Optimum Room Dimensions

[454Casull]

http://www.rpginc.com/cgi-bin/bytese.../roomsizer.pdf

I have two questions... Can anybody extrapolate the dimensions of the room that they found to be optimal, and second, what is the ratio of the room dimensions as specified by IEC/BS 1988 (the chart on the middle right of page 5 of 6)?

[Ron E]

possibly:
http://www.bwspeakers.com/index.cfm/...E100D0B74745A0

I once wrote a program that calculated the average, minimum and standard deviation of mode spacing of a huge number of rooms varied in dimension by an inch at a time in each direction. If it fell within a certain threshold, I wrote it to a file along with the specs calculated. Using the method I used, optimum dimension ratios seemed to vary with room height.

Thanks for the link.

A file that may be of interest to you may be found at the FRD consortium - the room refection response calculator by Yavuz Aksan.
http://www.pvconsultants.com/audio/frdgroup.htm

[454Casull]

Can anybody answer my questions?

[AndrewJ]

I can answer the second question. The answer is actually buried in the text if you look carefully. If you look around the area on page 2, equation 5 along with checking the references at the end of the paper, you will see that IEC1988 is specified as 2.59:1.96:1 (room size 7m x 5.3m x 2.7m) and the older standard IEC1987 is specified as 2.39:1.5:1 (room size 6.7m x 4.2m x 2.8m). The ratio quoted in the paper (1.59:1.5:1) is actually a typo.
The author of the paper does not actually give the ratios he found for his optimum dimensions. I guess RPG is keeping this info for itself. However, in looking at his results I don't think that they are such a big improvement upon those for the latest IEC room.
Hope this helps you

Andrew

[454Casull]

Thanks, buddy!

[a31_ford]

Louden's Ratios are well known in western Canada, I had a fair amount of involvment in designing most of the upscale bars & nightclubs in the Edmonton area.

In Louden's 1-1.4-1.9 ratio, I would say it best fits "Rock Music" IF one had to assign a ratio a subculture style, Bonello's ratios would be more "Clasical" in my eyes (and ears) Bolts would be Barroke.

In case you are wondering the first number would be length, the second width, and the 3rd height, so in theroy lets say

L 16ft, W 22.4ft H 30.4ft now most of us don't have spaces that are 30+ ft tall and this is a problem, the reason being that TDF (Time Displacement Factor) says that we can hear laterly quite well, however, vertically we are quite bad at it. This "raised roof thing" is the method of stale-maiting all the reflections below 200hz.

Wow ! Is a "ratio-ed" room starting to look like a Transmission Line ported enclosure or what !

Who said a VERY tall church sounds bad, have you ever spoken loudly in one, or listened to a good set of speakers in one?

[Timn8ter]

My current listening room has 11 foot ceilings. It makes a big difference.

(Nice cat Greg)

[planet10]

Originally posted by Timn8ter
My current listening room has 11 foot ceilings. It makes a big difference.

BIG Diff ... my ceiling goes fom 7 ft to 17 ft.

dave

[a31_ford]

I remember a guy, that wanted to try a 4 sided room BUT with no ceiling, funny thing is, when he and I where talking about it, It would have been very early in my life, hence early in my small knowlage of sound. AT the time, I really kinda thought this guy was "out there" NOW, I am starting to think the same.... AM I "out there" now also ?? OR was he really smart for his age ?

Now I want to try that room with no ceiling... I'm seeing(hearing) a point to it....

Would make a GREAT setup for a speaker mfg. at a home show!

[Ron E]

The IEC specification is not just a room ratio. At least as important is the specified balanced and even RT60 (acoustic decay) at various frequencies - especially difficult to achieve in the bass.

The room mode distribution method that is used is somewhat artificial in that they put a speaker in one corner and the micophone in the diagonal corner - this measures the activity of all modes. In a real listening room, the placement of the speakers and the listener will affect the sound perceived to a large extent., because te hspeaker will activate some modes mor than others and teh listener will perceive some more than others due to placement.

The link to the FRD program I posted is to point out a program that calculates frequency response that depends on room placement issues. The method used to calculate is the "image method" - the same one used in the RPG paper. You can play around with your own room dimensions and reflection coefficients - even check te hpaper's calculations (like the pic). Notice the locations of speakers and listener in the room.