New Construction, Theater Size & Ratio Help For Best Sound - AVS Forum
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post #1 of 9 Old 11-04-2009, 07:53 PM - Thread Starter
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We are designing a new home that will have a dedicated home theater. I've done research on the web regarding the ratios of height, width and depth.

Basically, I have learned that no dimension should be within 5% of a multiple of another dimension. For example, my ceiling is 10' high so therefore the width of the room should be less than 19' or greater than 21'.

My present design has a 10' ceiling, a width of 17' and the length varies between 20'-6" and 20'-8". Ideally, the length should be 21" or greater. The screen will be on the short wall (17') and is inset into that wall about 2". That is why the length varies.

The wall opposite the screen will have a window (the only window). In front of that window will be blackout drapes that will likely be the entire width of that wall. So the drapes will effectively shorten the room to about 20' in length (about twice the room's height).

The drapes will probably be pretty good sound absorbers and we will have other furniture in there as well.

I am interested in opinions from people experienced with this issue.

Thank you for your assistance.
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post #2 of 9 Old 11-04-2009, 10:11 PM
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Forget acoustic ratios....its a nice to have, but you're still going to need to treat it.

Pick how many people you want it for.

Pick a type of chair and layout.

Design the room size around that.

Pick a screen size and determine good viewing angles/distances. The rest will take care of its self.

You're going to need to do some more reading if you think drapes are an adequate form of treatment. Start with Flyod Toole's book called Sound Reproduction.

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post #3 of 9 Old 11-04-2009, 11:04 PM
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Quote:
Originally Posted by Elill View Post

Forget acoustic ratios....its a nice to have, but you're still going to need to treat it.

I will have to disagree with this.
You have to treat and design the room to be ideal.

If you end up with a very poor room characteristics then treatments can not compensate. A room with excessive harmonics can't be patched up with a few bits of fiberglass here and there.
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post #4 of 9 Old 11-05-2009, 02:25 AM
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Quote:
Originally Posted by Goshwin View Post

I will have to disagree with this. You have to treat and design the room to be ideal.

Toole says "the acoustical performance of rooms cannot be generalized on the basis of their dimensional ratios and that reliably hearing superiority of a “good” one may not be possible." pg 207 of Sound Reproduction. He explains it further in much more detail, but it is like 3 chapters.

Do you disagree with him? if so, show me the papers/science to back it up and I'll be all ears.

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post #5 of 9 Old 11-05-2009, 03:17 AM
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Peter's advise is correct. Just try to avoid making the obvious errors like building a cube.

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post #6 of 9 Old 11-05-2009, 03:30 AM
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In residential rooms, this room ratio business isn't worth the time you've already spent on it. On the other hand, there's a whole gob of "good ratios" so pick your dimensions ... you'll likely find a "good ratio" that maps to your room dimensions.

Dennis Erskine CFI, CFII, MEI
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www.erskine-group.com
www.CinemaForte.net
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post #7 of 9 Old 11-05-2009, 08:39 PM
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There is volumes of science and engineering that has gone into this topic, but I am not here to teach. But I will be more exact with my point of view.

I find the statement "Forget acoustic ratios....its a nice to have, but you're still going to need to treat it." to be misleading. This implies you will have to treat the room anyway so its no big deal. But it is important and as Cathan warns "don't build a cube" this is due to the severe problems that it will cause which is the point I am making, and you can't treat those problems away.

So if you are building a room, and if sound quality is important to you, then room ratios is an important element of the total picture. This is in addition to the other elements of screen, seating and so forth.

Now for the other view, if you are setting up a casual home theater where audio is not that important to you then its it does not matter since many people don't care if the room reverberates at 80 hz or stereo imaging is non existent. most rooms would work well and get you lots of thrills no matter what ratio you have.

But here is the critical point that many might ignore, if you have spent some time with high end audio then pay attention to room ratio, you will notice the effect by a large margin. If not, then it wont really matter (but still don't build a cube)
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post #8 of 9 Old 11-06-2009, 06:23 AM
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Guess its time to pull this link out again:

http://www.avsforum.com/avs-vb/showthread.php?t=793482

Erskine, Kras, Bpape, Terry (especially) are all very knowledgeable on acoustics. Read their posts closely.
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post #9 of 9 Old 11-06-2009, 04:02 PM
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I was told use the 1.618 rule.

Width x 1.618 = Length

Width / 1.618 = Height

Mike Miles

ICR [ Sales Consulting and Small Part-Time AV shop, very small...  ]

Process Integration, Inc. [ contract sales consultant ]

Eastern Shore of Maryland

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