If you think that someone may have changed the setting inside your empress compressor, be it a weird friend or a previous owner, you can calibrate it yourself if you want!
No compressors leave our shop without being calibrated by Mike himself, so if your pedal is new you will not need to do this.
You will need :
2 multimeters measuring ACvoltage
1 function generator
1 open male patchchord jack
FET calibration
Set all settings on pedal to 12, power and turn pedal on
plug open male jack into sidechain
multimeter 1 connected to ground and 'in' test terminal on lower left
multimeter 2 connected to ground and 'out' test terminal on lower left
*you're looking to achieve a 30% ratio*
Typically, you will see something like 31mV so you'll want 950 to 1000mV showing on one end (does not have to be exact thanks to the tolerances)
you will adjust with trim pot U51
Metering calibration
Pull out sidechain jack
adjust input pot to roughly 60mV
set ratio to 10:1 and meter to gain reduction
adjust U2 so that all of the LEDs just begin show full red
You're done!