Moog Music Forum

I'm borrowing a Grandmother from my bandmate and we've been having some weird tuning issues with it.

1) The fine tune knob doesn't seem to do anything at all.
2) All oscillators (including the LFO when patched from the KB) are out of tune by 0.5-2.0 semitones.
3) doing a complete firmware flash, recalibrating the pots, and retuning will get it into tune, but the problem returns after a power cycle.

I don't know if it's still in warranty or not. He had contacted Moog about the problem, and they had him reset the firmware. He thought it was fixed, but he also barely uses it, and isn't the best at troubleshooting things.

Does anybody know what could cause these issues? The fine tune knob issue seems like a big red flag. I'm wondering if there's anything I can do to get it in order, or of the thing is just toast.

not sure if this is of any use, but my Grandmother was acting weird when I didn't use it's power button to turn it on/off

I had it hooked up to a power bar with some other gear, and was using that to power cycle everything

it has worked fine since I reverted to using the Grandmother's power switch for on/off.

( it is still plugged into the power bar with everything else )

I’ve always powered it on and off via the power switch, but thanks for the suggestion.

Did you ever find a resolution to this? I’m on my second GM and I am experiencing the same issue. Where the second oscillator will be stuck on a note about 5 semitones above the note being played. The fine tune knob doesn’t do anything to tune the oscillator.


The modulation module is also acting up by modulating the waveforms when the mod wheel is pulled all the way down.

Sometimes the envelope will start triggering when in KB RLS mode on the VCA and switching to other modes doesn’t fix it.

Power cycling using the switch on the GM doesn’t resolve any of the issues when they appear. The only thing that fixes it is calibrating the oscillators, calibrating the pots, invalidating, erasing, and then sending the firmware via 5 pin midi din cable (usb doesn’t seem to be as reliable at resolving the issues on my unit). Even then, I need to calibrate the oscillators a second time to get them fully in tune. Then the GM works fine for a bit, until the issue(s) appear again and then rinse and repeat.

Does this happen on anybody else’s GM? I returned the first one I bought because of this same issue. I’m starting to wonder if this behavior is normal? Or perhaps I just got unlucky.

Hello,
I have the same issue...
I have a modualire, and when i send a cv (1v/oct) to the pitch in the oscillator n1, the oscillator is detuned, i play in the keyboard C,B,A,G, and i heard C, Bb,F#,D, wtf???

Power cycling using the switch on the GM doesn’t resolve any of the issues when they appear
Do you have a solution?

Oliver

Has anyone tried the oscillator calibration? Here's a guide on how to do it: https://www.sweetwater.com/sweetcare/ar ... iasupdate/

I had this issue also. I calibrated all pods, but I did calibrate fine tune "wrong way". So try to put fine tune high in low, center in center and low in high. That worked for me so that I can tune Grandmother again.

bichuelo wrote: ↑Mon Oct 26, 2020 11:18 am Has anyone tried the oscillator calibration? Here's a guide on how to do it: https://www.sweetwater.com/sweetcare/ar ... iasupdate/

FYI - That link no longer works - says 'Page not found'.

GregAE wrote: ↑Tue Feb 09, 2021 7:50 am

bichuelo wrote: ↑Mon Oct 26, 2020 11:18 am Has anyone tried the oscillator calibration? Here's a guide on how to do it: https://www.sweetwater.com/sweetcare/ar ... iasupdate/

FYI - That link no longer works - says 'Page not found'.

Here's the correct link for the GM calibration:

https://www.sweetwater.com/sweetcare/ar ... vyQ0YPWw5U