[sdiy] Later MS-20 filter with 2164

[David G. Dixon]

> Don't say that 'til you've heard it (have you played an MS-10 or -20?)
> -- it can be very, very appealing indeed. :-) 

I've only played an older one with the Korg35 (which sounds awesome).

I've just been simulating my 2164 Korgasmatron with adjustable zener
limiters in the resonance feedback loop (as per the IC Opamp Cookbook, 1st
ed., pg. 202, with 3.3V 1N4728s back to back and a 20k pot), and I would say
that the diodes don't distort the resonance waves (by clipping) so much as
limit them to a smaller amplitude so that they maintain a lower amplitude
than the filtered signal.

It's going to be very interesting to stack this circuit up against an actual
late-model MS-20.  Does anybody in the Greater Vancouver area have one???