Discussion about the Korg PolySix synthesizer

Good work!   My tuning is pretty close, but I have not touched the antilog trimpots, so
I am looking forward to getting this really nailed so that I can get it even better, as you did.   One thing I don't understand is how the 4051's are being used to change the behavior of the circuit.  And what is the fcn of the opto-coupler?   Any thoughts?

   Bob




________________________________
 From: Malte Rogacki <gacki@gacki.sax.de>
To: PolySix@yahoogroups.com 
Sent: Sunday, March 2, 2014 9:05 AM
Subject: Re: [PolySix] RE: Polysix tuning difficulties.
 


  
And finally:

I've tuned the Polysix (so far just preliminary). There still is some small
room for improvement but except for the lowest 16' octave I have a pitch
deviation  better than the one shown in the service manual. Some notes have
a 1 to 2 cent deviation but most are spot on. The lowest notes in the
lowest octave have currently a deviation of about 7 cent.

I had to use VR15 a lot though which means that probably the basic offset
was not so good. The whole antilog circuit calibration could probably be
shifted a bit upwards and then compensated for again with VR15. This could
possibly bring VR2 away from its end position.