SV: Re: SV: [sdiy] QVCO schemo up

[Ian Fritz]

At 08:04 AM 11/12/05, JH. wrote:
> > infact this cirquit is nothing more then a variation of the SVF!
>
>Sure - what else should it be?
>It's a 2nd order differential equation in the most direct realisation.
>If it's dampded, it's a filter. If it's not, it's an oscillator. The art
>lies
>in keeping it _just_ so undamped, that it oscillates without increasing
>amplitude.

Right.  In fact the AD handbook writeup presents it as a state-variable 
oscillator and indicates on a drawing how to use it as a filter.

This brings up the possibility of making a synth module functioning either 
as a SV filter or quad osc.  In fact, one could probably make a small 
add-on circuit with a panel switch to hack up existing SV filters to add 
the quad osc function.

   Ian