Sansui introduced the QS quad encode/decode system in February 1972. Similar to SQ and EV-4, QS can decode any matrix-type quad encoded record along with synthesizing quad from a stereo source. Often, QS is shown on quad equipment with the designation “RM.” This stands for Regular Matrix. Supposedly, RM is the QS type without logic in the decoder.
I think Sansui’s grooviest invention was the famous Vario-Matrix circuitry. Various audio magazines described this circuitry in a most confusing manner. Some described Vario-Matrix as a “logic circuit” that improves channel separation. Another writer said it was specifically designed to synthesize a stereo source into a quadraphonic output. Whatever it was intended to do, it sure does sound good. Almost everything I play; FM, Compact Discs, records, whether it’s a quad or stereo version, is passed through my Vario-Matrix circuitry. Stereo sounds dull, lifeless, and boring compared to the sound of my quad receiver pumping out the tunes through its Vario-Matrix decoder.
One of Sansui’s first, if not very first, quad units was the QS-1 decoder with “Quadphonic” synthesizing circuitry. An ‘ampless’ unit, it required outboard amplification to power the rear speakers. The QS-1 used electronic delay, phase shifting, and reverb to produce a form of synthesized quad. With a list price of 200 American dollars in 1971, it was rather expensive for its time. $200 was a LOT of shekels back then!!!
The first mention of Sansui’s Vario-Matrix circuitry in the print media was found in a March 1973 Audio-related magazine, where the QRX series receivers were mentioned in an advertisement.
Magazine advertisements telling of the splendid Sansui QRX-8001 and QRX-9001 receivers were still appearing as late as May 1978. From 1976 on, advertisements about quad hardware decreased rapidly in number. Based on just the number of audio magazine advertisements mentioning new quad equipment, 1974 and 1975 appear to have been quad’s peak years.
The Sansui Vario-Matrix decoder decodes an SQ-encoded vinyl record at the equivalent of a ‘half-logic’ SQ decoder.
Don’t confuse Marantz’s Vari-Matrix with Sansui’s Vario-matrix (note the lack of an ‘o’ in the Marantz offering). One source states that Marantz licensed Sansui’s Vario-Matrix circuitry (at least part of it) for use in their Vari-Matrix decoder. Other sources state the two systems only share a basic functionality: decoding and synthesizing quad. Whatever the true answer is, just be aware that differences probably do exist, despite the similarities in the name and spelling of the two systems.
Popular Electronics magazine found Sansui’s Vario-Matrix to be “. . . fascination and interesting.” I gotta’ agree. It does an awesome job decoding my quad records, whether they’re SQ or EV-4 or QS encoded discs. And, words can’t describe how well it synthesizes a stereo source, especially those from a CD. Yah gotta get it !!!
Sources disagree on how RM relates to QS. Both appear to be used interchangeably. Some sources say that RM is QS without a logic-type decoder. Whether this is true or not is not known. How about it readers. yah know the answer??
The QS decoder is often mentioned in 1970’s audio magazines as being better than SQ when synthesizing quad from a stereo source.
The July 1975 Hi Fi magazine says that QS gives 20db front to rear separation and 10db from left to right.
Advertisements in the May 1978 Stereo Review magazine show that the Sansui QRX-8001 and 9001 receivers were still available. Their list price of over $1,000 most likely limited sales.
When buying a Sansui receiver be aware that the “QR” series did not have the esteemed Vario-Matrix circuitry. You need a “QRX” series receiver to get it.