# 7.1 Rear Height and placement?



## puffinak (Apr 3, 2010)

This has probably been asked, but I having trouble finding the answer.

I'm planning on moving some things around and add 2 rear surrounds, to make my system a 7.1 system. I've discovered some confusing info on placing rears.

First question is, How high should I place the rear surrounds? It seems both the THX and Dolby guidelines are silent on this. I'm guessing this is for flexibility on placement?

Second question, The THX and Dolby guidelines disagree on how far apart the rears should be placed. Is there a generally accepted way to resolve the difference?

Below is the information I'm referring to.

http://www.dolby.com/us/en/consumer/setup/connection-guide/home-theater-speaker-guide/index.html

http://www.thx.com/consumer/thx-technology/thx-surround-sound-modes/


----------



## tonyvdb (Sep 5, 2007)

The rear channels should be about 3ft above ear height and be at least 4ft apart. For some reason THX still wants you to place them side by side in the diagram posted and I have no idea why that is because thats for a 6 channel setup not 7 channel.


----------



## Mopar_Mudder (Nov 8, 2010)

Idealy they are suppose to be the same height as the surround, but this is not always possible. For instance for me with a rear rise the rears are higher then the surrounds because if I put the rears at proper height for the first row of seating they would be right behind the head of the second row. Don't read to far into the diagrams and do what works for your room, if you have one level of seating it is easier. For me my sides are a little higher they they should be for the first row and low for the second row, you just have to find a happy medium.


----------



## puffinak (Apr 3, 2010)

Thanks everyone. Mopar, the link your theater's pictures are awesome. If you don't mind me asking, what are the dimensions of your theater? Alternatively, do you have a link to a build thread with all that info in it?


----------



## Mopar_Mudder (Nov 8, 2010)

puffinak said:


> Thanks everyone. Mopar, the link your theater's pictures are awesome. If you don't mind me asking, what are the dimensions of your theater? Alternatively, do you have a link to a build thread with all that info in it?


Sorry never did a build thread. It is 14'-9" x 22'-0" (19'-3" to screen wall)
Ceiling height varies from 8'-3" to bottom of soffit to 9'-5" at the star ceiling


----------



## Mark Techer (Jan 17, 2008)

Mopar_Mudder said:


> Idealy they are suppose to be the same height as the surround, but this is not always possible.


Cinemas with stadium seating keep the surrounds the same height off the floor, so as the floor goes up at the back of the room, so do the surrounds. There is no reason why your back surrounds can't do the the same in the home. 

I think the reason there is no too much info on this is because all the diagrams from Dolby etc show speakers on speaker stands and not wall mounted. THX do show wall mounted but promote their ASA which places the back surrounds very close. 

I have THX select 2 plus and the minimum setting for spacing it has is 0~3ft, so I placed the back surround at 3ft (centre to centre) and in my small room, it works a charm.


----------



## Mopar_Mudder (Nov 8, 2010)

That is basically what I was trying to say also. All of the Dolby and THX stuff also only shows one level of seating, so they "want" the sides and rear at the some hieght for the listener but this not posibble for multi level seating.

Same things go for the sound level of the rears. For the best sound in my front row I need to have the sound level of the rears loud enough to sound right in the front row. But this gets too loud for the back row that is right in front of the speakers, so you have to go with a happy medium setting.


----------



## tonyvdb (Sep 5, 2007)

Mopar_Mudder said:


> Same things go for the sound level of the rears. For the best sound in my front row I need to have the sound level of the rears loud enough to sound right in the front row. But this gets too loud for the back row that is right in front of the speakers, so you have to go with a happy medium setting.


That is not the correct use of the rear channels, they need to be adjusted for the listeners of the back row not the front row. The 6th and 7th channels are almost always matrixed from the side surround channels even in 7.1 mixes some are not true indepandant mixes. The rear row should be at least 2 ft away from the rear speakers anyhow.
Remember that in real life sounds do not come from behind you louder if your farther away from them.


----------



## Mopar_Mudder (Nov 8, 2010)

tonyvdb said:


> That is not the correct use of the rear channels, they need to be adjusted for the listeners of the back row not the front row. The 6th and 7th channels are almost always matrixed from the side surround channels even in 7.1 mixes some are not true indepandant mixes. The rear row should be at least 2 ft away from the rear speakers anyhow.
> Remember that in real life sounds do not come from behind you louder if your farther away from them.


I think you misunderstood what I was trying to say. For us the primary seating location is in the first row center, second row is only for bigger groups. When you calibrate your system and set sound levels to all be equal at the primary seating location. The side effect of this it in the second row the rear are over powering because you are close to the rears and further from the fronts.

If you level set your rears for the back row you might as well not have them because you aren't going to get alot of effect out of them from the front row.


----------



## tonyvdb (Sep 5, 2007)

Looking at your photos I can see two issues: One the rear speakers are to low, they should be higher and two your rear seats appear to be placed right up against the back wall? I understand that this is a limitation of the room but thats going to be two of the main reasons you find them too loud if sitting in the back row.
You are correct that a compromise is the only answer for the levels but that is why you have the issues you talk about.

Nice looking room by the way


----------



## Mopar_Mudder (Nov 8, 2010)

Exactly is is all compromises not mater what you do. unless you are going to have a theater room with one seat in it and everything dialed in to that one chair, dont see that happening.

I keep everything tuned for the front center seats, anyone sitting in the back row is a guest and are generally happy just to be their in the first place. That is why I think it is better to optimize as much as possible for the main seating position while keeping in mind what it will do to the rest, don't get too caught up on having everthing exactly perfect.

My rears are too low for the back row, but they are a little too high for the front row, it is a compromize.


----------

