no I haven’t built it , I was just saying . I have a pile of projects all ready lol …
I commend you for adding this. But I’d suggest you also put it IN the schematic, because search engines will find and publish it without the context explaining its status.
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May I suggest sending requests like these as private messages rather than as public posts? There’s little benefit in the rest of us seeing such things over and over and over. Thanks.
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There, it’s tested. It works.
Also, it sounds great!
Didn’t understand what the offset was going to do till I started messing with it. Really neat. I used the lmnc eg for gate and the lmnc lfo for messing with theoffset. The 3pdt gives you some nice subtle changes. “The deep” is more noticeable and more interesting, imo.
My resonance adjustments arent very noticeable, but I think I hear it. Unfortunately my only 50k pot is a trim pot so have to turn and turn and turn…and I haven’t looked with oscilloscope.
I used tl074s for both op amps, a 3M instead of a 4.7M(can’t find one atm), a 3.3v zener instead of 3.9v (I don’t have a 3.9v, I’ll try a 5.5 as well) finally I used a 2.2nf cap instead of 2nf.
Looking forward to this one @JonGreen
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The advantage of repetition is that repeating the message makes new comers / other people who have not seen them or did not read all threads so far read them as well. Its too bad that it is not customary or immediately obvious to annotate a schematic. And concerning repetitions, there are plenty of repetitions going round on a forum like this anyway. Those are the facts of forum life I’m afraid.
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Well now that saves me a hassle! Nice work man!
The resonance its one of the things that I was most concerned about being impacted by its journey from 15v to 12v supplies. It’s deeply linked to the vactols, so maybe playing with the 20k trimpot value to see if you can get any extra juice out of them. You could also try tweaking R22 a little as suggested by @analogoutput and reduce it a little.
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I haven’t noticed that repetition has led to any significant fraction of newcomers labeling their layouts/schematics as untested without being admonished themselves.
Yes, there’s lots of repetition, which is a good reason to find ways to reduce repetition.
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Hmm tried messing with all the pots, tried a 10k resonance pot with 10k resistor, same thing with 100ks. Changed r22 to a 200r, No change.
Also, without the deep switch turned on the other pots aren’t doing anything and overall the module is acting like a vca. I guess that’s how it works tho.
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I would definitely breadboard it how you have it on your latest version and play with it! I think it’s close. Do you have an example on YouTube or something of the resonance in action
Also I’ve been known to make a mistake or three soooo
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Right, well the deep switch not performing quite like it should suggests part of the issue is the vactrols not getting enough juice, and the amount of resonance you hear is directly related to the voltage applied to the vactrols. It should basically change the overall tone of the the output, rather than bringing the filter effect in. In a way I guess it does change the tone, but not in a helpful ‘boost’ way, more in a ‘get rid of the switch and just leave it adding extra feedback’ way.
Also, you can try lowering the value of C8 from 33pF (or removing it entirely even) in the resonance section. I have seen circuits implemented with it at 10pF, 22pF, 33pF and just plain absent so I would assume it has some effect on the output but I am not sure quite what it is there for. I have been considering messing with the value of R20 to add more feedback into the vactrol circuit. These are both on my list of ‘things to play with’ when I breadboard for myself but if you still have it set up you can play away to your hearts content. Again, thanks for actually bothering to put it together! I would have it up already myself but a lack of vactrols and Thonk being slow to ship is causing me delays.
EDIT: I have done some more poking around on the internet and the crazy folks over at NLC have done a resonant LPG based on the same design as this one. In their version the resonance section has a 10k pot / resistor pair, but the Vactrol OpAmp section is pretty much identical - If you still have it on the board can you just make sure its not the CV Summing input stage that is causing the issue (thats completely new on mine) and just connect the raw CV jack to where you see the connection between R9 and R10? If the CV sum is not putting out enough juice that would explain a lot and I will need to go back and rethink my choices. If its still not giving any kind of resonant squeal with a nice big CV in to that point then I am guessing its down to the few substitutions you have had to make with on hand componants and hope it works out better with the originally specced ones.
Edit some more!!: I tell a lie! The vactrol stage is a little different! Before ripping out the CV Sum stage, try swapping R21 to a 4k7 and R22 to a 1k.
Video of that one is here 
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Wow ok I would notice that. 
Ok, so your schematic except 10k res pot and resistor and swap R21 and R22
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And remove C8 - then try the CV stage swap. If its not any of those, its probably the 3.3v Zener or one of the other substitutions.
This board is pretty relaxed with rules about forum organization. This includes both reinforcement of the ideas of labelling untested schems, as well as being off topic which this is.
May I suggest sending requests like these as private messages rather than as public posts? You couls also create a new topic for this discussion, or we can continue like we tend to do here and go off topic frequently.
I’m detecting some mild annoyance. This is our community folks, lets just be cool to each other, and respectful to those who open topics with a specific goal.
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Even without resonance this a really cool module. In this patch I just have an arpeggio playing on the oscillator and it gets split. Once to the lpg breadboard and once to the ms-20 filter (so I get some resonance after all). The lpg is also getting the offset cv from the LFO
Kinda sub-osc feel. But with some movement on the bass. Really neat.
I tried swapping the resistors and removing c8. Still works as before. I also tried swapping the 3.3v for a 5.5v zener which made it too hard to open up the gate
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Now that is a rather nice sound, even with the resonance being low. I’ll double check with the spec’ed values once my vactrols arrive.
Excellent work that man!
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I wonder how much the choice in vactrol affects it. These are xvives from electric druid
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The longer the decay on the vactrol, the more pronounced the ‘ring’, and they vary hugely vactrol to vacrol, let alone between compounds.
Now I have actually heard it, it’s clearly working as intended in the original buchla 292 design, which didn’t ever have the resonance feedback circuit on its VCF function, despite its 12v supply. Maybe its just not got quite enough gain at the end there to drive that resonance opamp to self oscillation, which could well be down to that 3M resistor in place of the 4.7M letting too much of the input signal go to ground… either way, its a lovely LPG sound, and I will keep at it until it screams 
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Forgot to mention I swapped that too
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Bugger… oh well. I’ll see how far I get, maybe I’ll just have to settle for a straight up clone the 292’s functionality… or try with some other vactrols and see if it makes a difference, the VTL5C3/2 is the preferred one these days, and considering it only has one LED to drive rather than the two in series it might make more of a difference than I thought.
Turns out Thonk have (since I made my first order on Thursday) gotten the /2’s back in stock, so I have ordered a pair to try both types with and see what sounds better - still the xvives though. Plus a trio of genuine Rogan RB knobs in black and silver to make the prototype more ‘Bucla-esque’ - and qualify for free shipping.
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Been thinking about resonant LPGs and re-found this topic… Did you ever get any further with it?
Besides NLC, AI Synthesis has a version of this — maybe a little closer to yours, it has the depth switch with a pot instead of a fixed resistor. They sell bare PCBs without panels, I’ve considered putting one behind a Kosmo panel.