(updated March 2014. scroll to bottom for new addition to this post)

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


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.


Updated March 2014

Hello. Happy Quadding.  Since my wandering onto the Web in the latter part of 1995 I have seen the amount of information about everything imaginable grow and grow then grow some more and then… some more. And after it grew it just kept on growing.

This constant growth tells me that because you can not find a picture or information you are seeking now keep on looking. There may be somebody somewhere right at this moment placing what you are seeking upon the Web.

Search tip:  use different search words and terms. Be creative. Perhaps using quadrasonic instead of the more common quadraphonic may lead you to what is being sought.

Here is something new to me. The schematic and manufacturer’s information about the SQ full-logic decoder related to CBS records and containing some interesting information. The link leads to a .pdf file that is easily downloaded and opened in an Adobe .pdf file viewer. The viewer can be downloaded for free. My browser is set up to open .pdf file in the browser. Below is the link to that nifty file:


Here is a pic and a nifty mention of a SQ encoder… the device that altered the input so that a decoder could output at least some semblance of 4-channel soud:


SQ encoder

Thanks to Åke Holm of Sweden for posting the interesting mention of the seldom-seen encoding device.  EDIT: The link that was here that showed more pics is removed. The link was taken over by somebody selling work clothes.

That’s it for the update. Nothing so exciting that your liver starts to quiver with unadulterated ecstasy.  However, maybe this update was that exciting for you. If so, that would be excellent.

Have fun quadding out there wherever you reside upon the planet. That list I have on the main entry page to this site is amassing a growing list of visitors from countries across the world. That is immensely groovy, cats and chicks.




  1. Very interesting stuff. A friend of mine bought one of the first quad players released in Australia. I have been searching for years for information on a demonstration recording by Pioneer which came with it. The disc contained the usual bells and whistles of demo records but also an excerpt of “slaughter on tenth avenue” by a japanese swing band called (I think) the “Tokyo all-stars” and also, perhaps, a bit of Handel’s royal fireworks music. I would love to get a copy of the all stars original but can find no trace of them on the net. Can you help?

  2. If anybody wanted to play SQ or QS LPs
    There is a new Decoder made in Australia
    Called the Surround Master
    It is good as the (Sansui QSD1 QS) and the (TATE SQ )the best in both Systems
    in 1 unit there never has been a 1 piece decoder made before

  3. I designed and built a solid state SQ amplifier in about 1977 using the Motorola MC1312, MC1314 & MC1315 chips. I bought a set of spare chips that I think I may still have somewhere in my workshop.
    Used the amp for many years before going digital using HDMI.

    1. There is a groovy sense of accomplishment when building your own gear and it works. The closest I came was back in 1971 when I soldered the components onto the pc board the Radio Shack kit provided. A portable transistor AM radio that worked great and was all I needed back in those days when KFRC and KYA AM stations ruled the rock/pop music in the San Francisco Bay Area. Times have sure changed!!! Do younguns’ still build or assemble their own audio electronic goodies?

      1. People used to build their own gear to save money, but these days you would have trouble getting access to components. The component shops are now few and far between.
        There was one great benefit in self construction, in that you had a circuit diagram and became familiar with the innards. If there was a fault, you could nut out the cause and fix it.

  4. If they are functioning and the proper chips they may save you if your receiver or decoder dies OR . . . they may be worth a lot on eBay at auction. Is there a way to test them? If unable to test the best a person can claim is that they are new and never used and been in storage or that they were working when removed from a PC board.

  5. Today we have the ability to encode musical creations on the VINYL DISC in Analog Quadriphonie SQ format.
    Quadriphonie recording identical to the recordings of Vinyl Records in the 70s and 80s

  6. I have a MR-7 Quadraphonic Demo record from CBS Technology Center That was pressed in CBS Plant in Pitman,NJ Appx 1978 or so. It is SQD 101 7 inch Vinyl with 5 songs on each side making it a long playing (LP) 331/3 7 inch record. In an effort to save production coast on vinyl we tried this format. I can not find another existing copy and am wondering if anyone knows the rarity and or worth of this item.

    1. Hello,

      Here you will find the largest collection of quadraphonic experts on the planet: https://www.quadraphonicquad.com/forums/

      Scroll through the several forums covering different aspects of quad and quad related items and post your question there. Bookmark your post to assist with finding answers. I forget if joining the message board site is required to post there. I have been a member for years and can’t recall if posts can be made without joining. It is safe. The quad folks are regular people discussing their hobby. No spam ever. The site is a great resource for this interested in old quadraphonics from the Golden Age up to the latest in surround sound.

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