Re: Dead FM Broadcasting Technologies

["Brian Vita" <brian_vita@cssinc.com>]

> I still have several SQ-encoded albums from Columbia Records.
> Interestingly, when played on a Dolby Digital 5.1 receiver with it in Pro
> Logic mode, the rear channels come through ok on some songs.

The SQ format was copied by Dolby for use in their cinema and later their
"ProLogic" formats.  The major differences are that the two formats above
utilize a center channel and mono surround.

A very simplified explanation of the format is that a discrete four channel
master is encoded through a matix to a two channel format (in cinema called
Lt and Rt) this is what's printed on the film/video/LP disc.  At playback it
is run through a reverse matrix and brought back to four channels.  The
channel encoding (simplified) is like this:

Left = Left
Right = Right
When Left = Right you get Center
Surround is recorded on L+R out of phase.  That is to say that the image on
the left is out of phase with the image on the right.  If not decoded, it
cancels itself out.

The SQ format (which I believe was licensed by Dolby from Sansui) used Left,
Right, Left Surround and Right Surround.  It worked as L=L, R=R, L-R=Ls,
R-L=Rs.

Amusingly all of the cinema hi-fi tweeks rejoiced when digital brought six
(or 5.1) discrete tracks to the cinema. (Left, Center, Right, Left Surround,
Right Surround, Sub).  It was only a matter of time until the tweaks
screamed that they needed a back surround channel for Star Wars: Phantom
Menace.  The fix was to apply the much maligned matrix to the surround
channels and use the "center" channel as the surround back.  We've heard
rumblings in the past few months that some enterprising idiots, er, sound
editors, intend to use the surround's surround channel as Sc (surround
ceiling) or the "Voice of God" channel.  Oh well, I sell speakers and
amps...

Brian T. Vita, President
Cinema Service & Supply, Inc.
75 Walnut St. - Ste 4
Peabody, MA  01960-5626 USA
Sales: (800)231-8849/Sales Fax (800)329-2775
Bus Ofc +1-978-538-7575/Business Ofc Fax +1-978-538-7550
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