i would try to keep the 12ft ceiling if possible and just use a scattering of broadband absorption and diffusers to create a nice space - and perhaps some reversible treatments to permit changes in the overall room characteristics.
altered to 11' ceiling (updated - i had goofed...)
ratio size m sqrt(2) even ok h 1.00 11.00 3.35 0.61 FALSE TRUE h-ww 1.32 14.50 4.42 0.07 FALSE TRUE l-hl 2.27 25.00 7.62 0.22 FALSE TRUE l-w (h) bolt ebu iec >5% walker TRUE TRUE TRUE TRUE TRUE ax 1st ~note ax 2nd ~note ax 3rd ~note ax 4thh 51.18 G1 102.36 G2 153.55 D3 204.73w 38.83 D1 77.66 D2 116.48 A2 155.31l 22.52 F0 45.04 F1 67.56 C2 90.08 vol surf edge area T(ms) r(ms) Dcft 3988 1594 202 363 8.89 515.52 7.01m 112.91 148.09 61.57 33.68 rt60 eyring millington Fc Fs Fc2 davis 1.61 1.40 1.24 168.79 238.89 251.08 307.09 ~note ~note ~note ~note E3 A#3/Bb3 B3 D4 ratios diatonic phidev modes df h-w 1.32
avare wrote on Sun, 02 March 2008 16:54 |
No slight intended, it goes into several steps of depth after Ethan's calculator.
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No problem, and no slight taken. This brings up an important point. Every time I see Bob Golds post a list of 90-odd modes for someone's room I always expect the recipient ask "What the hell am I supposed to do with all those numbers?" But they never do. I guess they're too intimidated.
I've never been convinced that non-axial modes account for much, and when you include those you end up with so many modes only a few Hz apart that it's impossible to see the forest for the trees. However, some day I may add non-axials to my ModeCalc program, but shown as lighter colored lines with lower heights to reflect their lesser impact.
--Ethan
My bad. I didn't do the volume calculations from your dimensions. It took Glenn's post to open my eyes that your can almost 100 m^3. Trevor Cox has done leading research on modes and has an Excel that shows the best ratios for a room that big. Just pick and choose from the list.
The link to the file is about 2/3 down on:
http://www.acoustics.salford.ac.uk/acoustics_info/room_sizin g/?content=best
Enjoy!
Andre
Ok so I think I'm going to go for 25X14.5x11. Seems perfect and the slightly lower ceiling will be a lot easier to fit in the room.
Should I just build a rectangle or will a couple angled walls that average out to the above ratio end up sounding better?
I always seem to like the sound of irregular shaped rooms, but dont want to end up making bigger problems for myself then a properly treated rectangular room.
Most acousticians would agree that normal modes should be weighted more heavily than tangential & oblique modes. I've seen different suggestions on HOW to weight them, but in the end, it's a bit of a crap shoot.
I'll say this: relying exclusively on normal mode distribution is oversimplifying things, but so is weighting everything equally. There are some pretty interesting "goodness" functions out there in the literature that are worth exploring.
Quote: |
Should I just build a rectangle or will a couple angled walls that average out to the above ratio end up sounding better?
I always seem to like the sound of irregular shaped rooms, but dont want to end up making bigger problems for myself then a properly treated rectangular room.
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The answer is in your second sentence. If you like hte sound, use angled walls, and the average dimension for mode calculations.
Andre
I would just hate to build random angles and end up with some weird sounding reflections.
Is there anywhere I can read about the principles behind angling walls? Is there any science to it?
Sorry to be asking so many questions, I just want to make sure I get everything right before construction starts.
Chris Griffith wrote on Tue, 04 March 2008 10:56 |
I would just hate to build random angles and end up with some weird sounding reflections.
Is there anywhere I can read about the principles behind angling walls? Is there any science to it?
Sorry to be asking so many questions, I just want to make sure I get everything right before construction starts.
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It is difficult to answer generalities. Yes there is science behind splayed (another word for angled) walls. Remember that a ceiling is just a wall turned on it's side. It comes down specifics of any room. This thread provides an example of how frustrating it is to give a specific answer. In case you can not figure it out, the answer was "it depends."
Another thread that may help you is this one.
There is no simple answer to your first question. The requirements have gone beyond science (to know) to engineering (to use).
Keep the questions coming!
Andre
Chris Griffith wrote on Tue, 04 March 2008 10:56 |
Is there anywhere I can read about the principles behind angling walls? Is there any science to it?
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There are two reasons to angle walls, possibly three:
1) Angles of 6 percent on both opposing walls is enough to avoid flutter echo between those surfaces.
2) Angles of 30 to 35 percent are needed to direct first reflections around the listening position to the rear of the room, to avoid needing absorption at those places.
2-1/2) Angles might make room modes slightly less resonant, though I never tested this and can't say for sure.
--Ethan
I still havent decided as to how I want to build the room. I'm pretty sure I'm going to build it 11x14.5x25 in size.
Part of me is thinking I'll just build it with parallel walls but build some 4 ft wide splayed walls inside the room faced with thin plywood and stuffed with fiberglass that can serve as bass traps/reflectors. I know I want part of the room very dry and other part very live. That way I can keep drums on the dead side and get a little natural predelay before the sound hits the more lively side with the angled walls. Does this sound like a decent idea?
Ultimately I want a bright tight sounding room but still with a little bit of size.
I would concentrate on getting as much room interior volume as possible, especially for a live/drums room.
The flutter-free ambiance that you can possibly gain by using angled walls, can be easily obtained by some absorption/diffusion panels put on the walls on a non-angled room, and so saving precious space.
That is of course if your original walls are not already splayed by construction, in which case you will actually loose room volume trying to make them parallel
Thank you! This is exactly the type of information I've wanted.
I've been racking my brain trying to fit some 12 degree angles in the room without loosing a lot of space.
This is going to make construction so much easier!