Hi,
For the pitch tuning, if the anti-log converter adjustments
have been messed with, you would want to fix that up.
But I would check it first. Maybe it wasn't changed.
Unfortunately, since it's time-multiplexed its not as simple
to test as some other synths. The anti-log will affect the
tuning of all six voices, of course.
1) For the VCF res adjustment, you set the Cutoff Front
panel control to get 0V at the indicated point.
2) In step 4, you test the oscillation freq as a fcn of the cutoff
control. At the low end, it should be 10-25 Hz. At the upper end,
19-24KHz, which you won't be able to hear. The P6's I have seen
were more like 28 KHz at the upper end. I got 300 mV p-p.
Are you still probing at TP-1?
In step 4 of the pitch check and adjustment, instead of VR1
you should use VR15. I think VR1 would have been correct
for the older units. Actually, I haven't tried to use the Korg
steps to adjust the anti-log. There is a separate document in the files
section on how to do that. I think it's a little more usable than
what Korg suggests, but that's just my opinion.
Bob
From: "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com
Sent: Friday, November 7, 2014 10:11 AM
Subject: [PolySix] Voice board calibration
Once I got my clone board working on the Polysix I discovered that nearly every trimpot on the KLM-366 has been adjusted in some way. I've made a reasonable amount of headway calibrating but I have a handful of questions. Clearly there's a real relationship between all these sections. I want to make sure I get it right. Perhaps I should have broken out my questions to different thread but maybe it's useful if it's contained here. I guess we'll see.
1) In section (3) VCF Resonance it asks that I adjust to obtain 0.000V. It's referring to Cutoff, right? That's what worked for me but I just want to rule it out. It looks like a simple omission of what VR needs the adjustment.
2) In section (4) VCF f0 Adjustment step 4) Cutoff to 10: I don't hear a thing on my unit here. It's fine and audible when set to 8.000V in the previous step but at 10 I don't get anything close to 300mV p-p. It makes me wonder if my earlier assumption about question 1) here is incorrect.
3) Section (7) Pitch Check and Adjustment is really inconsistent for me. For one the keyboard tracking and all voice tune trimpots were set to all sorts of extremes when I started here. Would it make sense to base tracking on a calibrated Voice 0 instead of following these steps in the documented order? Octave changes are way off and playing a scale is inconsistent because the VCOs are not calibrated in the first place. I've done a few passes and am getting closer. I just wonder if I should go about it another way.
4) Also in (7) Pitch Check and Adjustment it says to set it Octave to 4' and tune C6. Really? The note is extremely high, barely audible. I have scope to try to perhaps capture the frequency but a tuner doesn't handle that pitch well.
A lot to ask of all of you, I know. But hey, we can finally shift the discussion away from a 367 for a little while.
That's refreshing, right?
:D