[email protected] wrote:But I have to say, I've never had an occasion when watching a movie when I said to myself, gee, I wish I had a little more separation between the audio channels.
It's more than just separation. Think about it this way - if you'd never seen a 50" HDTV picture then you'd probably think a 27" TV with Svideo looked fantastic. But once you've seen the 50" HDTV picture you'd never want to go back.
Check your local high end audio/video shop - I'm sure they have a good sound demo setup. The big box stores are set up more for Video than Audio.
I know that when a movie is made it is encoded with Dolby Stereo, and I believe that's the information that my Prologic surround sound amplifier is using. But when I looked at the spec on my Playstation 3, for example, there is no mention of Dolby Stereo encoding. I tried this out of my DirecTV signal, and it appeared to be getting rear channel information. Is the Dolby Stereo encoding being dropped, or are there newer methods that are simply enhancements? Or something else? Obviously it must be an encoding method because all systems still only have two wires to the source. If anyone wants to point me to a good technical discussion of this I'd appreciate it.
Henry - the easiest way to think of it is analog vs. digital.
Pro Logic is analog. They encode the center and surround channels into the normal L/R stereo signal. Your ProLogic receiver simply compares the left and right signals - anything that is in both channels and in phase goes to the center channel and anything in both channels but out of phase is sent to the rear surrounds. This is the only type of surround sound that can be broadcast over NTSC or on VHS tapes.
Dolby Digital and DTS (and variants) are digital. They all provide at least 6 discrete channels (no matrix processing required) of full range sound:
Left/Center/Right, LeftRear, RightRear (5) and LFE (subwoofer) (.1) giving you 5.1 channels. Some variants add one rear surround (6.1) or two (7.1).
ATSC broadcast TV uses Dolby Digital (although there is no requirement to use all 6 channels - sometimes only 2 are used but the format is still the same) while DVDs use DD or DTS. Digital sound is sent to a receiver for decoding either using HDMI or a digital audio cable (optical or coax).
On some receivers and DVD players the mfr may have chosen to output a Pro Logic analog audio stream using the stereo outputs and derived from the DD or DTS soundtrack but that is totally up to the mfr. Best way to tell is to test it like you already did - if you get rear surround and center channel from the stereo output jacks then it works. It won't sound nearly as good as a dedicated 5.1/6.1/7.1 DD or DTS but again, it's better than nothing and if you're happy with it then don't worry about it.
Thanks for the explanation. I have completed my installation and I'm happy to report that analog surround sound works on all sources including the Playstation 3. (You have to tell the Playstation what your intention is, however.) Using HDMI for video and analog surround seems to work fine no matter what the source.
I watched the beginning of "Blade Runner" on Blu-ray. The opening scene that has flying cars moving toward and away from the observer was a good test for my analog system and in my judgement the subjective direction of the sound tracked very well with the picture. The quality of the sound exceeded the theater experience to my ears, not to say that a digital sound system wouldn't be better, but I have to say I was very satisfied with the results obtained.
