Building a Music Room

[jcmusic]

I am toying with the idea of adding a music room on to my house. It will be for 2 channel only SET amp power and 110db efficent horns without any subs. With the speakers in the conners what are considered to be the best dimensions for such a room? Any advice or ideas will be appreciated!!!

Jay

[bobschneider]

For smoothest response, the ratio of 1 : 1.25 : 1.6 is best, as it spreads out the frequencies of the standing waves the most.  But it would be even better to build the room without any parallel walls.

[jcmusic]

For smoothest response, the ratio of 1 : 1.25 : 1.6 is best, as it spreads out the frequencies of the standing waves the most.  But it would be even better to build the room without any parallel walls.

Hi Bob,
thanks for responding, please explain a little more!!!

Jay

[steveidosound]

Anybody ever heard of "Bolt's Amoeba"?
http://www.keithyates.com/halcyonarticle.htm
It has to do with an amoeba shaped graph of ratios of cubic room dimensions that do or do not produce reinforcements of standing waves. I could find little except the above article on line. I saw it in an acoustics book. The idea was to stay out of  certain ratios as in the previous post that cause bad resonances and reinforcements.

[mikel]

i built a room. i had it designed by an acoustician and gave him a clean sheet of paper with no resrictions other than 25' x 37' as max dimentions. i built it exactly as he designed it.

my 2 cents would be that most audiophiles evolve. so i would not get too narrowly focused on one speaker design in the room design or you will be locked into it. another thing is that the 'Golden Ratio' does not scale. different frequencies do different things at different dimentions. accidently the Golden ratio does work at certain sizes. how the room is constructed will affect what dimentions work. so it's not just size.

if you are a DIY kinda person the Golden Ratio is pretty good, but not the last word.

and btw, my room shape resembles an oval, there are no parallel walls and the ceiling is very uneven. most importantly, my room has mostly diffusion, and the front third has hardwood floors over concrete, the rear two thirds are thick carpeting over concrete (think concert hall).

here is an article i wrote on my room building experience;

http://www.positive-feedback.com/Issue16/lavigneroom.htm

it was a very satisfying experience.

[jcmusic]

i built a room. i had it designed by an acoustician and gave him a clean sheet of paper with no resrictions other than 25' x 37' as max dimentions. i built it exactly as he designed it.

my 2 cents would be that most audiophiles evolve. so i would not get too narrowly focused on one speaker design in the room design or you will be locked into it. another thing is that the 'Golden Ratio' does not scale. different frequencies do different things at different dimentions. accidently the Golden ratio does work at certain sizes. how the room is constructed will affect what dimentions work. so it's not just size.

if you are a DIY kinda person the Golden Ratio is pretty good, but not the last word.

and btw, my room shape resembles an oval, there are no parallel walls and the ceiling is very uneven. most importantly, my room has mostly diffusion, and the front third has hardwood floors over concrete, the rear two thirds are thick carpeting over concrete (think concert hall).

here is an article i wrote on my room building experience;

http://www.positive-feedback.com/Issue16/lavigneroom.htm

it was a very satisfying experience.

Hey Mike,
Great story thanks for sharing it!!!

Jay

[ironbut]

I agree with Jay,.. that's a great article.
I'll bet there's a story or two regarding the main house too!

Thanks Mike.

[Teeg]

  A few weeks ago I decided to get going on a dedicated basement audio room, and hired a contractor to move some plumbing and do the rough framing. My current room is in an unused upstairs 'guest retreat', and while it has served me well for the past year since the house was built, it is rather small at 15 x 19 (it does have a 9 foot ceiling).  The equipment layout in the room is fine; it just doesn't have any space for media storage, and my larger studio decks look cumbersome and probably (definitely) affect the audio quality to some degree being so close to the speakers.
   The basement had some potential, but it had a few problems. The original plumbers ran the waste and clean water pipes pretty far from the walls; this would have reduced the room width from an anticipated 18 feet to less than 14, which was unacceptable. I hired a plumber who had worked for me before, he understood the problems and came up with a good, although expensive solution, and had to re-run a considerable amount of the piping. In the end, after framing, we wound up with a room 18.5 x 39.5, with 9 foot ceilings.  The only downside is that the stairs to the main house come down in the rear 2/3 of the room, but this creates a listening area 18.5 x 24, with two 'hallways' that lead to an 18.5 x 14 'media storage' room.
   This was the best we could do without major restructuring of the house, which is not an option at the moment. If I couldn't have at least 16 x 24, we would not have gone further. The extra width, plus the rear media room, basically came up while we were laying out the measurements for the framing and seemed like a good idea.
   Like Mike L's room, we did the rough framing, and will sheet rock it, to have a room within a room, so to speak, and then give the finished design more consideration from there. On paper the original concept looked promising, but I had to take it to the rough framed stage to get a good feel for how it would really work.

Tj
   
 

[PJ]

For smoothest response, the ratio of 1 : 1.25 : 1.6 is best, as it spreads out the frequencies of the standing waves the most.  But it would be even better to build the room without any parallel walls.

For what it's worth, you can do nearly as well with 1:1.6:2.5 ratios, which is often more amenable to normal house construction. The point of both is to space the axial resonances evenly - the higher order resonances bounce off more surfaces, are more easily damped, and hence less important. The ratio 1.6 is pretty close to the "golden ratio" which may be why both seem to work.

The point of non-parallel walls is to diffuse slap echoes, where high-frequency harmonics stay in phase with repeated reflections. In the really great old concert halls, they did this by accident using lots of marble statues in niches in the walls, Cyrill Harris accomplished the same goal here in Seattle at Benaroya Hall (home of the Seattle Symphony) using very shallow truncated pyramids - the deviation from parallel is only a few degrees. There are many ways to minimize absolutely parallel surfaces without seriously compromising normal rectangular construction methods.

[ofajen]

I am toying with the idea of adding a music room on to my house. It will be for 2 channel only SET amp power and 110db efficent horns without any subs. With the speakers in the conners what are considered to be the best dimensions for such a room? Any advice or ideas will be appreciated!!!

Jay

FWIW:

1) Generally, it is not usually a good practice to have speakers in the corner. That tends to maximize the coupling of the bass drivers to vertical modes and horizontal modes in both directions and doesn't make for the best distribution of bass in the listening region.  Many mastering folk just use two subs or two full-range speakers placed symmetrically left and right but spaced from the floor, side walls and back walls.  If you want to go that far, there is also research by a fellow at Harman who works with Pascal Sigen, a thoughtful fellow who works now with A Blue Sky monitors, indicating that the best bass response comes from a carefully arranged array of mono subwoofers.  More can theoretically be better, but four mono subs on the floor, one at the mid-point of the floor edge along each wall is about as good as you can do. 

2) Probably the best advice regarding room dimensions is: as large as possible, especially the ceiling height and use one of the cited sets of ratios to space the room modes as well as may be.

3) Regardless of dimensions, the quality of sound is mostly dependent upon proper installation of bass trapping to tame the room modes along with broadband absorbers to kill off first-order reflections and proper diffusers in the rear to create a sense of spaciousness.  You want a minimum of 20 milliseconds after the direct sound before the first reflected sound hits your ears, which is why you want larger dimensions and absorption of first-order reflections (ceiling, back wall, side walls, floor).  The bass traps help shorten the relaxation time of the room modes.

4) One simple example of a system that produces a high quality listening space is the ASC Attack Wall, which is basically a simple, portable system to produce a quality, repeatable mixdown listening space for audio production.  I have the pleasure of using such a system in my studio to mix and monitor playback of my studio recordings and it is really a wonderful thing.  The Studio Traps used to make up the Attack Wall aren't cheap, but apparently there are thousands of audiophiles around the planet content to spend far more on esoteric electronics (and high quality source material, such as the TP provides) without first ensuring they have a listening space that meets the specs we know are required for quality audio.  That's a shame! 

Cheers,

Otto

[jcmusic]

I am toying with the idea of adding a music room on to my house. It will be for 2 channel only SET amp power and 110db efficent horns without any subs. With the speakers in the conners what are considered to be the best dimensions for such a room? Any advice or ideas will be appreciated!!!

Jay

FWIW:

1) Generally, it is not usually a good practice to have speakers in the corner. That tends to maximize the coupling of the bass drivers to vertical modes and horizontal modes in both directions and doesn't make for the best distribution of bass in the listening region.  Many mastering folk just use two subs or two full-range speakers placed symmetrically left and right but spaced from the floor, side walls and back walls.  If you want to go that far, there is also research by a fellow at Harman who works with Pascal Sigen, a thoughtful fellow who works now with A Blue Sky monitors, indicating that the best bass response comes from a carefully arranged array of mono subwoofers.  More can theoretically be better, but four mono subs on the floor, one at the mid-point of the floor edge along each wall is about as good as you can do. 

2) Probably the best advice regarding room dimensions is: as large as possible, especially the ceiling height and use one of the cited sets of ratios to space the room modes as well as may be.

3) Regardless of dimensions, the quality of sound is mostly dependent upon proper installation of bass trapping to tame the room modes along with broadband absorbers to kill off first-order reflections and proper diffusers in the rear to create a sense of spaciousness.  You want a minimum of 20 milliseconds after the direct sound before the first reflected sound hits your ears, which is why you want larger dimensions and absorption of first-order reflections (ceiling, back wall, side walls, floor).  The bass traps help shorten the relaxation time of the room modes.

4) One simple example of a system that produces a high quality listening space is the ASC Attack Wall, which is basically a simple, portable system to produce a quality, repeatable mixdown listening space for audio production.  I have the pleasure of using such a system in my studio to mix and monitor playback of my studio recordings and it is really a wonderful thing.  The Studio Traps used to make up the Attack Wall aren't cheap, but apparently there are thousands of audiophiles around the planet content to spend far more on esoteric electronics (and high quality source material, such as the TP provides) without first ensuring they have a listening space that meets the specs we know are required for quality audio.  That's a shame! 

Cheers,

Otto

Otto,
Thanks for all your advice and comments but, my speakers are highly modified Klipsch korner horns. So they must be in the corners!!! I hope you understand!!!

Jay

[PJ]

Given a corner location for the bass speakers, it becomes important to look at the first few room modes. If we assume an adequate amount of low-frequency acoustic absorption - and that's a might big if, as well as being ill-defined! - then you can simplify to the longitudinal modes in the expectation that the 2- and 3-wall modes are more heavily damped.

Given that, the smoothest bass response is going to happen when the modes, and hence the room dimensions, are space at 1/3 octave intervals. That means room dimensions in the 1:1.26:1.59 ratio. For example, a room 20 feet by 25 feet, with a 16 foot ceiling.

Adequate damping is an issue. Corner horns like the Klipsch require rigid walls or else the bass gets absorbed before it escapes to the room, but the rest of the room is going to get its bass absorption from wall vibrations or massive amounts of tube traps, tuned appropriately.

This is only talking about the very low frequencies, say below 100 or 150Hz. Others have made excellent points about initial reflection delay time, diffusion, live/dead distribution, all of which are relevant in the more critical midrange and high frequencies and may have constraints incompatible with the bass requirements. It's not a subject with a simple answer!

[analogmaster]

Hello all,
I moved into my first new home just over 2 years ago and built the basement into a 2 channel listening room from scratch.  Some good resources that I used were Robert Harley's Guide to High End Audio book, the Cardas website, and ASC tube trap company from which I order and had installed wall damp treatments between 2 layers of staggered drywall on the walls and ceiling.  I was able to have 16x26ft room with a 10 foot average sloped ceiling (spreads out resonnant nodes in the bass frequencies-I recommend sloping as much as you can about 1 foot.  I had 2 layers of R38 insulation with a layer of air for the ceiling separating it from the floor in the kitchen above it.  I had a separate electrical line for this with 5 shunyata venom outlets installed on the line.  I love it.  The only change I would recommend is installing duct board in the ceiling above the 2 layers of insulation because believe it or not, if someone stomps hard enough in the kitchen, you can still faintly hear it if there is no sound in the listening room but even this is barely noticable.  I hope this helps.