Quadraphonic sound
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Quadraphonic sound uses four audio channels in which speakers are positioned at the four corners of a listening space. The system allows for the reproduction of sound signals that are independent of o
Sansui QS sound decoder
An RCA Quadradisc record
A four-channel reel-to-reel tape unit from the 1970s, one of the few ways to achieve discrete four-channel sound at home
Azimuth Co-ordinator used by Pink Floyd, made by Bernard Speight, 1969 (Victoria & Albert Museum, London)
Electro-Voice
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Electro-Voice is an American manufacturer of audio equipment, including microphones, amplifiers, and loudspeakers, focused on pro audio applications such as sound reinforcement and commercial and resi
Electro-Voice "Century" crystal microphone, model 915
Electro-Voice received a 1963 Academy Award for their 642 Cardiline shotgun microphone.
Electro-Voice RE-27N/D microphone
1978 US patent sketch of Electro-Voice constant-directivity horn