This completely self-contained amplifier module simply fits into the back of a sub-woofer cabinet. The unit will automatically spring into life from it's Standby mode once a signal is received. The Volume and Crossover Frequency Controls together with the Phase Correction Switch allows the sub-woofer to be set for a desired sound. Installation can be completed in just minutes, simply make a 235mmH x 175mmW cutout into the back of the enclosure and slip in the module. Overall depth is 100mm.