[sdiy] WP LM3900 VCF

[anthony]

So I'm in the middle of building an effects synth from 2 XR2206's. I came up 
with a good VCO set-up on my own (even a mode where they're both used as a 
100kHz beat oscillator).

For the rest of it there were too many good ideas for me to easilly pick the 
circuits I wanted to use. But I decided on Ray Wilson's sound lab. (It's a 
really cool design. I may end up making another one for my daughter.)

But after I decided this I looked at the older WP20 and I thought 'hey I 
have an LM3900...' So I could make the VCF, VCA and AR eg with one chip! (Er 
maybe there's a 555 in there too, but still...) This seemed cool to me. 
Anyone think of a good reason not to? Or rather what is it about the Norton 
amp that makes it special? Or /is/ it special? It almost seems like a 
backwards OTA...