A loudspeaker system comprises a housing consisting of three interconnected sealed enclosures. The primary sealed enclosure has an aperture in it in which a loudspeaker is mounted in a sealed relationship. This enclosure is interconnected with an intermediate sealed enclosure located between it and a third or output enclosure. The intermediate sealed enclosure has an aperture communicating between it and the interior of the primary sealed enclosure. A first passive plate is movably mounted in this aperture in sealed relationship. A second passive plate is movably mounted in an aperture between the second enclosure and the output enclosure in sealed relationship to form a sealed airspace between the first and second passive plates. The output enclosure has a port in it for communication with the air surrounding the enclosures. The system provides low frequency bandwidth and reduced distortion in a composite system, which has a significantly reduced volume compared with conventional speaker enclosures providing comparable low frequency response.