Schematics / Wasp Filter Clone
Wasp Filter Clone by Juergen Haible ,page dedicated to this filter is here with notes and more detailed description http://www.jhaible.de/tonline_stuff/hj_wasp.html this is comment by Juergen taken from the page :
It sounds considerably different than the ordinary SEM-type state variable filter. The maximum Q is lower on the Wasp version. And there is an additional distortion coming from the CMOS inverter nonlinearities. This distortion is gradually increasing with input level, and you can slightly hear it way before the circuit actually clips. The CMOS inverters seem to be the dominant source of distortion; the CA3080 input dividers are rather on the save side. (100k / 1k ; but remember the absolute maximum voltage swing is limited to 5V anyway.) I have replaced the 100k resistors with 51k without noticeable increase of distortion.
Ok, the Wasp Filter sounds different than other state variables. But what is it good? IMO, every filter's overdrive characteristic has its own special applications. The SSM2040 in LP configuration, for example, is unbeatable when you want to process a full chord of buzzy "Jump"-type saw voices. The Wasp Filter works best on Farfisa-type *organ* sounds. I tried various sounds from my OB-8, and really, the best results came with bright organ sounds. My favorite patch is the filter in LP mode with medium cutoff, and then an envelope with slow attack opening the filter (resonance quite low). This certain "edge" that is added by the filter's distortion is hard to describe, but very pleasant.