Discussion about the Korg PolySix synthesizer

Hi folks,

I have successfully implemented my unison detune mod. And its very easy
to do.

You need one 5K linear pot and a knob of some kind, I used one from a
Monopoly (thanks Andrew who gracefully answered my request for one the
other day). One 3.9K resistor. A 80cm piece of screened audio cable.

Remove R116, a 220 ohm resistor, from the voice board. You can do this
without taking out the board, but you will need to (re)move the
keyboard, as it sits under there. Take it out, and use wick to clean the
holes from solder. Now solder the 3.9K resistor in the same place as
R116. Solder the pot to the screened cable, the wiper should go to the
core, and the CCW pin to the screen. Now solder the other end of the
cable to the voice board. The core should go to the bottom solder pad of
the new 3.9K res, and the screen to the top pad. Make sure nothing will
short out, when the keyboard is put back on.

Now fit the pot somewhere on the front panel. I used the location used
by the LFO's LED. I simply removed the LED and fitted the pot in its
place. I used a low profile Alps pot I had from an old guitar effects
pedal that had died. I can live without the flashing LED, although I may
put it back on at a later stage in a different location.

How it works: The original 220R resistor changes the currents created by
the four tune setting resistors in the unison detune circuit to voltages
that control the pitch of each voltage. A larger value than 220R will
give greater detune, and no resistance (a short) at all will hold the
VCOs at the same pitch. By fitting a 3K9 and a 5K pot in parallel, you
can change the detune resistance from 0 to 2 200 ohms.

Have fun.

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan