[sdiy] Filter problems

[Neil Johnson]

Hi Tom,

> You’d recommend putting them in the feedback path instead, Neil?

Yes.

> It does make more sense in many ways (since what you’re trying to do is limit the resonance). But the problem is that VC-resonance control is really a “damping” control, so it’s not as simple as just moving them to the Res VCA’s op-amp. Would be nice if it was that simple.

Umm, yes it is:

http://www.milton.arachsys.com/nj71/pdf/cesyg/vcf-sch.pdf

You certainly don't want them anywhere near the integrator capacitors
otherwise you'll end up with the poles not aligned due to the diode
capacitance slugging one of the integrators.

Neil
-- 
http://www.njohnson.co.uk