Hi Guys
I have just been given a boxed set of Tchaikovskys 6 symphonies, recorded by EMI and I don't think the box was ever opened the condition is as new. However when I read the notes that came with it I found this note. Quote "These records are engineered to reproduce stereophonically , or when played on SQ equipment will reproduce quadraphonically". I may be displaying my ignorance but how is this achieved and does it reduce sound quality? The recordings have an indicated date of 1977. Light in my darkness guys.
Bandbox.
I have just been given a boxed set of Tchaikovskys 6 symphonies, recorded by EMI and I don't think the box was ever opened the condition is as new. However when I read the notes that came with it I found this note. Quote "These records are engineered to reproduce stereophonically , or when played on SQ equipment will reproduce quadraphonically". I may be displaying my ignorance but how is this achieved and does it reduce sound quality? The recordings have an indicated date of 1977. Light in my darkness guys.
Bandbox.
Quadraphonic was the latest gimmick back then and it never caught on. You needed a separate decoder to extract the encoded audio info. Surface noise was a huge issue with the 4 channel system.
CD4, QS,SQ and UD4 were I think all variations on the theme. Records had a "4" symbol indicating quadraphonic.
Here's a typical cartridge,
JVC X1 Owners Manual, Service Manual, Schematics, Free Download | Vinyl Engine
CD4, QS,SQ and UD4 were I think all variations on the theme. Records had a "4" symbol indicating quadraphonic.
Here's a typical cartridge,
JVC X1 Owners Manual, Service Manual, Schematics, Free Download | Vinyl Engine
I worked in a stereo store when Quadraphonic systems appeared, lived shortly, then died, 1971 to 1973.
There were a few discrete systems that used 4 seperate audio channels.All involved tape. I had a Quad 8 Track deck in my car, which could deliver 4 discrete channels, but there was not much music available that was properly remastered for the format. One Guess Who tape in particular was rather spooky though.
There were at least 4 competing non compatible "matrixed" formats that used phasing, filtering, addition, and subtraction to create the illusion of quad sound. If the material was encoded with the right encoder before mastering a perfect system could demonstrate 6db of front to back seperation over a small frequency range. If you played a QS recording on an SQ playback system the result could be 3db or worse. There seemed to be no degradation while playing these records on a conventional 2 channel system, and no special hardware was required for playback.
There were two systems developed for delivering 4 discrete channels of audio via a vinyl record. CD-4 and UD-4.
The CD-4 system delivered the two front channels via amplitude groove modulations in the record thus could be played on a conventional record player. Two additional channels of rear channel sound were encoded on a subcarrier at 30 KHz. A special cartridge with a "Shibata" eliptical stylus was required to accurately track the 30 KHz subcarrier. A CD-4 demodulator was required to be directly connected to the turntable. It was stated that repeated playing with a conventional conical stylus at high tracking force could damage the subcarrier information. I still have a Doobie Brothers CD-4 record from about 1973. Connecting a scope directly across the output of the turntable still reveals a faint 30 KHz sine wave between tracks.
I set up a few quad systems for customers back then and the effect was less than expected for most users. CD-4 was particularly hard to get working, interconnects from the TT to the decoder were critical as was TT setup.
The UD-4 system came out after I left the stereo store. It was said to be a major breakthrough, but it was never marketed in the US.
I got a job at Motorola in 1973 where I still work. We made a universal quad decoder chip, so I built a universal quad decoder box and a 4 channel amp. I also had a Teac 3440 4 channel real to real deck. The decoder box could switch from SQ to QS to vario-matrix, and a few others that I don't remember. It did not do CD-4. We discovered that some records encoded in one format sounded better when played back in another, and some unencoded records had better effects that real quad records. With any of the matrix systems, the listener position was the biggest variable. Best results were obtained with the listener in the center of 4 speakers.
By 1977 there was very little quad format media being released in any format.
There were a few discrete systems that used 4 seperate audio channels.All involved tape. I had a Quad 8 Track deck in my car, which could deliver 4 discrete channels, but there was not much music available that was properly remastered for the format. One Guess Who tape in particular was rather spooky though.
There were at least 4 competing non compatible "matrixed" formats that used phasing, filtering, addition, and subtraction to create the illusion of quad sound. If the material was encoded with the right encoder before mastering a perfect system could demonstrate 6db of front to back seperation over a small frequency range. If you played a QS recording on an SQ playback system the result could be 3db or worse. There seemed to be no degradation while playing these records on a conventional 2 channel system, and no special hardware was required for playback.
There were two systems developed for delivering 4 discrete channels of audio via a vinyl record. CD-4 and UD-4.
The CD-4 system delivered the two front channels via amplitude groove modulations in the record thus could be played on a conventional record player. Two additional channels of rear channel sound were encoded on a subcarrier at 30 KHz. A special cartridge with a "Shibata" eliptical stylus was required to accurately track the 30 KHz subcarrier. A CD-4 demodulator was required to be directly connected to the turntable. It was stated that repeated playing with a conventional conical stylus at high tracking force could damage the subcarrier information. I still have a Doobie Brothers CD-4 record from about 1973. Connecting a scope directly across the output of the turntable still reveals a faint 30 KHz sine wave between tracks.
I set up a few quad systems for customers back then and the effect was less than expected for most users. CD-4 was particularly hard to get working, interconnects from the TT to the decoder were critical as was TT setup.
The UD-4 system came out after I left the stereo store. It was said to be a major breakthrough, but it was never marketed in the US.
I got a job at Motorola in 1973 where I still work. We made a universal quad decoder chip, so I built a universal quad decoder box and a 4 channel amp. I also had a Teac 3440 4 channel real to real deck. The decoder box could switch from SQ to QS to vario-matrix, and a few others that I don't remember. It did not do CD-4. We discovered that some records encoded in one format sounded better when played back in another, and some unencoded records had better effects that real quad records. With any of the matrix systems, the listener position was the biggest variable. Best results were obtained with the listener in the center of 4 speakers.
By 1977 there was very little quad format media being released in any format.
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