I had always assumed these were just another RM/QS rebrand, so I was kind of intrigued by the recent string of posts started by @bigbillquad 's post in the What Is Your Latest Matrix LP? thread, so the did some digging through old trade magazine articles and came across a bunch of news items that I think shed a lot of light on the development and chronology of this series.
A couple of the articles reference an April 1971 AES presentation by D. H. Cooper that forms the theoretical basis for this matrix - according to @Mark Anderson 's list of quad publications, this was "T. Shiga. M. Okamoto, and D. H. Cooper, "Dual-Triphonic Matrix Stereo System," presented April 27, 1971 at the 40th Convention of the Audio Engineering Society, Los Angeles, preprint 783.". It would be nice to get a copy of this paper so one (or some) of the more technically-minded people here could go through it and confirm for sure what sort of matrix this is. Do we have any AES members here who could search through the AES e-library for it? @DuncanS maybe?
The reason I think it's worth finding is because while (as mentioned above) some of the text inside the album sleeves references EV-4, Sansui claimed these LPs were QS in their "The Complete Works of QS 4-Channel Stereo" advertisements (which purported to list every QS title ever released) in 1973 and 1974 issues of Billboard Magazine.
Billboard Magazine, August 7th, 1971 - I believe this is the first announcement of the release of any of these QX titles
Billboard Magazine, October 2nd, 1971 - information on new Japanese quad hardware, mentioning that the QX system features a "special placement" of speakers.
Radio Electronics Magazine, October 1971 - mentioning the five-speaker layout of QX
Billboard Magazine, August 12th, 1972 - information about the history of QX with what sounds like a suggestion that it's being sold as RM when it actually isn't (?)
Billboard Magazine, May 12th, 1973 - Interesting news item that suggests Decca's classical QS releases are actually QX.
Billboard Magazine, August 4th, 1973 - another mention of QX being based on D. H. Cooper's "dual triphonic" research.
Billboard Magazine, August 11th, 1973 - article announcing that both King and Columbia were ceasing RM (QS) LP production. King would switch to CD-4 for the remainder of their quad LP releases, while Columbia would switch to their newly unveiled UD-4 format, which I believe is a kind of discrete-matrix hybrid.
Billboard Magazine, March 30th, 1974 - excerpt from Sansui's 3-page "The Complete Works of QS 4-Channel Stereo" listing all the Columbia QX releases.
A couple of the articles reference an April 1971 AES presentation by D. H. Cooper that forms the theoretical basis for this matrix - according to @Mark Anderson 's list of quad publications, this was "T. Shiga. M. Okamoto, and D. H. Cooper, "Dual-Triphonic Matrix Stereo System," presented April 27, 1971 at the 40th Convention of the Audio Engineering Society, Los Angeles, preprint 783.". It would be nice to get a copy of this paper so one (or some) of the more technically-minded people here could go through it and confirm for sure what sort of matrix this is. Do we have any AES members here who could search through the AES e-library for it? @DuncanS maybe?
The reason I think it's worth finding is because while (as mentioned above) some of the text inside the album sleeves references EV-4, Sansui claimed these LPs were QS in their "The Complete Works of QS 4-Channel Stereo" advertisements (which purported to list every QS title ever released) in 1973 and 1974 issues of Billboard Magazine.
Billboard Magazine, August 7th, 1971 - I believe this is the first announcement of the release of any of these QX titles
Billboard Magazine, October 2nd, 1971 - information on new Japanese quad hardware, mentioning that the QX system features a "special placement" of speakers.
Radio Electronics Magazine, October 1971 - mentioning the five-speaker layout of QX
Billboard Magazine, August 12th, 1972 - information about the history of QX with what sounds like a suggestion that it's being sold as RM when it actually isn't (?)
Billboard Magazine, May 12th, 1973 - Interesting news item that suggests Decca's classical QS releases are actually QX.
Billboard Magazine, August 4th, 1973 - another mention of QX being based on D. H. Cooper's "dual triphonic" research.
Billboard Magazine, August 11th, 1973 - article announcing that both King and Columbia were ceasing RM (QS) LP production. King would switch to CD-4 for the remainder of their quad LP releases, while Columbia would switch to their newly unveiled UD-4 format, which I believe is a kind of discrete-matrix hybrid.
Billboard Magazine, March 30th, 1974 - excerpt from Sansui's 3-page "The Complete Works of QS 4-Channel Stereo" listing all the Columbia QX releases.