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understanding 6.1/7.1

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5 replies to this topic

#1 of 6 OFFLINE   Wayde_R


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Posted March 22 2004 - 05:03 AM


I believe that 7.1 and 6.1 are a bit misleading as terms. I think hardware is being marketed as 6.1 or 7.1 when there really isn't a 6.1 or 7.1 surround sound format available for home theater at this time.

Dolby Digital EX and DTS ES aren't really 6 or 7.1 they're 5.1. The extra back surround channels aren't really separate channels but matrix(ed) in from the left and right surrounds.

Please correct me if I'm wrong and I'd like to understand the term "Matrix" a little better. I understand that it's how surround systems like Dolby Pro logic creates its center and rear channels. But since they're matrixed can they (rear and center in Dolby PL) really be considered "channels"? What is this "matrixing" thing?

Dolby PL is a two channel system. I believe it must be because it travels over stereo RCA cables. Are the center and rear sounds simply some sort of algorithm knock off of the L and R channels? Or is there separate center channel information transmitted over the stereo jacks?

Thanks for reading and any information you can give is helpful.

Happy Halloween!

Wayde Robson

#2 of 6 OFFLINE   Blaine_M


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Posted March 22 2004 - 05:18 AM

It is my understanding that there are a few DVD's out there that have a discrete 7th channel for true 6.1, they are DTS ES Discrete, instead of DTS ES Matrix. The matrix 6.1 is just like what Pro Logic does for your front center, only in this case it is done in the rear. I don't have the link any more, but there are plenty of web sites out there if you do a search on DTS 6.1 or DD 6.1 you will find something that explains it.

#3 of 6 OFFLINE   Jeffrey_K



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Posted March 23 2004 - 01:34 AM

My understanding is the DTS ES Discrete is indeed a true 6.1 environment. In "Matrixed" environments (DTS as well as DD) the receiver takes sounds equal in both rear speakers and puts them in the center rear.
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#4 of 6 OFFLINE   Wayde_R


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Posted March 23 2004 - 06:27 AM

Thanks for the suggested reading. I did infact read that DTS ES Discreet is indeed a true 6.1 surround method.
Happy Halloween!

Wayde Robson

#5 of 6 OFFLINE   ChrisWiggles



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Posted March 23 2004 - 07:45 AM

You guys are correct, and for a more thorough discussion, see this thread:


A simpler explanation is also included in the beginner's Primer and FAQ, which can be found in a link at the top of the basics forum.

#6 of 6 OFFLINE   Michael Reuben

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Posted March 24 2004 - 04:55 AM

I believe that 7.1 and 6.1 are a bit misleading as terms.

The terms themselves aren't misleading. It's their misuse, mostly by equipment manufacturers, that has caused the confusion. (I've been saying this here for years.)

The notation "x.y" was developed to denote the discrete channels in the sound source. Today people often use them to refer to the number of channels in the playback system, which doesn't tell you much. If I play a mono recording through a seven speaker/one subwoofer system (which I often do), current usage would say that I'm playing back in "7.1", which is nonsense. And not so many years ago, when Dolby Prologic was still the ultimate in HT playback, no one referred to those systems as "5.1", although they often had five separate speakers and a sub. The "x.y" notation only appears when discrete multi-channel formats became available.

As noted, there is indeed a true 6.1 format for home theater, which is DTS-ES Discrete. (Note that this format is HT-only; there is no equivalent for theatrical exhibition.) There is no true 7.1 format for home theater, although there is one for theatrical exhibition: SDDS-8, which is now rarely used.

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