Polybeast Modified KORG POLY800 mkII

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Videos at the auction previously posted here.

"FILTER MODS:

Cutoff & Resonance Knobs: The new resonance knob can take the resonance well into self oscillation and far beyond what is normally programmable from the front panel. This can produce the kind of screaming top end and subsonic bass that gives these machines a whole new range of sonic possibilities. The filter cutoff knob allows you to perform long filter sweeps for those squidgy burbling analogue lines that you could never actually perform on a poly800 before now. 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 these machines 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

VCF CV input: This socket round the back of the machine adds an external 0 to 5v control voltage input that controls the filter cutoff. The new filter cutoff control knob is disabled when a jack is plugged into the socket.

AUDIO INPUT MODS:

External Audio Input: This accepts a line level audio signal and inserts it before the filter and delay effect so you can use it to process external signals. The input is set up so that when its turned up full, 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 audio input is not effected by the envelopes other than being gated on and off with key presses.

Input Level Knob: Its a knob that controls the level of the audio input. What more can we say?

FM MOD'S:

These consist of a source selection knob and an FM amount knob. Essentially VCF FM allows you to modulate the filter cutoff at audio frequencies to create all kinds of clanging cross modulation and bizarre alien splatters & sweeps. This effect works best with the resonance cranked up into self oscillation which is where the new resonance knob mod comes into its own. The source selection knob allows you to select one of four sources for the FM signal. These are DCO1, DCO2, Noise and audio input. The audio input takes its signal from before the input level knob so you can use the audio to modulate the filter cutoff but remove the actual audio signal from the mix. The source knob also has an off setting.

FX MOD'S:

Delay Feedback Knob: Controls the amount of delay feedback from a couple of repeats to a maximum well over 100% for those building dub delay effects that get louder and louder before finally decaying into a mess of distortion. This control works relative to the actual delay feedback setting parameter programmed with the sound.

Delay Time Knob: Unsurprisingly this controls the delay time but can also be used in conjunction with the feedback knob to create surges of sound or in realtime to create swept echos and loops as with any analogue delay. Again, this control works relative to the actual delay time setting parameter programmed with the sound.

DATA ENTRY KNOB:

This mod adds an endless rotary switch that does the same job as the UP/DOWN data entry buttons on the front panel. Turning the knob changes a parameters value so you don't end up continuously stabbing at the buttons, although they do still work if you want to use them. The knob has 20 clicks per 360 degree rotation, so it takes 5 full rotations to take the value of a parameter from 0 to 99. Normally we would use a standard rotary encoder for this, but on this machine we have used a very high quality endless rotary switch which feels a lot more solid.

We have also replaced the memory backup battery with a brand new one in a proper battery holder, so it should keep the memory alive for at least another 20 odd years!

This synth still produces all the normal Poly800 mkII sounds as well as a vastly extended sonic range. Below is a couple of Youtube demos of the mods on another poly800 mkII, using the onboard sequencer and processing external drums. Theres also some Soundcloud demos of a Poly800 mkI with the same 'polybeast' mods. The mkII can produce all the sounds from a mkI, and more."