Discussion about the Korg PolySix synthesizer

PolySix@yahoogroups.com wrote:
> Here I have a question for the truly experienced PolySix user: Suppose
> I did the mod on the LFO range. (I really,really  would like to take
> the LFO into the audio range). If I did this and made a setting with
> the new higher LFO frequency, would that setting then be saved as part
> of the sound patch, or does it still depend on the value of the
> resistor controlling LFO speed?
I am not sure about what you mean with "the LFO mod", but I suppose
that is a simple modification of the frequency range of the LFO by
changing a resistor or cap (C19 of KLM-367 is the timing capacitor
of the LFO circuit). It will be then still controlled by the saved
patch setting.

> The thing is I have made a number of sounds that really depend on the
> arpeggiator, and unfortunately the arpeggiator setting are not saved
> as part of a patch. They are obviously considered sort of 'performance
> parameters'. Too bad, because a fast arpeggiator is really cool for
> making very living sounds. So I have had to make a sheet of paper
> describing the manual mods I have to apply to get to the final sound
> in some cases - very much in MiniMoog style. I wonder if this also
> applies to the LFO mod?
If you really want, you can make the ARP speed programmable, too. The
ARP clock is generated by an 555 timer. The 555 in astable mode can
be voltage controlled on pin5, which is bypassed in the Polysix
(btw. the 555 resides on KLM-371, under the front panel, directly
beneath the ARP speed control knob). The data book says that the
control voltage should be between 1.7 Volts and Vcc (5V in this case).
The question is where to get the control voltage from. If you study
the sound parameters of the Polysix then you will find out that
one bit of memory is unused and that the PWM Speed control voltage
is (obviously) used in PWM waveform only; when playing Saw or Pulse
wave the PWM Speed control is unused. The same goes for the Effects
Speed/Intensity control with effects off.
I used the PWM speed for a (programmable) white noise source in
my MIDI retrofit kit ( http://analog.no/polysix/index.htm ) and the
free bit for switching the Pitch Bend wheel between VCO (Pitch Bend)
and VCF (Filter bend). If you want to have details on the circuit
you may email me.

Cheers

Johannes