VO-BB - 20 YEARS OLD!

[JSantucci]

I have three full rolls of paperbacked r-13 fiberglass insulation left over from a kitchen and family room remodel we did a few years ago. I was wondering if I could wrap them in fabric and stack them in the corner to use as bass traps. I wouldn't expect them to be as good as a superchunk or anything… just trying to use what I have on hand.

Thanks in advance for the advice.
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[Edo]

The situation you described leads to 'absorbers'... it won't be anything near the functionality of a bass trap as that involves very rigid materials and last but not least... mass.

[JSantucci]

Given that these are full rolls of insulation, there is plenty of mass. It's not rigid, but it is mass.
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[SkinnyJohnny]

I agree with Edo. Nowhere close to rigid.
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[JSantucci]

No, not rigid. But again, these are full rolls: http://tinyurl.com/2dqlhfs

I would set them on edge, resulting in 2 foot deep absorbers. That should provide plenty of mass and depth, even given that the material is not rigid, shouldn't it?
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[SkinnyJohnny]

It's probably worth a try and see how it sounds.
I know I'm getting old, but didn't realize I'm beginning to repeat myself.
Sorry for the double post!

Edit by MOD: Fixed the double post for ya
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[JSantucci]

Well, I checked out a few other sites, and here is what acoustics guru Ethan Winer says (http://www.ethanwiner.com/acoustics.html#bass%20traps):

"Another great and inexpensive way to make a bass trap - if you have a lot of room - is to place bales of rolled up fluffy fiberglass in the room corners. These bales are not expensive, and they can be stacked to fill very large spaces. Better still, they are commonly available and you don't even have to unpack them! Just leave the bales rolled up in their original plastic wrappers, and stuff them in and near the room corners wherever they'll fit. Stack them all the way up to the ceiling for the most absorption."

It surprises me that he says to leave them in the plastic. But I am going to give it a try.
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[Edo]

Okay... I think I unintentionally caused some confusion with my use of the word 'mass' in combination with 'rigid'. My best excuse is that English is not my native language... I'll try to be more specific this time.

The basic requirement of a bass trap is, as it implicates, sufficiant 'room' to trap the problem frequencies. The most obvious problems in any room are the frequencies around 125 Hz and below. The main goal is to get your frequency response as 'honest' as possible. Else you'll be unpleasantly surprised when there's considerable difference between a mix played in your room and then in another environment. That could be in a car or on headphones for instance.

Furthermore... when you're recording you might want to get rid of all the boomyness for it will definately give you less problems when you're voicing stuff. In order to make a bass trap work, you'll need very dense material of considerable thickness, ideally 'trapping' sufficiant air space. This often happens in corners of the room. And since sound is a 3D thing... I mean ALL corners including floor-to-wall and wall-to-ceiling corners. You can't have enough bass traps...

What your roll of insulation material will do is absorb some of the lower mid frequencies and some of the bass material in your room. It will most definately not be of any help when you're trying to get rid of low end standing waves in your room or 'nulls' for that matter. To get an accurate response in a room, every bit counts. Remember... you're not fighting sound leakage, you're aim is to avoid low frequency reflections within the room that leads to uncontrollable standing waves. And since low frequencies are related to larger wavelengths you're more likely to experience this since your room can easily accomodate standing waves of several meters. Now THERE is your challenge. And no amount of bass traps can ever get rid of stuff caused by poor design or shape of the room. Bare that in mind too.

EDIT: I was going to refer you to the Ethan Winer knowledge... I learned a lot from him as well as from acoustics guru John Sayers. His forum is considered one of the best in the world. You can find it HERE.

[JSantucci]

Thank you for the responses.

I understood exactly what you mean by mass and I get the physics of sound pretty well (I have taught high school science). The rolls of insulation are pretty heavy, large, thick, compressed fiberglass, as long as I leave them rolled up. That's the key - I will be leaving them rolled up, so they will be much denser than the unrolled fiberglass would be. That's why I suspected they might work as bass traps, and Winer has confirmed it.

Of course it wont be as good as building a superchunck in each corner. As stated initially, I would not expect it to be.

Thanks again for the responses.
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[Mike Sommer]

If these rolls were unbacked (no paper) it would work very well, yet what you have will work as a corner basstrap, but not as well if it they were un backed. These rolls will also eat up a lot of real-estate.

Though you have "density" (that's the key word here, not mass) you also have a barrier in the form of paper. We're not dealing with "sound" in the classic textbook description ripples on the water, but rather in terms of the dynamics of gas flow. How different frequencies behave in a box.

The reason you want to keep the plastic on, is that it will help keep the glass dust down, and it also helps with reflecting highs back into he room.

Some quick math tells me, for an 8-foot high ceiling one will need about seven 14-inch wide rolls to fill the corner. At $15 to $20 a roll there is not much of a savings. As a matter of fact it's cheaper to get INSUL-Shield and make 2-foot wide super chunks, since you only need six, 2-inch panels for an 8-foot high ceiling. (9 panels come in a bail, at about $95 per bail)


As far as the density/mass thing goes. Rigid insulation works best at about 3 pounds per cubic foot (703); this will control high frequency (above 500 Hz) very well and a good part of the low frequencies. To better treat low frequencies 5 pounds per cubic foot is better (705). Because of it's "density" it will reflect the higher frequencies back into the room, and thusly control low frequencies better.

Basstraps are notorious for sucking the life out of a room, knowing what to do and how to deal with it is where I come along. I can contour a room to sound alive while not feeling stifled.
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Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

[ballenberg]

[Mike Sommer]

[JSantucci]

Thanks, Mike. I knew the paper was a concern. That's why I thought putting them on edge might help, because then the paper would be perpendicular to the sound waves. But maybe it doesn't matter, especially if the plastic is left on.

The rolls are only $10 each, but like I said, I have a few leftovers from a remodel a few years ago. So I wouldn't be doing floor to ceiling with them.

But honestly, I'm not even sure I need bass traps. I just saw the rolls in the garage over the weekend and thought to myself, "I wonder if I could use those?" I actually like the way my setup sounds right now. I've got 4 rockwool-filled GOBOs and 2 panels of acoustic foam I place around me in a 6 sided "booth." Then I drape 2 layers of moving blankets over the gobos and 2 more over the top as a cloud/ceiling.
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[Mike Sommer]

I would say you are better off just laying them flat and stacking them to the ceiling. One or two rolls are not going to provide much of a noticeable difference, because we have 12 corners in a room, and in most cases we only end up treating 4 of them.

Yet overall, every room needs bass traps. Excessive bass muddies the voice and makes our listening environments boomy.

Even at $10 a roll, you're still ahead on the price with the ridged insulation (or coming darn close) because you're not eating up a lot of room; making it look attractive is a very simple matter; the effectiveness of rigid insulation is much better.

The blanket fort, is fine for a temporary set up, but one would be better served by treating the whole room, or building a 4-inch thick rigid insulation gobo partition that can surround you.
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The Blog:
http://voiceoveraudio.blogspot.com/

Acoustics are counter-intuitive. If one thing is certain about acoustics, it is that if anything seems obvious it is probably wrong.

[georgethetech]

8 corners, 12 edges. It is a LOT to treat it all properly.
The key is doing enough for your needs, and if it ain't broke, you know the rest.
Send me or Mike a sample of your audio and see if it really needs fixin' or not.
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