Hello Florian.

You're absolutely right about the different pinout! I should have taken a closer look at those schematics. I have the new version of the KLM-255C board, and it is indeed pin 3 and NOT pin 1 that I've disconnected. But I had confirmed the presence of the keyboard CV on that pin with a Voltmeter before doing anything else. When I saw 1 volt change per octave, I knew it was the right pin. I'm terribly sorry for the mix up.

As for the behavior in other key assign modes, it's true that it will be different than before since it will always follow OSC 1 now. And in Unison/Share mode it will be somewhat unpredictable depending on note assignment. But in Poly mode, you can play in a manner to have the first oscillator play a note in a chord that will reflect the cutoff value you want, with a little practice.

If I find it too awkward to use in Unison/Share and Poly mode this way, I might just install a micro toggle switch to flip between original wiring and glide wiring...

I wanted my mod to be as simple and "noninvasive" as possible, so that's why I used OSC 1 as source. Of course, anyone of the four oscillators pitch CV could do as well.

I know it's not a terribly useful feature to have a portamento on filter cutoff, but in order to play Tony Banks early Genesis ARP type synth solos (without using an actual ARP synth), you need it. Moreover, the type of portamento on the MP4 is logarithmic which is the same type used many ARP synths, as opposed to the linear ones used on the Moogs. To be truthful, I play the Mono/Poly as a great monophonic synth most of the time as I have other true (better) analog polyphonic synths to play chords. And I prefer the on/off pedal switching control of the glide on the MP4 to the manual toggle switch on the Minimoog.

Thanks again Florian, for pointing out very interesting facts. And making me aware of my pinout identification mistake! Next time I'll be more careful of what I write...

Alain.

--- In korg_mono-poly@yahoogroups.com , Florian Anwander <fanwander@...> wrote:
>
> Hello Alain
>
>
> > I've simply disconnected one wire (pin 1) on
> > connector 18 of KLM-355C (filter board) that was bringing the
> > keyboard CV coming from KLM-356D to the filter.
> Attention:
> The pinout has inverted between old and new version of KLM355 (You must
> read this with a monospace font like courier):
>
> PinOLD PinNew
> KEYBD-TRACK 1 3
> SINGLE-TRIG 2 2
> MULTI-TRIG 3 1
>
> > So the glide times are identical to that of VCO 1.
> This will be useful only in Unisono and Chord-Memory modes!!! In
> Unisono/Share and Poly modes the VCF should follow the CV of the highest
> VCO (that is what pin20-1 is delivering) - which is not necessarily
> VCO1. In the opposite: VCO1 is typically the lowest note (in Unisono/Share).
>
> > Korg should have added a portamento feature to the filter cutoff
> > in the first place (as on many Moog synths).
> I think Korg did it because of the mentioned dependency. And also they
> used a fourfolded potentiometer, which is already difficult to get, but
> a fivefolded seems close to impossible
>
> The better solution would have been (or would be) to establishe five
> voltage controlled portamentos, where the fifth portamento affects the
> KBD voltage of pin20-1/3
>
> Florian
>