# Now that we have 7.1, where do the speakers go?



## Sir Terrence (Jun 8, 2006)

Since the introduction of both Blu-ray and HD DVD, the promise of 7.1 surround sound is here. The thing that strikes me is that no one has released any mixing standards to sound designers. So how do we mix for 7.1? Most post production facilities that are wired for 7.1 have five screen channels, two discrete surround channels, and a LFE channel. Since it is not practical to have five screen channels in the home(not enough distance between the speakers for accurate separation), I wonder what SMPTE will approve for these new formats. 

My proposal would be three screen channels, left and right surround channels, and center rear, and a over head channel. I am sure other would prefer three screen channels, left and right surrounds, and left and right rear, but I am not sure that most listening rooms are large enough to create a convincing stereo rear imaging. 

What do you think a 7.1 speaker placement should be. 

Okay, talk amoung yourselves.......


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## Josuah (Apr 26, 2006)

Well, my 7.1 speaker placement is with two rear speakers. As are anyone else's who has a 7.1 setup right now. I would prefer any mixing engineers to mix the 7.1 channels in that manner, so as I hear the right thing, and don't have to rearrange my speakers when switching from DD, DTS, DD-EX, or DTS-ES to Dolby TrueHD or DTS Master Audio.


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## Otto (May 18, 2006)

Well, I'm just a 5.1 guy at this point... I see what Josuah's saying about having to move speakers around depending on the source format. I wouldn't want to have to do that either. 

However, that aside, I think that Sir T might be right. Most HTs don't have enough room in back to create a real stereo image. I think you can get most of that imaging from the side surrounds, especially if they are placed just _slightly_ behind the listening position. Use one of your remaining two channels for "rear" and one for "above". Used properly, I think the "above" channel will make for very convincing back-to-front (and vice versa) motion. Flyovers and such will be even more real...


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## Hakka (Sep 10, 2006)

I found these pics on the DTS website:

























































From the Dolby website:










I have mine set up like the dolby pic but my mains are spread slightly wider apart, my surrounds are about 2 feet above ear level.

Harry.


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## Steve Williamson (May 11, 2006)

Oh!, I haven't cabled for the centre overhead speaker yet :sarcastic:


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## brucek (Apr 11, 2006)

> Since the introduction of both Blu-ray and HD DVD, the promise of 7.1 surround sound is here


I'm a bit confused about the question. The 7.1 setup was determined a fair while ago with the placements as shown in the pictures shown above. It's been around several years...

Are you saying you think the standard is going to change?

Personally, I like the extra back channels. Even in a small room such as my own, adding the 6.1 back channel had a positive effect. I creates sound completely across the rear. I think DPLIIx does a good job of matrixing it for two channel material and DOLBY EX does a good job of adding the extra channels with 5.1 information.

brucek


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## Josuah (Apr 26, 2006)

I think the OP is unfamiliar with 7.1, thus the question. Also, even though it's possible to go with a single rear speaker, psycho-acoustically it doesn't work. It's just a compromise resulting from people who don't want to buy multiple rear speakers or who have receivers that didn't include the extra channel necessary.


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## brucek (Apr 11, 2006)

> even though it's possible to go with a single rear speaker, psycho-acoustically it doesn't work.


I've never heard that before. I thought the 6th and 7th channels contained the same mono information? I understood that the standard was 6.1 (i.e. DTS 6.1, NEO:6 etc) and that the 7th channel was only needed when there was a fairly wide rear area that the 6th single speaker couldn't cover.

brucek


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## Hakka (Sep 10, 2006)

brucek said:


> I've never heard that before. I thought the 6th and 7th channels contained the same mono information? I understood that the standard was 6.1 (i.e. DTS 6.1, NEO:6 etc) and that the 7th channel was only needed when there was a fairly wide rear area that the 6th single speaker couldn't cover.
> 
> brucek


I surround back spaker might work fine for 1 listener seated directly in front of it but as soon as you move off centre/add more people into the room it cannot match a dual back surrund setup.


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## Josuah (Apr 26, 2006)

Hakka said:


> I surround back spaker might work fine for 1 listener seated directly in front of it but as soon as you move off centre/add more people into the room it cannot match a dual back surrund setup.


Actually, that's opposite. The reason you need two rear speakers is because if the sound is coming from a single point source right behind your head your brain won't be able to distinguish it as coming from behind instead of coming from in front. Or at least it has a harder time doing so.

I found a paper that discusses this: Of vulcan ears, human ears and 'earprints'. The term they use is front-back confusion. It seems the degree to which you will suffer from this will be dependent on your pinna structure, which is something you'll inherit genetically (you can tell immediate relatives by their ear structure).


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## brucek (Apr 11, 2006)

Interesting. Makes you wonder why everyone always says that a single center is so important.


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## Josuah (Apr 26, 2006)

The single center is to make sure no matter where you sit, the sound sounds like it is coming from the center of the screen where people are talking. If you use a phantom center, then if you're not in the center, then you will hear someone's voice coming from the wrong place.

If you've ever sat in front of one of the left or right speakers, for example, you'd know that for anything that's coming out of the mains, it sounds like everything is coming from the speaker you're sitting in front of. The center channel at least makes it sound like some stuff is coming from the middle of the picture. Even if you sit slightly off center this can help, since the majority of people watching movies aren't actually always in the sweet spot, especially if there's two of you.

It's also a lot easier to discern the directionality of sound that is coming from in front of you, since your ears are designed that way. Cats and dogs can rotate their ears so they can better discern the direction of sound without moving their heads.


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## Sir Terrence (Jun 8, 2006)

Josuah said:


> I think the OP is unfamiliar with 7.1, thus the question. Also, even though it's possible to go with a single rear speaker, psycho-acoustically it doesn't work. It's just a compromise resulting from people who don't want to buy multiple rear speakers or who have receivers that didn't include the extra channel necessary.


Actually, I am VERY familar with a 6.1 set up with dual rear center speakers. I had this setup before most folks as I was a test case for the Smart matrix center rear processor that hit the market 7 or so years ago. It hit the market before THX EX did. 

There is no such thing as 7.1 for the home, and I am sure you are aware of that. What is currently out there is 6.1 with 8 speakers. So there is no reason whatsoever not to include a height speaker even in the presence of two rear centers, as they only output a single mono channel. Any attempt to do stereo across the back wall is a hit and miss proposition, in that not alot of rooms are wide enough for decent stereo image to be maintained. If you sit off center to any speaker across the rear, the image will pull to that speaker. That is a huge arguement for mono on each side and rear wall, and a mono channel from above. 

All of the illustration from the Dts website all assume a dedicated room, or a room with very large deminisions. If I put my surrounds to the sides of the listening position, I get the stereo in head phenomina in the midbass/midrange area, and wide open highs. If I move them farther down the sides to the current position they are in(115 degrees from center front), then any speaker on the rear walls except dead center behind my head(which is problematic as well) will be swamped by output from the L/R surrounds. 

There is a way to conquer the effect of a single center speaker imaging problem behind the head(it can sound like it is in front of you), and that is to not point the speaker directly at the head. If it is ceiling mounted and pointed down the back wall, you will get a backwall fill just like two spaced speakers would provide. It will also keep its imaging position stable for more than one listener off axis. 

None of the examples of speaker positioning for 7.1 from Dts or Dolby's website have been officially adopted by the post production facilities. We are still working with the SDDS 7.1 pallette. We have already explored all horizontal directional positions in the current 6.1 setup. The only position left is up over the head. An overhead positioned speaker would be helpful with front to rear pans and any overhead action such as helicopters and jets flying overhead. This has already been tried in the theater sucessfully, and is the only logical extension of what we currently have. 

Remember that any channel assignment that is done for the home, has got to be done in the theater as well. It will be VERY expensive to try and mix for two widely different channel configurations.


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## Sir Terrence (Jun 8, 2006)

Hakka said:


> I surround back spaker might work fine for 1 listener seated directly in front of it but as soon as you move off centre/add more people into the room it cannot match a dual back surrund setup.


Not exactly. Two monopoles are desired for center rear because of the coverage in the room. If you try a single wide dispersion speaker like a bipolar speaker mounted on the ceiling facing downward in the center rear position, you will have the coverage necessary for more than one person, and without the interference effects that can come from two spaced speakers playing the same information (comb filtering).


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## Sir Terrence (Jun 8, 2006)

brucek said:


> I'm a bit confused about the question. The 7.1 setup was determined a fair while ago with the placements as shown in the pictures shown above. It's been around several years...
> 
> Are you saying you think the standard is going to change?
> 
> ...


Bruce,
There is one standard for 7.1, and it doesn't include four surrounds speakers. It includes five screen channels. There has never been a single mix created for a 7.1 setup with the examples above. There has yet to be ANY standard for 7.1 in the home environment. We have only had 6.1 up to this point, with a mono center rear reproduced by two speakers. That is not 7.1. 

The back channel is fine and should stay. You now have a extra channel that is not in use, the question is should it be overhead? Or should it be another rear wall stereo channel? (which wouldn't really work that well in most rooms).


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## brucek (Apr 11, 2006)

Yeah, I did some playing around with my 6.1 and 7.1 setup (Bryston SP2), but found the 7.1 too much for the small area. The best results came when I used the single 6.1 setup with the back 6th channel speaker set lower than the height of the back of the couch so it hits the couch back and disperses the sound quite nicely. The sound from the rears and back now seem to fill the area without being too directional.

This might not be kosher, and it might offend some purists, but I don't really care, since in my setup it sounds the best to me.....

brucek


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## Josuah (Apr 26, 2006)

Thanks for the clarification of your post, Terrance. I understand your question better now. I was under the assumption though that the 8 channels available on the new movie formats would be to match the 7.1 speaker setups people have at home, not result in still one channel to two rears, with a new channel for use somewhere else. This assumption is incorrect?


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## Hakka (Sep 10, 2006)

Cant remember the title, but there is a PS3 game that supports 7.1 PCM, this is the only 7.1 source I know of.

Harry.


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## khellandros66 (Jun 7, 2006)

I have 6.1 setup in my small bedroom and it works really well. Content from the rear center which is directly above me reflects sound across the ceiling making for a more top overhead feel.

~Bob


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## Sir Terrence (Jun 8, 2006)

Josuah said:


> Thanks for the clarification of your post, Terrance. I understand your question better now. I was under the assumption though that the 8 channels available on the new movie formats would be to match the 7.1 speaker setups people have at home, not result in still one channel to two rears, with a new channel for use somewhere else. This assumption is incorrect?


Josuah, nobody has a true 7.1 setup in their hometheaters. Just because you have two center rear speakers doesn't mean you have 7.1. What you have currently is 6.1 with the mono center rear coming from two speakers(some folks have just one speaker). Any professional dubbing stage or theater currently supports this setup. What has not been discussed is how to setup a theater(home or professional) for 7.1 that is non SDDS related, hence the topic of this post. 

Keep this in mind, while 6.1 receivers are now the norm, most people still have a 5.1 systems. I am really surprised this has not been a topic at any of the SMPTE meetings I have attended in the last year. I am also surprised that not a single studio I have been in lately hasn't taken any steps to at least create a mixing room for 7.1, even at an experimental level.


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## Josuah (Apr 26, 2006)

My preprocessor is outputting 8 channels: left, right, center, right surround, left surround, right rear, left rear. And this is going to eight different amplifiers. In the case of DD, DTS, DDPL, DD-EX, and DTS-ES, the pre-processor is decoding the single rear channel into two outputs.

If, however, my preprocessor were to decode one of the new formats carrying 8 independent channels such that each of the rear outputs got a discrete signal, then would that not mean the mix for those 8 channels better match the 7.1 setup?

I don't know if that is what a preprocessor or one of the players does with 8 discrete channels right now though. Maybe someone working on support for the new formats in their processors would have an answer as to where they will send the signals when they get 8 discrete channels in the audio.

Do you know what the people writing code for that are doing with the 8 discrete channels?


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## Hakka (Sep 10, 2006)

For anyone who has a 6.1 receiver and wants to try a 7.1 speaker configuration, you can connect two speakers in series to the single surround back channel (red on AVR to red on speaker1, black on speaker1 to red on speaker2, black on speaker2 to black on AVR).

The series connection will cause your amp to see 2 8ohm speakers as a 16 ohm load, you might need to boost that channel by 1 or 2 db, it will not put more strain on your AVR.

Before 7.1 AVRs were available I used a Yam DSP-a3090 5.1 DD AVR and a cheapo Yam pro logic receiver. The DSP-a3090 powered the front speakers, the rear preouts were connected to the CD input of the 2nd AVR, pro logic decoding engaged, the left and right rears connected to the main speaker jacks of AVR2 and the surround back (2 speakers) connected in series to the front centre channel of AVR2. 

I have thought of using a similar setup to extract 6.1 signals from HD-DVD, my 3803 cannot do post processing on the 8ch analog input, so the surround preouts from the HD-DVD player could go to a second AVR to be decoded into pro logic , while the front channels go to the Denon. 

Volume matching is the only hassle with the above setup.

Harry.


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## Bob in St. Louis (Oct 21, 2006)

I've tried the 7.1 in my room (still have the brackets on the walls) and it was a sonic mess.
I've since thinned in down to a 4.2 rig. This is the best I've heard on this system yet.
The idea of having overhead content that was made that way (No NEO stuff!) sounds intriguing.
How about a front overhead center,(over the screen), an overhead center (geographically center of the room), and a rear overhead center?
I realize this isn't directly answering Sir T's question, but I had this extra center speaker laying around.:bigsmile: 
I'm all for the overhead content. I don't think most rooms are large enough to take advantage of that many discrete channels without a few of them being "up there."

Bob


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## Sir Terrence (Jun 8, 2006)

Josuah said:


> My preprocessor is outputting 8 channels: left, right, center, right surround, left surround, right rear, left rear. And this is going to eight different amplifiers. In the case of DD, DTS, DDPL, DD-EX, and DTS-ES, the pre-processor is decoding the single rear channel into two outputs.


I am curious, where sources do you use to get 8 channel output? I know of none. Is your processor creating a channel?



> If, however, my preprocessor were to decode one of the new formats carrying 8 independent channels such that each of the rear outputs got a discrete signal, then would that not mean the mix for those 8 channels better match the 7.1 setup?


The answer to your question is no. We first need to dispense with the 7.1 nomenclature, it doesn't exist. Secondly all speaker setups that took 6.1 into consideration include two rear center speakers(Widescreen Review recommends one speaker however). Having a stereo backwall is pretty useless, I have already participated in enough speaker positioning tests when I was in film school to confirm this, UNLESS the room was VERY wide. Most rooms in homes would not qualify unless they were built from the ground up with this in mind. 

Mixing for a stereo backwall would produce only subtle tracking as our ears are not as accute to tracking left to right behind our heads. HRTF would somehow break down some of the transition at a certain point. As a audio engineer, I would use the much more dramatic left surround, center rear right surround as a much more effective pan around the rear, rather than trying a left to right backwall pan. Its just not as effective. 



> I don't know if that is what a preprocessor or one of the players does with 8 discrete channels right now though. Maybe someone working on support for the new formats in their processors would have an answer as to where they will send the signals when they get 8 discrete channels in the audio.
> 
> Do you know what the people writing code for that are doing with the 8 discrete channels?


Since no one is working with 8 channels anymore(even SDDS 8 releases are pretty much nil), this pretty much sums up why I posed the question. This is one of the few times where the hardware beat the mixing community. Usually we are asking for more channels before the hardware delivers.


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## bobgpsr (Apr 20, 2006)

I think that the standard 7.1 speaker placement with two rear surrounds matches what Dolby Labs decodes to when it applies Pro Logic IIx to a 5.1 discrete source (AC3 or dts via S/PDIF).

A lot of discussion has taken place in the past saying the reason for two rear surrounds rather than one center rear is to help ensure that center rear sounds don't get misinterpreted by the fraility of human hearing to come from the front instead.


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## Josuah (Apr 26, 2006)

Sir Terrence said:


> I am curious, where sources do you use to get 8 channel output? I know of none. Is your processor creating a channel?


To quote myself: "the pre-processor is decoding the single rear channel into two outputs."

I guess we need someone who's implementing one of the 8-channel decoders to answer the question. Anyone know anyone?


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## Hakka (Sep 10, 2006)

Josuah said:


> To quote myself: "the pre-processor is decoding the single rear channel into two outputs."
> 
> I guess we need someone who's implementing one of the 8-channel decoders to answer the question. Anyone know anyone?


I'm assuming you mean PLIIx as the '8 channel decoder'?? If using DDEX or DTS-ES played back through a 7.1 system the surround back channels are dual mono. If you apply PLIIx decoding to either DDEX or DTS-ES it performs some processing that results in different signals from each of the surround back channels, so you have 8 speakers all playing back discrete signals.

There is still no official 7.1 standard as far as movies go, 6.1 is it for now. As mentioned earlier, the only true 7.1 source currently available is from the PS3 - apparently the intro is 7.1 PCM and at least one game in 7.1 PCM (I cant remember the title). All movie soundtracks are 5.1 or 6.1.


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## Josuah (Apr 26, 2006)

I'm just talking about having 8 outputs. I didn't say the output signals were different. Maybe I wasn't clear enough when I was talking about the outputs each going to its own amplifier input....


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## Guest (Feb 23, 2007)

I always found this list interesting. :reading: It's eye-opening to see how many different sound formats have been used in movies.

Well, it's easy to get hung up in the terminology but some people can indeed claim to have a "7.1 system" whether or not source material and decoders are available.:dontknow: I realize part of that is marketing/future-proofing but there are many preprocessors on the market that will take 8-channel analog inputs, keep them in the analog domain, and output them as 8 discrete channels. Some even apply the same bass management and speaker configuration settings as in the digital domain.

Having said that, that does nothing to address the original question. Which is how to mix and subsequently decode the signal... but hopefully this will cut down on the "you don't really have 7.1" - "yes I do" discussion...:boxer:

P.S. Danger, I just found the smileys


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## Sir Terrence (Jun 8, 2006)

garcianc2003 said:


> I always found this list interesting. :reading: It's eye-opening to see how many different sound formats have been used in movies.
> 
> Well, it's easy to get hung up in the terminology but some people can indeed claim to have a "7.1 system" whether or not source material and decoders are available.:dontknow: I realize part of that is marketing/future-proofing but there are many preprocessors on the market that will take 8-channel analog inputs, keep them in the analog domain, and output them as 8 discrete channels. Some even apply the same bass management and speaker configuration settings as in the digital domain.
> 
> ...


Well, where do I start. You cannot say that you have a 7.1 system without knowing the typology of the system. Some systems that claim 7.1 status have a single channel amp with two outputs. In some the decoder will only handle one rear channel, even if there are two amps and outputs. 

If there are no 7.1 decoders or software, then how can one lay claim to a TRUE 7.1 system? How do you say you have a TRUE(as opposed to a marketing driven) 7.1 system when the defination of what that system is for the home isn't set? Unless you know the signal path of your system remains truely discrete from the input to the output, then it is impossible to say that you have a 7.1 system. 

For those processors that have 8 discrete outputs, are all of those channels full range?(with the exception of the LFE). Are there any filters in use? IN most EX systems there are, and most THX EX systems do not qualify as TRUE 7.1 systems because of the requirements of THX. 

Any claims to 7.1 right now are market driven claims.


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## bobgpsr (Apr 20, 2006)

There has been much discussion for the last 3 years or so if Dolby Pro Logic IIx applied to a 5.1 digital source to drive the back surrounds is really *true* 7.1 surround. Granted it is not *discrete* channel 7.1 but rather *matrix decoded *7.1 YMMV.


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## Sir Terrence (Jun 8, 2006)

bobgpsr said:


> There has been much discussion for the last 3 years or so if Dolby Pro Logic IIx applied to a 5.1 digital source to drive the back surrounds is really *true* 7.1 surround. Granted it is not *discrete* channel 7.1 but rather *matrix decoded *7.1 YMMV.


This would be easy for me. Does the decoder create the matrixed rear, or was it mixed that way. If DPL II generates the stereo channels, its not real 7.1. If it was mixed with stereo rear channels in mind, its real. If an engineer didn't hear it in the control room, then it is made up which makes it not real. I am really speaking to discrete channels mixed by an engineer in this case.


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## Josuah (Apr 26, 2006)

I think if people are talking about the system, then the X.Y refers to speakers and subwoofers, not what the source is. So you can say you've got a 9.3 system, but that doesn't have anything to do with playing back two-channel CDs. That's how I've always thought about it at least, but that's coming from the home theater world and not professional sound editing.

So, I have a 7.2 system. Deal with it.


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## Hakka (Sep 10, 2006)

Josuah said:


> I think if people are talking about the system, then the X.Y refers to speakers and subwoofers, not what the source is. So you can say you've got a 9.3 system, but that doesn't have anything to do with playing back two-channel CDs. That's how I've always thought about it at least, but that's coming from the home theater world and not professional sound editing.
> 
> So, I have a 7.2 system. Deal with it.


Yeah, I agree with what you're saying, I've always referred to my setup as 7.2.

Harry.


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## Guest (Feb 26, 2007)

Sir Terrence said:


> Well, where do I start.


I get it now. Thank you. 

I have to admit I fell for this thread.

So...

Steinberg Nuendo 8-channel recording
M-Audio Revolution 7.1 24bit/192khz sound card
Outlaw 990 with 8 analog inputs in analog bypass mode
7 Polk Audio Speakers
1 Sunfire Subwoofer

is called a "5.1 system"

8-channel "5.1" test file


I don't belong here.

I hope you get the answer you are looking for.


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## Woochifer (Oct 19, 2006)

T-man!

Good to see that you've found a new landing spot! I'd been lurking on the site in spurts to document my adventures with the REW application, but hadn't checked in a couple of months.

Anyway, on the topic at hand ... there were already experimental variations on the six-speaker alignment, where the center and/or subwoofer channels get swapped out for uses such as high mounted effect speakers and overhead channels. While movie soundtracks tend to solidly anchor the dialog to the center channel, the use of the center channel can drastically vary from one recording to another when we're talking about multichannel music. Some recordings (like the Peter Gabriel _Play_ DVD compilation) mix the majority of the lead vocals and instrumentation through the center channel, while others (like Pat Metheny Group's _Speaking of Now Live_) completely eschew the center channel, while still others (like Boz Scaggs' _Greatest Hits Live_) use the center channel but only use it for a select few sound elements and at very low levels. 

I know that Chesky Records issued some "2/4/6" DVD-A titles a few years ago featuring a two-channel track, 4.0 (L/R/LS/RS) track , and 6.0 track that features two high mounted effect channels up front (these would be aligned at 55-60 degrees). Chesky to this date does not use the center channel in its multichannel mixes, and does not use the subwoofer channel either. This would be kind of a hybrid between two of the potential alignments shown on those DTS diagrams (great pics BTW!), high mounted speakers only spaced out at a wider angle.



















Chesky also supposedly submitted an AES working paper outlining the advantages of his 6.0 alignment. Obviously, it never went anywhere because it's just not practical to reconnect the interconnects and speaker outputs everytime you want to hear one of Chesky's recordings.

And I believe that DMP and Telarc have done their own experiments with overhead channels (I don't think that either of them have issued any titles with this feature).

With a 7.1 alignment, obviously this creates a lot more flexibility to assign overhead and/or high-mounted ambient channels, without having to reconnect the wiring everytime you want to listen to a particular title. In a 5.1 world, Chesky's setup did not make a lot of practical sense because the vast majority of 5.1 material uses the center and subwoofer channels, so you can't leave your system connected for 6.0 listening all the time. But, with discrete 7.1, I'm still not so sure that having two back surround channels necessarily make the best use of those two extra channels. 

It would be nice if the newer HDMI 1.3 receivers and processors allow the flexibility to assign the 6 and 7 channels through more than just the back surround outputs in order to accommodate more creative uses for those channels. But, unless there's an outcry, I have a feeling that everything will simply use the back surround channels by default or just go with 5.1, since the vast majority of multichannel titles even now don't include any kind of ES or EX enhancement.


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## Sir Terrence (Jun 8, 2006)

Holy Woochifer,
This made my day. I am really glad you decided to hang out bro. How are things at AR? We have some catching up to do brudda.

Back on topic. When we speak of being immersed in sound, that would mean covered. Once again, there is no audible benefit of a stereo back wall. However a ceiling channel would complete the sonic puzzle and add true immersion to any mix that incorporates it. It is a much wiser use of the 7.1 palette than a stereo backwall, and it wouldn't require moving speakers around to accomodate the different audio formats.


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