Model D Reissue Oscillator Mod Switch Changes Pitch

[Mr Analog]

I just purchased a new Model D. It sounds amazing and everything works fine except for one issue: the pitch goes up by a few cents whenever I turn on the Oscillator Modulation switch. I have to decrease the Tune knob to about -0.5 to compensate. I found an old discussion of this same problem but it's not clear if this is just a calibration issue, or a defect that requires a factory fix or an unfixable byproduct of the design.

I sent an email to Moog about this today, but I assume it will take a few days to hear back. In the meantime I would really appreciate hearing about any experience you guys have with this issue.

[Analog Prophet]

First of all: congratulations to a one of the greatest synths ever made! When I asked the same question to Moog as I had the same issue they replied it’s in the original construction and they chose to keep it as the original. So it’s nothing wrong, just as the original. It can not be calibrated to disappear. Anyhow It can be solved by a modification: https://www.virtual-music.at/en/moog/#1 . Alexander (the Muse guy) is very helpful, kind and trustworthy.

[Mr Analog]

Thanks for the answer! It’s good to know there’s nothing wrong with mine and I suppose I’ll get used to the tuning adjustment.

[ikazlar]

First of all: congratulations to a one of the greatest synths ever made! When I asked the same question to Moog as I had the same issue they replied it’s in the original construction and they chose to keep it as the original. So it’s nothing wrong, just as the original. It can not be calibrated to disappear. Anyhow It can be solved by a modification: https://www.virtual-music.at/en/moog/#1 . Alexander (the Muse guy) is very helpful, kind and trustworthy.

Did you install the Muse? If so, what's your opinion about it?

[Analog Prophet]

No, I have not installed it yet, it has been laying here on a shelf for some months waiting. I probably can install it myself as it is “technical easy done” but as a technical novis I’m a little bit scared to open up the Moog and dig in (I recently opened up my Oberheim Xpander and replaced 5 chip to the latest firmware and were shaking and sweating... but I succeeded... after a second trial). Alexander at Muse wrote me some emails and let me know I can contact him for any questions. But I will probably invite some friend, more technical than myself, for a dinner and to support me install the Muse.

If someone has documented/will document by pictures step by step I could do it. Someone here?

[Minimooger]

i found this video very helpful . however the manual of the muse described the installation quite thoroughly .

https://www.youtube.com/watch?v=YiHztAj7hLE

[Analog Prophet]

Thanks, just what I needed. The only thing I’m concerned about is the glue moment - can hot glue ruin the board?

[Minimooger]

Thanks, just what I needed. The only thing I’m concerned about is the glue moment - can hot glue ruin the board?

i don´t think so , but rather ask alexander from virtual musics . he surely knows .

[mpaulcurreri]

Hi guys.
I’m also searching for a solution to this issue (activating the Osc Mod switch affects the pitch by about a quarter tone). I was momentarily excited to see the link about the Muse. But clicking over, I didn’t actually see anything about this issue on the Muse website. That mod seemed more geared toward the pitch and mod wheel. Am I nuts?

Not positive I could talk myself into the cost anyhow (100 euro to mod the original MM, but 354(!!) for the reissue — yikes!!), but I’d still love to know if it actually solved the problem.

Many thanks!
Paul

[Markyboard]

First of all: congratulations to a one of the greatest synths ever made! When I asked the same question to Moog as I had the same issue they replied it’s in the original construction and they chose to keep it as the original. So it’s nothing wrong, just as the original. It can not be calibrated to disappear. Anyhow It can be solved by a modification: https://www.virtual-music.at/en/moog/#1 . Alexander (the Muse guy) is very helpful, kind and trustworthy.

True there is no internal calibration for zeroing the out of tune effect when enabling the mod wheel switch for the oscillators. But I'm not sure the Muse devices (either one) solve this problem. It does fix the pitch wheel return offset that most are aware of but no where in their description does it mention the mod wheel other than adding midi to it and reducing the sensitivity of the wheel to 25%. Maybe this effectively resolves the problem, but maybe not.

Listening/watching the video clip that pitch change is extremely small and not something I would have even noticed. The only time I can see this being an issue is if the mod wheel is set to other than 0 and you want to enable/disable the mod effect with the switch. Still this is analog and the least of any pitch problems I've experienced.

Edit: Ah, Paul beat me to it.

[mpaulcurreri]

Cheers, Marky
I’ve been in touch w Alexander (the Muse guy). Together we realized that the FILTER mod switch causes an even larger jump. You can hear it if you make it self-oscillate (w no Osc on), and then hit the switch. The Muse is an admittedly expensive fix for this particular issue (tho I love what else it does). Anyhow, Alexander is going to investigate this weekend and see if the Muse can in fact do the trick.

[Markyboard]

Interesting Paul. I just set up the self oscillating filter and enabled/disabled the filter mod switch on my original Mini and the difference is almost if not totally imperceptible. There is a very noticeable difference in the middle of the switch throw but that's understandable since it create an open input to the modulation summing circuit.Setting the mod switch (filter or oscillator) to off or setting it to on with the mod wheel completely off should provide ground to the mod summing input. I suspect that your mod wheel isn't fully disengaged and showing something other than ground. It's certainly easy enough to measure on the bench. Several milliVolts (or ceratainly tens of milliVolts) will be perceptible.


Without having a re-issue here I can't determine whether I think this is a real problem or not but next time I come across one I'll check it out.

[mpaulcurreri]

Hey Marky.
Indeed, the filter mod switch causes a pretty signifanct change. Your thoughts are a little worrisome, as it sounds like my machine may need some tech attention — not too many where I live. Next time I’m in the studio, I’ll do my best to hear if there is any mod wheel bleed — say in the LFO.
Thanks so much,
Paul