The B4-SUB is a compact high performance cardioid subwoofer for use with d&b E-Series and T-Series loudspeakers. The B4-SUB houses two long excursion neodymium drivers in an integrated cardioid setup: a 15“ driver in a bass-reflex design facing to the front and a 12” driver in a 2-chamber bandpass design radiating to the rear. The arrangement and tuning provide a cardioid dispersion pattern using a single amplifier channel. Its frequency response extends from 40 Hz to 150/100 Hz. The B4-SUB cabinet is constructed from marine plywood and has an impact and weather resistant black paint finish. The front of the cabinet is protected by a rigid metal grill in front of an acoustically transparent foam. At the top and bottom the cabinet front is fitted with catches for securing an optional transport lid E7922. The cabinet incorporates a pair of handles, and mounted on the rear panel are two EP5 or NL4 connectors and four heavy duty wheels. An M20 threaded flange in the top panel accepts the d&b Z5013 Loudspeaker stand for the deployment of d&b E-Series or T-Series cabinets. Two plastics runners prevent cabinet movement and protect the bottom panel against scratching. Correspondingly shaped recesses in the top panel of each cabinet prevent cabinet movement when stacking B4- SUBs.