Expert Sleepers Silent Way v1.7.3 - Manual (Page 39)

The ‘ES-4 Mode’ button enables this
mode.
The three ‘Bipolar’ buttons should be
set to reflect the ES-4’s jumper settings.
‘Create ES-4 Calibration’ overwrites
the current calibration (if any) with a
perfect 1V/octave curve, assuming the
ES-4’s hardware factory calibration.
The 0V point is set to MIDI note 48 (C below middle C) - you may like to use the Voice
Controller’s Transpose setting if this is not suitable for your needs.