All Empress pedals with the exception of the discontinued Superdelay use center negative power supplies.  The Superdelay uses a center positive power supply.  Please never attempt to power an Empress pedal with the reverse polarity as this could damage the pedal.  Most power supplies will have a graphic like the following picture indicating what polarity the power supply is.  You can find a list of compatible power supplies here.  If you have any questions about if your power supply will work please contact

If you are using any Empress pedal besides the Superdelay the power supply should be center negative.