How to tell if it's really quad....

[Bob Romano]

I have been thinking abotu something for a bit of time now...

I have found many of the King Biscuit shows from the 70's during the time that the show was "broadcast in compaible stereo and SQ quadraphonic sound". Many of these shows claim to be from the original discs (i assume vinyl) or pre-fm reels. I also have attempted to decode several titles that are known to be QS or SQ with varying success. Sometimes it is apparant that it actually is quad. In cases like the KBFH stuff, there may be a couple of instruments in the rear and some crowd noise.

So... is there a sure fire way to figure out if what I am decoding is really quad or if the stereo it is just being effected by the SQ or QS script?

This really hit me when I did the samples of the Pink Floyd show... If you listen to the DTS samples you will hear what I mean.

 

[Lucanu]

That's a difficult question to answer because I once did a comparison from Genesis "As Though Emerald City" vinyl copy, supposed to be QS encoded, and its Wolfgang's stream live that is the same concert, and with my big surprise it is NOT quad for sure. I cannot even hear the crowd in the rears while with the lp is clear as light!

I think with the help of Audition phase analysis scope, the only way to "presume" which encoding was used is to hear if there is a full left or full right sound, that would be SQ.
Or during the "supposed quad" effect if you will see a circle it could be SQ encoded or a "x-cross" if it's QS.
I once played the QS tone test and it happened to look like this on Audition phase analysis (no decoding here):
Front QS left

Front QS right

Rear QS left

Rear QS right