9V Sallen-Key LPF for WTPA!

edited February 2010 in WTPA1 Mods
I have been thinking about buildling this as a pedal. There is a veroboard layout for it that is pretty simple, that I haven't built yet. This is a public domain circuit by pedal hero Tim Escobedo that is a 9V version of the LPF section (no HPF/parallel bandpass, sadly...so not a "full" ms20 filter) of the Korg MS20 filter.

What I've heard about this is that the lack of clipping diodes makes it pretty distorted on high resonance settings. Probably pretty industrial sounding. Probably very functional with the resonance brought down. Some of the people on diystompboxes.com forum build this pretty happily. I'm sure a pcb or perf layout exists, but I haven't foudn it yet.

At 9V seems pretty convenient to run from Vcc on the WTPA. Sorry this did not come up sooner...

Schem: http://www.jiggawoo.eclipse.co.uk/guitarhq/Circuitsnippets/snippets.html (scroll down)
Vero layout: http://img401.imageshack.us/img401/9132/ms20lpvcf.gif

I think I'm going to eventually try this, but I'm still trouble shooting WTPA!

- Strategy


  • You have a source on LM13600s?

    I'm ready to drop the modular filter and go with a stomp box one instead and this looks like exactly what I am looking for
  • Futurlec.com stocks them for $2.90, they've got a good selection of hard-to-find stuff but they take forever. Highly reccommended if you've got a month to wait.
  • yeah, I get stuff from Futurlec all the time, first class from Thailand takes at least 10 days to Michigan.. I guess it's time to order a bunch of shit from there anyway. I may just etch some PCBs for this, looks like a decent and simple filter..
  • edited February 2010
    Ok. I am onboard for this single supply VCF dealio. How about something like this:



    LP/HP/BP with an envelope follower..
  • Envelope follower - fun. The Rick Holt (FrequencyCentral) projects seem bulletproof.

    smallbearelec.com has NJM13600 too. They def dont take as long as futurlec.

  • Well after some reading it looks like the EF part of that design is problematic and the only one that actually worked was the OP's. No one else has successfully built one. I'll bread board up just the filter portion of the circuit and see how it works without the EF. I like the sound and the 3 filter modes would be nice.
Sign In or Register to comment.