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Dolby Digital 5.1 Vs PCM 2.0

post #1 of 6
Thread Starter 
I have a PS3 connected to a Bose Lifestyle 28 Series III receiver through an optical cable (the Bose doesn't have HDMI).

I have two setup options:
1. Go with Linear PCM on the PS3, and the Bose will display PCM 2.0
2. Go with Bitstream on the PS3, and the Bose will display Dolby Digital 5.1

I understand that optical cable can only carry 2 channels of uncompressed audio, hence the PCM 2.0, but I have a few questions :

- In PCM 2.0 mode, I still hear sounds from the surround speakers, that are clearly different from the front speakers, and seem to be effects. How come if I am only playing 2 channels? Does the receiver decode 2 channels into 6? How does the process work : does the receiver have an algorithm to separate sounds from 2 channel or is the information of what goes into which channel somewhat encoded in the 2 channel audio?

- Which of the two setup would you think is better and are you more likely to choose when watching a movie (type action movie) ?

- Also, will there be a difference of quality between the two configs : optical between ps3 and receiver VS hdmi between ps2 and TV and optical between TV and receiver.

Thanks for your help
post #2 of 6
the bose system is creating the surround sounds from the info in the 2 channel sound. Just like various other systems do. It is not the same content you'd get in surrounds if you used the actual multichannel feed. Really you should listen both ways and see what you think. Generally I'd opt for the "real" surround that the movie's directors and sound folks spent tons of time creating, rather than using the bose's best guess (and this comes from a guy that lets his receiver do best guess (Dolby process) extraction of surround material on most 2 channel inputs). The real surround will always, I think, be the better surround mix, and especially with BDs it's fairly well established that there's very little audible difference between DD or DTS lossy (at higher rates BDs use) and lossless. Of course if you can have it all you'd want to do lossless sdiscrete surround but that's not where you are right now.
post #3 of 6
Quote:
Originally Posted by dannydan View Post

I have a PS3 connected to a Bose Lifestyle 28 Series III receiver through an optical cable (the Bose doesn't have HDMI).

I have two setup options:
1. Go with Linear PCM on the PS3, and the Bose will display PCM 2.0
2. Go with Bitstream on the PS3, and the Bose will display Dolby Digital 5.1

I understand that optical cable can only carry 2 channels of uncompressed audio, hence the PCM 2.0, but I have a few questions :

- In PCM 2.0 mode, I still hear sounds from the surround speakers, that are clearly different from the front speakers, and seem to be effects. How come if I am only playing 2 channels? Does the receiver decode 2 channels into 6? How does the process work : does the receiver have an algorithm to separate sounds from 2 channel or is the information of what goes into which channel somewhat encoded in the 2 channel audio?

Most likely the receiver is using a matrix surround mode to create surround effect from the 2-ch signal.


Quote:
Originally Posted by dannydan View Post

Which of the two setup would you think is better and are you more likely to choose when watching a movie (type action movie) ?

As mentioned, try both and use the one you like best. Myself, I'd tend to use bitstream though as that should pass the discrete surround to the BOSE system.


Quote:
Originally Posted by dannydan View Post

- Also, will there be a difference of quality between the two configs : optical between ps3 and receiver VS hdmi between ps2 and TV and optical between TV and receiver.

Yes, there will be a difference. Optical between PS3 and receiver will give you the discrete surround, "true" surround, if you will.

HDMI from PS3 to TV and TV optical to receiver will almost certainly put you back to the 2.0 PCM scenario because most TVs do not function as passthrough for surround information from external sources.
post #4 of 6
You want the 5.1 out.

And to sell the bose.
post #5 of 6
The 5.1 will offer much better channel separation. To hear the difference run the test tones on some DVD's.

Chris, I know Bose doesn't provide the best sound for what they cost but some people have SAF to deal with.
post #6 of 6
Thread Starter 
I agree, I am disappointed by Bose especially with regards to the price I paid (but I didn't know much at the time).

Btw, the TV is a 3 yr old Sharp Aquos and it seems to pass through DD 5.1 as the receiver displays Dolby Digital 5.1.

- Should the pass through be lossless?

- It works for Blu Ray, but for video games or some PS3 streaming, no sound at all would come out of the receiver in this config (although the TV would play the sound, which is very strange). Any clue why?

Thanks for your help again,
Dan
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