Room Ratios

[onlyone-jc]

Hi.

When working out a good ratio for a room, how do you make it fit correctly?

For example, if you have a high ceiling in a small room, most of the ratios that you're calculating are requiring either a much lower ceiling height in order to work (in theory) with the current length and width of the room, or a much larger room in order to work (in theory) with the current high ceiling height.

Or, if you have a low ceiling in a large room, most of the ratios that you're calculating are requiring either a much smaller room in order to work (in theory) with the current low ceiling height, or a much larger ceiling height in order to work (in theory) with the current length and width of the room.

Example
1:1.14:1.39

If you required a much larger room, and to make this example easy, in which being double the length and width of the above ratio; would it be acceptable to simply half the required ceiling height, and so resulting in a ratio of 0.5:1.14:1.39, or effectively 1:2.28:2.78? Or, would this cause a lot more modal problems than the original ratio?

I hope I've explained this properly, I know it may seem like a load of babble.

I'd appreciate all of your knowledgeable explanations.

Thank you,
onlyone-jc.

[Ethan Winer]

JC,

> When working out a good ratio for a room, how do you make it fit correctly? <

Either it fits or it doesn't.

1) Room ratios are relevant only if you have the luxury of building a new room, or are able to move walls. If you have an existing room all you can do is treat it with as many bass traps as possible.

2) If you have a small space - less than 1500 cubic feet - forget the ratios and just build the room as large as possible.

3) Acoustician Floyd Toole recently published an article that makes a good case for not worrying much about room ratios. I'm not saying I agree with that completely, but he makes some good points. The main point is that most loudspeaker locations will not excite all room modes equally, so some of the modes don't matter anyway. However, if you have a subwoofer in a corner it will excite all the modes, and Floyd did not mention that in his article.

4) I think the main thing to avoid are dimensions that are the same or 2-to-1 multiples. So a room 10 by 10 or 10 by 20 is not good, but most other combinations are not so terrible they can't be wrestled into submission given enough bass trapping.

--Ethan

[onlyone-jc]

Thanks for that, Ethan. Much appreciated!

onlyone-jc.

[knightfly]

One thing to keep in mind; it doesn't matter from a modal standpoint whether your 1:00 dimension is height, width or length. The BBC used to build voice-over rooms with intentionally high ceilings in order to NOT take up valuable floor space and still get the ratios they wanted. Example - modally, a 10 x 16 room with a 23.3 foot ceiling is still the same as a 16 x 23.3 foot room with a 10 foot ceiling... Steve

[onlyone-jc]

That seems like a very valid point! Thank you, knightfly!

onlyone-jc.

[Ethan Winer]

Steve,

> modally, a 10 x 16 room with a 23.3 foot ceiling is still the same as a 16 x 23.3 foot room with a 10 foot ceiling... <

That's a good point, but I'll clarify one thing: What seems to matter most is having enough room length. If for no other reason, being farther away from the rear wall behind you avoids the worst of the non-modal peaks and nulls.

--Ethan

[knightfly]

Agreed; given the choice, I'd take a room where ceiling height is the shortest dimension (as long as it's at least 12 feet, that is ) Steve