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Stereo Quadraphonic
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Stereo Quadraphonic
SQ Quadraphonic ("Stereo Quadraphonic") is a matrix 4-channel quadraphonic sound system for vinyl LP records. It was introduced by CBS Records (known in the United States and Canada as Columbia Records) in 1971. Many recordings using this technology were released on LP during the 1970s.
Record companies who adopted this format include: Angel, CTI, Columbia (internationally called CBS Records), EMI, Epic, Eurodisc, Harvest, His Master's Voice, Seraphim, Supraphon and Vanguard.
With matrix formats, the four sound channels (forward left, forward right, back left, back right) are converted (encoded) down to two channels (left, right). These are then passed through a two-channel transmission medium (usually an LP record) before being decoded back to four channels and presented to four speakers.
The SQ encoding is based on the work by Peter Scheiber and further developed by Benjamin Bauer. His basic formula used 90 degree phase shift circuitry to enable enhanced 4-2-4 matrix systems to be developed. This 4-2-4 process could not be accomplished without some information loss. That is to say, the four channels produced at the final stage were not truly identical to those with which the process had begun.
In 4-2-4 matrix four channel stereo, the rear speakers should be of the same or almost same size quality and have the same or almost same frequency range as the front speakers.
The early SQ decoders could not produce more than 3 dB of separation from front to back. Early "Front-rear logic" circuits were introduced to enhance separation to 12 dB and later "Full logic" circuits 20 dB, but both provided poor performance, very noticeable gain-pumping and an unstable 'swaying' sound field.
The SQ system also faced resistance from broadcasters since, while essentially a two-channel system and stereo-compatible, it could have substantial mono compatibility problems, which posed serious problems with all televisions and monophonic radios of the era. By the time that the most advanced logic system was introduced for SQ, the Tate Directional Enhancement System, by Martin Willcocks and Peter Scheiber, realized into the superb Tate II 101A decoder by Jim Fosgate, "quad" was already considered a failure.
Of Pink Floyd's The Dark Side of the Moon, engineer Alan Parsons recalled: "It was certainly the band's intention, when we recorded the album, to mix in quad. All the effects on 'Money' and other tracks were recorded on four-track, so they could be heard in true quad on the final record… But by the time the mix stage was upon us, quad hadn't really taken off as a medium in the way it was expected to, so it was a little bit of an anticlimax. Then, as we know, the whole thing died a death".
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Stereo Quadraphonic AI simulator
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Stereo Quadraphonic
SQ Quadraphonic ("Stereo Quadraphonic") is a matrix 4-channel quadraphonic sound system for vinyl LP records. It was introduced by CBS Records (known in the United States and Canada as Columbia Records) in 1971. Many recordings using this technology were released on LP during the 1970s.
Record companies who adopted this format include: Angel, CTI, Columbia (internationally called CBS Records), EMI, Epic, Eurodisc, Harvest, His Master's Voice, Seraphim, Supraphon and Vanguard.
With matrix formats, the four sound channels (forward left, forward right, back left, back right) are converted (encoded) down to two channels (left, right). These are then passed through a two-channel transmission medium (usually an LP record) before being decoded back to four channels and presented to four speakers.
The SQ encoding is based on the work by Peter Scheiber and further developed by Benjamin Bauer. His basic formula used 90 degree phase shift circuitry to enable enhanced 4-2-4 matrix systems to be developed. This 4-2-4 process could not be accomplished without some information loss. That is to say, the four channels produced at the final stage were not truly identical to those with which the process had begun.
In 4-2-4 matrix four channel stereo, the rear speakers should be of the same or almost same size quality and have the same or almost same frequency range as the front speakers.
The early SQ decoders could not produce more than 3 dB of separation from front to back. Early "Front-rear logic" circuits were introduced to enhance separation to 12 dB and later "Full logic" circuits 20 dB, but both provided poor performance, very noticeable gain-pumping and an unstable 'swaying' sound field.
The SQ system also faced resistance from broadcasters since, while essentially a two-channel system and stereo-compatible, it could have substantial mono compatibility problems, which posed serious problems with all televisions and monophonic radios of the era. By the time that the most advanced logic system was introduced for SQ, the Tate Directional Enhancement System, by Martin Willcocks and Peter Scheiber, realized into the superb Tate II 101A decoder by Jim Fosgate, "quad" was already considered a failure.
Of Pink Floyd's The Dark Side of the Moon, engineer Alan Parsons recalled: "It was certainly the band's intention, when we recorded the album, to mix in quad. All the effects on 'Money' and other tracks were recorded on four-track, so they could be heard in true quad on the final record… But by the time the mix stage was upon us, quad hadn't really taken off as a medium in the way it was expected to, so it was a little bit of an anticlimax. Then, as we know, the whole thing died a death".