[sdiy] polyphonic synthesis

[Matti]

Look maybe at the schems at code for the sequential circuits' prophet
five. Everything is controlled via d!gital means, sure, bu it is
polyphonic.

--------------------------------------------
I wanna see it painted, painted black
Black as night, black as coal
I wanna see the sun blotted out from the sky
I wanna see it painted, painted, painted black

On Fri, 16 Mar 2001, Ingo Debus wrote:

>
>
> deega wrote:
> > I'm with ya.  I'd love to do a poly synth myself.
>
> I've built one. I used Doepfer's voice cards from the 80s. This is a
> synth voice (2 VCOs, 1 VCF, 2 VCAs, 2 ADSRs, all CEM ICs) on a 100mm *
> 160mm PCB. The CV generation is done by an ancient 6502.
>
> > Regardless, I still give it thought.  Here's what I think is needed for a ten
> > (hell, I gots ten fingers) voice polyphonic analog:
>
> Mine is 5 voice, with two VCOs per voice.
>
> > 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.
>
> Make everything voltage-controllable.
>
> > 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.
>
> Many people here said a polyphonic analog synth *needs* some sort of
> autotune. Well, mine has none... It works ok-ish for 9 of the VCOs, one
> is drifting heavily. I still have to try and replace this 3340. It's not
> perfect without autotune, but hell, this is analog... :-)
>
> Ingo
>