Acoustic suspension

The acoustic suspension woofer is a type of loudspeaker that reduces bass distortion caused by non-linear, stiff mechanical suspensions in conventional loudspeakers. It was invented in 1954 by Edgar Villchur and Henry Kloss with the founding of Acoustic Research in Cambridge Mass.

Description
The acoustic-suspension woofer (sometimes known as “air suspension”) uses the elastic cushion of air within a sealed enclosure to provide the restoring force for the woofer diaphragm.

Unlike the stiff suspension of conventional speakers, the trapped air inside the sealed-loudspeaker enclosure provides a more linear restoring force for the woofer's diaphragm, enabling it to oscillate a greater distance (excursion) in a linear fashion. This is a requirement for clean reproduction of deep-bass tones by drivers with relatively small cones (e.g. smaller than 12-16 inches in diameter) not mounted in a horn or other increased coupling at low frequencies enclosure.

Acoustic suspension woofers are very popular because of their low distortion, although they are less efficient speakers than systems with, say, vented enclosures.

*This article is licensed under the |GNU Free Documentation License. It uses material from the Wikipedia article http://en.wikipedia.org/wiki/Acoustic_suspension