BenignVanilla
New member
I keep seeing "treat your corners, make them at least 4'' thick". Lucy, some splainin' to do please?
Corner Bass Traps Must Be 4'' Thick
- Thread starter BenignVanilla
- Start date
Weasel9992
New member
What would you like explained? The panels have to be at least 4" thick before they'll start working low enough. 2" panels wil only get down to about 250Hz-350Hz. 4" panels will get down as low as 70Hz.
DrewPeterson7
Sage of the Order
If it helps, it has a lot to do with the wavelength of the sound, as I understand.
BenignVanilla
New member
I would suspect that the material matters before the thickness, which is why I asked. Four inches of what? It just seemed like a mantra, so I was curious what was behind it.
Jeff_D
New member
Rigid Fiberglass or Rockwool. Owens Corning 703 is popular. Knauff, Johns Manville, etc have comparable products. Roxul Safe is a comparable rockwool.
DrewPeterson7
Sage of the Order
Oh, sorry - almost every tutorial I've ever seen specifies OC703 or some equivalent under a different trade name. There's evidently a denser version as well, where 2" will give you the same trapping as 4" of 703, but it's more expensive as I recall.
RICK FITZPATRICK
New member
If anything, the phone books could produce a Transmission Loss factor by virtue of mass...that is if you had enough of them.
The reason these products work vs phonebooks is DENSITY. The density of these products is around 3 lbs per cubic foot. The simple answer to why density is important is because these type absorbers are called RESISTANCE absorbers. They allow air molecules to move within the "interstices" of the fiberglass fibers(gas flow), which at 3 lb density, is just enough to provide a resistance to this movement when the air molecules are excited by a sound source. This resistance results in absorption of the energy which is transduced into heat. No different than rubbing your thumb on your jeans.
The reason you use these absorbers in the corners, is thats where low frequencies terminate, as the wavelengths are room dimension related. Also, the depth from the face of the absorber to the corner, relates to 1/4 wavelenghth....ie...at the boundary(wall etc), there is zero velocity-maximum pressure. At 1/4 wavelenth, there is maximum velocity, minimum pressure. At 100 hz, the wavelength is approx 11.3 feet long...which means for maximum absorption of 100 hz sound, a resistance absorber would have to equal 1/4 of that...or approx 38" thick. That doesn't mean that absorbers with a depth to the boundary of less than 38" won't absorb a portion of the 100 hz sound. This is where absorption "coefficients" come in. Not only that, they have to be located WHERE the occilations occur. This explanation is highly simplified and my disclaimer is in full force here. If you want to truly understand...read all of these ......
http://forum.studiotips.com/viewforum.php?f=8
Perhaps, but I've never seen it. From what I understand, more than 3lb density, the LESS it will absorb. If this were truly the case, then CONCRETE would be the best absorber available.
However, I'm always willing to learn.It depends. If big enough, as a membrane absorber.... maybe at 1hz
Weasel9992
New member
That's the right answer. Rigid fiberglass or mineral wool with a density between 48kg/m3 and 60kg/m3 is best, but if you'd trying to get down really low, then less density but more thickness and airspace is better.
Phone books would indeed work as bass trapping, but only down very, very low. They would make better insulators in terms of transfer reduction as Rick indicated.
RICK FITZPATRICK
New member
Ok, just to illustrate the use of 703 as basstraps in PRO studios, here is a GIANT basstrap at the wall/ceiling intersection of Manifold studios CR. This one will absorb down to 50hz(according to the designer). It hasn't been filled with many layers of 703 yet, although there is an area behind it that is over 5' deep
as well, which as you can see has been filled. This also illustrates the use of basstraps at wall/ceiling intersections.
Here is the control room at Bridge studios. Note the use of alternate patches of wood over the insulation. This is an "inside out" design, where insulation fills the stud cavities, and the wood provides reflection at higher frequencies, which also provides a better absorption by virtue of "diffraction", and because it is in patchwork, provides a diffuse sound field as well(note the various angles of the wood patches. Also note the 703 traps in the corners. These are about 3' thick. Even patchwork wood panels over these help with diffusion, although LF are still trapped as low frequencies simply diffract around the panels.
Maybe these will illustrate some pro designs that you can use in your own rooms.
fitZ
as well, which as you can see has been filled. This also illustrates the use of basstraps at wall/ceiling intersections.
Here is the control room at Bridge studios. Note the use of alternate patches of wood over the insulation. This is an "inside out" design, where insulation fills the stud cavities, and the wood provides reflection at higher frequencies, which also provides a better absorption by virtue of "diffraction", and because it is in patchwork, provides a diffuse sound field as well(note the various angles of the wood patches. Also note the 703 traps in the corners. These are about 3' thick. Even patchwork wood panels over these help with diffusion, although LF are still trapped as low frequencies simply diffract around the panels.
Maybe these will illustrate some pro designs that you can use in your own rooms.
fitZ
RICK FITZPATRICK
New member
Right answer?
ummmm,
Which is it? Less density or more.
DrewPeterson7
Sage of the Order
Ok, just to illustrate the use of 703 as basstraps in PRO studios, here is a GIANT basstrap at the wall/ceiling intersection of Manifold studios CR. This one will absorb down to 50hz(according to the designer). It hasn't been filled with many layers of 703 yet, although there is an area behind it that is over 5' deep
Rick - how would something like that be finished, in a pro studio? Fabric over the framework?
LDS
New member
I kind of follow your logic, but let's take it a step further. If you've ever been in a warehouse or storage area for steel, you'll know that it's generally a pretty noisy place.
Now let's examine a place were people store and read books - the library. Very quiet.
So obviously the books would do a better job.
R
RAMI
Guest
How do we know? A library is quiet because people are quiet in a library. I'm sure a steel warehouse would be just as quiet if nobody made any noise in there.
....speaking of which...I was at the corner store the other day, reading a magazine. The clerk looks at me and says "Hey! This not a library". So I said "OK! I WILL TALK LOUDER THEN!!!!".
Last edited:
Weasel9992
New member
Gaaaaahhh...plywood on the console with the meterbridge uncovered...makes my chest hurt.
nate_dennis
Well-known member
RICK FITZPATRICK
New member
Me too. Fortunately, the Neve channel/master section buckets were completely empty. They went completely through this beautiful console to re-commission it. Take a gander at the credenza too.
Talk about pro? This is as Pro as it gets. Absolutely stunning. If you can stand a dose of reality checks, look at the whole build here. Unfreakingbelievable. Who says big studios are a thing of the past. But it sure takes some DEEP pockets
http://www.gearslutz.com/board/phot...cts/341598-bridge-recording-studio-build.html
