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room dimensions

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Posted on October 11, 2009 at 14:06:24
dazzdax
Audiophile

Posts: 109
Location: Diemen
Joined: February 26, 2005



Hi folks, this is a schematic drawing of my house that is going to be built in the near future. As you can see the living room/listening room is quite long in comparison with it's width. The dimensions are (in feet): 42(L)x18(W)x11(H). Somewhere in the middle at one side of the room there will be a gas fire that is protruding into the room. The kitchen is semi open. What do you think of these dimensions? Are they OK for audio? Thank you in advance.

Chris

RE: room dimensions, posted on October 12, 2009 at 02:21:26
KlausR.
Audiophile

Posts: 1867
Joined: November 17, 2004
 Basically there is nothing wrong with those dimensions. The fact that the room opens to the kitchen makes room mode behaviour unpredictable. The pressure lines will no longer be parallel to the walls but curved, or there may even be "pressure islands". The only way to know beforehand is finite element analysis.

If the fire place is floor-to-ceiling, it too will affect mode behaviour.

Should there be still budget, I recommend an acoustic ceiling, especially if the walls are brick 'n mortar or concrete and the floor is tiled. Our Plameco ceiling has 26 cm air gap above and is extremely effective. It acts as a huge membrane absorber (read bass trap) and handles both vertical and horizontal room modes.

Klaus

Ain't quite as simple as that…, posted on October 11, 2009 at 16:11:29
David Aiken
Audiophile

Posts: 5108
Location: Brisbane
Joined: September 25, 1999
 because you got the dimensions wrong. You didn't consider the bend in the room at the back which is also going to have a noticeable affect on the acoustics, and the gas fire will have an impact too though that impact is going to depend in part on it's vertical dimensions and the nature of the walls of the fire that are exposed to the room.

It's a big space which is all to the good. The length isn't an exact multiple of the width which is good. 18' is quite enough width to allow the speakers to be kept away from the side walls if necessary which is good. It's a relatively high room which is good.

In short there are a lot of good things about the room and its size gives you considerable freedom to experiment with speaker and listening position placement, even in the area below the gas fire in the diagram. I see no reason why you shouldn't be able to get quite good sound in the room with a bit of work on the setup side of things. Depending on furnishings and whether or not you can use physical acoustic treatments to modify the results to suit your taste, you will probably be able to achieve very good results.

Dimensions don't guarantee results but they can help, especially if they provide ample space to work in. Good sound is a matter of setting things up to get the most from your system, especially from your speakers since the speaker/room interface is critical and different speakers can have very different requirements as to placement. Acoustic treatment can reduce some room effects such as modal effects in the bass frequencies and also reduce or eliminate other problems introduced by the room as well as tailoring the overall result to your particular tastes.



David Aiken
RE: Ain't quite as simple as that…, posted on October 12, 2009 at 11:23:55
dazzdax
Audiophile

Posts: 109
Location: Diemen
Joined: February 26, 2005
 Thanks for your input guys, it certainly helps a lot! The room is very lively because the walls are concrete, the floor and part of the gas fire surrounding is granite. I do have a rug for the floor in front of the listener between the speakers and I will have curtains in front of the windows.

Chris

Reverberation, posted on October 13, 2009 at 00:49:08
KlausR.
Audiophile

Posts: 1867
Joined: November 17, 2004
 We have friends in The Hague who have a dining room with wooden floor, table and chairs, light curtains. Intelligibility is very bad which makes the room extremely uncomfortable, in my opinion.

When we built an extension to our house in 2002, I took the occasion and included acoustic treatment, as invisible as possible. This ceiling is perfect because you can see it without being aware that it's an acoustic ceiling.

To the best of my knowledge there is no research re: reverberation time in small listening rooms, so I would not bother too much trying to find stuff that has even absorption coefficients across the frequeny spectrum. Anything absorptive will be fine and your ears will tell you if you feel comfortable in the room or not.

When we discovered Plameco I asked for technical info, in particular for absorption coefficients. If you wish, I can scan and mail that info.

Klaus

RE: Ain't quite as simple as that…, posted on October 12, 2009 at 13:09:36
David Aiken
Audiophile

Posts: 5108
Location: Brisbane
Joined: September 25, 1999
 If the room is very lively then you may need more absorption to tame the sound than soft furnishings can provide, especially if the overall absorption spectrum of the furnishings is not tonally neutral and it would be exceptional for furnishings to provide a wide band, tonally neutral absorption profile. For that reason I'd recommend going with good quality commercial products if you need to add absorption.

Bass trapping would be my first priority and, because of room shape, I'd go for floor to ceiling traps in the corners behind the speakers or something like the acoustic ceiling Klaus mentioned if you could cover the whole ceiling area or at least the area forward of the fireplace. Reverberation time is longest at low frequencies and effective bass traps will reduce that considerably.

Apart from that I think a lot will depend on your choice of speakers and how they interact with the room, especially in regard to side wall reflections, and the kind of presentation you like your sound to have in terms of things like detail and accuracy of imaging. Once you move past bass trapping, different treatment choices have different effects on the way the sound is presented and basically you should opt for an approach which enhances the type of presentation you want to hear.



David Aiken

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