PolyKit 16 Polysynth

Just started a new Polysynth based on the PolyKit DCO, it will be 16 voice, bi-timbral and mounted in a 3U rack, programmable upper and lower sounds or a split or whole mode. Very similar to the PolyKit DUO 6 voice I made earlier but with a few more options on the front panel.



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Looks amazing. Out of interest how are you doing the key tracking for the filter?

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I run a second Pico driving two 8 channel DACs for keytrack and velocity

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Dam, I havent even started the 6DCO yet :wink: … I am off work the week after next and re-desiging the DCO to a Kosmo rack is my goal…

Good work!!

Rob

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Thanks, no idea if this project will even work, but I can back it down to a dual 6 voice if necessary.

I built a modular version of the DCO using a Seeed XIAO RP2040 and just made it dual oscillator. Added level controls, FM, PWM etc all in one module.

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Front panel completed and ready for connection to a demux board to generate some CVs.


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hi,
So after the DCO’s you’ll have 12 analog VCF’s and 12 analog VCA’s? Or is the whole synth digital?

After the DCO will be 16 VCF and 16 VCA and 32 EGs and 4 LFOs and 2 noise sources.

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Sounds awesome , be interesting to see.

Full of flu all week so no real progress, but before it kicked in I’d done a quick redesign. Rotated the display through 90 Deg to give a better layout and relocated a few of the buttons. Also swapped out the 4051 mux chips for 4067, I couldn’t get the pot readings stable with the 4051 so swapping them for 4067 seems to have resolved that issue.just enough room between the pots to squeeze them in.

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The buttons look much better under the display than they did beside it.

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STOP IT!! STOP IT!! STOP IT!! STOP IT!! STOP IT!! STOP IT!! STOP IT!!
I am struggling with my unfinished modules and haven’t even started to think about how to power them …

IMPRESSING project and hopefully there will be no kit or PCB to buy. However I am interested in the huge board - where did you get that (and please to don’t tell me).

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Thankyou very much, I have had to stop this week, absolutely full of flu and trying to figure out why the mux was making random reads occasionally. I can’t really think straight but now I’ve realized very stupidly that these green LEDs are power hungry little buggers and can kill a USB powered input to the Teensy, voltage drop was almost 0.3v when testing. So I fitted a seperate LM317T regulator to maintain a seperate 3.3v supply to the 74HC595s and this seems to have resolved the issue.

Its been a terrible week of flu, power outages, loss of heating, air raid sirens, random fuse trips in the house etc.

Glad its sort of over and my flu is clearing up.

Large boards are available from AliExpress

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Some further progress now my health has improved slightly.

I built a mother board to hold a total of 12 daughter cards. The first card being a 40 channel CV DEMUX and 32 shift register outputs. Added onto that card are the LFOs for FM, TM and PWM and their respective control VCAs. Then there’s just enough room to squeeze in the noise source. This daughter card will be replicated halfway down the motherboard to provide the same for the lower 8 voices.

So far so good, all working as expected.





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As always it looks amazing !
It is funny how your work looks satisfying for me, nearly relaxing.

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A 16 DCO voice board sandwich.

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Do you use those female stacking header strips often? I had a couple of problems in my latest build that I traced back to loose connections with them. Was just wondering if you’d had the same experience or if I was unlucky?

I’ve used them on a few with no problems.

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First voice card taking shape, same as before with dual multi-pole filters, dual ADSR, but I’ve moved the mixer VCAs to this board and added wave shaping for triangle and a sub oscillator with VCAs for these too. Running out of parts fast.

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Impressive progress. is it a one off or are you going to PCB it? I expect the BOM will be quite a bit?

Rob