About to begin construction of sound proof room, need help!

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bobbyang1

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Hi, I'm new to this forum, but it seems to me that there are people here that really know their stuff.

I am about to begin wrapping several pieces of fiberglass panels with muslin. The room has already been covered with fiberglass panels cut to shape. It is simply my job to wrap them, and figure out how to attach the panels to the drywall.

I am unsure about how to actually go about wrapping the fiberglass. I am planning right now on wrapping nearly the entire piece of fiberglass with the muslin, then hotglueing the back surface of the fiberglass to the muslin, while stretching it slightly to give it some taughtness. Has anyone had experience with wrapping fiberglass with muslin?

As for attaching the wrapped panels to the dry wall, I am currently using small 2x2" velcro squares, four per panel, to stick the panels to the dry wall. I will be hotglueing the velcro pads to the muslin wrapped panels. Is this the only way to "stick" the panel up? Or has anyone else used different methods?

Hope I can get a few words of wisdom!

-Bobby
 
Just so you know, it's not going to be sound proof. Meaning, sound *will* excape from your room, no matter how much 703 you use.
Sound proof is almost impossible.

What you're doing is acoustic treatment. You're going to absorb certain frequencies of sound in your room, which should help the acoustics, assuming you put all that 703 in the right places.

Can't really help ya with the construction -- just wanted to make sure you're clear on the terminoligy.
 
If you cover the entire wall surfaces with fiberglass, you're going to have a room that's overly bass heavy.

You should read Ethan Winer's Acoustic FAQ/Primer before you go ANY further.
 
Ok, I just experimented today with a full size piece of fiberglass, and the results, while excellent, took a very long time to get. Hot glue is a very time consuming adhesive to use... it's also inconvenient. Also, thanks for the clarification about sound proof vs. acoustic treatment.

It seems I need to use an adhesive that I can just brush on quickly. Most likely some sort of rubber cement??

Thanks for the advice all.
 
Ever think about sewing? It takes more fabric, but four straight lines on a sewing machine ain't tough, and it's easy to rip the seams to reuse the fabric or insulation at a later date. There are commercial acoustic panels that are basically exactly that, fabric sewn over rigid fiberglass. If you don't want to cover the back, just fold the edges a few inches over the back, sew the corners of three folds together, place around panel, then stitch the last by hand.

For attaching to the wall try using grommets and nice brass screws into wall anchors.
 
You'll get much better treatment if you use Ethan Winer's design rather than just stick a fabric-covered piece of fiberglass directly against the wall with Velcro.

www.realtraps.com
 
Actually, C7, it would depend on what you're treating - Ethan's trap designs are for lower frequencies, where the rigid fiberglass/rockwool thing directly on walls is more for midranges. For an optimum sound field, you need a BALANCED range of reverb times/frequency response, so it gets more tricky than just this vs. that - even wallboard in a room contributes to absorption, mainly at low frequencies close to that of ethan's traps, and with the same physics involved (panel resonator)

If you don't plan for a balanced RT-60 in your room, whatever you get will be mainly "luck of the draw", which can sometimes be wonderful and other times really bite you in the ass... Steve
 
Thanks all for the input. I think i mis-stated the purpose of the room I am constructing. Basically, the room will be used exclusively for research in the field of acoustical engineering. By using the fiberglass, we are producing a low reverberation time. Of course, we can't make it perfect, so fiberglass is the option we chose. I am simply looking for a way to give the room more asthetic appeal. Once again, thank you all for your input!

-bobby
 
How low of an RT are you shooting for?

From what I understand, most rooms will do nicely with RT's under a half-second across the audible spectrum, and that really well engineered rooms (like for mastering) will have RT's below a quarter-second.
 
The easiest way to do the panels is to glue them onto a wood frame using spray adhesive. Then attach the fabric to the wood frame and secure the frame to the wall. The wood can be lightweight 1 x 1/2" and you can build them as big as your fabric covering will allow.
 
you can also use Liquid Nails instead of a spray adhesive.
 
How wide a frequency range are you looking for when you say "low reverberation time"? Because what you're doing won't help much at all at frequencies below about 4-500 hZ - for that, you need a combination of different approaches, and quite a bit of depth BEHIND your treatments (1/4 wavelength of the frequency you want deadened)

Just saying "low reverb time" means nothing without a specified frequency range - if you really don't know this, the first part of your experiments should be to buy Everest's Master Handbook of Acoustics (as a bare minimum) and read all 615 pages of it (includes the index) - without a knowledge of the basic principles, experiments won't tell you a lot... Steve
 
In terms of RT, we have so far come up with around .25 seconds using a not-so-accurate method (we have a Pulse, but we're running into trouble with the Reverb Time calculator). Basically so far we have a plot in increments of .25 seconds of decibels v. time for a frequency of around 2000 Hz. For a spike of noise (i.e. a clap), the sound level drops roughly 60 dB in .25 seconds (although our measurements weren't very good).

As far as what we're trying to do, we understand that the room is not going to give us a good RT in low frequency sounds, but that's just what we have to deal with for now. We're not constructing a super-fancy and expensive room, just something simple (so far at least). There are certainly ways we can improve the current setup, but for now we are going with just rigid fiberglass. Thanks for all the help! People definetly know their stuff around here.
 
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