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Discussion Starter · #1 ·
I have an old Sony receiver that has the original pro logic processor and I have enough equipment to do a 4.0 setup in my living room.(Phantom center, 2 surrounds) It will be used for casual TV watching and some gaming. Will cable TV/Xbox 360 send pro logic over the stereo cables? I know Xbox can do PL but I'm not sure if it needs to be one of the newer versions of PL. If not that's OK, I'll just run it stereo. I've got 7.1 in my media room so I'll still get my surround sound fix.
 

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Pro logic derives the surround info from stereo sources based on phase differences between the two channels. So, as long as the cable box provides stereo output, you will get pro logic.
 

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Discussion Starter · #3 ·
Pro logic derives the surround info from stereo sources based on phase differences between the two channels. So, as long as the cable box provides stereo output, you will get pro logic.

The way you are describing it makes it sound like some sort of "virtual surround" that would work with any stereo signal. The way I understood it was that a center and rear channel could be "hidden" in a stereo signal, then decoded to get the 4.0 audio. Assuming I'm right, wouldn't you need a PL matrixed signal, rather than any old stereo signal? Is this kind of signal something that would be broadcasted over cable currently?
 

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I'm not aware of anything being "recorded" in pro-logic". pro-logic mearly takes any stereo signal and process it into a sort of synthetic surruond signal.
A phantom center speaker shouldn't be a problem an the center signal in pro-logic is derived from the sounds that are common to the main channels in the stereo signal. Your old Sony should do just fine.
 

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I agree. The surround information is derived from phase differences in the program material. The center is derived from info that is common to both left and right channels. Movies will definately sound more realistic than studio recorded music. Live music, such as classical in concert halls, does very will with Pro Logic.

Of course, DTS, DTS-MA and other discrete encoding methods will always sound more realistic than derived channels.
 

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Discussion Starter · #6 ·
OK that makes a lot of sense, thanks for the explanations guys. By the way, it was this line from wikipedia that had me confused: "When a Dolby Surround soundtrack is created, four channels of sound are matrix-encoded into an ordinary stereo (two channel) sound track". I interpreted it as some but not all stereo signals were purposely encoded with extra audio data.


So I hooked it up and it sounds great, definitely exceeded my expectations. It even has some options like time delay so now I just gotta dial it in. :)
 

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Encoding is true to an extent. For example, signals that are purposely recorded out of phase will be decoded to the back channels in mono in Pro Logic (or stereo back channels in PLII). I have heard some local commercials recorded that way to get your attention by changing from the front to the back.

Most music won't be recorded that way, but you will hear some ambience sound from the back.
 
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