A loudspeaker is disclosed having an enhanced response at bass frequencies. The loudspeaker includes a tubular enclosure having a pair of outwardly directed, opposing loudspeaker drivers mounted over each end. A port is provided through the enclosure midway between the drivers and is coupled to the exterior of the loudspeaker by a perpendicularly projecting duct. The length and cross-sectional area of the duct, as well as the enclosure, are selected to describe an acoustic cavity having a predetermined mechanical resonance. The opposing nature of the drivers, spaced apart by the continuous curved walls of the enclosure, reduces spurious resonances within the enclosure. In addition, the resultant T-shaped configuration of the loudspeaker maintains the loudspeaker substantially stationary in a moving vehicle without the need for auxiliary fastening devices. In other arrangements, a longitudinally extending duct having a crescent-shaped cross section is employed instead of the perpendicularly projecting duct and the cross section of the enclosure may, for example, be elliptic rather than circular.