Speakers & Subwoofers

Subwoofer refers to either a woofer, or a complete loudspeaker dedicated to the reproduction of bass audio frequencies, typically from 150 Hz down to 20 Hz. In the case of a rotary woofer, it is possible to reproduce frequencies down to 1 Hz. more...

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Bass frequencies below about 80Hz become increasingly difficult for typical floorstanding or bookshelf loudspeakers to reproduce at high playback levels (100 dB or more) because they do not have large enough drivers to generate the required amount of air displacement. Therefore, subwoofers are useful for augmenting main loudspeakers by providing playback of low bass frequencies at high levels.

History

The first subwoofer was developed during the 1960s by Ken Kreisel, currently president of Miller & Kreisel Sound Corporation in Los Angeles. Kreisel's business partner, Jonas Miller, owned a high-end audio store in Los Angeles, and customers buying some of the high end electrostatic speakers complained about a lack of bass response in the electrostatics, compared to conventional loudspeakers; Kreisel's solution was to design a powered loudspeaker that would reproduce only those frequencies that were too low for the electrostatic speakers to convey and thereby fill in the missing sonic information.. Infinity's full range electrostatic speaker system of about the same time also used a subwoofer to cover the lower frequency range the electrostatic arrays did not handle adequately.

The first use of a subwoofer in a recording session was 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 continuing to the present day), and in the 1970s and 1980s by engineer John P. D'Arcy; record producer Daniel Levitin served as a consultant and "golden ear" 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 came into greater popular consciousness in 1974 with the movie Earthquake which was released in Sensurround. Sensurround was initially installed in 17 U.S. theaters. Six very large subwoofers were driven by a pair of 1600w amplifiers that 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. Energy in the range of 5 Hz to 40Hz was generated at the level of 110-120 dB. Much publicity was given to the new low frequency entertainment method and the film was a box office success. More Sensurround systems were assembled and installed. By 1976 there were almost 300 Sensurround systems leapfrogging through select theaters. Further films to use the effect include Midway in 1976 and Rollercoaster in 1977.

Read more at Wikipedia.org