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I have an area in my basement that is unfinished that I would like to convert into a listening room. The area is 17' 6" x 10' 10" and is 9' 5" tall. Those dimensions are from concrete basement wall to the edge of an existing stud wall for the width. That said, the width is fixed (10' 10") the length however, can be changed + - about 10" to adjust for acoustics. The ceiling could be lowered to a reasonable height as well. Probably no lower than 8" so it doesn't feel too cave-ish.
Primary would be for a great 2 channel setup with a single "hot seat." Secondarily I'd like to put some more seating and have a basic multichannel setup with a motorized screen / projector. For now though it's going to be just 2 channel.
Can anyone weigh in on room dimensions? I know non parallel surfaces would be ideal, but I don't know that it will be feasible.
If I had to do over i would....
Angle the walls like an auditorium so that the front wall is 2' shorter than the rear.
Ramp\valt the ceiling in one foot ramps.
Angle the front in two sections.
Build four subwoofers one in each corner, right into the wall.
Build panel traps into the corners of the room tuned to 80hz or so.
Wire for surround sound.
these things will eat up some space but wouldn't cost that much and flutter would be non-excistant. You would be very far ahead before you started treating.
Scott
I would just make a manifold towards the front of where your main speakers are located and make an Infinite baffle subsystem with the same 4 subs......
You would have increased efficiency, which would require a lot less amps, would only need one.... And you can get pretty low, and not have worry about localized bass
-chris
All formulas for room mode calculation are based on the assumption that the room is empty (no furniture), has no wall openings (doors, windows), and has perfectly rigid and reflective walls.
Large absorbing furniture is capable of shifting mode frequencies and lower mode levels. Large reflective furniture is capable of splitting up modes, hence generating two modes instead of one. Wall openings are structural weaknesses and locations of pressure maxima and minima are shifted.
When using room dimension optimizers one should keep in mind that such optimizers try to place ALL modes that are possible in a room on the frequency scale according to certain criteria. The only location where all of the possible modes can be excited is a corner. The only location where all of the modes excited in that manner can be perceived is a corner. Hardly a practical setup. Everywhere else you will excite only a fraction of the possible modes and of those you will perceive only a fraction. The chances that those remaining modes are spaced according to the optimizing criterion is close to zero.
What you can do is to optimize room dimensions for pre-determined positions of loudspeakers and listening chair.
In rooms with non-parallel walls axial and tangential modes are not excited, only the oblique ones (which involve all six room boundaries). You still get strong pressure maxima and minima, but rather randomly distributed across the room.
The only way to know beforehand how the mode distribution in a given room looks like is finite element analysis.
De Melo et al.(2007), “Sound absorption at low frequencies: room contents as obstacles”, J. of Building Acoustics, vol. 14, no. 2, p.143
Bork (2005), „Modal analysis of standing waves (in German)“, Fortschritte der Akustik, DAGA ’05, 31. Jahrestagung für Akustik (Deutsche Gesellschaft für Akustik), München 2005
Welti (2006), “Low-frequency optimization using multiple subwoofers”, J. of Audio Eng. Soc., p.347
Toole (2006), “Loudspeakers and rooms for sound reproduction – a scientific review”, J. of the Audio Engineering Society, p.451
Bolt (1939), “Normal modes of vibration in room acoustics: experimental investigations in nonrectangular enclosures”, J. of Acoust. Soc. of America, vol. 11, p.184
Van Nieuwland (1979), “Eigenmodes in non-rectangular reverberation rooms”, Noise control engineering, Nov., p.112
Klaus
Reducing the length to 17 feet is not terrible. You can experiment with dimensions and see what happens acoustically using my Graphical Mode Calculator
--Ethan
I understand that the dimensions will obviously be subject to whatever wall construction is in place as well. So, 2x4 + drywall surface will be subtracted from overall dimensions.
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