[sdiy] Anyone make KLM-129 & other portions of Korg MS-20/MS10 etc.?

[anthony]

I got the idea the other day to make the External Signal Processor (KLM-129) 
from the Korg MS-20 because I happened upon a GE "quad stereo" receiver that 
someone had thrown away. The outside was pretty well trashed and the circuit 
boards were littered with painted-on resistors where 1/4 resistors would 
be - and I just can't abide circuitry that I can't easilly modify. But the 
other parts were great: lots of epoxy sealed Sanyo electrolytic caps 
(although every now and then I entertain the possibility that these are 
tantalums but I really don't think so...), paint daubed 2SC693's, etc... But 
even better were the controls: yes the quad-panning joystick with 4 
individual 200kOhm pots that moved in pairs (this seems to make for a 
smoother action than some other joysticks I have even the one from the 
Panasonic "quad-stereo" receiver...); but the true gems were the 3 identical 
50kOhmAx4 slider pots. This is smaller than the 2 100kOhmCx4 on the KLM-129 
filter controls, but with a slider pot I don't have to worry about the 
reverse taper.

Korg circuits are some of my favorites and I follow avidly discussions about 
the filters. I'd really like to make a faithful copy of the original 
Sallen-Key version of the filter or whichever ones used that custom chip 
htat is impossible to find now.

It's too bad that these Korg synths weren't V/Oct. I guess the MS-02 makes 
that a moot point.

Now to find another use for that one remaining 50kx4 slider pot...