The power density of a bass-reflex enclosure is improved by providing
transducers in pairs, with the members of each pair being oriented front
to back with respect to one another. The transducers are mounted on the
enclosure with at least one of the transducers being substantially
perpendicular to a front face of the enclosure and having its backside
partially rested in the second transducer of the pair. The gap between
the transducers is wider on the side open to the surrounding environment
through the front face. Directivity may be provided by incorporating a
second pair of transducers.