[sdiy] SSM2164 state variable filter

[David G. Dixon]

> http://www.synthfool.com/docs/Oberheim/sem2sch.pdf
> http://www.synthfool.com/docs/Oberheim/
>
> Is there any reason to not use the SEM method of "deadband" type diode
> network in the feedback network from the bandpass output, so that even
> when the resonance control is set for no damping once the bandpass output
> reaches a certain threshold the signal will be fed back to the filter
> input,  thus dampening the response?

I know this is Oberheim, but this looks really dicey to me.  My simulation
of it within the context of my 2164-based SVF was not very promising, to say
the least.
 
Zeners across the first integrator cap work perfectly and are very simple.
As far as the designer in me is concerned, this case is closed.