[sdiy] 2164 4P LPF board for sale

[David G. Dixon]

Hey Team,

(With apologies in advance for posting an advertisement to SDIY...)

I have a fully built and tested four-pole lowpass filter board based on
cascaded 2164 VCAs and integrators which I built to serve as the core of a
Oberheim-style multimode filter.  It also has inverted outputs at each stage
for eight quadrature sine waves at self-oscillation.  And, as I've discussed
here before, it has distributed resonance gain (using an extra 2164 -- this
gives equal sine wave amplitudes without sacrificing equal signal amplitude)
with the "reverse exponential" response for a smooth approach to
oscillation.

I've panelized it, tested it, calibrated it and even used it in a jam
seesion, and it works perfectly.  It has a cutoff frequency range from about
4 minutes to about 25kHz, three CV inputs, coarse and fine cutoff adjust,
resonance, resonance CV, adjustable zener voltage (from about +/-5V to about
+/-10V), a 3-input mixer with mixed (unfiltered) output, and multiple stage
outputs and with two spare cross-connected 5-pin connectors for easy
connection to any multimode interface.  It features all 1% resistors, four
1% silvered mica 205pF filter caps, machined IC sockets, 18-turn trimmers,
0.1" off-board connectors, and a standard MTA-156 power connector (MOTM
format).  It's handmade (well) with tinned traces, and is a compact 4" x 5".

All this can be yours for the cost of the parts: CDN $45 + $5 shipping =
$50.  I'll ship it anywhere in the world.

Why am I selling it?  Because I want to build another one with a slightly
different layout incorporating two slight modifications: an extra trimmer in
one spot (totally not needed but I'm a bit obsessive), and an extra opamp to
convert one of the CV inputs into the +/- format that we've been discussing
here over the last few days.  Of course, the latter could easily be added by
hanging the opamp off a pot chiclet (a la the Grenader Gizmotron) but I hate
doing that.

If I don't sell it, I will probably cannibalize it for parts, but that seems
a shame, since it's only had about 2 hours of actual playing life.

Please respond privately if you're interested, and I can send photos, etc.
I use PayPal.

(We now return you to our regularly scheduled programming...)