The E15X-SUB is a compact, lightweight, high performance subwoofer for use with d&b E-Series loudspeakers. The built in passive crossover network allows the E15X-SUB to be operated in parallel to E12 or E12-D loudspeakers on the same amplifier channel, greatly extending the low frequency headroom and bandwidth of the systems. Alternatively it can be operated actively driven by its own amplifier channel without the need for any changes to the subwoofer. In Active mode the E15X-SUB can be used to supplement any of the E-Series cabinets. The E15X-SUB cabinet is constructed from marine plywood and has an impact resistant finish, a pair of handles and an M20 threaded flange on the top to accept the d&b loudspeaker stand winder.