Foam facts?

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HapiCmpur

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I've finally got a room dedicated to music (instead of just a corner in the bedroom), and now I must figure out how to "tune" that room for decent acoustics. (Notice I said "decent," not "perfect.") Naturally, there are a lot of differing opinions in the literature on acoustics. Perhaps someone here – someone who presumably isn't trying to sell me expensive room treatments – might have some suggestions.

My room will be a small project studio in which I will record vocals, guitars, a drum machine, and a digital keyboard using a 16-track digital workstation. Nearly everything except the vocal and acoustic guitar tracks will be recorded without mics directly into the workstation. I don't have the money, the need, or the inclination to sound-proof the room. The house is generally pretty quiet anyway. All I want is a fairly accurate listening environment for mixing my own stuff as a hobby.

The room is 14' long and 12' wide. (See attachment.) The floor is carpeted, and the ceiling of textured drywall is 7'-8" high. There's a window on one of the long walls and another on one of the short walls, and I have covered both with heavy drapes. My mixing setup faces the window on the short wall, and my monitors sit just to the left and right of the drapes. The short wall behind me (as I sit at the mixer) is pretty well broken up with shelves and storage units. In fact, it was originally a long, shallow closet, but I removed the doors to eliminate the flat surface and in the hope that I might be able to make it into a three-sided vocal booth.

The room's biggest challenge is probably the long wall with no window. I've hung some artwork on it for now, but I know I'm going to need something else to get rid of the slight slapback and "room ring" that still exist.

I've consulted the experts at Auralex who have faxed me a free room analysis. They've recommended their Project 2 Roominator Kit ($400!), which includes nothing but foam panels and wedges. This raises three questions:

1. With all that foam and no diffusers, will I over-deaden my little room?
2. Will the foam wedges that Auralex calls "bass traps" really trap bass, and if not, are wedges still worth installing anyway?
3. For my humble purposes, are Auralex panels and wedges any better than other acoustic panels and wedges?

One last thing: My room (which is partially underground, by the way) has a 9” deep ledge running along one short wall and one long wall. And it’s not just a ledge like a shelf – the walls below the ledge intrude into the room about 7 or 8” deeper than the walls above the ledge. My monitors, on stands, rise just above that ledge, giving them a little more breathing room, so to speak, from the wall behind them. Do I need to put anything (like wedges, for instance) on that ledge either directly behind the monitors or in the corners to the left of the right of them?
 

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HapiCmpur said:
I've consulted the experts at Auralex who have faxed me a free room analysis. They've recommended their Project 2 Roominator Kit ($400!), which includes nothing but foam panels and wedges. This raises three questions:

That kit gives you 96 sq ft of coverage plus 16 ft of bass trap.

If you can find a supplier, $400 buys a lot more rigid fiberglass than that. Plus foam looks ugly compared with fabric wrapped panels.
 
Auralex's bass traps are "okay", specifically the larger ones (12"?). Anyway, they are rather expensive but available in many colors, but only do a mediocre job, especially "way low" in the <50hz range. A good subwoofer will make the auralex rather useless.

A better option is to build your own bass traps out of rigid fiberglass, stuffing it into a 4'x8' pine frame. Cover the front of the frame with a cotton fabric of your choosing, put the fiberglass inside the frame on that, then staple more fabric across the back to encapsulate the fiberglass for safety reasons. You can use colors of your choosing of course, and fabric is fairly inexpensive. Jo-Ann Fabrics has stores across the country, I'm there all the time these days (making drapes, buying vinyl for armrests, monitor shelfs, even automotive interior stuff!).

Once you make a few, you can stand them up in the corners of the room or hang them using a picture frame wire.

I'll be using a mix of auralex and rigid fiberglass here.
 
Hapi,

I agree with the other posters. If $400 is a lot of money to you, your best option is to build your own treatment using rigid fiberglass. You'll find a lot of good advice in the Acoustics FAQ, second in the list on my Articles page:

www.ethanwiner.com/articles.html

--Ethan
 
Thanks!

You guys have inspired me to at least ATTEMPT to build my own bass traps. Ethan's article was outstanding, and tomorrow I will begin my quest for OC705 first thing in the morning. I'm still wondering, though, if I might not end up overdeadening my little room with all that sound absorption. Should I add some diffusers along the back wall or perhaps on the ceiling, or will the spaces between the bass traps probably give me all the diffusion I'm likely to need?
 
Well, we're guessing in what you need based on your description :) Once you treat the room a little bit, you'll know more of what you need as you go.

I for one wouldn't make 20 bass traps and hang them everywhere. I'd make one for each corner, and start with that. If it sound good to you, you're done. If it needs a llittle more, then you make a few more. A friend of mine finished his bedroom studio middle of last summer, and essentially covered the entire room in framed rigid fiberglass, walls and ceilings (clouds) and auralex foam in between. The room sounded dead. Couldn't really see what color he painted the room either.

Do it in phases... this way you don't buy and install more than you need.

I'm of the opinion that diffusion doesn't help *that* much in a small space.
 
HapiCmpur said:
You guys have inspired me to at least ATTEMPT to build my own bass traps. Ethan's article was outstanding, and tomorrow I will begin my quest for OC705 first thing in the morning. I'm still wondering, though, if I might not end up overdeadening my little room with all that sound absorption. Should I add some diffusers along the back wall or perhaps on the ceiling, or will the spaces between the bass traps probably give me all the diffusion I'm likely to need?


My understanding is that in a small room you want to stick with absorption.

And keep in mind this is only what I've read here and at John Sayers sight, but if there is less than 25 ft from the back of your head at the mix position to the back wall and then back to your mix position then you want absorption on that back wall as diffusion would give you a muddy sounding room.

Again this is what I've read so if anyone knows differently feel free to correct me. :)
 
You heartless bastards!

You guys got me all hot and aroused about making my own fiberglass bass traps, but you didn't tell me that I'd never be able to get my hands on the most important ingredient: fiberglass. How cruel, how cruel...

I got a list of local vendors from the Owens Corning website and started calling them this morning. None of them knew what I was talking about when I asked for rigid fiberglass. I finally went to the source, called Owens Corning, and was told by the nice lady that OC won't sell directly to me, OC won't sell to vendors unless they order in huge quantities, and that the only way I'm ever gonna get my hands on OC rigid fiberglass is by calling local building contractors to see if they have any leftovers they'd be willing to sell me. Arg! After that I went to the websites of the other companies that Ethan's article recommended, but all similar products are listed as "commercial," meaning that they aren't sold in small batches.

Surely, there must be a better way than begging table scraps from local contractors. So I'm asking all you bass trap makin' do-it-yourselfers out there: Who did you have to kill to get your fiberglass?
 
Answering your question would be more feasible if we knew where you are - also, keep in mind that mineral wool, rockwool, slag wool, these are all acoustically EQUAL - other, more friendly source companies are Certainteed, Roxul, Knauf, Johns Manville, probably a few others.

What you're looking for is 3 to 6 pounds per cubic foot density, NO facing, usually 3 or 4" thick. Expect to pay anywhere from $.50 a square foot up to $2 a square foot, depending on weight. 6 PCF stuff will likely cost twice what 3 PCF stuff costs - there is a little benefit in lower frequency absorption with the heavier stuff, and it is stiffer so retains its shape without a frame better - other than that, the 3 pcf stuff has better absorption at other than direct incidence (works better when the sound hits at an angle)

Let us know where you're from and we can probably "get you a fix"... Steve
 
knightfly said:
Let us know where you're from and we can probably "get you a fix"...

I'm in Silver Spring, MD, just north of Washington, DC. Know any place around here where I can score some good ‘glass, man? I think what I need is about 8 sheets of 4" thick OC 705 (without the facing) or OFI 64, but I'm new to this so I'll gladly take advice.

Once I get the rigid fiberglass, I was planning to put it in frames made of 1x4 lumber and then wrapping those with some kind of cloth. (Somebody at another site suggested using black polyethylene weed blocking film, the kind made for gardeners.) Then I was thinking of suspending them from the studio ceiling so that they hang a few inches away from the walls and corners. I don’t know how heavy these things are going to be, though, so I may have to mount them securely to the walls instead. We’ll see.
 
Look for construction supply firms (not home improvement stores) until you find one that specilizes in insulation. Once you find them you will usually be able to buy a bale (2' high stack of 2x4 sheets) cash and carry. Nobody will ship such a small quantity and nobody will do credit/billing on such a small quantity, but if they have any on-site stock at all they will let you come and pay for one and take it with you.

Also if they have 703 instead of 705 take it and go with it. And if they only have one or two inch thickness take it. Layering up two 2" panels or 4 1" panels is just as good (as long as they are unfaced).
 
HapiCmpur said:
I'm in Silver Spring, MD, just north of Washington, DC. Know any place around here where I can score some good ‘glass, man? I think what I need is about 8 sheets of 4" thick OC 705 (without the facing) or OFI 64, but I'm new to this so I'll gladly take advice.

http://acrinsulation.com/contactus.htm

4" can be tough to get, might be special order. 2" should be stock though.
 
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