[sdiy] polyphonic synthesis

[deega]

Seb Carr wrote:

>     But, i understand that poly synths are far more complex.  Would i be
> correct in saying that a poly synths needs  ( at least ) 1 VCO per note of
> polyphony?  I read that you would also need a VCF and a VCA for each note,
> but surely the synth could be simplified so as the individual oscillatos wer
> combined and then put through a single VCF and VCA?

(I appologise for this blatently newbie post)

I'm with ya.  I'd love to do a poly synth myself.  Unfortunately, my (lack of)
experience gets in the way.  I have recently completed my first project (PAIA
Fatman) and am eager to do more.  Naturally, a polyphonic analog is what I'd
_like_ to do.  Then reality sets in -- I'm extremely wet behind the ears and
need much more experience before I tackle a monster like that.

Regardless, I still give it thought.  Here's what I think is needed for a ten
(hell, I gots ten fingers) voice polyphonic analog:

A MIDI>CV converter with 10 output sets (at least CV and GATE), cascading to an
unused set with each note-on.  The closest I've found to this is the midi2cv8
kit from PAIA: http://www.paia.com/midi2cv.htm.  This kit only supports 4
voices.  I suppose you could daisy chain 3 of these and mod the firmware so
only unplayed notes are kicked over to the next converter.

I really wouldn't want to skimp and pass the sum of all VCO's to a single
filter and VCA set.  All modules would need to be built 10 times, with a single
control panel.  I believe this would be tough.  I need to learn how to make one
pot/switch control ten devices.  Relays come to mind for switches, but pots...
oh boy.

Patches could be passed through DIN jacks.

I can see tuning each voice to sound exactly the same becoming the biggest
issue.  With all the talk on this list stressing the need to match components,
I'd imagine matching components across 10 identical modules would be a
nightmare (understatement?).  And what of thermal stability?  Even if matched
well, the boards will still behave differently due to temperature difference on
each.

Basically, I'd like to do something like this before I die..  ( :

If I'm off base here, someone please set me straight..

Daniel