page_title: Subwoofer
section_title: Amplification
hierarchical_section_title: Subwoofer / Construction and features / Amplification
caption_attribution_description: Deutsch: Aktives Subwoofer Modul in Front- und Rückansicht.
context_page_description: A subwoofer is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be generated by a woofer. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-approved systems. Subwoofers are never used alone, as they are intended to augment the low frequency range of loudspeakers 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 enclosure, often with a built-in amplifier.
  Subwoofers are made up of one or more woofers mounted in a loudspeaker enclosure—often made of wood—capable of withstanding air pressure while resisting deformation.
context_section_description: 'Active subwoofers' include their own dedicated amplifiers within the cabinet. Some also include user-adjustable equalization that allows boosted or reduced output at particular frequencies; these vary from a simple "boost" switch, to fully parametric equalizers meant for detailed speaker and room correction. Some such systems are even supplied with a calibrated microphone to measure the subwoofer's in-room response, so the automatic equalizer can correct the combination of subwoofer, subwoofer location, and room response to minimize effects of room modes and improve low frequency performance.
  'Passive subwoofers' have a subwoofer driver and enclosure, but they do not include an amplifier. They sometimes incorporate internal passive crossovers, with the filter frequency determined at the factory. These are generally used with third-party power amplifiers, taking their inputs from active crossovers earlier in the signal chain. Inexpensive Home Theatre in a Box packages often come with a passive subwoofer cabinet that is amplified by the multi-channel amplifier. While few high-end home-theater systems use passive subwoofers, this format is still popular in the professional sound industry.
caption: This picture of the internal components of an active (powered) subwoofer shows the circuitry for the power amplifier.
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