# 7.1 speaker layout.



## Scuba Diver (Sep 28, 2007)

My brother and I are setting up some speakers for his home. He has a THX system. He is using all monopole built in speakers. His seating will be near the back wall. 

Here is my question: If using the Advanced speaker array it says to place the rear speakers next to each other on the back wall facing the front of the room. However, using TRUEHD or DTSHD it say to spread out the rear speakers to provide a 60 degree angle from the main seating area. 

Which do you think would be better.


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## eugovector (Sep 4, 2006)

If you're talking about the setup diagram I've seen, with the rear channels right next to one another on the back wall, I've never understood the reasoning behind it. Seems like spreading out the rear channels would give you more of a 360 sound field.

Anyone care to enlighten me on the benefits?


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## bobgpsr (Apr 20, 2006)

Scuba Diver said:


> My brother and I are setting up some speakers for his home. He has a THX system. He is using all monopole built in speakers. His seating will be near the back wall.
> 
> Here is my question: If using the Advanced speaker array it says to place the rear speakers next to each other on the back wall facing the front of the room. However, using TRUEHD or DTSHD it say to spread out the rear speakers to provide a 60 degree angle from the main seating area.
> 
> Which do you think would be better.


My understanding was that Dolby & dts reccomend seperating the 7.1 rear surrounds (even when only driven by a matrix rear sound recovery from the side surrounds). This is to avoid the phantom rear channel sound from seeming to come from the front (center) which was a problem with 6.1 systems.


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## Scuba Diver (Sep 28, 2007)

OK. So which is better, letting THX Advanced Speaker Array work its magic or using the separation as recommended for Dolby?

The picture of proper layout was provided on the THX website. The first link is for THX Advanced Speaker Array. http://www.thx.com/home/setup/speakers/71.html
My only guess is that THX processing provides an effect for this type of setup. 


The second link shows the Dolby recommended setup. 
http://www.thx.com/home/setup/speakers/dolby.html
My concern is he does not have extra speakers to work with. So once the speakers are placed there will be holes in the walls.

I don't claim to know it all and that is why I love this site. :dontknow: Any help here would be great. Just an explanation of why THX recommends the set up this way would be very helpful. Is one better for movies. It is a movie room and will be the primary purpose for the room.


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## eugovector (Sep 4, 2006)

I'd go Dolby.


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## Scuba Diver (Sep 28, 2007)

Any reason?


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## bobgpsr (Apr 20, 2006)

Scuba Diver said:


> Any reason?


you heard mine:

"to avoid the phantom rear channel sound from seeming to come from the front (center) which was a problem with 6.1 systems"

Do you have evidence that says this is not true?


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## Scuba Diver (Sep 28, 2007)

:bigsmile: Yes I guess I did. 
Do you know of any posts or articles that recommends Dolby setup over THX array? If not I still appreciate your feedback.


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## eugovector (Sep 4, 2006)

Scuba Diver said:


> Any reason?


Same as mentioned in my previous post, for 360 degree sound, it would seem that putting two speakers next to one another would be counterintuitive.


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## Scuba Diver (Sep 28, 2007)

I have found more information on DTS and am very certain I will going with the Dolby recommendations. 

The Dolby website offers many alternative speaker layouts compared to the limited THX website suggestions. http://www.dtsonline.com/dts-hd/71-full-rear-surround.php This is the link to the Dolby HD site.


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## Sonnie (Apr 11, 2006)

You know... looking at this recommendation...











It would seem to make sense that on 5.1 the rear surround speakers should be placed in the rear corners, instead of on the sides as I've typically seen.


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## Scuba Diver (Sep 28, 2007)

Sonnie I agree. Did you look at the other alternative setups as well? It is very interesting. Some of which I would never have though of trying. Like this one...


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## Sonnie (Apr 11, 2006)

Hmmm... an overhead center... now that is interesting.


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## John Simpson (May 10, 2007)

A centre overhead?? Wow, what a bizarre concept. I guess all they're trying to do is fill the soundstage, and the listening position has always been a bit of a hole. Did you guys see the article in a recent Popular Mechanics about a 22-speaker surround system? Speakers placed in a *sphere *around the listeners...

Regarding the rear speakers, I'm more inclined towards the THX recommendation of two rear speakers, reasonably close together. The rears receive a markedly different signal to the side speakers, and having them too close together will skew the soundfield towards the sides of the room.

That said, every room is different. I've mentioned this previously, but surround sound utilises _reflective _sound properties of the room, as well as direct sound, to give the illusion of an encompassing sound field. As every room is different in this regard, so will be speaker placement. Finding those ideal speaker placements are another story (and a solution I don't have!)...


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## eugovector (Sep 4, 2006)

Sonnie said:


> You know... looking at this recommendation...
> 
> 
> It would seem to make sense that on 5.1 the rear surround speakers should be placed in the rear corners, instead of on the sides as I've typically seen.


Dolby's always said 90-110 on the sides, so it's within their spec.

It looks like the picture is deceptive, where the speakers are drawn, that's def not 110.


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## F1 fan (Jul 6, 2006)

Humm, I find it abit puzzling that they recommend using the two rear channel speakers beside each other.Two speakers in close proximity reproducing the same signal will suffer the affects of comb filtering.


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