Room treatment help - Page 2 - AVS Forum
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post #31 of 42 Old 06-20-2013, 05:13 AM
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Originally Posted by DonH50 View Post

The cheapest/easiest corner trap is to cut sheets of OC-70x or Roxul into triangles and stack them. You can tack cloth to the front to make them look better.

yep gonna make these possibly http://nagasakisound.com/how-to-build-corner-bass-trap/

will cost me about $160 for 4 traps, which will cover floor to ceiling of two corners, not too bad. And it's nice they can just sit on the floor and on one another

Yet another one of those wasteful designs that carries the absorptive materials all the way into the corner. If you left an empty space near the apex of the corner and increased its depth you could probably move the bandpass of the bass trap in a favorable direction.
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post #32 of 42 Old 06-20-2013, 06:40 AM - Thread Starter
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Yet another one of those wasteful designs that carries the absorptive materials all the way into the corner. If you left an empty space near the apex of the corner and increased its depth you could probably move the bandpass of the bass trap in a favorable direction.

have any links to one that's built like that?

I can't find one build that doesn't just use triangles of fibreglass.

I am thinking of maybe doing it like this now http://www.gearslutz.com/board/attachments/bass-traps-acoustic-panels-foam-etc/214363d1295031852t-new-kind-diy-corner-bass-trap-stackedpanels.jpg

basically going 24" wide then 16" wide then 8" wide so there will be a good amount of air behind the panels. And I'd be able to do two 8 feet tall corner bass traps for my two rear corners with just 1 package of insulation.
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post #33 of 42 Old 06-20-2013, 06:40 AM - Thread Starter
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I can't believe that someone is going to charge you > $100 for mounting clips.

I was talking about absorptive materials, and if you are already using Roxul from a local source then you are pretty much doing what you can. Then I remain mystified about the > $100 shipping charges.

Yeah anything shipped to Canada is ridiculous, I'm not buying it from there though, i would never pay that much shipping.
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post #34 of 42 Old 06-20-2013, 11:11 AM
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...Yes I have REW and all that stuff, my computer is at my desk, which is why I have a desk there.
If you have access to "REW and all that stuff" why aren't you using it?

If can be fun to build and experiment blind, but blind men rarely paint a masterpiece. You need measurements to guide your treatment of the room - identify a problem before building and installing something to fix it.

What you'll find is that your room's already pretty good - most residential spaces are - so general-use acoustic devices are not going to be helpful. There are a lot of acoustic devices available to you, but specific problems require a tailored solution. One-size-fits-all approaches could take you the wrong way.

So measure first, then build what the measurements say will be effective.

Have fun,
Frank, whose room's pretty good with no added treatment, just normal furnishings. (Good = RT40 around 0.3 sec above 100Hz, rising to 0.5sec. at 20Hz)
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post #35 of 42 Old 06-20-2013, 11:33 AM - Thread Starter
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I have measured it and it is awful. Huge 10-12 dB swings at certain frequencies.

I can't measure what will happen when I put stuff in, before I build it lol, so I am asking what I'll need to build so I don't build stuff I don't need or build the wrong things.

Everything I've read about room treatment has said you can't specifically do something to treat a specific frequency, everything you add will impact the whole range.
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post #36 of 42 Old 06-25-2013, 12:57 PM - Thread Starter
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So what is the general consensus of how to build corner bass traps? Just a big stack of triangles, or with some space behind it, something like this http://www.gearslutz.com/board/attachments/bass-traps-acoustic-panels-foam-etc/214363d1295031852t-new-kind-diy-corner-bass-trap-stackedpanels.jpg
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post #37 of 42 Old 06-25-2013, 02:08 PM
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You have to experiment a bit. Try one and then the other, move them different distances rom the wall, make a pyramid pointing to the corner. Try a bi-lelvel with different elements facing different ways. Every room or media center has a prime listening area, dictated by all the interaction with all the furniture, windows and doors.
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post #38 of 42 Old 06-25-2013, 02:10 PM - Thread Starter
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I can't experiment as that would require cutting them different ways and that would just waste material..
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post #39 of 42 Old 06-25-2013, 02:59 PM
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You needn't experiment, the science involved is well understood, the best practices well vetted.

The approach one decides to take depends on the space you wish to forfeit to treatment, and the overall goals.

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Originally Posted by WagBoss View Post

So what is the general consensus of how to build corner bass traps? Just a big stack of triangles, or with some space behind it, something like this http://www.gearslutz.com/board/attachments/bass-traps-acoustic-panels-foam-etc/214363d1295031852t-new-kind-diy-corner-bass-trap-stackedpanels.jpg


In this previous post on page one of this thread, I outlined out the various approaches for porous absorption.

A sampling;
For 4" thick, the dense stuff (OC703 or equiv) is the best.
For 4"-12" use 4" of 703 like and the rest air gap, or use Rockwool Safe-N-Sound up to 12"
For 12" and up, fluffy fiberglass approach works great.

The issue is if you use too much thickness of the more dense material, it begins becoming less effective. Typically, the thicker the trap, one can utilize the less expensive, fluffy type insulation.

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post #40 of 42 Old 06-25-2013, 07:28 PM - Thread Starter
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I will be using roxul safe'n'sound.

So basically I can do a stack of triangles, or 3 panel thick pyramid type thing with an air gap behind it. From what I understand, adding an air gap is basically just as good as adding material.
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post #41 of 42 Old 06-26-2013, 06:57 AM
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Quote:
Originally Posted by WagBoss View Post

I will be using roxul safe'n'sound.

So basically I can do a stack of triangles, or 3 panel thick pyramid type thing with an air gap behind it. From what I understand, adding an air gap is basically just as good as adding material.

Yes, the total thickness from the front face of the panel, to the boundary behind it is one important design component.


Other considerations include;, if you utilize an air gap, assure the gap is "sealed", from the room, ... as the energy can diffract around the panel and short circuit the effectiveness. The frequency range of interest are large waves, thus the panels need to be large with respect to wavelength. The smaller panels are effective too, just at a higher frequency. When I say "sealed", I mean just assure the material spans the entire width firmly.


Also, this may not apply to you, however total surface area is more important than thickness. What I mean is if you had only one case of rigid 703 insulation 2x4 panels, it'd be best utilized by spreading it all around, and treating four corners, rather than two corners twice as thick. With Safe-N-Sound, many DIY'ers just fill the entire area, and that's great.


Another important consideration, if you find too much MF/HF energy if removed from the listening experience, then you can apply 6mil plastic (Visqueen), or craft paper, to the face off the treatment panel. This will begin to return the energy above about 500Hz. There's even more sophisticated approaches utilizing wood slats. Effectively these facing techniques create a low pass filter in front of the absorption, without altering the overall effectiveness of the bass traps.

---

How many corners are you considering?

There are varying triangle cutting techniques/stacking, how thick are the traps you're considering?

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post #42 of 42 Old 06-26-2013, 09:29 AM - Thread Starter
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I am doing the two rear corners. I am putting two 2x4x2" panels at the first reflection point on each side wall, one 2x4x2" panel at the first reflection point on the ceiling (these 5 panels made out of roxul RHT80) I am putting three 1.5x1.5 QRD diffusors behind the listening position, and also another 2x4x2" panel below the diffusors. The bass traps in the corners will use a 2x4x3" roxul safe'n'sound as the outer panel, and then one more panel cut into 2/3 and 1/3 in a pyrmid style behind the original panel, so at the thickest it's 9" and average thickness is 6". The corner bass traps will be floor to ceiling which is about 93" high. This way I will only need one package of roxul, as I only need 8 panels. With the triangle stacking method, I'd need 16 panels. And the room is a bedroom so I don't need it to be 36" wide or whatever the triangles work out to be, the 24" wide I'll have will be good.

Also I have 3 spare subwoofers so I might just set them all up in the room which will really help smooth the bass.

And I have 100 band parametric EQ I am going to set up with REW.
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