|
A subwoofer (or sub) is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies known as bass. 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 intended to augment the low frequency range of loudspeakers covering higher frequency bands. 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. 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. The first subwoofers were developed in the 1960s to add bass response to home stereo systems. Subwoofers came into greater popular consciousness in the 1970s with the introduction of Sensurround in movies such as ''Earthquake'', which produced loud low-frequency sounds through large subwoofers. With the advent of the compact cassette and the compact disc in the 1980s, the easy reproduction of deep ''and'' loud bass was no longer limited by the ability of a phonograph record stylus to track a groove, and producers could add more low frequency content to recordings. 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 theater systems. During the 1990s, subwoofers also became increasingly popular in home stereo systems, custom car audio installations, and in PA systems. By the 2000s, subwoofers became almost universal in sound reinforcement systems in nightclubs and concert venues. ==History== In September 1964 Raymon Dones, of El Cerrito, CA, received a US Patent (numbered US3150739) which was the first for a subwoofer specifically designed to omni-directionally augment the low frequency range of modern stereo systems. Able to reproduce distortion-free low frequencies down to 15 cycles per second, a specific objective of Dones’ invention was to provide portable sound enclosures which provide for high fidelity reproduction of-low frequency sound waves without giving an audible indication of the portion of the room from which they emanate. Dones' loudspeaker was marketed in the US under the trade name "The Octavium"〔Octavium Product brochure Aladdin Electronics, Inc. Copyright 1965〕 from the early 60s to the mid-1970s. The Octavium was utilized by several recording artists of that era, most notably the Grateful Dead, bassist Monk Montgomery, bassist Nathan East, and the Pointer Sisters. The Octavium speaker and Dones' subwoofer technology was also utilized, in a few select theaters, to reproduce low pitch frequencies for the 1974 blockbuster movie "Earthquake". During the late 1960s Dones’ Octavium was favorably reviewed by audiophile publications including Hi-Fi News and Audio Magazine. Another early subwoofer enclosure made for home and studio use was the separate bass speaker for the Servo Statik 1, by New Technology Enterprises. Designed as a prototype in 1966 by physicist Arnold Nudell and airline pilot Cary Christie in Nudell's garage, the design used a second winding around a custom Cerwin Vega 18-inch (45 cm) driver to provide servo control information to the amplifier, and it was offered for sale at $1795, some 40% more expensive than any other complete loudspeaker listed at ''Stereo Review''.〔 In 1968, the two found outside investment and reorganized as Infinity.〔 The subwoofer was reviewed positively in ''Stereophile'' magazine's Winter 1968 issue as the SS-1 by Infinity. The SS-1 was reviewed very highly in 1970 by ''High Fidelity'' magazine.〔 One of the first subwoofers was developed during the late 1960s by Ken Kreisel, the former president of the Miller & Kreisel Sound Corporation in Los Angeles. When Kreisel's business partner, Jonas Miller, who owned a high-end audio store in Los Angeles, told Kreisel that some purchasers of the store's high-end electrostatic speakers had complained about a lack of bass response in the electrostatics, Kreisel designed a powered woofer that would reproduce only those frequencies that were too low for the electrostatic speakers to convey. Infinity's full range electrostatic speaker system that was developed during the 1960s also used a woofer to cover the lower frequency range that its electrostatic arrays did not handle adequately. The first use of a subwoofer in a recording session was in 1973 for mixing the Steely Dan album ''Pretzel Logic'' when recording engineer Roger Nichols arranged for Kreisel to bring a prototype of his subwoofer to Village Recorders. Further design modifications were made by Kreisel over the next ten years, and in the 1970s and 1980s by engineer John P. D'Arcy; record producer Daniel Levitin served as a consultant and "golden ears" for the design of the crossover network (used to partition the frequency spectrum so that the subwoofer would not attempt to reproduce frequencies too high for its effective range, and so that the main speakers would not need to handle frequencies too low for their effective range). Subwoofers received a great deal of publicity in 1974 with the movie ''Earthquake'' which was released in Sensurround. Initially installed in 17 U.S. theaters, the Sensurround system used large subwoofers which were driven by racks of 500 watt amplifiers which were triggered by control tones printed on one of the audio tracks on the film. Four of the subwoofers were positioned in front of the audience under (or behind) the film screen and two more were placed together at the rear of the audience on a platform. Powerful noise energy in the range of 17 Hz to 120 Hz was generated at the level of 110–120 decibels of sound pressure level, abbreviated dB(SPL). The new low frequency entertainment method helped the film become a box office success. More Sensurround systems were assembled and installed. By 1976 there were almost 300 Sensurround systems leapfrogging through select theaters. Other films to use the effect include the WW II naval battle epic ''Midway'' in 1976 and ''Rollercoaster'' in 1977. Deep-Bass speakers were once an exotic commodity and are now much more popular with different sizes and capabilities of sound output.〔L. B. (1995, Oct 01). How low can a speaker go? listen up. New York Times (1923-Current File) Retrieved from http://ezproxy.library.arizona.edu/login?url=http://search.proquest.com/docview/109399149?accountid=8360〕 For owners of 33 rpm LPs and 45 singles, loud ''and'' deep bass was limited by the ability of the phonograph record stylus to track the groove.〔 Some hi-fi aficionados solved the problem by using reel-to-reel tape players which were capable of delivering accurate, naturally deep bass from acoustic sources, or synthetic bass not found in nature. With the popular introduction of the compact cassette and the CD, it became possible to add more low frequency content to recordings, and satisfy a larger number of consumers. Home subwoofers grew in popularity, as they were easy to add to existing multimedia speaker setups and they were easy to position or hide. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「subwoofer」の詳細全文を読む スポンサード リンク
|