Quick question . . .

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chessrock

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Hi,

I have sort of a dumb question.

I was thinking of treating a few extra rooms in my basement for extra tracking space.

What I have:

* I've got a bunch of rigid fiberglass panels.
* I've also got a bunch of drywall.

Anyway, would it make any sense if I were to cover the drywall with the rigid fiberglass (705, I believe) and place the fiberglass-covered drywall a few feet in front of the existing (concrete) walls?

Or would attaching the insulation directly to drywall negate any benefits of the fiberglass? I was thinking of allowing a few inches of space between the insulation and the drywall . . . but there will already be several feet between the drywall and the actual existing (concrete) wall when I'm done, if you know what I'm saying.

What do you think?

Thanks in advance!

- Chess
 
Are you talking about having the drywall mounted on stud frames, or just free-standing? And how thick is the 705? Also, do you need sound PROOFing, or just conditioning?
 
knightfly said:
Are you talking about having the drywall mounted on stud frames, or just free-standing? And how thick is the 705? Also, do you need sound PROOFing, or just conditioning?
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Hey Knightfly,

I'm not sure yet, but was thinking about a stud frame. I have several panels of the the fiberglass which I suppose could be layered to go as much as 4" if I wanted them to. It would be simply for conditioning.

I guess it's a stupid question, but I was really just wondering if drywall would be too thick of a material to mount it directly to? Supposedly, it's a good idea to leave some space between the fiberglass and the wall, right? I figured why not take it a step further and build a thin "dummy" wall (made of drywall) a few feet or so in front of the existing concrete wall and cover it with the fiberglass? Hell, if I can get my hands on some more of the insulation, I could even cover both sides of the drywall with it. Overkill?

That could potentially give me a couple feet between the fiberglass and the existing wall. And perhaps I could even put some other stuff between the dummy wall (drywall) and the existing one (more insulation?).

Thanks again!
 
The theory behind spacing the fiberglass from the wall is so that sound goes behind the fiberglass and bounces back into it to increase absorption. Having more space also allows you to absorb lower frequencies. You need several feet of space to really increase the bass absorbtion very significantly. The exact distance is 1/4 of the wavelength you are trying to absorb.

With that in mind having Drywall directly behind it would negate most of the benefits and would not be considered spacing it out. You need a frame that holds the fiberglass but blocks as little of it as possible. If you don't need the drywall for isolation or bass trapping then just mount the 705 to the existing walls. Better yet make some lightweight frames that you can glue the 705 to and hang the frames a foot or so off of the concrete wall.

You can get some ideas here-
http://www.homerecording.com/bbs/showthread.php?s=&threadid=85873
 
Hey, thanks so much for the reply, Tex!


So what you're saying is that the drywall might actually reflect some of the bass back instead of just letting it pass on through ?

And passing through is good, because it will come out the other end in a weakened state, then it will bounce off the concrete and try to work it's way back through the fiberglass board in an even more weakened state.

:D What if I were to punch holes in the drywall so as to make it pourous? :D

you can tell I'm really (fishing) trying to find a use for this drywall, can't you? :D
 
I think you would be better off to first figure out what you're trying to accomplish - then, and ONLY then, you can figure out HOW you're going to accomplish it. There's a very good chance that, once you've thought it out and asked specific questions on the HOW, that you'll already have most of the materials necessary to pull it off... Steve
 
Yeah, its hard 2 beleeve that sicks munce ugo I cudnt evun SPEL in-tuition, fug-get about akshully havin the muney fer skool...:=)
 
chessrock said:
So what you're saying is that the drywall might actually reflect some of the bass back instead of just letting it pass on through ?

And passing through is good, because it will come out the other end in a weakened state, then it will bounce off the concrete and try to work it's way back through the fiberglass board in an even more weakened state.

:D What if I were to punch holes in the drywall so as to make it pourous? :D

you can tell I'm really (fishing) trying to find a use for this drywall, can't you? :D
Click to expand...

lol, Along with the double filtering I think the idea for the space behind the absorber is more so that any sound that hits the wall at an angle will then go behind the absorber and bounce back and hit the back of it. Does that make sense?

If the panels were flush mounted then more sound could bounce off the bare parts of the wall and miss the absorber. Even the exposed sides of the absorber can help. Adding a hard surface with holes to either side can be done to use it as an absorber/diffuser but then again drywall is probably not the best or most practical material for that. Wood is usually preferred.

My understanding of Drywall is that it's only real acoustic use is for adding mass and seperation. It doesn't really absorb that much and it's so damn heavy it would be counter productive to use it with the panels. It might work well if you put some 703 on them to use as gobos with some type of floor stand.
 
According to Mr. Everest, 1/2" drywall on 16" centers has an absorption coefficient of .29 at 125 hZ, and "even more at 63 hZ" - That's the main reason I've been looking for info on wall construction (actually TESTED) where one leaf of the wall is multiple layer sheet rock and the other leaf is just ONE layer. If the TL is about the same for equal TOTAL mass, REGARDLESS of whether it's balanced between the two leaves, then I would go for an inner leaf that was just ONE layer, and put the rest of the mass on the OUTER leaf.

That way, I would need a LOT less bass trapping to balance the response of the room.

As if that weren't enough, I just found THIS !@##$%!@##$%

http://www.electroacoustics.co.uk/article/essroom.htm

Now, I've got to re-think a bunch of crap ALL OVER - Tex, don't read that link or you'll be REALLY pissed at me, worse than last time :=)

Oh well, the good news is that article only crapped on a SMALL part of my acoustic knowledge, and actually re-inforces a few things I told Michael a while back... (sigh)
 
knightfly said:
Now, I've got to re-think a bunch of crap ALL OVER - Tex, don't read that link or you'll be REALLY pissed at me, worse than last time :=)
Click to expand...

That one doesn't bother me too much because I'm not quite that anal yet. I was actually planning on doing diffused ends when I am finally finished with my room. There is a brick fireplace in the middle of the wall centered a feet behind where my mixer will eventually be. I was going to absorb the sides and let the fireplace diffuse.

My room is 31'x16' so I'm planning on diffusing the short walls and absorbing the long walls. My theory (probably wrong) is that by diffusing the walls with the greatest space between them I can make the room sound bigger. I use the room for tracking and mixing so I need a best (or worse) of both worlds type of setup.
 
TexRoadkill said:
My understanding of Drywall is that it's only real acoustic use is for adding mass and seperation. It doesn't really absorb that much and it's so damn heavy it would be counter productive to use it with the panels. It might work well if you put some 703 on them to use as gobos with some type of floor stand.
Click to expand...

Hey thanks, Tex. The stuff I have is paper-thin. It could barely even be called drywall. I like your Gobo idea. Maybe I could come up with some sort of contraption using skateboards and/or rollerskates. :D :D Following me? :D
 
chessrock said:
Hey thanks, Tex. The stuff I have is paper-thin. It could barely even be called drywall. I like your Gobo idea. Maybe I could come up with some sort of contraption using skateboards and/or rollerskates. :D :D Following me? :D
Click to expand...

I think I follow ya. Your gonna get some hot high school skater chicks to roll around and hold up the gobos. I like the way you think :D
 
I like the "rolling around" part, but FORGET the gobo's, what we need here is "mojo's", instead... :=)
 
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