Subwoofer

A subwoofer is a loudspeaker designed specifically to reproduce low-frequency audio, typically from about 20 Hz up to 200 Hz. It provides bass and sub-bass content that smaller speakers struggle to deliver, adding depth and impact to music and film soundtracks.

Most subwoofers are active (powered) units with a built-in amplifier; passive subwoofers require an external amplifier. They connect to a home stereo, AV receiver, or car audio system, often through line-level or speaker-level inputs. A crossover network directs low frequencies to the subwoofer while higher frequencies are handled by main speakers.

Enclosures influence performance. A sealed (acoustic suspension) enclosure yields tight, accurate bass with good transient response but typically less low-end extension. A ported (bass-reflex) enclosure uses a tuned vent to increase efficiency and extend low-frequency output, often at the expense of some transient precision. Other designs include horn-loaded and bandpass configurations, which aim for higher output in specific bands.

Driver size commonly ranges from 8 to 15 inches; larger drivers move more air to produce lower frequencies but require more space and power. Subwoofers may offer adjustable volume, low-pass filters, phase alignment, and room EQ to integrate with main speakers. Placement in a room affects perceived bass due to room modes; common strategies include near-wall positioning, corner loading, and calibration with a room correction system.

Applications span home theater, stereo systems, clubs, cinemas, and car audio. Performance is described by frequency response, maximum SPL, input impedance, power handling, and the interaction of the enclosure, driver, and room acoustics.