Abstract: A planar loudspeaker system having an elongated and substantially planar enclosure, configured to house tweeter, midrange, and a pair of upper and lower woofer diaphragms in its median, longitudinal section. A pair of woofer labyrinths, acting as quarter-wave transmission lines, extends throughout the remainder of the enclosure's volume. The labyrinths vent the substantially in-phase backwaves forwardly, toward the listener, through a pair of shared ports in the mid-frontal region of the enclosure. An electro-magnetic drive unit, employing bar magnets, pole pieces and thin encapsulated moving coils, all of elongated and symmetrical configuration, is also disclosed. Three versions of the drive unit are shown, each being adapted to provide a distributive driving force to the planar diaphragms of the loudspeaker.