I have a project that is pretty much wide open. I would like your opinions on room dimensions for the theater. The customer has set aside a 25x25 x10 area but this is a house in the planning stage so plans can be changed. I understand we need to stay away from a square room but not sure of correct dimensions. We are looking at 8-12 seat and he wants it done right. No budget set aside yet. I have never done a true home theater so any input would be welcome.

AV RoomService would be happy to assist regarding optimal room dimensions and any other acoustical issues. Check out http://www.avroomservice.com or call 740-924-9321.

The purpose of managing room dimensions is to assist (not solve) in managing modal response in rooms. However, when we start getting into small room acoustics, particularily in residential sized rooms, making dimensional changes to meet one of the many magic ratios is rather counter productive. First, you’re going to have modal response issues regardless. Second, in a residential setting as much as you say you have some freedom in changing those dimensions, making a foot or two change isn’t really going to help anything. Third, modal calculators assume a 100% reflective wall but at modal frequencies that simply isn’t going to be true; and, fourth there are a long list of excellent approaches which can be taken in the room design and engineering phase to address modal response. If you want to assume changing dimensions will have a dramatic effect, then you also have to prevent anyone from moving their heads. Oh, and let’s not forget, we don’t care about modal response where no one will be seating.

In the end, find an experienced, well known designer (Norm with AV Room Service is one), examine all your constraints (room size only being one of those), and work with that designer to achieve your end goals with a good looking, good sounding space.

Best wishes and Happy New Year

Dennis Erskine
Erskine Group, Inc.
Architectural Acoustics
http://www.erskine-group.com

I agree completely with the two previous posts. 

Room dimensions get the most attention possibly because its easy to find a room mode calculator. 

Don’t forget about seating positions.  Even if you do have good dimension and good construction placing the seating in the wrong spot (s) can be just as detrimental to low frequency behavior as a poor room shape.     

A designer should be able to help you with that issue as well. 

I applaud you asking questions early.

Thanks for all the help. I feel I have an idea on how to proceed now. This is my first projection project and your responses have been helpful. I have talked with a few people I consider pretty good in the home theater market and I will probably have a consultant work with me on this. This is an extremely big project that it is just part of the bigger project of getting a 5 bedroom home set up with all the amenities including automation, distributed audio, and so on.

You’re most welcome. Getting a true expert involved at this stage in such an important project is the right way to go ... and a way to begin learning of the many issues involved in designing, constructing, specifying, and calibrating such a space. This appears to be a “launch pad” job into a new price point for you (I could be wrong); but, if so, that makes it all the more important this one is memorable and a reference point for your business. Such a person will educate you AND your client in the process!

The problem you’re facing now, is, well, you don’t know what you don’t know and could be foiled by someone who tells a good story but really has no real specific training or education in this field. Off the top of my head, I can think of not more than a dozen people so qualified in this type of room in North America! Surprised? Actually, it’s pretty disgusting more people in the industry don’t acquire the professional training needed to do the jobs they do.

So, if the first thing your “consultant” wants to talk about is the equipment, fire him and move on.
If he/she cannot provide academic, professional, or certifications specific to Home Theater or Home Screening Room design, move on.Check their creditials and professional associations. There are few you can seek out straight away such as Norm Varney, Dean Gainer (I don’t know him personally), Tony Grimani, Keith Yates, Russ Berger, Shawn Byrne, Gerry Lemay, and myself (I blush to disclose). (I’m going to get nailed by someone I forgot on this list.).

The other thing you could consider, is to have the client install a THX Certified Residential Screening Room. He may not be impressed with the idea of a THX logo for his room; but, view the THX process as one where you have an independent third party auditor involved making certain the client is getting what he paid for. Rather like having Ernst & Young come in at the end of the year to audit your books ... a third party auditor making certain there aren’t any “stooopids”.

Enjoy the journey!

Dennis

Thanks for the added information. You are exactly right in this stepping up a notch up (or two) in all aspects. I’ve always looked at the credentials with those I work with. I have a lot to digest and I know I will need a 2nd and or 3rd party to step in to attain the desired results for all aspects of this job. Do you know the current pricing of engineering and calibrating a THX Certified theater.

I do. If you’d like to email me or call me (number on the website), I can discuss their process with you.

Happy New Year

Following up on the idea of increasing your training and knowledge moving forward, CEDIA has available a 3 part webinar recorded (ESD301 - 303) from last summer.  Dr. Floyd Toole presented home theater audio and acoustics fundamentals over 9hrs.  I highly recommend taking time to listen to those webinars (atleast the first one in the short term).  Dr. Toole provides a great deal of background about what you need to know about small room acoustics plus insights on the snake oil being sold in the marketplace.  In particular, for part I he identifies room resonance concepts plus the speaker’s contribution over frequency spectrum.  He also provides some background about the origins of the “golden ratio’s” and the assumptions behind them.  This is an excellent place to start the journey towards a better understanding of what you don’t know, and will help you when working with the consultant on the room design from a sound quality perspective.

I’ve personally attended training from Anthony Grimani and Gerry Lemay.  IMHO, both would be excellent sources for an enigineered solution.  I noted from your original post that a budget has not been established with the client.  This is another key area where an expert can help you work with the homeowner on establishing the budget priorities and managing expectations.

connect,
I’d be more than happy to help you out. What you’re attempting to do is actually very simple once you have the right people & equipment in place.

I invite you to send me a private e-mail and I’ll spend all the time you need to help you make this project a total success for you and your client.

Dave