Korg Poly 800 II Analog Synthesizer synth mod

via this auction
"Korg Poly-800 II. This model includes a wonderful, warm digital delay (with modulation!), a true analog Voltage Controlled Filter, three envelopes (one for each of the two oscillators, and one for the noise source/VCF), and an LFO to modulate filter cutoff or pitch.

I've also added a several well-designed modifications on this unit:

1- VCF CV Input.
This allows you to modulate the filter cutoff from a modular synth, CV pedal, or other signal generator. The input is designed to receive the standard 0-5 Volts, though the circuit ensures that voltages outside of that range will not hurt the Poly800.
2- External Audio Input w/Level Control.

This input is for processing other synthesizers, guitar, vocals, or any other sound source. It will work perfectly for guitarists, because the added circuitry provides just enough gain (and just the right impedence match) to boost the guitar's low level signal.
3- Filter FM Control.
This potentiometer controls the depth of Filter Cutoff Modulation from DCO1's audio. This modification allows for an extreme range of sounds- from growling synth bass to Ring Modulator-type noises.
4- Cutoff and Resonance Controls.
These potetiometers allow you to control the cutoff point and amount of resonance in the VCF!
5- Noise / External Audio Switch.
This switch disables the white noise source, so that the External Signal can run through the Poly800 alone. The switch also holds Envelope 3 at the maximum level (regardless of the settings on parameters 61-65).

Here are a few sound samples that I improvised to demonstrate some of the more unique features of this unit:
FMsyn
SHgtr
spacegtr
SHsyn
wackygtr"

via Robert