question to paul perry...filters

[swt]

Hey Paul!!. lately i've been diggin a lot my ms20 clone. And after adding some cool controllers, like s&h, Lfos, Step, etc, been toying with audio signal at the input of the controllers. It's amazing, really like the effect, but of course what comes in...comes out...is there any way you could tell me if i can reject that audio a bit?. or maybe a gate is the solution?. What gate do you think would be better, fet or ldr?. Thanks a lot for your reply!!

[Processaurus]

Did you make your ms20 filter?  I really want to make a standalone one because I love the original so much, I tried a 3080 based one that didn't work and Tim Escobedo's 9v one that worked but didn't sound that great.  If you had any tips I'd love to hear about yours.

for patching in audio to the CV inputs, you could rig something together with a boss NS-2, because it has a sidechain, to gate the control audio with the audio that is going to get filtered.  Or use any noise gate scheme and patch in the audio to drive the sidechain/envelope detector, and run the CV through the gate.

[swt]

yeah. it's an unbelievable filter. Lots of resonance, somewhat tricky to set up at the edge of it. I made it from a pcb i found somewhere, and the rene version 2 schem. i used +-15 volts. it's going into one of my guitar synth,actually i'm designing one mixing stuff from everywhere i can. Snippets, synths, ideas, octavers. etc. If i can help you in any way, just let me know. Build it, you won't regret.

[Paul Perry (Frostwave)]

I would think that if you are using a straight audio signal as a controller, then yes, plenty of that is going to be present at the output.
The thing to do, would be to have the controlling audio go to an envelope following circuit (that is, a rectifier like in an envelope wah) and, use that output to control the MS20 clone. That is to say, an envelope follower with a MS20 filter section...
Nothing to stop you having an adjustable blend of audio and rectified audio envelope as a control. that is the beauty of DIY - it can be 'too weird' or take 'too many knobs' but, that isn't a problem for the DIY brigade