Quadraphonic records (LPs to you and me)

The demodulators are for the CD-4 LPs.

I remember all this stuff, but doubt I ever even heard a CD-4 record back in the day set up on a system to properly decode it; the SQ and QS formats had more market penetration, at least where I was in the NE in the early ’70s, but even those faded pretty quickly-
I gather there are people who like the effect of some of the matrixed (not discrete) mixes for two channel playback, never really bothered, though every once in a while an old record will come across my path where it is claimed to be ’quad mix’ (presumably SQ).
And in addition to the Shibata, CD-4 is what got us that lovely JVC vinyl compound for a while. 

@tatyana69

The Bryston very successfully codes 2 channel into 7.1.
I never play analogue into stereo

Why do you need 7.1 if you’re playin’ stereo vinyl at home ?

Proper stereo set-up reproduce holiographic 3D imaging and this is all about analog, you don’t need another speaker on the back of your chair and additional side speakers to play stereo vinyl.

If you playing 2 channel stereo via home theater 7.1 setup then i don’t know what you’re actually listening to, but definitely not what is on the record (mixed and mastered for 2 channel stereo in the studio). The sound/mastering angineer has just Left + Right monitors in front of him. 

When you decodes 2 channel to 7.1 how come it can be better than just Left + Right if the recordning was made for Stereo?

I had a 4 channel system; you need a 4 channel pre-amp, a 4 channel amp, and 4 speakers to get the full benefit of a 4 channel record; it produces something akin to surround sound.


  https://www.google.com/search?q=phase+linear+4000&oq=phase+l&aqs=chrome.3.69i57j0l5.17975j0j...


You will also need a 4 channel amp


      https://www.google.com/search?q=dynaco+qsa+400&tbm=isch&source=iu&ictx=1&fir=1kHUCYG...:


It was a system I enjoyed for many years. Although not high end in the sense I enjoy stereo high end today, it was fun.

Why do you need 7.1 if you’re playin’ stereo vinyl at home ?

I do not have at the moment a separate 2 x  mono preamp (one however is being built for me bespoke by Tom  Evans)
So the phono goes into my sp3 where it is decoded into 7.1 - which separates the signals into excellent splits around surround speakers. It does not just "surround" the sound but splits them up in a good way. E.g in Mandolin Wind there are 3 guitars that in stereo sound like one or maybe two (dependent on the speakers!). The Bryston splits those into different speakers so you can hear quite distinctly. Often also percussion is separated to hear the decay of those items well as they are often coming out of a surround and not L or R. Great for me as I used to play in an orchestra and I love being "in" the sound rather than face a wall of it.
Not many companies' products do this. Bryston and Lexicon do very well and Chord did some time back