KORG POLY 800 with Mods

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"The Korg Poly800 came from that strange era of Korg synths where they couldn't seem to decide between analogue and digital, and so came up with a selection of hybrid synths that didn't seem to excel as either sound. On paper the Poly800 was a pretty well endowed machine but in reality it always sounded a little thin and never really fulfilled its potential, which is why these modifications are so useful and crucial to making this item as powerful and flexible as it is.

Modifications include:
Cutoff & Resonance Knobs: This mod adds knob controls for the filter cutoff and resonance parameters for realtime control. The resonance knob can take the resonance well into self oscillation and far beyond what is programmable from the front panel. This can produce the kind of screaming top end and subsonic bass that gives this machine a whole new range of sonic possibilities. The filter cutoff knob allows you to perform long filter sweeps for those squidgy burbling analogue lines this Korg is capable of but could never actually be programmed. Both parameters are still also controlled by the normal programming methods which can set the range of the knobs control.
12dB / 24dB Filter Response Switch: Somewhat mysteriously the filter chip used in this machine has both 12dB/Oct and 24dB/Oct outputs but only the 24dB one is actually used. This mod adds a switch to select either a 24dB or less drastic 12dB filter response

External Audio Input: This accepts a line level audio signal and inserts it before the filter and chorus effect so you can use it to process external signals. The input is set up so that a loud signal will slightly overdrive the filter for a dirty sound

External Audio Path Switch: This switch sends the audio from the external input either via the DCO1 or DCO2 signal path or turns it off completely. The input doesn't respond to the DEG audio level envelopes but instead is gated on and off by the noise gate that korg implemented to silence the synth when all the envelopes are completely closed. i.e. when the DEG envelope for the chosen path closes completely at the end of the release phase, the noise gate is activated and the external audio input is cut. The audio input is still effected by the filter envelope. An external input can easily be filtered without having to hold down a note by setting up a patch with all the oscillator tones turned off, but the DCO 'level' parameter set to full. If you use the note 'Hold' function and press a key the audio input will be audible and can be processed with the filter etc

Input Level Knob: Controls the level of the audio input.

VCF FM Knob: Adds the ability to control Filter Cutoff with DCO1. This is commonly known as FM control of a filter."