[sdiy] Patchable polyphonic synth with FM or AM transmission idea

Donald Tillman don at till.com
Wed Dec 26 21:50:25 CET 2018

On Dec 25, 2018, at 11:49 AM, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> I was thinking again about how you could do a modular polysynth well,
> and it occurred to me that you might be able to use frequency domain
> multiplexing (FDM) to put several signals over a single conductor
> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
> digikey but it's a tiny 3x3mm QFN device that performs complete FM
> transmission. In a 16 voice system, at about 5 output functions per
> module, and 12 modules, you can easily use up ~1000 of those, which
> drops the price to $4. I was wondering what everyone thinks about this
> sort of scheme.

The FDM approach will likely create a lot number of problems and nasty side effects.

Why not just use those 0.1 inch Molex board connectors with ribbon cable?  They've been readily available and dirt cheap for 30-something years.

But whatever solution is determined much more by the practical use cases.  Do you really have 16 VCOs?  And 16 VCFs?  And 16 EGs?  Why 16?  And once you have those, how many ways are there of wiring them up?

So it would be helpful if you described how you are planning on using this beast.


People my age might remember a 1973 album by Robert Mason's ensemble Stardrive called "Intergalactic Trot".  The story is that Robert Mason developed an early polyphonic synth out of parts of an ARP 2500 and his own electronics, and as a musician, could play the hell out of it, and was able to round up top talent to do an album.

    The Intergalactic Sonic Travels of Robert Mason and His Synth

Check it out.

  -- Don
Donald Tillman, Palo Alto, California

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