Did you get a resolution to this?
I’m in the same position… built it an just get oscillations… have reflowed, checked components, swapped out… fettled… but still the oscillation remains!
Think I am in the same boat.
Unfortunately no,
I spent ages on it, at one point the res started to do stuff but then it stopped again. On the U6C LM13700 on PIN 5 is that meant to have no signal? without any reference reading it hard to know.
I’ve had a degree of success - reflowed again and made sure that all solder was consistently filling the holes, particularly around the capacitors.
With some tweaking of the ‘tuning pot’ it’s almost there, but does seem sensitive to variations in capacitance - I’m tempted to replace the caps as the tolerances on cheaper components is probably enough that where they’re meant to be ‘paired’ the differences cause problems.
A reference set of scope traces for a working module would be great - althought it might be tricky to ensure all the potentiometers are set the same when that’s taken.
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hey yes well it does sound like its going to be something a tad loose do you have a temperature control on your soldering iron? for the solder points attaching to the ground plane, because in this project the ground plane is huge it may take a tad more heating to get a good contact to the ground on things. so maybe reflow at a higher temp the ones that look like they are attached to ground (the look like they have a cross around the actual ground lug).
because you have had more luck it would definitely seem its contacts
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if you look at the pinout on the lmq3700 pin 5 is the output however it may be problematic listening to it because thee impedance of what your plugging it into to listen at that pin may cause it to not show anything up.
also another thing that came to mind is the fact that the resonance signal comes from after the final buffer. which also if plugged into a listening source that is causing the above problem it may also fluff about with the resonance function.
have you tried plugging the output of the filter into a mixer then your listening source??? make sure the output is buffered by something and see if that does anything
it may very well be what your listening to it with that is messing with the resonance
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Thanks, Sam for your suggestions ill take a look 
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Thanks for all the advice - I’ve got a temp controlled iron and cranked it up to 340 to deal with the problematic connections (that’s my ‘go to’ temp for that kind of thing - happy to take advice on that!)!
Good contact absolutely made the difference… going to reflow others which look like they might be bad this weekend!
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thats awesome! !!! yeah it seems a problem that has come up a couple of times on the filter and the delay, I think its because there are a few quite important connections to the ground plane within the 2 modules so its always worth looking through on a slightly hotter setting for the ground plane
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Happy Day, I Plugged the output into my mixer then into the headphone and success. So looks like plugging headphone directly was fluffing stuff up Thanks for the pointers.
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Yeah, don’t try to plug headphones directly into synth modules (unless it’s an output module with a specific headphone output, of course). That’s not what they’re meant to drive.
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yep that will do it! the impedance sort of sucks all the juice from the output meaning none is left to feed back into the circuit to make the resonance (resonance is like feedback putting your mic to the speaker) so yeah! thats what will happen! :D. just be aware plugging headphones into modules can effect them in different ways due to the difference in impedance. I sometimes do it when I know its buffered on the out and stuff. but a lot of the time it wont work right! 
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anyone brave enough to drill a hole and spin around the trim pot to the other side of the PCB for front adjust? I about to attempt this mod tonight
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Sounds very sensible. Stick it on a couple of long leads and mount it wherever you like.
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its done, it fits perfect between to panel and pcb, and i even drilled “ok”, may i should buy a lottery ticket?
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nice all those trim pots should be on the front , so much easier . but the MFOS vco’s have 7 trim pots lots of holes .
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Did anybody ever make a stripboard version of this? Circuit looks really similar to this: STUFF - LOOK MUM NO COMPUTER with extra inputs, but I don’t see the trimpot anywhere in that guy. I’d buy the real thing but I don’t have any space left! 
Hi guys. I am sorting out a list of components to order for some modules. I noticed in the BOM for the Performance filter it says 6.35mm Jack Sockets. In the BOM for the the Dual VCA it says 6.5mm Jack Sockets. Is the 6.35mm a typo or are they different? Thanks Chris.
6.35mm on all of them , 1/4" in imperial.
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Old school imperial rubbish. 