TT> I'm interested in the theory behind surround sound.  In fact, I would
 TT> like to  use it in an upcoming project.  Where could I get a hold of a
 TT> surround sound  encoder, and at about what cost?  Does it merely take
 TT> four channels of audio  and phase shift them into two audio tracks?
          *L*     Front        *R*
          * *                  * *
          + -                  - +
          *                      *
          *                      *
          *                      *
          ***Left*********Right***
                   Rear
    Well this is the setup I use on my stereo to give me a "surround" sound   
    
It may not be Dolby (TM) but it is apparently supposed to be the same.    
I also use an amp on the rear channels, since the signal is weak.
This system works by cancelling the like charges across the two positives to
give the rear channel the sounds that are NOT in the centre of the recording.
There is no encoding involved, although a randomizer is used to record songs
in this way, to make sounds appear everywhere. The thing to remember with
this system is that no sound can every be heard in only one speaker, and that
it is not possible to make the rears work independently.
As for Dolby Pro-logic, I have no idea. THis involves a centre channel, and
seems to put only the bass and treble signals into the front left and right
speakers.
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