Subwoofer

A subwoofer (or sub) is a subwoofer, or loudspeaker, that is dedicated to the reproduction of low-pitched audio frequencies known as bass and sub-bass. The typical frequency range for a subwoofer is approximately 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-approved systems. Subwoofers are designed to boost the low frequency range of speakers that cover the higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker box (cabinet), often with a built-in amplifier.

Subwoofers consist of one or more woofers mounted in a speaker box, often made of wood, capable of withstanding air pressure while resisting deformation. Subwoofer enclosures come in a variety of designs, including bass reflex (with a port or vent), using a subwoofer and one or more passive radiating speakers in the enclosure, acoustic suspension (sealed enclosure), infinity baffle, horn and bandpass designs, which represent unique trade-offs with respect to efficiency, low frequency range, cabinet size and cost. Passive subwoofers have a driver and a subwoofer box and are powered by an external amplifier. Active subwoofers include a built-in amplifier.