I don't recall if the Sansui chip was used or not. EPRAD did use a Sansui chip on their STARSCOPE unit. I look into the Cat. 116 and get back to you.

Steve

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Of course this doesn't change the fact that matrixing was indeed invented by Scheiber, if fact those patents of Sansui's that were filed in the USA (most were only filed in Japan) reference Schneider's original patent. Sansui simply added the phase shift as a different means of providing two rear channels. If you go back before Scheiber there was a guy called Rogers who filed a patent for a derived centre channel in 1961, but this was a playback only arrangement and quite different from the encode/decode matrix systems that Scheiber invented.

Dolby's own encoder (used in the DS4 etc) works very differently from the QS encoding scheme, in that it uses a single 90 degree phase shifter in the surround channel and then applies this signal in phase to Lt and in antiphase to Rt.

One other tid-bit of useless information - QS was also known as RM and was very similar to Sony's SQ system. Anyone interested in the details of these two sytems can refer to a US patent 4,021,612 which descibes a decoder suitable for both systems. You can view this patent by going to here and typing the patent number into the search engine.

BTW I mentioned above "Sony's SQ" system. In actual fact the SQ system was developed by CBS, however Sony was probably it's biggest promoter so SQ came to be closely associated with Sony.

Michael Schaffer mentioned he heard there were three competing quad systems. In fact there were at least four commercial matrix arrangements - SQ, QS, EV Stereo-4 and Dynaco. There was also a four channel discete disc format called CD-4 developed by Matsushita.

I must apologise to Frank for my correction regarding Dolby's use of the Sansui matrix (in the early days at least). None of us has all the answers and one of the great things about this forum with it's many knowlegable contributors is that between us we can usually uncover the whole story.

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Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Just as a footnote to all of this, Steve Guttag kindly sent me a copy of the schematic for the Cat116 card. As predicted earlier, the left back and right back outputs of the QS matrix are indeed summed for the single channel required for the cinema matrix. In fact the QS system (as one would expect) is significantly modified by Dolby to achieve the required characteristics for a cinema adaptation. Looking at the schematic one can see how the Cat150 evolved from those early beginnings. Interesting little segment of history.

In retrospect I should not have mentioned the Cat116 schematic as I did not want to give the impression that Steve (or anyone else on this forum) hands out the schematics of other companies willy nilly. All companies, inclduding my own, are very protective of their intellectual property and normally only supply schematics to those that have a legitimate need and are known and trusted. In this case the document could be considered historical in nature, and knowing that I would not use it for any purpose other than historical interest is why Steve sent it to me.

However, in the interests of this thread...there was nothing like the schematic to end the "Debate" about the whole "Did they or didn't they use the Sansui QS technology in the development of the Dolby SVA evolution".

Steve

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