Dual SVF CS80 Gain Staging

Hi crowd,

I’m tweaking my Shruthi CS80 dual SVF from Scott Rider and first off I noticed two things

  1. There are no good internet demos and
  2. The thing distorts like a demon in serial mode even without resonance. With resonance it screams like a trapped badger.

What the hell. I was expecting silky CS80 dreams oozing from my speakers, not this broken two-stroke in a tin can. (sarcasm, by the way. My most sincerest admiration and gratitude to both Emilie, Scott and all of the wonderful people involved.)

So figuring I messed up somewhere, out came the multimeter and oscilloscope where many a resistor was replaced and experiments ensued.

I switched out R12 from a 33k to a 10k. It’s now quieter and doesn’t overload my soundcard, but still distorts. Ok, now trying the inputs. Changing R13 from 33k to 20k helps too. So does reducing R33 from 470 to 330. But with resonance it STILL DISTORTS. :’’’(. Noticing that in parallel mode it now sounds fine, I figure it’s all in the serial mode. I pulled out pin 5 from IC 12 and tacked a 150K from it to pin 5 on IC 13 and voila. It’s quieter, but it does not overload (well, it does with both resonance levels cranked to 63 but that’s just extra tweaking). Hooray!

Thank you for listening to my story.

Edit: Changed a name to another name.