| STEREO QUADRAPHONIC |
| SQ was created by the CBS Technology Center and was made available to the public in April 1971. Rear channel information was placed on a vinyl record by adding "...double helical groove modulations... alongside . . .vectored modulations..." that produced the sound for the front channels. The SQ decoder sensed the different signals and did its best to send the appropriate sound to the correct speaker. One source says the SQ decoder ". . . uses sophisticated control of phase relationships between channels. . ." to produce the quad effect. The December 1976 issue of Popular Electronics magazine states, the ". . . non-symmetrical phase matrix using phase shift networks. . ." is what allows a SQ decoder to create a quad effect. Okay, I believe 'em. Early SQ decoders were capable of only around 3db (decibels) of channel separation between the front and rear speakers, creating only a small amount of quad effect. Later research produced "logic" decoders which improved channel separation to as much as 30-40db in some cases. From the start CBS wanted to maintain excellent Left/Right Front stereo effect to the detriment of the quad sound. SQ-type quad is a 'matrix' quad, as are the QS (RM) and EV-4 types. Any matrix-type decoder will 'decode' a matrix-type encoded record. However, the sound coming out the speakers will usually vary from a little to a lot since each system used a slightly different approach at decoding encoded quad input. My own experience has been that the QS (RM) decoder tends to synthesize quad from a stereo source better on around 90% of the music I play. The SQ system does a better job on the other 10%. The EV-4 system died out early and was never a big player in the quad market, though it was similar to the other matrix types. |
| Some reviewers proclaim the best SQ logic decoder types were "wave matching" and "variable blend". These became available around 1974. Original non-logic SQ decoders only had about 3db separation between channels. That ain't much, boys and girls. Tis better than nuthin', though. Supposedly, the Lafayette LR-440 was the first receiver with a built-in SQ decoder. Interesting, if true. Somebody had to be first The very first 7" 45rpm SQ encoded single record released by CBS records was by Art Garfunkel: Mary Was an Only Child b/w All I Know. Thanks to Curt Lundgren of WCCO Minneapolis for this info, along with the proof. The April 1972 Hi Fi magazine says: ". . . SQ opens up the sound . . .but can be gimmicky." Bummer. But, those were the days of early decoders. Later ones with logic circuitry improved the quad sound. Beware, though, not all logic decoders are equal in performance. The famous Tate and Tate/Fosgate decoders are considered by some quaddies to be the ultimate SQ decoders and awesome quad synthesizers of stereo sources. Like QS and other matrixed quad systems, SQ does not need a special stylus to convey encoded quad info on a vinyl record to your receiver or decoder. SQ decoders using 'cross blend' logic decrease left/right separation while increasing it for the front/rear channels. Decoders work on matrixed quad like QS, SQ, EV-4, etc. and synthesizes quad from a stereo source. Demodulators extract the high-frequency info from CD-4 Quadradisc records and do not synthesize quad from a stereo source. The first preamp with a SQ decoder was the Pioneer QC-800A One of the earliest full-logic decoders was the Sony SQD-2000, a SQ-type, with a price of $300 in 1972 dollars. That was a LOT of $$$$$ back then. Even the partial-logic units, which most were in 1972, were very expensive at the time. The Nov. 1974 Stereo Review wrote a glowing report on the Tate SQ decoder. The writer compared it to discrete quad tape. He was also extremely impressed with the Tate's ability to synthesize quad from any stereo source . . . even FM radio, which for some reason doesn't synthesize into quad as easily as other stereo sources. So, if yah see a Tate, better grab it !!! The April 1977 Stereo Review says the Deltek Super SQ Model One is the ultimate in SQ decoding. It better work good with a list price of $2,150 !!! That's roughly the equivalent to $5,000 today !!!! Inflation Sucks |
| SQ LOGIC TYPES Front-Back Logic is designed to keep vocals positioned properly; generally at the front speakers. Wave-Matching Logic (also known as gain-riding) operates similar to front-back but operates individually on each speaker. Variable-Blend Logic senses signals from the front channels that are 'leaking' into the rear and electronically cancels out the leakage. Full-Logic combines two or more of the above to minimize signal leakage from one channel to another. Non-logic decoders suck but are better than nuthin'. Some logic decoders operated 'better' than others. A common complaint with logic decoders was the "pumping" of sound . . . actually hearing the logic working on the sound and detracting from the sounds' 'naturalness.' This discussion is greatly condensed due to the technical complexity of the info sources referred to. A look at the old audio magazines will better define the various aspects of logic circuitry and the pros & cons of each type. Three commonly used IC chips for building SQ decoders were made by Motorola. The MC1312, MC1314, and MC1315. These are very hard to find. They gotta be out there somewhere, though. Perhaps sitting in a warehouse waiting for an inquiry to buy so you can build your own decoder. Perhaps a cross-reference catalog will list any other types which will also work. Any tech-types in today's audience who can enlighten the masses???? In My Humble Opinion......... Okay, it isn't THAT humble, but, it's still my opinion. I've heard several Pioneer quad receivers. Some were high-end units made around 1976-77 with full-logic SQ decoders. I was not impressed. None of the Pioneer quad units decoded or synthesized quad as well as the Sony and Sansui units I've heard. Also, Pioneers seem to break down more than other name-brand units. I've noticed that many tend to get "noisy" in one or both rear channels. However, if you do run across a Pioneer quad unit, take a listen. It may be just what YOU are looking for. Site Map Next Page: QS Quad |