EDP WASP Filter using vactrols?

[gasboss775]

It occured to me today that the famous CMOS filter from the EDP WASP synth could be realised using vactrols in place of the CA3080 OTAs.

Has anyone done this before?

Other possible substitutions could be JFETs, MOSFETs Or FET optocouplers, possibly even bipolar transistors if signal levels are kept low.

[stolenfat]

I find vactrols fun but messy...

I know there's a different version out there that replaces the 3080 with a single 13700 since they are a little harder to find.

I etched a board a while back but It was one of my firsts and it turned out terrible... perhaps it's time to revisit.

http://electro-music.com/forum/topic-30946.html

[okelk]

I haven't done it, but it's certainly possible to build a 2-pole state variable filter with vactrols and cmos-buffers.
The results may be nice, but keep in mind that it probably won't sound like a wasp filter since some of its distortion probably not only comes from using cmos-inverters as linear amplifiers but also from underpowering the OTAs (which have a recommended minimum operating voltage of 9,5V on a single supply...)

but hey, give it a try!
I'd love to hear the results.

[Cynosure]

As mentioned, it should be possible with vactrols, but they are slow and sloppy. There is a Fonik schematic of the JH version floating around this site that uses the LM13700. I have built it a few times and it sounds great. I recommend using that. He might still sell DIY kits too.