Absolute Ideal Theater Room Dimensions?

[Dominick22]

So I am finishing my basement and trying to figure out the best dimensions for the dedicated theater room. The space I have as of right now is 25' 2'' by 15' 6'' which I am thinking is a bit longer than optimal dimensions.

I can shorten the 25' 2'' by any amount, but what would match the 15' 6'' best? Is there a dimension rule to use like the width should be 2/3 the length?

The monitor will be on the 15' 6'' wall by the way so I just need to figure out how long to make it??

Theater i, Ascent i, Clarity, Descent

Thanks guys,

Dominick

 

[zaphod]

would it be too long? the best room i ever heard, bar none, was 35 by 17 by 12 high. and very little acoustic treatments - bookshelves across the back wall, light weight curtains behind the speakers, wool rugs on a hardwood floor. just great sound.

my room is 18 long and once i have the sofa at the correct position for the 90" screen even with the CLS, i get only 4 or 5 feet behind my head until the back wall is hit. i'd much rather have 2 more feet behind me.

don't trim down the 25 foot length.

 

[DrJRapp]

What is the ceiling height?

 

[risabet]

Using Phi or the Golden ratio
<dl><dd>

<sup id="cite_ref-quadform_0-1" class="reference"></sup></dd><dt>a 15.5' room should have a length of 25.1' or so. Using the GR gives your room ideal dimension regarding standing waves. A ceiling height of 9.6' or so rounds it out nicely. Using this as a measurement assures that there are no common frequency multiples along different room dimensions, i. e. no shared standing waves in the room. All in all it appears that your room is very close to the GR which has pleasing connotations for both the eye and the ear.
</dt></dl>

 

[RUR]

Here's some information from a 2004 AES paper,
http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=best

Dunno the extent to which this applies to HT, though.

 

[MiTT]

Using Phi or the Golden ratio
<dl><dd>

<sup id="cite_ref-quadform_0-1" class="reference"></sup></dd><dt>a 15.5' room should have a length of 25.1' or so. Using the GR gives your room ideal dimension regarding standing waves. A ceiling height of 9.6' or so rounds it out nicely. Using this as a measurement assures that there are no common frequency multiples along different room dimensions, i. e. no shared standing waves in the room. All in all it appears that your room is very close to the GR which has pleasing connotations for bo0th the eye and the ear.
</dt></dl>

Exactly what I was going to recommend. The Golden Ratio works very well for many design ideas.

 

[Dominick22]

Thanks guys! I guess I just kinda figured that it would be too long and that I could make better use of the space in another room.

I think I will leave the dimensions alone since they just so happened to work out so well.

Only problem I see is universal 8 foot ceilings but still pretty close to ideal!

I knew I would get the answer here!
Thanks again,
Dominick

 

[JonFo]

Hi Dominick,

I'll not be recommending a specific dimension or ratio for you, but instead will point you to a couple of sources that will help you determine what will work best for you.

I'll also throw in some ideas, but you know that was coming as well

First, you are lucky to have the option of adjusting one of your dimensions to help improve the results.

You can read more about optimum room sizing (and get a demo of the software to explore this) at RPG site:
http://www.rpginc.com/products/roomsizer/rs_compareo.htm

The discussion is very cogent and coverts the bases. Keep in mind that you are really looking at it this for small rooms. Some of the research applies only to larger volumes.


RPG also has an application that not only helps you see what would happen in your room, they provide some recommendations for treatment and placement. But and this is major, it's all based on monople, wide-radiation pattern (in the HF) point source speakers. Not what an ML is. So its results need to be adjusted (and in some cases ignored). So it's not a go get it and follow it type solution. But for $99, seems to give a lot of info. I used it 9 years ago when I designed my room.

Bass, which is the biggest small room issue, is fortunately agnostic as to style of speaker. therefore up to about 300hz, most of the advice is applicable.

http://www.rpginc.com/products/roomoptimizer/index.htm


Idea:

As long as you are ‘adjusting’ the length of the room, you could actually build-in some of the bass traps into the rear of the room. Just leave part of the drywall off, stuff the cavity with fiberglass (and use some high-density stuff (2” OC 706) at the room juncture, and then seal the aperture with GOM stuffed into Fabricmate tracks. We can start a separate thread about that in the acoustics forum.

 

[JonFo]

Here's another article on room ratios:

http://www.cinemasource.com/articles/room_modes/modes.html

But it seems to limit one to Sepmeyers ratios.

 

[JonFo]

This graphic correlates a lot of research info into one nice graph.
This one is based on Louden’s research.

Just calculate your width and length ratios (vs your height) and then see how close to one of the darker green areas you really are.

 

[JonFo]

Thanks guys! I guess I just kinda figured that it would be too long and that I could make better use of the space in another room.

I think I will leave the dimensions alone since they just so happened to work out so well.

Only problem I see is universal 8 foot ceilings but still pretty close to ideal!

I knew I would get the answer here!
Thanks again,
Dominick

Dominick, not so quick

If your ceilings are indeed 8' (eight feet), then you have some work to do.

Your volume is definitely large enough, but the ratios of your length (3.15) and width (1.94) relative to your fixed height are way off the recommended zones in the graph above (and several other guidelines).

The problem is the low ceiling, and even if you truncated the length to 21', you're barely getting into the Louden zones.

More work and exploration to be done here.

What are your goals and constraints regarding the length. Do you have a proposed layout of speakers, seating, screen?