[sdiy] SVF question

[David G Dixon]

> Yes.  I think we came to the conclusion that there were a 
> couple of good places to put the diodes.  I settled on 
> putting them across the first filter cap (the one which gives 
> the BP output, and which generates the feedback for 
> resonance), with a tiny bit of the BP signal shunted around 
> the resonance amp network through a large (1M or so) and back 
> to the input to ensure robust self-oscillation.  At 
> self-oscillation, simulation gives sines from the HP and LP 
> outputs with 0.042% THD, and from the BP output with 0.144% 
> THD.  I haven't built this filter yet -- haven't had the time 
> -- but I think it's going to be a good one.

Sorry -- that came out kinda garbled.  The LP output feeds back, the
"inverted" BP output dampens, and a bit of "non-inverted" BP output fed back
keeps things self-oscillating nicely.

If anybody's interested, I'm happy to send along a PDF of my schematic.
Send me a PM.