There are two access holes located between the MUTE SWITCH jack and the PITCH CV OUT jack. These provide access to the two trimpots that control the Pitch to Control Voltage (CV) circuit. The one closest to the PITCH CV OUT jack controls the Scale parameter; the one closest to the MUTE SWITCH jack controls the Range parameter.
These are calibrated at the factory to deliver a 1V/OCT change in theremin frequency, with the C below Middle C generating zero volts. Access to adjustment is offered for those who may need to “fine-tune” their Pitch control setup. Scale adjusts for 1V/OCT, and Range adjusts for the C note one octave below Middle C to output zero volts.
UNDERSTANDING THE SCALE AND RANGE PARAMETERS
To increase the gain of the CV output to provide a value greater than 1V/OCT, gently adjust the Scale control trimpot in the clockwise direction. To decrease the gain of the CV output to provide a value of less than 1V/OCT, gently adjust the Scale control trimpot in the counterclockwise direction.
Adjusting the Range control should not ever be necessary; external devices controlled by the Etherwave Theremin PITCH CV OUT can be tuned to match the Etherwave Theremin frequency if desired.