A subwoofer (or simply "sub") is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies (the "bass"). The typical frequency range for a subwoofer is about 20–200 Hz for consumer products,[1] below 100 Hz for professional live sound,[2] and below 80 Hz in THX-approved systems.[3] Subwoofers are intended to augment the low frequency range of loudspeakers covering higher frequency bands.
Subwoofers are made up of one or more woofers in a loudspeaker enclosure capable of withstanding air pressure while resisting deformation. Subwoofer enclosures come in a variety of designs, including bass reflex (with a port or passive radiator in the enclosure), infinite baffle, horn-loaded, and bandpass designs, representing unique tradeoffs with respect to efficiency, bandwidth, size and cost. Passive subwoofers have a subwoofer driver and enclosure and they are powered by an external amplifier. Active subwoofers include a built-in amplifier.
