For those who have the luxury of actually building a room dedicated to home theater, who can choose the dimensions in advance, the "golden ratios" apparently will go a long way to minimizing pesky standing waves.

The idea of the golden ratio is to find a combination of height, width, and length wherein the room dimensions are not arithmetic multiples of each other. An asymmetrical room, where no single dimension equals or is a multiple of any other, would approach the ideal.

I'm wondering what people think of ideal in terms of room dimensions and contruction technique when it comes to building a new contruction home theater. For so many years now, I have had the 'golden aspect ratio' memorized which is essentially a 20' x 30' x 12' room. However, maybe this is not correct. Are the golden ratios: 1 x 1.6 x 2.33, or are they 1 x 1.67 x 2.5?

Secondly, how do people feel about using the golden ratios in addition to non-parallel walls (sloping ceiling and sloping walls)?

I was thinking that 20' x 30' x 12' was a little too small for my tastes. However, to squeeze out a little more width and depth, you need to raise ceiling height when sticking to the golden rules. For instance, you need a 14' ceiling height to get a 23.33' x 35' room. To me a 23.3' x 35' room sounds about the right size for me. In fact, I wouldn't mind going even slightly bigger, but that would require 15' ceilings or such. Being this is new construction, this could be done, but I think ceiling height getting to large is a waste of square footage, especially in a place like california where the 10,400 sq foot lot is 1.4M. Any thoughts would be appreciated.

I have owned Allison's "Master Handbook of Acoustics", and "Sound Studio Construction on a Budget" for over 10 years but still have not had the time to read them. Being in California, we cannot build true basements here, so I'm wondering what sort of wall construction people recommend? Cncrete walls with floating gypsum board, staggered stud walls, etc...

Never mind the golden ratios:

http://www.avsforum.com/avs-vb/showthread.php?p=9564177#post9564177

There are several heavyweights posting in that thread (Krasmuzik, Bpape, Montlick, Erskine, etc), who seem to agree - avoid square/cubes - try to avoid having dimensions being multiples - get the biggest room you can. The ratios don't work in home theater settings as the rooms are too small compared to symphony halls.

As for building techniques, either hire Dennis Erskine (we owe him a referral after some of the nonsense he's gotten lately) or look at the 4th link in my sig and follow the link to the soundproofing company for their articles. Short answer - room within a room framing, multiple layers of drywall with green glue, well sealed heavy solid core door, thought out HVAC for comfort and flanking, outlets and wires in soffits & columns to avoid penetrations in your sealed drywall envelope. No can lights or use backer boxes for lighting.

Thank-you. I did understand the one argument about making room modes predictable, so you could more easily eliminate them. However, I'm more along the lines of thinking about sloping ceilings and non parallel walls, or at least wondering about them... as well as other shapes besides rectangles since this would be a new contruction house.

Thanks for the nutshell on construction principles as well!!

How do you feel about the use of splayed walls and sloping ceiling to improve diffusion?

After looking at my current room, I really think that I would like a width of 27-30 feet. I'm looking to do front row and a second row only. What depth do you recommend if I have a width of 30 feet? What ceiling height would you recommend?

Thank-you,

Chris

On another note, I'm sure there are completed plans for new construction home theater. It seems to me to try and find completed architectual designs and just use those. No reason to re-invent the wheel, just find a theater that is close in size to what you want and use those plans. Thoughts?

I though about doing angled walls inside my room, but my research suggested that the angle had to be fairly substantial, like 20 degrees, to be effective. I don't remember the exact number, but it was large enough that I would have lost a large part of my front wall. If you're building new that may not be an issue.

I have no problem doing that... I'm looking at Alston's Sound Studio Contruction on a Budget... and the Master Handbook of Acoustics... I've owned them for 10+ years, so not sure if they are dated.

I really like a nice wide room. I really think something on the order of 27-30 feet wide would be desirable. Perhaps a 30'W x 24' long room would work? If acoustics weren't the issue, I'd do a 30' x 30' room, however, that obviously isn't desireable. What is the depth required for two rows of seating with a 13' wide 2.4 screen? Personally, I like closer than recommended viewing distances. I prefer a 1:1 ratio for the first row (in this case it would be 13' feet). Thoughts?

With these types of room aspirations, why wouldn't you make sure the job was perfectly and hire a designer? Might be the best dollar spent.

I'm here for discussion at this time. Since this is new construction, all it takes is an already known floor plan similar to my size requirements...

No reason to re-invent the wheel, just find a theater that is close in size to what you want and use those plans. Thoughts?

There is more to it than just the floor plan when it come to designing the room. You may be able to lift the room dimensions from a professionally designed space shown here, but you aren't going to get how the thing was built, treatment specs, etc.

That being said, use the theaters as inspiration to help you figure out what is right for you. If you think you can then design it on your own, go for it.

Does anyone here have a 25+ foot wide theater?

I have clients and Post houses with 25' widths ... but more than 30' in depth.

Golden Ratios: Pick one. There are hundreds and they equally do the same thing ... little to nothing. The thought behind a "golden ratio" is to reduce the negative audible impacts of room modal response. The problem is you're going to have modal response anyway and the tools, methods, strategies and tactics to deal with them are the same Golden Ratio or not. In the end, smooth bass response at the seating locations requires far more than what any Golden Ratio can provide.

With a sloped ceiling, the modal response would approximate the modal response of a flat ceiling with the same height as the average height of the sloped ceiling. Rectangular rooms with different dimensions (niches, atriums, etc) have multiple modal responses based upon each rectangular area.

Asymetrical rooms are problematic.

Ok, so essentially splayed walls with sloping ceilings is not worth the trouble and makes modes harder to correct I guess. Well, that is good news I suppose, it makes construction that much easier... I went and looked at my current room and without question, the range I'm looking for would be 27-30' wide and 37-39' long; essentially 28' x 38' seems about right. Not sure if the ceiling height matter in this scenario, but it really could be anything. Certainly 10' ceilings seem about right, but could do anything from 10-14' if something is more ideal. Well, at least now I know what I am shooting for in room size, that is step one: 28' x 38' x 10'

Asymmetric and splayed are two different things.

Ok, so essentially splayed walls with sloping ceilings is not worth the trouble
You're getting oncogenes and aneuploids mixed up (I stayed at a Holiday Inn). Splayed walls can be beneficial (or not); but, not for modal response. The only real way to accurately know what modal response is for a room is to measure it once the room is built. Splayed walls, sloped ceilings in a room of that size affect in room response above about 300Hz.