## Need advice on room proportions.

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### Need advice on room proportions.

Hello all! I am looking at a room wich I plan to use as both tracking and
mixing room. It is part of a 7 x 12 m room, so I will be putting up a wall
making my room 7 x 3,75 m. The 3,75 measure is set by a 1,5 m wide pillar,
which I find it easiest to integrate as part of the wall. Room height is 2,5
m. So proportions are 7 x 3,75 x 2,5 m or 23´ x 12´3´´ x 8´2´´.

Anyway, the front end of that room to be has a lot of water pipes and vent
ducts hanging across the ceiling. I would rather have those outside the
studio. One solution would be to get the landlords permission to move those
close to the wall and then make my room a bit shorter. The resulting slot
(correct word?) could be used for storage and computers.

I could also after they´re mounted close to the wall let them be and use the
full room. If they are disturbing I could house them in gypsum later on.

If I shorten the room I could make it fit the proportions of the Volkmann
ratio 2:3:5 as mentioned by Everest, making it 6,25 x 3,75 x 2,5 m. This
would, on paper, produce a nice series of modes with three specific
problematic modes at 138 Hz (3), 276 Hz (3) and 413 Hz (2), (from the

My question is: Which is to prefer with a room small like this one. Room
size or ideal proportions?

Jonas
detlof

Posts: 17
Joined: Sun Feb 08, 2004 9:14 pm
Location: Sweden

Jonas:

It is hard to conceptualize all that might be involved, but I think I would try and clean up the look of those pipes without moving them... to me that would be a big pain in the butt, and you might be opening a real can of worms [the law of unintended consequences].

OTOH if all your stuff fits in the smaller room and the layout fits your needs, I see no reason not to build the smaller room [other then the time/money involved in moving pipes around] as the overall room volume change is small.

Good Luck
SRF
Scott R. Foster

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Joined: Mon Feb 02, 2004 12:41 pm
Location: Jacksonville, FL USA

Hi Scott! So you don´t think that the proportions for a room this size is all that important. If I get you right, you´re saying: "Yeah, if you can afford to get rid of the pipes by means of a wall, go ahead, otherwise don´t bother - the room will be OK. "

I´m just trying to get clean cut answers here.....(I know there aren´t any). Should I consider the room proportions or not? - will there be a big difference regarding acoustic qualities of the room between the two alternatives?

Room modes can be seen here http://members01.chello.se/detlof/lk3modes.htm

"bef" is the longer room and "235" is the one following the Volkmann 2:3:5 proportions. To me both seem fairly equal, the longer room even having fewer stacked modes, though the 235 ones seem a bit more evenly spread. The longer room doesn´t even go within Bolts range. Does these things matter much? Should I bother? Does the 235 proportions have qualities in the tangential and oblique modes that I should consider?

I am happy for all thoughts here.

regards Jonas
detlof

Posts: 17
Joined: Sun Feb 08, 2004 9:14 pm
Location: Sweden

Jonas,

I ran your dimensions through my RMmapper program and assumed that 7m x 3.75m x 2.5m were maximum dimensions. It looks to me like a room around 6.95m x 3.65m x 2.5m will give you about the best modal spread with the maximum space. The Bonello chart for this room has one isolated axial way down in the 20-25 Hz bands and a dip in the 63 Hz band, but is otherwise pretty nice.

Hope this helps!

Regards,
John
jcgriggs23

Posts: 257
Joined: Tue Feb 10, 2004 2:53 am

Thanks a lot John! It´ll be hard though to build to those exact proportions, but I can at least get close. Still I am trying to figure if it is worth the extra money and labour to get close to the ideal proportions. Of course thats up to me to decide, but i am not sure about the differences.
detlof

Posts: 17
Joined: Sun Feb 08, 2004 9:14 pm
Location: Sweden

Dennis Erskine (an experienced home theater designer and acoustics engineer) wrote
With respect to general issue of room size: If one can build the room avoiding coincident modes, then that is the better choice; however, larger is better than smaller. If when examining the constraints, changing the dimensions makes the room impractical (too narrow, too low a ceiling, too short), then build the room anyway. It is doubtful, or at least questionable, that changing a dimension less than a foot is going to make a real world difference in any case. The actual as built physical characteristics of the walls, the addition of design elements, platforms, seating, and stages are going to throw their two cents into the mix and result in something different than the modal spreadsheet suggests in any case. If, when designing the room, you know in advance that you have a potential coincident modal issue, then within the design you can accommodate, or plan for the use of, any one of several mechanisms to deal with the modal problem. I would suggest an 11' wide room with no coincident modes, is less attractive than either no room, or a 13' wide room (with coincident modes) when all other needs are addressed.

Dr. Floyd Toole http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf explains this in more detail. On page 8 he goes so far as to suggest that for home theater 5.1 setups the room sizing may be pointless. And shows a room that modal analysis predicted would be bad, but wasn't.

Also, most room mode calculators are based on the concept that Axial, Tangental, and Oblique modes combine equally, and some don't even bother with Tangental or Oblique. But Axial modes are more powerful than Tangental, which in turn are more powerful than Oblique, because the walls may tend to not reflect all the energy, and more walls/reflections are involved in Oblique paths than in Axial. The degree of difference depends on the regidity of the walls and other factors, none of which the common room mode calculators ask for. That doesn't mean you can ignore Oblique paths. Ethan of realtraps recently did a show to attempt to prove a point, and he depended on some room mode calculator's modal frequencies, and Jeff D. Szymanski did a quick calculation and discovered that two of his 'non modal frequencies' were in fact tangential, which somewhat deflated Ethan's argument, or at least his data.

Still, you want to listen to the music, not the room. And designing with room modes in mind may help, because room modes are a part of the sound you hear. This fellow, who otherwise made several mistakes, was very happy with a smaller room sizehttp://www.decware.com/paper36.htm

So the bottom line is design the room with the modes in mind, but build a room you can use and enjoy first.
Last edited by Bob on Tue Feb 17, 2004 4:20 pm, edited 2 times in total.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
Bob

Posts: 4360
Joined: Sun Feb 08, 2004 4:37 am

jcgriggs23

I tried your RMmapper.exe, but I just answered the questions and didn't provide any -r command line options. What options did you use when you ran it for his room ?
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
Bob

Posts: 4360
Joined: Sun Feb 08, 2004 4:37 am

Bob,

Actually, I lied a bit - I really used my new, Java replacement for RMmapper, tentatively called ModeWizard, which has a nice GUI so I don't have to remember all those options 8^). It's still kind of in a pre-Beta state while I get some advice on technical and mathematical matters and complete the basic features. There'll be a Beta release at least through this group. Eventually. I hope.

Jonas,

I picked a room sort of in the middle of a group of rooms that looked decent (they were all close enough that it was hard to choose a clear winner) that had the largest volumes. As long as you can build to a 2cm or so tolerance, you should be OK. IIRC, height is where you have the least room for error (stay as high as possible)

As another poster has pointed out, bigger rooms make most things easier so I always try to maximize volume if other things are roughly equal.

Hope this helps!

Regards,
John
jcgriggs23

Posts: 257
Joined: Tue Feb 10, 2004 2:53 am

John, Bob and Scott,
Thanks a lot! Really helpful comments and links! And extra thank you John for doing the calculations!

The costs for moving pipes around seem to be in the 1000 - 2000 \$ range. So I´ll have to buld a wall crossing those pipes and let them sit where they are. I might have to make a "housing" for the pipes instead (a big one). Problem is then I get a front end last 1,5 meter of the room with a ceiling height of approx 2 meters. Do you think that is enough to create resonance problems?

And I still have the costs for moving the housed vent fan that sits right where the new wall will meet the existing one........

again thanks a lot!

Jonas
detlof

Posts: 17
Joined: Sun Feb 08, 2004 9:14 pm
Location: Sweden