Moog Mother 32 VCO pitch, keyboard tracking and Glide problems

Mother-32, DFAM, Subharmonicon, Grandmother, Matriarch
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lesliemakin
Posts: 3
Joined: Sun Apr 18, 2021 12:14 pm

Moog Mother 32 VCO pitch, keyboard tracking and Glide problems

Post by lesliemakin » Sun Apr 18, 2021 12:31 pm

Can anyone assist with the problems I am having with my Mother 32. Please see details below:

Unstable VCO frequently.
The frequency of the VCO is unstable. For example a C4 which should be approx 261Hz is constantly moving by approx +/- 10 to 15 cents. The frequency movement can sometimes be by more than this amount, almost by up to +/-a semitone and therefore be very noticeable. It is as if the VCO frequently is being modulated by a LFO at a varying random freqency and random amount. This frequency movement happens regards of which note is played.
It is not possible to calibrate the M32 with any accuracy as the with a constantly changing VCO frequency. Both VCO and VCF modulation are fully CCW / negative so not modulating the VCO. I am playing a sawtooth with the cutoff fully CW.

Keyboard tracking.
I should be able to play a chromatic scale using the M32 keyboard but cannot. With no patch cables connected - When a scale is played (from C to C) the range of notes played is acctually C to approx F#. Play a 2 octave change in note ie C4 to C6 then actual note played by the M32 is a 1 octave range - from Ç4 to C5.

It is only possible to get a correct 1octavce scale by connecting the M32's own KB out into the M32 1 volt / oct input. With this patch in place it is possible to play almost an octave up or down in tune. Play any further than this range the inaccurate pitch tracking mentioned above becomes very noticeable.

Glide. This is constantly on even when the glide control is fully turned CCW / negative. If I play notes 1 octave apart a short portamento glide can clearly be heard

Any suggestions would be appreciated.

lesliemakin
Posts: 3
Joined: Sun Apr 18, 2021 12:14 pm

Re: Moog Mother 32 VCO pitch, keyboard tracking and Glide problems

Post by lesliemakin » Mon Apr 19, 2021 8:47 am

Link to a YouTube video showing my M32 and the problems described above.
https://youtu.be/J-vMUiv0X3o

lesliemakin
Posts: 3
Joined: Sun Apr 18, 2021 12:14 pm

Re: Moog Mother 32 VCO pitch, keyboard tracking and Glide problems

Post by lesliemakin » Wed Apr 21, 2021 3:32 pm

I now have a borrowed digital multi meter and have measured the voltages and Hz at C3 to C7. As u can see 1volt per octave is not happening more like +/- 0.5V per octave. I also recorded the Hz (pitch) direct from the sawtooth wave patch out.

Power adapter +12.13V I think this is close enough to 12v. I also measured this in some different sockets in my home and always got close to 12.13V.

Taken from the KB out
Ç3: -1.020V / - 1.054V
134 / 136 Hz
C4: - 0.479V / - 0.506V
188 / 190 Hz
C5: +0.038V / +0.060V
258 / 262 Hz
C6: +0.492V / + 0.525V
385 / 362 Hz
C7: +1.055V / +1.071V
510 / 514 Hz

When I patch in the KB out into the 1v octave input I can achieve closer to the correct Hz.

C3: 65 / 69Hz
C4: 131 / 135 Hz
C5: 247 / 252 Hz
C6: 484 / 496 Hz
C7: 1015 / 1050 Hz
Note the C5 Hz has reduced from the measurement above but I have not moved the frequency pot this is an example of the M32 pitch instability changing over approx 10mins.

I have no ideas on the glide problem.

I got a response from Moog advising I return my M32 to UK service at Sonic Distribution. Moog's comment was they thought it could be a component failure. I wouldn't expect them to say much more than this.

So This is what I am going to do. I will respond and advise when my M32 is (hopefully) fixed. Looks like the Mimeophon purchase is delayed for a few months.

Thanks for your interest. Hopefully I can report back with positive news in a few weeks.

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dct
Posts: 18
Joined: Thu Feb 20, 2020 10:31 am

Re: Moog Mother 32 VCO pitch, keyboard tracking and Glide problems

Post by dct » Mon Apr 26, 2021 5:07 pm

(watching)

Good luck, curious if the replacement works well
keys: CX-3 II, GRANDMOTHER, streichfett

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