What is the best shape for an audiophile listening room?

I was wondering, if you had an opportunity to build a custom listening room, what would be the best shape, in 3 dimensions, of that room. For instance would a half sphere or dome shape be best? What about a cube or an elongated cube?

Also where would be the best location to place the speakers in within that shape?

I know this might get scientific but I don't mind.

I am looking at achieving the ideal sound both on and off axis.

Thanks for your input.

 

I suggest you do a Google search or a search of Amazon.com. There have been many books written that provide the information you seek.

The "...ideal sound on and off axis..." is also very dependent on your speakers. If you have speakers that are very directional (some planars come to mind) then you will have a problem off axis.

An important consideration in designing a listening room is to avoid, if possible, 2 sets of parallel walls. That configuration can create standing waves in the bass frequencies, especially near the corners.

 

I would recommend the following:

1. Look at George Cardas comments at www.cardas.com

2. Pick up Bob Harley's Guide to High End Audio book which discusses listening rooms.

Overall you want a rectangular space with room nodes minimized. Stereophile had a free download program at its site at one point...

 

I always heard just the opposite, that you do not want a rectangular space.

 

I would start with a room of 4 non parallel walls, ceiling and flooring...

 

The good thing about a rectangular room is that it is very predicatable (plus it's cheaper to build than odd shapes!). Yes, you do get standing waves (you get standing waves in any room) but they are predictable and easy (easier) to deal with.

In a room with non-parallel walls, you still have standing waves. However, it is a lot harder to work out what the standing waves are doing in the room and their effect on the sound. Small changes of position (speakers and listeners) can also have surprisingly large changes in sound, compared to a rectangular room.

There are certain ratios of room dimension that spread out standing waves in a rectangular room. There are plenty of books that explain these and the physics behind them.

 

Hello GS.

You may find useful my Mediaroom spreadsheet (MRSS), its Read Me file and bibliography.

The MRSS advocates the following room ratios: 2.21, 2.10, 1.

The floor plan is almost square which allows then for a diagonal orientation. My current thinking these days is along diagonal orientation of the equipment and listeners/viewers

All room have resonant nodes. Fancy shapes only make them more difficult to predict and tame.

Request the MRSS by sending mail to [email protected]

 

From everything I've read, a rectangular room with solid floor and walls is a good place to start. Things to avoid are dome shapes, openings to other rooms off of the listening room, and peaked cathedral ceilings. Some of the recommended dimensions I've seen include: 10'Hx16'Wx26'L, 9'Hx18.5'Wx28'L, 10'Hx17'Wx27'L. My listening room is close to these dimensions and after some wall treatment is very good.

 

No room shape does entirely away with room modes and specular reflections. In rectangular rooms, however, they are much easier to map and are, thus, easier to predict and remedy. Dimensional ratios are also important and there is a wealth of information about this, most of it good, available on the net.

Cubes are bad, you've got three identical sets of modes reinforcing each other. Domes, since they are round at the floor level, have one extremely dominant mode with, since they are half-round in cross-section, another reinforcing it one octave higher (the floor-to-ceiling distance would be half the diameter of the floor dimension). Additionally, there may be one symmetrical, dominant echo that, if the room is large enough, may be delayed from the direct sound to be a problem. One of the colleges I attended had a domed gymnasium that we used once in a while for choral concerts; and the easiest way to talk to someone backstage was to go backstage- the second easiest was to go to the opposite side of the gym.