New Model D filter eg issue

[smv]

Hello,
I just bought my Model D reissue. It sound fantastic, but I have a problem.
When I use the filter eg to modulate the pitch, to raise up the pitch and after come back to the nominal note, it is coming back around one semitone up of the note it should be. Of course mi filter eg settings are : ATTACK Time 5 seconds, Decay 5 seconds and no sustain to come back to the original pitch.
Did anyone experience this problem?
Thank you

[ummagumma]

If you turn off the "oscillator modulation" switch, does it return to the correct pitch?

I think there is something inherent in the design that makes it go sharp a bit, when that switch is on

[smv]

yes and pulling back the mod wheel at the min position. The same issue is if i use the noise as a pitch mod source which the oscillator mod switch engaged. When i move the mod wheel up, the note goes a semitone up. I contacted the Moog support, and they told it is normal. They tested it on both 2016 and 2022 models, and they had the same thing. He also told me that he re-calibrated the mod wheel, but nothing changed. Anyway is something related to the mod wheel. I would like to know if any of other model d owners, has the same problem, But sadly, i saw that even if many users read this post, you were the only who gave me an answer . Thanks

[sdwillingham]

This is all normal behavior. The Mini uses very simple transistor circuits, which are generally not very precise. The contour generator internal voltages don’t really go to a precise zero volts (and don’t need to for the original intent of driving the filter and VCA circuits).

Also, the modulation mixer is not a precise opamp circuit, so it suffers from some DC offset that varies from unit to unit and with different settings. That is just the nature of the mini’s 1970s economic circuit design. Modern trims or improvements are possible, but most players just work around the limitations.

[smv]

thank you, sdwillingham, for your explanation.