Listening Room Dimensions

If you were building a dedicated listening room from scratch, what dimensions would you make it and why? Is there an optimal size or a happy medium that would work well for most applications?

Vintagear said:

If you were building a dedicated listening room from scratch, what dimensions would you make it and why? Is there an optimal size or a happy medium that would work well for most applications?

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I'm not sure there is a single optimum size, but I would definitely avoid one with even multiples of room dimension and height. I built a house in '96 and specified to the builder a dedicated listening room in the basement. Unfortunately, I didn't control the result and ended up with a large - but undesirable result. The room was 14x28x7. There were bass modes aplenty!

The dedicated room in my current house is far more linear with 16x25x7 dimensions with angled walls and two dormers that break up the four wall box I used to have. Measured bass response with the stats is now +/- 1.5 db from 30 hz to 200 hz.

Before you build, get acquainted with room modes. There's books and software readily available.

The quickie description is available on wikipedia:
http://en.wikipedia.org/wiki/Room_modes

The actual room size (small, medium, large) isn't important from a sonic perspective--you can get good sound from headphones having almost no space beyond your head; as long as you're willing to do it alone. (Multiple people listening to the same thing in the same room via headphones is like the sex scene in the movie Demolition Man.)

http://www.youtube.com/watch?v=k80UQWWUIYs

You'll want the room big enough to serve the expected number of people you intend to put in the room; and then you need to decide if they'll be standing, milling around, seated randomly, or seated like a theatre. How big is the TV/projection screen? IS there a TV?

Speaker selection also plays a part in room size--or the other way around. Panel speakers like Magnepans would like to be pulled away from back walls, Polk SDA and many other speakers would like to be pulled away from side walls. Speakers that don't like walls--which is most of them--are a pain in the ass because you can write-off most of the area behind or beside them. Klipsch corner-horns are very friendly because they want to park out-of-the-way in the corners, tight against two walls--maximizing usable floor space, and automatically toed-in to a central seating area.

With any listening room, you're more-or-less locked into a centralized seating area--doubly so with surround speakers in the room. How big does your room need to be to put your desired number of people in the middle of it, with lots of "wasted space" all around them?

I might go with the "golden mean", or Fibonacci's number.
Get the dimensions to be in multiples of,
1.618 or 0.618,
this seems to be a good dimension to avoid reflections.

I'd use a sonically transparent screen and have 3 identical speakers (NO horizontal center channel speakers) at the same height for L/C/R that would sit behind the screen. I'd deploy a distributed bass system. And I'd also get some measuring equipment and use DSP. I'd also set some $ aside for room treatments.

I'd investigate all of the above long before jumping in and buying any equipment.

Interesting comments.

Thanks to all for the input.

One should try to avoid appearance of standing sound waves. Try to avoid cubic rooms as a starting point. Try to avoid regular shapes and perfectly parallel walls. Try to avoid perfectly reflecting surfarces, if possible.

I designed the whole back of my house to be one large listening area when the blueprints were draft.

The room with my speakers is 23.5 ft x 17ft x 8ft ceiling which is open to my 19.5 x 12.5-15 ft kitchen with a 13.5ft ceiling.