2 VCO's - 1 Log convertor (polysynth design)

[WeAreAs1 at aol.com]

In a message dated 5/25/99 6:53:19 AM, you wrote:

<<what Im wondering is , does anyone know a way of driving 2 VCO's 
(usual ramp/square) from one log convertor>>

One way to do it is the Korg method, as found in the PolySix and the Trident 
synths.  These units had just one exponential amp for all VCO's, but it was 
"time shared" by placing it inside a Mux/Demux circuit (using 4051's).

The Trident had two VCO's per voice, and the PolySix had one.

I'm pretty sure the PolySix schematics are somewhere out there on the web, 
but I don't know where.  You might try Tony Clark's DIY schematic archive.

Juergen Haible could probably explain this circuit better than I - maybe 
he'll add some comments to clarify.

Michael Bacich