Quote:
|
Originally Posted by DeeDrive I've been looking over Ethan's DIY bass trap designs, and I trying to figure out what would be the best traps to go with would be. I am unsure of how tall to make them, and also what the best placement would be. My room will be used mainly for mastering, so I'm looking for the flatest response possible, and bass is hugely important.
I've included some rough sketches of the room at the bottom of this post. What would you guys do in this situation? Feel free to be as specific as possible, I want to get all the input I can. Would you use 703 fiberglass for bass traps or 705? I've seen a lot of people talk about 4" 703 panels, but Ethan's designs call for 1". Would there be a disadvantage to using 4" of 703, is this overkill?
It seems like the more I read on this subject, the more unsure I am of what I thought I knew, so if anyone can give some specific advice on what would be best for this type of room, I would really appreciate it.
Also, are there any specific problems I might encounter with the odd shape of the room? Is this shape typically better or worse for acoustics? It seems like there would be less parallel wall space, which sounds good, but does this room shape have it's own issues I should be aware of? |
I don't want to sound discouraging, but that room looks like an acoustical nightmare. A 12' X 12' square is not going to be your friend. The low ceiling, especially with the even lower angled sides will cause trouble as well. You won't get very accurate sound out of this room, certainly not a response suitable for mastering. As a small composer's suite it could be a nice little room, but as a mastering suite it will be disappointing.
You'll need plenty of targeted trapping at the frequency whose wavelength is twice the room dimension and multiples as well. So, where both dimensions are 12' (ignoring the height dimension and non-axial modes), you look for the frequency with a 24' wavelength, and wavelength = c/f, where c is the speed of sound, and f is the frequency. C=1130 ft./sec at 70 deg. F at sea level, (or 344 meters/sec.), so 1130/f=24. Another way to say it is f=1130/24, which gives you a standing wave at 47.083 Hz, and harmonics thereof.
Traditional traps require 1/4 wavelength traps to absorb the bass, so a 6 ft. trap is probably out of the question, as is a 3 ft. trap even if you only wanted to get the next harmonic. That's where the membrane absorbers come in. You can certainly make a 94 Hz trap that is shallow enough to hang on the wall. That 47 Hz wave is still going to be trouble though.
You could construct several Helmholtz resonators, though that's not very easy. I could give you the math if you wanted to try. They can actually be pretty reasonably sized, especially if you can put the resonant cavity in an adjoining space. I'm guessing that the angles in the ceiling are due to a roof above you, which implies there's a triangular cavity above the flat part of the ceiling that you can use for trapping bass.
You'll also need absorption to eliminate first reflections, including those angled ceiling areas. I'd use 703, and using 4" is not going to provide meaningful help for the bass. You need membrane traps where 1" of 703 inside will do. Those kinds of traps don't work in the same way as just having deeper frictional absorbers. I'm not sure of how much more to say... Is there anywhere else you can set up your studio? I really don't want to be so negative, but this room will give you trouble no matter what you do. Sorry to be the bearer of bad news, and please don't shoot the messenger!