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Subject: Re: [korgpolyex] Technical info on Poly800 & analog mods

From: Michael Hawkins <korgpolyex800@...>
Date: 2015-02-06

Check out the files section and you will find the schematics for the Poly.

The LFO's are all software. But the control signals could be intercepted and set up to be controlled by CV with some op-amps to match the 01V to the required voltage swing range.

VCF cut off is easy. Just intercept the cut off control signal and set up some op amps to converts the 0-1V range to whatever is required. Check the power supply rails to see what the range needs to be.

Amplitude - there are two master control signals for DCO bank 1 and DCO bank 2. They could be intercepted and the same CV with op-amps.

I don't think anyone on this list has done this sort of CV type mod (most use POTS to intercept and get manual control). So you are sailing into uncharted waters but it's relatively straightforward if you know your analog electronics.

Modding to send audio through the filter is very common. Though we don't have any specific mod details in our files section.

/Mike

From: "chillipower.uk@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: korgpolyex@yahoogroups.com
Sent: Friday, February 6, 2015 6:59 AM
Subject: [korgpolyex] Technical info on Poly800 & analog mods

 
Hey group,

Been interested in modifying particularly the analog side of a few old analog synths I have.
Particularly with some CV in/out so they can modulate each other, with LFO or oscillator signals.
Doesn't need to be real CV conforming to a standard, I'm not playing pitched notes with it. More gentle modulations or FM modulations, of pitch, cutoff and amp etc. If I can find the routing into the analog side I'll add some jacks onto the back of the synth.

I wondered if:
Anyone has a circuit diagram for the Poly800 and/or has tried this.
Knows about the Korg LFOs, are they software or hardware generated on the Poly800?
Also might have details of a line-in mod. I think I could run the line-in as an alternate (or mixed with) the noise source, so that it runs through the filter and MIDI notes/CC can be used to alter the line signal in interesting ways.

Any thoughts or discussion about these ideas, perhaps some of you have tried out these things already. If so I'm really interested to hear about it.

All the best, Louis