MXR® DYNA COMP® MINI COMPRESSOR M291 The Dyna Comp Mini Compressor combines classic tone and modern convenience in a housing that's nearly half the size of the original, featuring an all-new Attack switch to toggle between slow and fast attack times. This pedal can be powered by a Dunlop ECB003 9-volt adapter, or the DC Brick™, Iso-Brick™, and Mini Iso-Brick™ power supplies (not included).