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WIGGLING 'LITE' IN GUEST MODE

OBX voice card (with non-custom CEM3310 equivalent circuits)
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 61, 62, 63 ... 67, 68, 69  Next [all]
Author OBX voice card (with non-custom CEM3310 equivalent circuits)
oberling
Hi again crowbx wigglers,

after some time of just waiting for more wigglers to catch up and dust around this project to settle I just took out my "crowbx - unfinished" box again this weekend. Looking at it it seems to be all soldered up and the LFO and -1Oct/+1Oct switch are working correctly.

I did not yet wire all the jacks up but the next step in the calibration-manual is to have some CV-Input - so that's what has to be done now: wire the damn thing up!

I have searched the thread back and forth and only found some "in progress" on the wiring diagram front...
So I opened up gimp, took some pcb-images from crows website and began gimp-wiring the crowbx.
Don't use it yet - there are most certainly some faults in it!
I will edit this post to update the "diagram" when you pointed out my faults and give a "finished" at the end of this process Mr. Green
At least one error is, that the MOD PEDAL Connector is not yet connected - I just did not know where to connect it to (simply the EXT FM LVL - since that's left?).
And I'm fairly sure there is something wrong with the LFO TRI / VIB PEDAL wiring... But that was what I read somewhere in this huge thread.

Also I am not sure what to do with OUTPUT from the Host board and MONO from the carrier board (I would use just the left or right output for MONO).

help


update 2015-07-13: flts assumed on 2014-05-27 that EXT FM LVL could be connected to MOD PEDAL - as I was assuming above as well... so I just connected it now... let's see if someone objects razz
Also I learned that VIB PEDAL should be an TRS jack - whereas all the other jacks are TS(+Switch) jacks ...

update 2015-07-21: as nobody seemed to care about this but I wanted to continue my journey I eventually decided to give the wiring a try... for now I have wired everything up the way I depicted it in the graphics and applied another smoke test: nothing cought fire cool ...
Plugged in a random voice card to slot 1 and my minibrute playing a sequence on KeyCV1 and Gate1 and BOOOM - it works smile although it's pretty quite right now... but that's probably only because of some trimming issue/calibration that needs to be done somewhere.
LFO TRI out always gives a nice triangular (sine=triangular on those instruments) and LFO OUT gives the selected output for LFO (triangular, pulse or sample and hold) - so that seems to be right there as well.
I used VCO-2 of my TTSH in LFO-Mode to check on the other inputs with the result that almost everything seems to work properly and as expected.
Sadly the PWM switches are not doing anything for me right now - so I cannot check the pulse width inputs for the oscillators. But as they are clearly labeled the same on PCB and front panel that's probably not an issue of wrong wiring there. Also the MOD PEDAL and VIB PEDAL don't do anything... but that's most certainly due to the fact that my input signal is not as expected... I'll have to dive in deeper there...
For now I consider the wiring diagrams as almost final but at least not causing any smoke smile

TLDR: wiring diagram doesn't cause smoke for me - seems to be accurate; have a single voice crowbx working on my bench - really proud right now; Issues with MOD PEDAL, VIB PEDAL, PWM1, PWM2 are certainly due to trimming/calibration issues and not caused by wrong wiring;
EMwhite
puggle wrote:
just discovering this project, damn cool idea! don't know why someone didn't try this before. I've started digging through the forum here, but having trouble finding answers to a few ques.


1) am I right that the 4 voice version of this project (w/o midi, patch memory storage) requires approx $1000 (USD) in materials, and approx 100 hours of labor (from someone who knows what they're doing with assembling)? how much more for a 6 voice?

May as well estimate $250 a voice. Some of the parts are relatively expensive, if not rare to find in original form. It's all +/- depending on where you source your parts from.

2) since it has diff cv inputs for each voice, what would be needed to get it to talk to midi in the manner of a standard midi keyboard with all the voices mapped properly? What else might be needed to get it to function like a standard synth module (ie: power supply?)

A multi-voice Midi->CV interface. If you 'only' want to build a 4 voice there are a number of solutions for this; one of which, while you are speaking about DIY is the HexInverter interface; it's low cost and has a flexible alternate (now standard) firmware branch in development and mature by now.

Power supply, yes. Crow recommends one early in this thread. That will set you back about $80-$100. You'll also need a panel depending upon how you plan on mounting.


3) has anyone yet tried to build this with patch memory, or ability to be used with a midi editor program of some sort? if so, how much did that end up costing?

You'll need to add-on something to do this. Crow was talking about something along these lines and there are a few pages of discussion about it. If you could get started with the voice boards in a basic 4 voice and get that all to work, I think that would be a massive achievement considering that dozens of us bought the board sets and I think only about 4-5 have indicated that they've completed the project.

3) I've heard some soundclips on here, but seems there's only a small few. any others? any comparing it head to head with the orig ob-x?

You have two #3's hihi but seriously, yes the amount of clips is even fewer than the list of people who have completed them or maybe people are selfishly keep it all to themselves or no longer have eyesight sufficient to operate a computer in order to post after all of that soldering and detail work.

It's an awesome project and I've got a 6 voice in build with no planned completion date. Originally I was to have a single voice working by a particular date and a two voice by another date, I think I missed it by a full year already. I WILL finish, just not anytime soon.

You may find that the board sets are no longer available so best to contact Old Crow directly to see what he has left or what he might be creating soon.

One thing is certain; the original voice boards (whatever the latest rev is) was engineered to be plug and play with an OBX, so you might consider them equal from a capability and sound perspective. But this really means two things:

a. it will sound no better or have a more capable filter (because the original did not). That said, there is something to be said about aged components or variance in tolerances used then vs. now as common.

b. No harm in building it now, regardless of how the rest of it might bolt together (with a fancy 8 voice backplane, with or without an integrated Midi-CV voice assigner, with or without patch memory).

You will see that folks have gone on to implement more of the original SEM multi-mode filter and that is awesome but at a certain point you need to just settle on something and get a move on. Unless you are very very fast or maybe do not have a day job, it's a lot of effort and time for mortals which do have day jobs and families, etc.

Which reminds me, I spend too much time reading and posting to this forum... hihi
puggle
Hi EM White, thanks SO much, that's really amazingly helpful. The hexinverter tip is particularly nice.

Right now I'm comparing this and an ob-xa. It just seems to me that the ob-xa is missing the clarity and warmth of the original ob-x. I think a 4v crowbox with standard ob-x style filters with midi would be amazing, even w/o patch memory. it's not too hard to remember how to redial a patch in, ob-x's don't have a huge number of controls. The bigger issue is how quickly 4v becomes a limitation w/ pads w/ long release times.

So it sounds to me that a 4v w/ full cv to midi, power supply, case, face plate, about 1500 USD parts, and 110 hours labor (if you include the hexinverter). Wish I could compare the sound to an orig ob-x or ob-xa. Anyone out there got some audio clips to share?
EMwhite
There is a guy around here named "MC" (his first name is Mike) and he owns a vintage but rebuilt and improved OBX, an OB-SX, and I 'think' he was working on a crOwBX or at least had a completed voice card and was to land it into an actual OBX to see how it played/compared. Not sure if he ever got that far.

Af for you statement about long decay/release patches running out of voices quickly... yeah, that's going to be a problem. Even 6 voices become limited but to be frank, you get a few OBX voices cranking and it's an absolute WALL of sound, so really, how much do you need.

My opinion on the OBXa... don't bother : ) Personally, if you are going to go for a vintage instrument, go all the way analog and discreet if you can manage; avoid custom chips which tend to be lighter and also somewhat susceptible to failure.

I've got 5 SEMs and will be picking up a 6th as soon as I can sell my other kidney; to date, I've messed with a 5-voice so to speak. It has a common ADSR envelope and I just use the VCA envelope which is built into each SEM. It's pretty amazing and remember, the SEM has the multimode filter as well.

It takes work to get it all in synch, but it's worth it.

There are tons of OBX videos out there and I cannot recommend any one in particular but here is the granddaddy of all SEM videos, since we are talking Oberheim. To me, the ability to tune/detune voices or have differing patches on each with a reset to voice one just adds to the fun. There is plenty of frustration in cobbling together a multi voice analog synth, but also plenty of fun.

freestatefx
Repairing a crOwBX at the moment.

Got several of the small issues worked out (i.e. power supply and backwards IC on a voice card).

Big issue is that is not passing audio after power up. When I first power on the module there is sound, but only one ADSR cycles worth, and then after that there is no more audio present at the output.

Using my scope I see the CV's at both the Amp and Filter ADSR headers so it looks like the main board is functioning properly and outputting ADSR CV's to the voice boards.

Tried adding diodes at IC11 but that did not change anything. Actually I tried it on one voice card but not the other. Since it did not alter anything on the first voice card I did not perform the mod on the second voice card.

I am stuck on what to try next. The complexity of the module and the fact I did not assemble the unit makes this repair extra challenging.

Any suggestions? Can I provide any additional info to help with the debugging?

Thanks!
oberling
So I managed to get my crOwBX all wired up (see my post above) and working - also sorted out the PWM-Switch Issue (I just changed the 4011 which I thought I had a equal part of but with different name) and thought you guys are missing some videos...
It's not calibrated and also only one voice installed right now and I don't play pad sounds but only sequence the beauty via my minibrute... but you get a glimpse of what the front panel designed by oldcrow enables you to do and how the thing sounds being uncalibrated hihi



If I find some time I will calibrate every single voice, implement a 4 Voice MIDI-CV-Converter (I know there are plenty out there but you know: what I can do myself I will do myself :-) ) and take another shot...

The noise does not have these artifacts... that must be something with the youtube video conversion...

edits: video tag only takes non-https and not the short URL...
medbot
I would love to build one of these one day but I can't imagine spending so long to build such a great sounding synth and then having to use those little plastic shaft pots. Congrats on the build, between that and the TTSH you've surely earned some kind of DIY medal.
oberling
medbot wrote:
Congrats on the build, between that and the TTSH you've surely earned some kind of DIY medal.

Thanks smile

medbot wrote:
I would love to build one of these one day but I can't imagine spending so long to build such a great sounding synth and then having to use those little plastic shaft pots.

Well the "interface" really has it's quirks - that's for shure grin (but oldcrow only considered it a sort of debugging interface... so that's understandable)
I already exchanged all knobs to some with slightly longer shafts - but those don't feel that good... The main problem is those pots being so close - I have a lot of fine knobs... but not such small (diameter) ones cry
Perhaps if everything works great and I have sorted it all out with that beast I will build my own front panel as others have (slaughterhousesam and EMWhite for example have posted some really nice pictures)...

In the meantime I figured out my low-volume issue - was exactly the same mObiTh had over a year ago and sorted out very frustrating I also did not omit R158 and R14 on the carrierboard while having the Diodes 1-6 and 7-12 installed - stupid me...
edit: Also noted that the distortion trimming is only measurable and therefor doable when the volume is at a reasonable level...

Also I ran into the portamento issue as mObiTh has... well at least I only have to read through his findings now - the waiting on others to do the dirty work of figuring out issues with the BOM and description pays of a little lol
home_listening
Hey Crow,

I'm finalising my panel design at the moment (I'm going to be hardwiring everything to slide potentiometers) and was wondering if you had an ETA on the filter modification PCB? I'm in no rush, but want to know if its worth me pouring over the SEM schematics and making my own.

Kind regards
oberling
oldcrow wrote:
Hm, I updated the doc but never pushed it to the site. I'll fix that. screaming goo yo

jflower wrote:
So R1-R4 should not be 100k 1% like on the BOM?

cheers!
jf


Am I not looking at the right spot or is it still not pushed to the site (www.cs80.com/crowbx/)?

iirc it was not only the 0,1% resistors that had some faults... would be great if you managed to put up the updated BOM, oldcrow hihi
edit:also a note to ALWAYS use sockets for the ICs of the voice card would be nice - those sockets are not in the BOM and I thought "well - if they are not in the BOM and the voice cards mount in such limited space maybe I really should not use sockets for this project after all"... well it turned out I was bloody wrong with that and had to desolder at least 8 ICs from each voice board to calibrate it and fix the filter lock up issue (3 for each EG and the two filter ICs) cry

Also I second the question for the ETA of the filter board - that would be such a great addition... SlayerBadger!
(although I would have to desolder another IC per voice card here again very frustrating )
oldcrow
I stopped getting new post notifications again. I will reply to the various posts later today.

The latest shipment of crowbx boards is finally here. I will be sending out orders next week. The factory was 3 weeks delayed, but I have inventory at last. screaming goo yo screaming goo yo
Sir Ruff
EMwhite wrote:
There is a guy around here named "MC" (his first name is Mike) and he owns a vintage but rebuilt and improved OBX, an OB-SX, and I 'think' he was working on a crOwBX or at least had a completed voice card and was to land it into an actual OBX to see how it played/compared. Not sure if he ever got that far.

RealMC brought his OB-X to the AHMW meet in 2014 and Scott put his CrowBX right above it so you could do a pretty nice A/B. Unfortunately the CrowBX was pretty out of tune and needed calibrating (which Scott himself admitted) so it was hard to really compare one to one. But just comparing single voices, the CrowBX was very very close. To my overly anal ears, there were some small differences in the filter tone, and other hard to describe nuances, but again, it wasn't really a fair comparison when each new voice was totally out of whack from the last. It also wasn't the best listening environment--PA in a crowded room with lots of other synths being played nearby!

Anyway, there's no doubt in my mind that for someone working from the ground up, the CrowBX is a no-brainer replacement for the OB-X. The ability to replace voice cards hasn't really been confirmed yet by RealMC or anyone else AFAIK.
oldcrow
We did put a voice card in MC's OBX during that day. It tuned up and played fine. It was slightly louder than the others but we didn't do any adjustments as the machine was set for the original card.

Sir Ruff wrote:
Anyway, there's no doubt in my mind that for someone working from the ground up, the CrowBX is a no-brainer replacement for the OB-X. The ability to replace voice cards hasn't really been confirmed yet by RealMC or anyone else AFAIK.
Sir Ruff
oldcrow wrote:
We did put a voice card in MC's OBX during that day. It tuned up and played fine. It was slightly louder than the others but we didn't do any adjustments as the machine was set for the original card.


Ah ok! I recall it was put in but didn't see/hear what the outcome was.
The Real MC
The pitch tracking between OB-X and crOwBX voicecards were fine. Only differences was scaling of VCF and VCA, which we later uncovered to be PNP transistor 2N3096 which should had been 2N3905 in the original circuit. The 2N3906 has higher beta (aka current gain) which was why the crOwBX sounded louder.

Crow also had his crOwBX four voice there the same day and we compared a patch between it and OB-X, damn close. That VCF girth and resonance is a difficult nut to crack but the crOwBX nailed it. He even went as far as configuring the OTAs to match the old 3080s whose distortion and low fidelity is a big impact on the sound.

After AHMW, Crow did have an OB-X on hand to tweak the crOwBX to match originals before he started the mass assembly process.

I never did finish my crOwBX card due to health and work issues. I really want to finish that, and also restore this basket case Four Voice that I just landed.
jhulk
scott when are you doing another run of the 8 voice board

do you have a pre order list thanks
coon
also v interested in the 8 voice board
ultravox
Well, Roland effectively crushed my dreams of a revamped analog Jupiter 8. So now I'll be getting off my duff and finish building my 8 voice crowbx.

Old Crow I sure hope you're still working on the midi/cv controller and patch memory...I'm lazy and those will certainly ease my pain. hihi
cLOWNgOD
oozitron wrote:
I'm amazed at how fast you put this together Scott... it was just a couple weeks ago when MC's OBX was the center of attention (mine at least!) in the library. Call me foolhardy, but I would choose it over any polysynth It's peanut butter jelly time!

I would love to have a 4+ voice OBX. Even if it wasn't programmable.

Drew




Yeah there's something magical about the OBX even over other Oberheims. Definitely my first choice.
apoisontree
Hi Oldcrow, any news on the multimode VCF board?

You showed us an eagle file 6 months ago, so what's taking so long?

If the manufacturing is too much trouble, could you at least share the file so we can make our own and finish that synth. That would be great.
Thanks!
The Big Ear
Anyone in europe who can burn a noise pic for me?
I'll pay for all expenses and a couple of beers!
Cheers,
Techman
The Big Ear wrote:
Anyone in europe who can burn a noise pic for me?


I've just burnt one for you. Pm me your address.
Cheers, Andy.
The Big Ear
I finally got my 1 voice system ready to give it a first try.
However, I would like to verify a few bits so I'm looking for the schematic's of this thing. I can't find them anywhere.

Anyone?

Cheers,
oberling
there you go: http://www.cs80.com/crowbx/schempdf/
The Big Ear
oberling wrote:
there you go: http://www.cs80.com/crowbx/schempdf/


Cool! Thanks!
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