If you want to build a great home theater, the place you’ll be starting is the actual room itself. The size of the room, and the shape of the room, both will have a significant impact on the performance of your home theater. The room really is the key “component” to the entire project.
The room is the most important part of your entire system, which is the core philosophy of this entire site and all the resources available here. You can take incredible equipment and place it in a horrible room, and it will sound way below average – while on the flipside you can take average equipment and place it in an excellent room, and it will sound way above average.
In other words, your room is the critical element during the entire process of making your home theater dream come to life.
Of course, unless you are building a room addition, you do not have unlimited space to work with, and will have to deal with the constraints and limitations of the space you have available to you. And for most home theaters, the shape will be a rectangle, which is the easiest to work with, so that is a good thing.
The Bad Ratios
When we start getting into room dimensions, where we are talking about Length x Width x Height, there are some clear ratios that you should avoid, if at all possible.
If your only option is to work with a space that is exactly like one of these ratios, don’t let that stop you from building and enjoying your home theater, just do so with the knowledge that you will have to really work on the acoustics inside the space, once it is built.
So the worst room ratio, meaning the worst shape, would be a simple cube. For example, if you had a room that was ten feet long, ten feet wide, and ten feet high. That would be bad, very bad.
If you have a room where one dimension is an exact multiple of another dimension, that also would be bad (not as bad as a cube though). For example, if you had a room that was 16 feet long, 16 feet wide, and eight feet high, that would not be a good set of dimensions.
Related to the above, you should also avoid ratios that are all simple multiples of one another. For example, if you had a room that was 24 feet long, 16 feet wide, and 8 feet high, that wouldn’t be an ideal set of dimensions, because you have exact multiples of 8 in each dimension.
Modes, Waves, Peaks, and Valleys
The reason for not wanting a theater with these exact multiples is related to how sound actually moves around and resonates inside a room. That will be discussed in depth in another library article, but at the high level, room dimensions can make certain frequencies seem louder, and others softer, which is not something you want to have happening too much in your theater.
The Golden Ratio
OK, so this part of the discussion can quickly bring out some strong opinions. There is a school of thought that you can build a room with a “golden ratio”, which means the ideal and perfect ratio of length to width to height and your room will be wonderful.
The reality however, is that there is no perfect ratio. All rooms will have modes, all rooms will have acoustic issues to deal with, and all rooms have challenges. Since you cannot build a room without these, the issue then is to work with a ratio that is known to give you the least amount of trouble.
In Alton Everest’s Master Handbook of Acoustics (which is the best reference on these subjects) lists the ratios of four industry experts. Here are the four ratios:
Sepmeyer: 1.0 : 1.28 : 1.54
Louden: 1.0 : 1.4 : 1.9
Volkmann 1.0 : 1.5 : 2.5
Boner: 1.0 : 1.26 : 1.59
You’ll notice that even with these four experts, there is no one single Golden Ratio that everyone agrees on.
In almost all home theaters, the limiting dimension is height, we simply don’t have unlimited vertical space to work with. So when you are calculating your room, using one of these ratios, the 1.0 ratio will be your height, and you work out the other dimensions from there.
An eight foot ceiling height is average for many home theaters, so below are the dimensions using the ratio of height : width : length, and using eight feet as the ceiling height.
Sepmeyer: 8.0 : 10.24 : 12.32
Louden: 8.0 : 11.2 : 15.2
Volkmann 8.0 : 12.0 : 20.0
Boner: 8.0 : 10.08 : 12.72
Using this example and the Volkmann ratio, you would have a room that is 8 feet tall, 12 feet wide, and 20 feet deep.
What This Means
At the end of the day, though the theory is nice, you have to work with the space you have available to you. If you have a large open space, or if you are adding on a new space, you can create a room that is using one of these more preferred ratios, dimensions without multiples of one another.
If you are working with a room that is already defined in dimension, then that is what you work with – don’t skip out on all the fun of home theater, just because you have a wall that might not be in an ideal location.
If you are building in a basement, for example, and you can move a wall to give yourself a bit better room dimension ratio, go ahead and do that. Yes it is a little bit of work, and has a little bit of cost, but for a space you are going to enjoy for years and years, moving that wall will improve your theater experience.
The last point is simply this, don’t get too stressed about the dimensions. Home theater is an incredible opportunity to have a space in your house unlike any other. Work with the space you have, change it as you are able, and then enjoy your room!
If you want to learn more about how to make a room like this come to life, you need the Ultimate Course on Designing and Building Your Dream Home Theater.