This is common to units that use an external power supply such as the ECC or BCC, FXR series and personal processors like the Tube MP series, Levelar, and FX-1.

All ART products (excluding ARTcessories) use a 9 volt AC supply. The key word is AC. DC will not work. If you use DC, no harm will come to your ART gear, but then again, no sound will come out either! Polarity? With AC, there are no polarity issues.