page_title: Loudspeaker enclosure
section_title: Sealed (or closed) enclosures
hierarchical_section_title: Loudspeaker enclosure / Types / Sealed (or closed) enclosures
context_page_description: A loudspeaker enclosure or loudspeaker cabinet is an enclosure in which speaker drivers and associated electronic hardware, such as crossover circuits and, in some cases, power amplifiers, are mounted. Enclosures may range in design from simple, homemade DIY rectangular particleboard boxes to very complex, expensive computer-designed hi-fi cabinets that incorporate composite materials, internal baffles, horns, bass reflex ports and acoustic insulation. Loudspeaker enclosures range in size from small "bookshelf" speaker cabinets with 4" woofers and small tweeters designed for listening to music with a hi-fi system in a private home to huge, heavy subwoofer enclosures with multiple 18" or even 21" speakers in huge enclosures which are designed for use in stadium concert sound reinforcement systems for rock music concerts.
  The primary role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open speaker driver interacting with sound waves generated at the front of the speaker driver.
context_section_description: The loudspeaker driver's moving mass and compliance (slackness or reciprocal stiffness of the suspension) determines the driver's resonant frequency (Fₛ). In combination with the damping properties of the system (both mechanical and electrical) all these factors affect the low-frequency response of sealed-box systems. Output falls below the system's resonant frequency (Fc), defined as the frequency of peak impedance. In a closed-box, the air inside the box acts as a spring, returning the cone to the 'zero' position in the absence of a signal. A significant increase in the effective volume of a sealed-box loudspeaker can be achieved by a filling of fibrous material, typically fiberglass, bonded acetate fiber (BAF) or long-fiber wool. The effective volume increase can be as much as 40% and is due primarily to a reduction in the speed of sound propagation through the filler material as compared to air. The enclosure or driver must have a small leak so internal and external pressures can equalise over time, to compensate for barometric pressure or altitude; the porous nature of paper cones, or an imperfectly sealed enclosure, is normally sufficient to provide this slow pressure equalisation.
caption: Sealed enclosure
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