Developing AS 3372 VCF / VCA

This is getting fun- developed a board around a CEM3372 clone (Alfa Rpar’s 3372) and now have it controlled from VCV Rack. Integrates with a backplane and a AS3340 VCO board I’ve previously developed. The '3372 is notable for being the filter chip used in the Oberheim Xpander/Matrix12 and Sequential Prophet 600 (first MIDI synth!).

The cool thing I like with this is it gives decently complete control over parameters from VCV Rack. All those signal go to DACs under the hood for control elements. Patching is also easy-peasy. Modulation from analog components is also there: VCOs modulate each other or the VCF/VCA. And audio path is entirely analog. With all its quirks.

Some hacks/bodges along the way but for a V0.1 board I’m quite happy. The creativity on the demo is a bit lackluster; my musical talents…well, I like developing the stuff and wiggling the knobs. At some point I’d like to get this into some more capable hands. In the interim if someone has anything they’d be interested in “porting” for playing with 2~3 VCOs and a VCF send it my way. I still need to build out a few more boards but end state would be any combo of up to six boards. So 4 VCOs with 2 VCFs for example; but that’s going to be a ways down the road.


This looks like something I might want to try doing. Is it a public project ? Schematics/codebase anywhere yet ?

Looks like great fun. :slight_smile:

1 Like

@Jens.Peter.Nielsen beat me to sending my own link LOL, thanks Jens!

I’ve been developing this for a year now (wow, can’t believe I just wrote that). Still a lot of rough spots in there. Pretty excited to get the project this far, with the VCF board it’s now a complete synth voice. I’ve got half of a datasheet written up for the 3340 VCO board that I need to add to github. Eventually to add datasheets for the other boards as well.

I keep a project blog as well with occasional updates: