Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

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Subject: Re: [PolySix] RE: KLM368a diod

From: Terje Winther <terje.winther@wintherstormer.no>
Date: 2014-01-21

Hi Yash,

I was wondering about the Jürgen Haible mod for VCO-to-VCF. Do you have a link to the description or some instructions or schematics, please?

Most of the mods I found here:
http://www.acc.umu.se/~amber/Poly6/

The instructions regarding the VCO-to-VCF mod is rather thin:
http://www.acc.umu.se/~amber/Poly6/stuff/p6digi2_

The original info regarding Jürgen Haible´s Oberheim mod is here:
http://www.jhaible.com/hj_pmob8.html

I couldn´t use the mod directly transfered to the PolySix. Only on my third attempt did it work, and in the end I used the one of the VCA´s of Bergfotron:
http://hem.bredband.net/bersyn/VCA/lm13600%20vca%202.htm
I built 6 x VCAs based on the LM13600, but didn´t use the output transistors in the chip, as explained here, but used TL074 as buffers. Also, I only build one exponential converter, and it could easily drive all 6 VCAs.

In addition I put in switches so I could turn each VCO-to-VCF effect on and off, and build a pot as a voltage divider to give the circiut the required control.

The last (or primary!) part is to know where to hook up this extra circuit to the Polysix analog circuit board: the signal output of each VCO and the control input summer of each VCF.



Terje Winther