Moog Slim Phatty | My Slim Phatty is out of Tune

The Slim Phatty features an automatic note calibration accessible from the menu. Allow the Slim Phatty to warm up for approximately 45 minutes, then perform a Note Calibration from the System Utilities submenu within the Master menu. Refer to the menu tree here; this information is located on p.45 of the manual.

Note Calibration

This calibration option enables you to choose Note calibration, adjusting each note precisely for every oscillator and octave setting. Press ENTER  to access the Note calibration menu.

The Note calibration menu will be displayed, permitting you to set the calibration range. The default note range spans MIDI notes 12 - 116. Each of these notes is calibrated at all octave settings, from 16’ to 2’. To adjust the range, utilize the CURSOR  button to navigate to either the starting or ending field, and use the VALUE knob to select the MIDI note value. After that, press ENTER. 

A comprehensive Note calibration using the default range (12 - 116) may take around two hours to finish. However, by defining a narrower note range, you can reduce the calibration time.

You will be prompted to confirm whether you wish to continue. Use the VALUE  knob to select YES  or NO. If you're unsure or reconsider performing this calibration, select NO  and press ENTER. You will be redirected to the System Utilities Calibration menu. Otherwise, select YES  and press ENTER.

The calibration will commence, and the display will indicate as shown. The values shown represent the MIDI note number being calibrated, the calibration value (stored in the SP’s EEPROM), and the actual measured note in MIDI Note Number Cents (the displayed value of ‘32.01’ signifies MIDI note 32, with the actual measured note being 01 cents sharp). 

Note calibration will proceed through the range, tuning each note individually, starting with oscillator 1 followed by oscillator 2.

You may exit the Note calibration at any moment by pressing the MASTER  button. Only those notes calibrated up until then will be retained. The remaining notes will revert to their previous calibration values. Interrupting the Note Calibration process in this way may lead to incorrect tuning.

Upon completion of the Note calibration, a ‘SUCCESSFUL’ message will be displayed, and the new calibration values will be stored in the SP’s EEPROM. To exit the calibration, press ENTER  to go back to the System Utilities Calibration menu or press MASTER  to exit the calibration and return to the top level of the System Utilities menu. 

It is advisable to conduct the OSC 2 FREQ calibration immediately following the conclusion of the Note Calibration (refer to p.47 of the manual)

Oscillator 2 Frequency (OSC2 FREQ)

This option permits the selection of OSC2 Frequency Calibration. It calibrates the OSC2 FREQ control so that turning the editing dial fully CCW lowers OSC2  by exactly a fifth (-7 semitones), while turning it fully CW  raises OSC2  by exactly a fifth (+7 semitones). Press ENTER  to access the OSC2 Frequency Calibration menu.

You will be prompted to confirm whether you wish to continue. Utilize the VALUE  knob to select YES or NO. If you are uncertain or change your mind about performing this calibration, select NO  and press ENTER. You will be returned to the System Utilities Calibration menu. Otherwise, select YES  and press ENTER.

Calibration will commence, with the display showing the initial number as the base note for calibration (MIDI note 60). The second number represents the calibration value (this is the stored value in the SP’s EEPROM), while the third number indicates the actual measured note, displayed in MIDI Note Number Cents (for instance, ‘64.37’ signifies MIDI note 64, with the actual measured value being 37 cents sharp).

As calibration begins, the SP first tunes itself to the base note, and you will notice the measured note value approaching 60.00. The calibration value will subsequently adjust, reaching 67.00, at which point it has calibrated the maximum value (+7 semitones), followed by a descent to 53.00, corresponding to the minimum value (-7 semitones).

Upon completion of the calibration, the display will show the message ‘SUCCESSFUL’, and the new calibration values will be stored in the SP’s EEPROM. To exit the calibration, press ENTER  to return to the System Utilities Calibration menu or press MASTER  to exit and return to the highest level of the System Utilities menu.