TUNING THE OSCILLATORS

The new oscillator board (Serial Number 10175 and Above) uses temperature regulated circuits and because of the very precise tracking of the three oscillators on this board, it may seem at times that the instrument does not produce the “fat”, rich, multiple oscillator sound. This is NOT the result of a change in the sound of the oscillator but can be the result of setting the oscillators too precisely at the same pitch. To achieve the rich sound, it may be necessary for the customer to detune the oscillators slightly as desired for the rich, rolling sound.

Text taken from the service manual


Tuning the Oscillators

Only the SHIFT, OCTAVE, and SCALE trimpots are accessable through the access holes on the rear cover. So to get access to the HI END trimpots you have to take off the rear cover. Anyway, it’s better to take the rear cover off, because only the HI END trimpots need to be adjusted by a screwdriver, the other trimpots can be adjusted just by hand, which is easier and even more precisely than with a screwdriver. Last advice: An Auto Tuner can be very helpful to tune the oscillators without listening to it (it can really hurt your ears after a while).  Just be sure that the Auto Tuner is always showing an A tune at 0 cent, which is in the middle.

Set the front panel controls as follows:

TUNE=0
GLIDE=0
PITCH WHEEL=CENTER (detent)
MOD WHEEL=OFF
OSCILLATORS
OSCILLATOR MOD=OFF
OSC 3 CONTROL=ON
ALL OSC RANGE SWITCHES=16
ALL OSC WAVEFORMS=RAMP
OSC 2 RANGE=0
OSC 3 RANGE=0
MIXER
ALL OSC MIXER VOLUME=7
NOISE/EXT IN=OFF
FILTER
FILTER MODULATION=OFF
KEYBOARD CONTROL 1=OFF
KEYBOARD CONTROL 2=OFF
CUTOFF FREQUENCY=(+)5
EMPHASIS=0
AMOUNT OF CONTOUR=0
CONTOURS
ATTACK=1M
DECAY=1M
SUSTAIN=10
MAIN OUTPUT VOLUME=10
MAIN OUTPUT=ON

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 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 until no further adjustment is necessary.

Repeat for each oscillator.
Repeat SCALE and HI END sections 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 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.
Congratulations, your minimoog is tuned now!

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2 thoughts on “TUNING THE OSCILLATORS

  1. una volta fatta la prima taratura (osc scale) è meglio evitare di modificare shift trimpot nei passaggi sucessivi (Hi end octave e shift)
    Maurizio

  2. there are many differences between older and newer minimoogs which makeup for the sounddifferences.
    besides this, thank you very much for this beautiful dedicated minimoogcontribution. very interesting,
    fr.gr. sunny

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