Empress Effects Tremolo2 - Manual (Page 7)

Expression Pedal
Each parameter, with the exception of the mode switch, can be
controlled simultaneously via the expression pedal.
To control a parameter with the expression pedal, move the
parameter's knob to the desired heel setting, then hold down the
save button and move the knob to the desired toe setting, then
release the save button. Multiple parameters can assigned for
expression pedal control simultaneously by repeating this process
for each parameter to be assigned. Each parameter can be set with
independent heel and toe settings.
To release a parameter from the expression pedal's control, simply
move the knob or switch that controls that parameter. To clear all
of the parameters from expression pedal control, press the save
switch 3 times.
Any expression pedal used with the Empress Tremolo
2
should have
the following connections: tip to signal, ring to power, and sleeve to
ground.