support
aka Monobass
Posts: 8830
Joined: Fri May 29, 2009 5:39 pm
Location: Brighton, UK

Post by Thonk Support » Thu Jan 29, 2015 10:58 am

Dogma wrote:does anyone have a BOM for this fine VCA? Im sure there was one in this thread...
first post ;)
Thonk - CLICK HERE - Modular Synth DIY + Eurorack Accessories Store

AS of October 2020 this account which used to go by the name of Monobass is now manned by various staff at Thonk.

Dogma
Super Deluxe Wiggler
Posts: 4166
Joined: Wed Aug 28, 2013 10:46 pm

Post by Dogma » Thu Jan 29, 2015 11:05 am

Monobass wrote:
Dogma wrote:does anyone have a BOM for this fine VCA? Im sure there was one in this thread...
first post ;)
Im sorry I dont understand. Have i faux pared?
look up!

Dogma
Super Deluxe Wiggler
Posts: 4166
Joined: Wed Aug 28, 2013 10:46 pm

Post by Dogma » Thu Jan 29, 2015 11:15 am

Ahh - first post. Right :doh: :doh: :doh: :doh: :doh: :doh:
look up!

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Mon Feb 09, 2015 5:27 pm

I finished the VCA yesterday but unfortunately it isnt working as yet.

After plugging it in i noticed that the input was not responding at all (no signal getting through).

With every input patched , i can hear a little of the CV from CV1 and CV2 at the Output but none of the signal from the IN (in this case , a Model15 VCO Triangle Wave).

I've checked the input voltage , its fine.

The voltage on the TL074 are +2.5V , -11.55V , LME49710 is +2.7V and -11.55V.

I had a hot 1N4001 on the positive rail last night but that seems normal today (maybe blown?)

TP measures 120mV and the trimmers are pretty much unresponsive.

Cam see any solder bridges and joints look good.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Mon Feb 09, 2015 5:41 pm

Did you cut the traces and install the wire jumper? (See OP)

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Mon Feb 09, 2015 6:43 pm

Drokk ! No I didn't. Bugger !! My bad.:deadbanana:

I'm on the way to teach but I'll let you know
How it goes when I get home. Cheers Jason.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Tue Feb 10, 2015 1:17 am

Those are the exact symptoms you'd get in that case, so I think you're probably on the right track. :hihi:

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Tue Feb 10, 2015 2:37 am

All good Jason , thanks ! Sounds incredible !! :sb: :sb: :sb:

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Tue Feb 10, 2015 12:40 pm

Woo! :sb:

User avatar
fluffymuff
Common Wiggler
Posts: 134
Joined: Sat Jan 24, 2015 7:41 am
Location: Leeds

Post by fluffymuff » Sun Feb 15, 2015 10:31 am

I've put my VCA together and trimmed it fine but i'm having the same issue as jflower and get no audio out. Like jflower if i trim the unit with much more gain I can hear the CV clicks faintly and a small amount of audio and if I go even further I can hear distortion (but muffled). I've checked continuity on the jacks and can't see any obvious mistakes/shorts on the board, any ideas?

jflower did you manage to fix yours?

jflower
Common Wiggler
Posts: 84
Joined: Sat Jan 29, 2011 8:53 pm
Location: Boston, MA

Post by jflower » Sun Feb 15, 2015 1:46 pm

Unfortunately, no. I have another 2180 in my shopping cart at mouser to see if by chance the one I have is fried. I have replaced the other ics with no change. I have one working unit and I can compare between the two but cannot find where the one goes wrong. Maybe I will look at it again tonight.

Jason, did you ever find that circuit drawing? I wouldn't mind taking a gander at it to see if it shows me my faults.

Love the one that works and am thinking that I will grab some more in a bit.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sun Feb 15, 2015 3:02 pm

I'm assuming since you have one working that you've not forgotten to cut the traces and add the jumper... Doublecheck that there are no odd shorts from solder pads to the ground plane under the mask. Every now and then that pops up.

I had the schem all set to post when the forum died, I'll get that back together. ** up now, check the OP.
Last edited by negativspace on Tue Feb 17, 2015 11:44 pm, edited 1 time in total.

jflower
Common Wiggler
Posts: 84
Joined: Sat Jan 29, 2011 8:53 pm
Location: Boston, MA

Post by jflower » Sun Feb 15, 2015 11:06 pm

Yeah I have the traces cut and jumper installed. I will dig into this tomorrow, got caught up wiring a funky drummer tonight. :omg: :omg:

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Tue Feb 17, 2015 11:43 pm

Oh boy, that's a task... I haven't done the Drummer but I've put together a few MSUs and a WCMS. (Never again... lovely module, but holy crap. :doh: )

Image

User avatar
polyot
Common Wiggler
Posts: 173
Joined: Thu May 08, 2014 2:21 pm
Location: Reading, PA, US

Post by polyot » Sun Mar 22, 2015 3:00 pm

jflower wrote:Yeah I have the traces cut and jumper installed. I will dig into this tomorrow, got caught up wiring a funky drummer tonight. :omg: :omg:
Hey jflower, you get anywhere with this? I'm not having the same issues as you, but curious about any other troubleshooting you've tried.

Mine passes audio straight through to the output, with no effect of the offset or CV. I'm also unable to trim, I get nothing on the TP and can't track down why. My IC voltages match yours exactly on the last page, which is either a good sign or a bad one. Traces are definitely cut, and the jumper is in place. Went over my soldering painstakingly. I have been in touch with Jason but if any one else has any thoughts I'm all ears.

jflower
Common Wiggler
Posts: 84
Joined: Sat Jan 29, 2011 8:53 pm
Location: Boston, MA

Post by jflower » Sun Mar 22, 2015 7:46 pm

I have troubleshot everything up until the 2180. I have a new 2180 that showed up a last week or so, but I haven't brought myself to de-solder the one on the board. I am seeing all the right voltages at the 2180.

jf

Post Reply

Return to “Music Tech DIY”