Abstract: A loudspeaker enclosure is disclosed herein having a hollow box provided with a pair of air chambers separated by a partition or baffle. Coaxial openings are incorporated into the two outer walls of the box and the inner partition. An inner and an outer passive speaker cone is disposed in each opening associated with the inner partition and one of the box walls respectively in a back-to-back relationship. A rigid coupling connects the passive cones together so as to operate as a single unit. A woofer speaker cone is mounted in the other box wall which is operated by a suitable amplifier network. The mounting of the speakers creates sealed, air tight chambers and the outer passive cone is larger in diameter than the inner passive cone so that at very low frequencies the outer passive cone displaces more air than the woofer speaker cone.