Subwoofer

[4] Subwoofers can be positioned more favorably than the main speakers' woofers in the typical listening room acoustic, as the very low frequencies they reproduce are nearly omnidirectional and their direction largely indiscernible.

However, much digitally recorded content contains lifelike binaural cues that human hearing may be able to detect in the VLF range, reproduced by a stereo crossover and two or more subwoofers.

As well, during the 1990s, DVDs were increasingly recorded with "surround sound" processes that included a low-frequency effects (LFE) channel, which could be heard using the subwoofer in home-cinema (also called home theater) systems.

This is largely due to the subwoofer driver's non-linearity producing harmonic and intermodulation distortion products well above the crossover frequency, and into the range where human hearing can "localize" them, wrecking the stereo "image".

[10] In the late 1930s, Lansing created a smaller two-way speaker with a 15-inch (38 cm) woofer in a vented enclosure, which he called the Iconic system; it was used as a studio monitor and in high-end home hi-fi set-ups.

[11] In the mid-1950s, the Academy of Motion Picture Arts and Sciences selected the "big, boxy" Altec A-7 as the industry standard for movie sound reproduction in theaters.

The Octavium speaker and Dones's subwoofer technology were also utilized, in a few select theaters, to reproduce low pitch frequencies for the 1974 blockbuster movie Earthquake.

Initially installed in 17 U.S. theaters, the Cerwin-Vega "Sensurround" system used large subwoofers that were driven by racks of 500 watt amplifiers, triggered by control tones printed on one of the audio tracks on the film.

[20] In the early 1970s, David Mancuso hired sound engineer Alex Rosner[21] to design additional subwoofers for his disco dance events, along with "tweeter arrays" to "boost the treble and bass at opportune moments" at his private, underground parties at The Loft.

[36] In 2015, John Hunter from REL Acoustics stated that audiophiles tend to "have a love/hate relationship with subwoofers" because most subs have "awful", "entry-level" sound quality and they are used in an "inappropriate way", without integrating the bass seamlessly.

Enclosure variations (e.g., bass reflex designs with a port in the cabinet) are often used for subwoofers to increase the efficiency of the driver/enclosure system, helping to reduce the amplifier power requirements.

[44] Subwoofers are typically constructed by mounting one or more woofers in a cabinet of medium-density fibreboard (MDF), oriented strand board (OSB), plywood, fiberglass, aluminum or other stiff materials.

[45] While not necessarily an enclosure type, isobaric (such as push-pull) coupled loading of two drivers has sometimes been used in subwoofer products of computer,[45] home cinema[46] and sound reinforcement[47] class, and also DIY versions in automotive applications, to provide relatively deep bass for their size.

Hofmann's Iron Law (the efficiency of a woofer system is directly proportional to its cabinet volume (as in size) and to the cube of its cutoff frequency, that is how low in pitch it will go) applies to subwoofers just as it does to all loudspeakers.

[3] Subwoofers vary in terms of the range of pitches that they can reproduce, depending on a number of factors such as the size of the cabinet and the construction and design of the enclosure and driver(s).

[58] Designers of active subwoofers sometimes include a degree of corrective equalization to compensate for known performance issues (e.g. a steeper than desired low end roll-off rate).

A subwoofer does not necessarily provide superior bass performance in comparison to large conventional loudspeakers on ordinary music recordings due to the typical lack of very low frequency content on such sources.

[80] Some users add a subwoofer because high levels of low-frequency bass are desired, even beyond what is in the original recording, as in the case of house music enthusiasts.

Other major car audio manufacturers like Rockford Fosgate did not follow suit since non-circular subwoofer shapes typically carry some sort of distortion penalties.

Specific cinema subwoofer models appeared from JBL, Electro-Voice, Eastern Acoustic Works, Kintek, Meyer Sound Laboratories and BGW Systems in the early 1990s.

[101] Not naturally weatherproof, Baltic birch is coated with carpet, thick paint or spray-on truck bedliner to give the subwoofer enclosures greater durability.

This method reduces forward output relative to a tight-packed, flat-fronted array of subwoofers, but can solve problems of unwanted low-frequency energy coming into microphones on stage.

Even though a bass reflex port or vent creates some additional phase delay, it adds SPL, which is often a key factor in PA and sound reinforcement system applications.

For most bands and most small- to mid-size venues (e.g. nightclubs and bars), standard bass guitar speaker enclosures or keyboard amplifiers will provide sufficient sound pressure levels for onstage monitoring.

[119] The advantage of tactile transducers used for low frequencies is that they allow a listening environment that is not filled with loud low-frequency sound waves in the air.

By not having a large, powerful subwoofer monitor, a bass shaker also enables a drummer to lower the sound pressure levels that they are exposed to during a performance, reducing the risk of hearing damage.

The Matterhorn is a subwoofer model completed in March 2007 by Danley Sound Labs in Gainesville, Georgia after a U.S. military request for a loudspeaker that could project infrasonic waves over a distance.

[123] The container doors swing open to reveal a tapped horn driven by 40 long-throw 15-inch (40 cm) MTX speaker drivers each powered by its own 1000-watt amplifier.

[121] Instead, using only a single 20 amp electrical circuit for safety, visitors were allowed to step inside the horn of the subwoofer for an "acoustic massage" as the fractionally powered Matterhorn reproduced low level 10–15 Hz waves.

A single 60-inch (1,500 mm) diameter subwoofer driver was designed by Richard Clark and David Navone with the help of Eugene Patronis of the Georgia Institute of Technology.