Surround Sound - How many speakers needed? - Page 15

It is incorrect as the audio is meant to be heard over at least a 7.1 system. Compressing the lossy or non-lossy audio to 5.1 just distorts the 7.1 arrangement into 5.1. Such distortion is never "correct".

Of course, a 7.1 track is meant to be heard in 7.1. It is also meant to be heard in 5.1 and stereo. That's not distortion. That's the real world of cross compatibility. The content makers ensure it works in all cases. BTW, compression is not the correct term. The 7.1 stream carries a complete 5.1 mix. That is what is being played.

Excuse me, but the 7.1 DTS-HD Master sound track of most newer Blu Rays, is not a 5.1 mix. Most of what I now use is that, a 7.1 DTS-HD Master sound track.

The DTS core contains a complete 5.1 mix. Playing it on a 5.1 system is not "incorrect" and it's not a downmix, it's just different.


COMPATIBILITY AND A BOOST IN QUALITY
DTS-HD encoded content contains a DTS surround sound "core", plus an "extension" that delivers even higher quality. When you play a DTS-HD encoded disc through an older DTS-capable receiver, the DTS-HD extension is simply ignored and only the DTS core is decoded — but not at ordinary quality levels. Your older receiver will play back DTS-HD material with DTS surround audio at twice the data rate of other DVD video surround formats. Meaning? You get immediate compatibility and a boost in quality.

HOW DOES CORE + EXTENSION WORK?
The original DTS engineers designed a unique, future-proof coding system that has a “Core + Extension” structure. The DTS “core” contains data for a 5.1-channel system, operating at 44.1 or 48kHz, with a bit rate of 1.5Mbps (mega-bits per second). As DTS has introduced new technologies, these new “extensions” can then be added onto the core, providing higher performance. So, if you have an older DTS-capable receiver, it will “ignore” any extensions and just decode the core — ensuring you of compatibility and very high quality. And, a newer DTS-capable receiver will decode both the core AND the most recent extension it’s capable of handling, for compatibility and even higher quality. The result: An immediate boost in quality vs. other surround formats, and compatibility into the future.

Don't let the makers, DTS, fool you, people. Just because something is "higher quality" doesn't mean it is any more "correct". [sarcasm]

While everything you stated and quoted is correct, the particular description of "core plus extension" is referring to a lossy core and the lossless extension. The means for carrying a 5.1 lossless signal inside a 7.1 lossless stream also uses an extension, but in this case rather than adding lossless data, it adds 2 more channels.

The 5.1 mix is indeed a downmix of the 7.1, but the downmix settings are adjustable if so desired, by the engineers preparing the encoded streams. Once the 4 surrounds are folded into two, they are delivered as part of the 5.1 mix. Systems that can handle 7.1 audio decode the extra 2 channels and these new signals feed the rear surrounds (in this example). These same signals are subtracted from the Ls/Rs of the 5.1, thus revealing the discrete surrounds from the original 7.1 mix.

Thanks for the clarification. By saying it wasn't a downmix, I was referring to an on-the-fly downmix done by the end user's processor. If there's a 5.1 mix in the stream, then I consider listening to it in 5.1 to be a "correct" experience.

A downmix may be correct for a 5.1 system, but it is clearly not channeling 7.1 DTS-HD Master, making the 5.1 system incorrect for that media. I am certain one day, a 7.1 system will be bypassed. That day, I'll be upgrading.

That it is.

7.1 is the best for SURROUND SOUND system

I like 7.1 when its a real 7.1 mix. I don't like when they take 5.1 mix and make it 7.1 , it adds noting.

Please help our fellow forum member. He's in an organization who's doing a great service by putting together a traveling theater for needy children, seniors and war vets. He needs advice on surround sound systems along with other AV gear. Please give him some good advice and spread the word.http://www.avsforum.com/avs-vb/showthread.php?t=1335936

I would say 7.1
Lots of people use devices that only go up to 5.1, and 7.1 would be a great choice since it will take a while for devices (like the Xbox 360) to move up to 7.1 let alone higher than that. Although, I would reckon when the next Xbox comes out it will support 7.1 Dolby TrueHD and DTS-HD.

I like 7.1 when it is real, and when PLIIx or z makes a 5.1 soundtrack to a 7.1 soundtrack. It adds quite a bit of depth to the sound.

7.1 is what I'm getting ready to put together. Adding more non-sub speakers then 7 is overkill especially in the average sized home. If you have a commercial location or a really big room you could then justify the more to more speakers.

Given the way sound - like other radiant energy like radio waves and light - falls off at the square of the ratio of the increased distance (2x as far = 1/4 as strong, 3x as far = 1/9 as strong, etc), setting up a 7.1 system is much more problematic than a 5.1 system, since the "sweet spot" for listening is much smaller.

With a 5.1 system, there's more tolerance in seating front-to-back, allowing public movie theaters to set up pairs of left and right surrounds marching down the side walls. Once you add rear speakers for 7.1, the distance front to back becomes more critical, leaving a very small area for seating.

I initially set up my surround speakers in the back of my theater, following the illustrations in my equipment manuals, until it was pointed out to me here that this was not how theaters are set up and movies mixed. I also realized that when the surround speakers were behind me - and balanced with a sound pressure level meter - I could seldom tell whether they were even putting out any sound without getting up and going over to them, since the pinnae of my ears were filtering out the sound from those speakers. So I remain to be convinced that even 7.1 is worthwhile. Electronics makers will happily upgrade their equipment to 7.1, since that makes the price easier to accept (kind of like the way restaurants psychologically justify the prices they have to charge to cover their rents and payrolls by giving us portions too big to eat.)

Think of 3D. I've seen two features in 3D: Avatar and Tron:Legacy. Neither impressed me with their use of 3D. In fact, I don't even remember any 3D effects in Tron:Legacy! The only 3D that impressed me was in the trailer before it, for a nature documentary, where I found that I could actually chose whether to focus on the animals in the foreground or the background.

But in a dramatic film, the director can't afford to give the audience that freedom of choice. That's why shallow depth-of-field and devices like pull-focus are used to guide the audience's attention. True 3D would undermine the director's ability to control what the audience is looking at.

But manufacturers will force 3D capability on buyers of equipment in order to justify high prices.

If a friend asks you how to set up a great home theater without breaking the bank, there's a primer to help get them up to speed, in the form of at a site I just set up: http://PRO-Home-Theaters.com. (I link from that site to these forums.)

It's not argumentative like this post (but this place is for those already deep into the hobby), but simply lays out suggestions for how to get started.

Phil

I dropped by your site, and I admire your ambition and the effort you've put in to get it going. And you offer some good, common sense advice in places. But since we're here in the department of arguments, I'll also say that I did not find anything there about setting up a home theater. Nothing about how to determine the best seating area, the optimal screen size, where to put the speakers, or room acoustics or treatments. I did find a pitch for your services.

Frankly, I'd be a little skeptical of that considering you think it is necessary for the rear speakers in a 7.1 system to be pumped up unrealistically loud in order to hear them. Or that DLP creates colors by tilting the mirrors. Or that rainbows can be reduced by a particular screen paint. It's not really helpful to potential home theater customers to spread misinformation. That's why we treasure AVS Forum--all of these topics are deeply covered here, so might be useful to brush up a bit before hanging out the shingle.

Hi, Roger.

As you may or may not recall, it was you who told me to move my 5.1 surround speakers out of the back of the room to the sides.

My observation that doing so enabled me to actually hear them was what I was talking about. I don't think that rear speakers set to the correct level are audible in the "sweet spot" if you're looking at the screen. I wasn't advocating boosting them, I was challenging the need to have them at all!

I'd always heard that DLP uses moving mirrors. I just took a look at the Texas Instruments page on how its invention works, and it's true, the mirrors' movements merely turn the light path on and off. A separate spinning color wheel is often used. I do know that with my original projector, a Dell 3100MP XGA DLP unit designed for PowerPoint presentations, my first experimental screen was shiny drymount board that was prone to hotspotting, and I saw rainbows fairly often. When I changed to using the flat white latex painted wall, the rainbows went away.

After I got my current PJ, the LCD Panasonic PT-AE2000U, I painted the wall with the original Cream&Sugar paint mix, which has a metallic silver paint mixed in with a flat white latex paint. I didn't test that screen with the DLP projector, so I don't know whether the DLP rainbows would have returned because the paint was more reflective.

It's not my intention at my site to give detailed advice, only tips for getting started and leads to sites with more info, like this one. I know that my preference for sitting one screenwidth away is controversial, so I didn't put it up there. I did advise carpeting the floor, but I'm not an acoustician, or I'd probably get into trouble with advice like making the walls all non-parallel (like in recording studios) to spread out the resonances across many frequencies.

I'm glad you moved the speakers and got better results. I do not know why so many AVR manuals showed the speakers in the wrong places. I'm glad you point this out at your site.


That's what this thread is all about--expressing an opinion on the number of speakers needed. I take no exception to opinions.


Indeed it does.


Exactly my point.


The mechanism that causes the rainbows, however, is still present (time division color rendering), and I have yet to see a single-chip DLP that does not have rainbows to some degree. If the screen could magically make that go away, Joe Kane would beat a path to your door!


I'm not advocating that you do things at your site you are uncomfortable doing. I was just a little confused about the invitation to visit the site to get a primer on setting up a home theater vs the nature of info I read there. Thanks for clarifying.

7.1 should do the trick

I think 5.1 is enough.... or maybe a Sound projector

5.1 will do, but 7.1 is better.