Subwoofer

Subwoofer is a type of loudspeaker that is designed to produce low frequencies, example 20 - 200 Hz. Usually subwoofers are quite big and heavy. Frequencies below 20hz are typically not able to be heard. In some cases, with enough sound pressure, the listener will not hear the sound but will be able to feel it.

Subwoofer Media

12-inch (30 cm) subwoofer driver (loudspeaker). A driver is commonly installed in an enclosure (often a wooden cabinet) to prevent the sound waves coming off the back of the driver diaphragm from canceling out the sound waves being generated from the front of the subwoofer.
A typical Hi-Fi subwoofer (r.), with the subwoofer loudspeaker built into a cabinet. On the left, a version with transparent cabinet is shown where the large magnet (grayish color) of the speaker driver can be seen in the middle, close to the brown damper.
A display of Cerwin-Vega speaker enclosures at the 1975 Audio Engineering Society meeting
A crew sets up a sound system, including large bass bins, in Jamaica in 2009.
The 1987 Bose Acoustimass 5 stereo bass driver contained one six-inch (152 mm) driver per channel and provided crossover filtering for its two cube speaker arrays.
Cross-section of a subwoofer drive unit
Bass reflex enclosure schematic (cross-section)
Heavily braced and built subwoofer enclosure
The internal components of an active (powered) subwoofer, showing the circuitry for the power amplifier

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