attempted to control my Slim with an external CV source (expert sleepers ES-4) controlling the osc pitch and discovered my slim doesn’t track 1v/oct? pretty close but not really - my scale goes flat and can’t even get an octave- is there any way to adjust the Slim’s tracking? (my DIY synth experiences have had me adjust a fair bit of trimpots to fine-tune v/oct response) Looking over the manual I see no mention of 1v/oct although I thought that’s what I had remembered.
the filter cutoff is actually slightly closer to 1v/oct calibration when attempting to control from external CV
Using MIDI input and the auto tune works nicely but you have to turn the auto tune off for external CV control, correct?
You are correct. I think it is .97v/oct or something like that. You can attenuate the incoming pitch CV with an external device. Not the easiest solution. I know the tribute LPs have internal trim pots installed and stages can have them installed at the factory. They can be set so the phatty tracks 1v/oct. I do not know about slims. You’d have to call or email moog support.
Also, make sure tune is set to manual when using the pitch CV in. Auto tune will try to correct the voltages you are applying and screw everything up.
To help you deal with pitch scaling issues, besides internal calibration checked or performed at the factory, here are two ‘possible’ Moog based external solutions.
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The MP-201 pedal controller can do midi-to-CV with preset 34. The v/oct value can be fine tuned in both directions with the MP-201.
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The CP-251 has a voltage attenuator (two actually). The mixer can also be used as a voltage attenuator. But if you require to boost voltage instead of attenuating it, the CP-251 can accomplish that as well. It can also do that in a more precise way that an internal trimpot can. Whatever voltage tweaking you do with the CP-251 is related of course to the stability of the unit you are sending pitch voltage to.
Very fine tuning of pitch will always be an issue on any CV controlled analog gear. Have you checked that your ES-4 is totally up to specs? Using shorter patch cables, a minimum of patching connections, avoiding patch bays, no cold solder joints in the chain are all factors that will help minimize tiny voltage losses, thus helping achieve better pitch CV accuracy.
have been using my ES-4 with my Doepfer Dark Energy for a good bit now and it’s been just dandy tracking at 1v/oct both VCO and VCF
we’re not talking ‘slightly out of tune’ here - the Slim goes flat by over a semitone by the time you hit an octave
sounds like I’m SOL at the moment unless I can adjust some sort of trimpot which seems likely not present on the Slim given its stripped down construction - I likely will contact moog support at some point soon to see if anything can be done
it’s likely the MP-201 can account for the not-quite 1v/oct tracking from what I remember of reading its literature, but the CP-251 can merely apply an offset to the pitch CV coming out my ES-4 (I have a CP-251 but not an MP-201)
I can actually ‘tune’ the ES-4 to the Slim’s output, I will try that sometime but likely the results will not be that great as the ES-4’s output resolution is only 8bit. (the ES-3 however could easily deal with the Slim’s goofy tracking)
The CP-251 can do much more than offset… it can scale up your pitch voltage to extremely fine tuning, with a degree of precision beyond that of internal trimpots. By doing so , I would think the 8 bit resolution of your ES-4’s dac would probably swamped out to an acceptable degree. I am not familiar with the ES-4, I only caught a small bit on the web.
Read my post on [u]this page[/u] to see how to patch the CP-251 both for offset and voltage scaling up.
Now regarding the tuning of the SP, I will abstain from derogatory comments since I don’t own one, but reading from the LP/SP forum, the situation seems very murky at best, for the time being.
a semitone at an octave is way off
I would expect less than a semitone at 5 octaves. Something doesn’t seem right.
Maybe the solution could be found [u]here[/u] .