Hey, I am just wondering if its normal for the oscillator to go out of tune when I change the octave? For instance Ill tune the octave 32 and then go to 16 and it will be out of tune. Thanks!!
It’s not normal.
On earlier boards, they had one trim pot (the lowest on the board) that adjusts all 3 OSCs to perfect octaves.
On later boards, they had a separate trim pot for each OSC. Refer to the service manual for their locations and how to adjust them.
A Minimoog should also have a small added board inside called a buffer board.
If you see two small black philips-head screws on the top panel (where the jacks are) and they’re located directly in back of the oscillator section, you probably have one already installed. (good)
If these screws aren’t present, you probably don’t have one installed and tuning can vary greatly as the octave switches are changed. (bad)
Most Minis nowadays have buffer boards installed.
I have many originals and copies, but don’t sell very many nowadays due to such low demand.
Moog first offered them as an improvement mod, but later included them on all production models.
hi,
I have the same problem, the scale trimpot for each oscillator enables me to set the correct scaling between low and hi notes, but not betwwen 32’ 16’ 8’ 4’ 2’ which goes completely out of tune.
there’s a hole below the 3 “scale” holes but no trim pot inside.
This short thread should help tuning with new osc board.
http://forum.moogmusic.com/viewtopic.php?f=1&t=14464&p=104282&hilit=new+vco+board+tuning#p104282
Thanks yes Alien666!
I have the plastic sheet with the label so that’s OK, but I couldn’t find a good guide for tuning it, between the different manuals found in links in this forum , and people saying there are mistakes in the manuals, I found this guide on GearSlutz (by RealMC) to be the most helpful.
I used a couple of free VST tuner plugins to get the frequency figures right (GTune and tuneit)
To get the high frequency 3520Hz (Hi A in 2") which was not detected properly by the tuners I had to have them show 880Hz, a multiple of 3520Hz.
here’s the guide , (starting at 27, as it’s the follow up to the old board)
SCALE
OSCx=OSC1, OSC2, or OSC3
-
Turn on OSCx in the mixer on the front panel. All other switches in the
mixer should be OFF. -
Change OSCx RANGE switch on the front panel to 16.
-
Hold down the LOW A key and adjust OSCx SHIFT trimpot for 55hz.
-
Hold down the HIGH A key and adjust OSCx SCALE trimpot for 440hz.
-
Repeat steps 29 and 30 until no further adjustment is necessary.
repeat for each oscillator
HI END
OSCx=OSC1, OSC2, or OSC3
-
Turn on OSCx in the mixer on the front panel. All other switches in the
mixer should be OFF. -
Change OSCx RANGE switch on the front panel to 2.
-
Hold down the LOW A key and adjust OSCx SHIFT trimpot for 440hz.
-
Hold down the HIGH A key and adjust OSCx HI END trimpot for 3520hz.
-
Repeat steps 34 and 35 until no further adjustment is necessary.
repeat for each oscillator
37) Repeat SCALE (steps 27-31) and HI END sections (steps 32-36) until no
further adjustment is necessary.
OCTAVE
OSCx=OSC1, OSC2, or OSC3
-
Turn on OSCx in the mixer on the front panel. All other switches in the
mixer should be OFF. -
Change OSCx RANGE switch on the front panel to 32.
-
Hold down the HIGH A key and adjust OSCx SHIFT trimpot for 220hz.
-
Change OSCx RANGE switch on the front panel to 2.
-
Hold down the HIGH A key and adjust OSCx OCTAVE trimpot for 3520hz.
-
Repeat steps 39 through 42 until no further adjustment is necessary.
repeat for each oscillator
SHIFT
OSCx=OSC1, OSC2, or OSC3
-
Turn on OSCx in the mixer on the front panel. All other switches in the
mixer should be OFF. -
Change OSCx RANGE switch on the front panel to 16.
-
Hold down the HIGH A key and adjust OSCx SHIFT trimpot for 440hz.
repeat for each oscillator
That appears to be the calibration procedure for the later VCO boards. Earlier boards do not have a SHIFT trimpot.
yes indeed MC, I thought I’d mentionned it but it wasn’t clear at all. So yes that’s for newer boards.