ABSTRACT
A subwoofer loudspeaker is a separate enclosure from the main loudspeakers that is specifically designed to reproduce low bass. The filtering in a subwoofer is not strictly speaking a crossover, because instead of splitting the input between two or more outputs, it simply rejects all high frequencies; it is more accurate to simply call it a lowpass filter. In home entertainment the subwoofer is normally of modest size and is often installed under the television screen, in front of the listeners, though other placements are possible, exploiting the non-directional characteristics of its output. A classic application of stereo subwoofers is the extension of the bass response of electrostatic loudspeakers, notably those by Quad, such as the ESL-57, introduced in 1955, and the later ESL-63. The transient response of a ported subwoofer is usually worse than that of a sealed-box system using the same driver.
