Auralex or 703?

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cgarges
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Post by cgarges » Thu Dec 20, 2007 10:12 pm

Would 703 not be more effective than Ultratouch? It seems to me that if 703 is more rigid, that probably means more mass, which means more effective low-frequency absorption, right? Let me know if I'm wrong about that. I'm seriously curious.

Chris Garges
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Post by chorga1 » Thu Dec 20, 2007 10:20 pm

Don't worry about all that stuff. Just check this, and yer golden:


http://bobgolds.com/AbsorptionCoefficients.htm[/url]

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Post by toddpipes » Fri Dec 21, 2007 5:21 am

you can make the panels 'self rigid' with some fiberglass resin hardener--it's super cheap and easy. just brush a light coating around the edges and let it dry. the end result looks really professional and eliminates the need for framing of any kind.

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JWL
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Post by JWL » Fri Dec 21, 2007 9:12 am

cgarges wrote:Would 703 not be more effective than Ultratouch? It seems to me that if 703 is more rigid, that probably means more mass, which means more effective low-frequency absorption, right? Let me know if I'm wrong about that. I'm seriously curious.
Hi Chris, the answer to your question depends on how thick the 703 is (or, for that matter, how thick the Ultratouch is). These 2 materials have similar absorption specs, so it really comes down to how much mass of each material there is. The Ultratouch comes in 3.5" thick and 5.5" thick batts. So if you're them to, say, 1" of 703, then the Ultratouch will be much better.

I haven't measured them side by side (plus it's hard to measure this stuff anyway), but 5.5" of Ultratouch seems to perform about as well as 4" of 703. Most companies only release specs down to 125Hz, so it can be tricky to do a direct comparison.

Another way to compare the 2 materials is with how much of it you can get with a certain budget. If you have a local dealer for Ultratouch so you don't have to pay shipping, you will almost certainly get more performance out of, say, $500 of Ultratouch than you will out of $500 of 703, simply because that will buy you so much more mass.

I've not seen any proof one way or the other, but there are many who believe that less dense material actually performs better for corner bass traps (ie, superchunks or bass trap soffits in the corners), meaning 703 outperforms 705 in this context, etc. Again I've not seen any numbers on this, but this premise seem to be accepted as true.

From my point of view, the main difference between the 2 materials is that 703 is a bit sharper under cloth wrapping, they generally look nicer than the Ultratouch which is quite floppy. I like Ultratouch because it's green. If you need a lot of mass of material behind cloth panels, I think it's ideal. If you're making panels and want a sharp appearance, I'd go with fiberglass. Rockwool is between the 2, floppier than rigid fiberglass but not as floppy as Ultratouch.

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Post by Leviethan » Wed Jan 02, 2008 2:01 am

So we ended up using 5.5" thick Ultratouch cotton batts with a plywood back to make 2X6' bass traps, and Owens Corning 703 2X4s with soundboard back for hanging panels. We didn't need to make frames, we just wrapped each panel tight with burlap stapled to the back. However, we did have the strap the Ultratouch to the plywood with twine so it wouldn't sag. Let me know if anybody wants any more info. Go to http://www.deepnorthmusic.org/studio.html to see pictures our progress. Later this week, we'll start hanging the panels in the room. The room sounds much better already, but I'm still hearing flutter echos up top. Anybody think I should hang anything from the ceiling?
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JWL
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Post by JWL » Wed Jan 02, 2008 7:24 am

Looks good, Leviethan.

The only thing that concerns me is the plywood back for the bass traps. This will reduce the effectiveness of the traps if they are straddling corners. For a bass trap like this to work effectively, sound has to be able to pass through them; the sound is absorbed as it passes through. The plywood prevents this from happening, so sound below a certain frequency will just go around the trap. The frequency where this starts to happen will have a wavelength of about 2' (width of trap), which is about 565Hz.

What you're left with is a panel that will absorb lots of high frequency energy, and not do too much in the bass.

Don't want to be the bearer of bad news here.... :-(

There is a reasonably simple fix, though. If you can disassemble the bass traps to get the plywood out, you could then cut most of the plywood out, leaving (say) a 2-3" ring of plywood all the way around, hollowing out the inside (think big rectangular plywood donut, 2-3" wide). This would still give you the structural support you need to hold the cotton up (and staple the cloth to), and greatly improve the effectiveness of your traps.

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Post by JWL » Wed Jan 02, 2008 7:25 am

Also, getting some absorption on the ceiling is a good thing. I'd pay particular attention to above the mix position (to absorb first reflections from the speakers), as well as above any recording areas, like if you have a drum kit set up or something.

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Post by bluesman » Wed Jan 02, 2008 10:06 am

blocks of cellulose insulation work quite well & are a fraction of anything else I have found.
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Post by LeedyGuy » Wed Jan 02, 2008 11:01 am

JWL wrote:Looks good, Leviethan.

The only thing that concerns me is the plywood back for the bass traps. This will reduce the effectiveness of the traps if they are straddling corners. For a bass trap like this to work effectively, sound has to be able to pass through them; .
I assume this is also true if I simply put the Ultratouch in the walls like they are doing in the picture. I would order the heck out of that stuff right now if I could just put it up behind my paneling as insulation. Will that do a damn thing for me? How about if I just put the insulation up and ditch my paneling completely and be down the studs? That's not a bad idea, is it?

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Post by Leviethan » Wed Jan 02, 2008 2:04 pm

Really? The plywood is only about 1/4" thick. I got the thinnest plywood I could find just to give it a rigid back. Does the wave get absorbed by passing through and bouncing back in?
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Post by Leviethan » Wed Jan 02, 2008 2:10 pm

I think I could cut out the middle of the plywood like you suggest without taking the whole thing apart. I will give this a shot if you think it will help.
Leviethan

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Post by JWL » Wed Jan 02, 2008 6:44 pm

I definitely think it will help for the panels that are straddling the corners. The ones flush up against the wall, it's not as big a deal.

Keep in mind, the way absorbers work is by absorbing sound as the sound passes through the absorber. If in any way sound is blocked from passing through, then the effectiveness of the absorber will be reduced. This will only be noticeable in the low end. So yeah, the 1/4" plywood will block less sound than 3/4" plywood, but it does still block some sound, thereby reducing the effect of the absorber.

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Post by Leviethan » Wed Jan 02, 2008 9:37 pm

OK, I will cut out the middle of the back of each bass trap. It shouldn't be a big deal. Thanks a lot for all the info!
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Post by LeedyGuy » Sat Jan 05, 2008 6:19 am

I just talked to someone at a local building supply place by me (they don't carry 703 unfortunately) and he suggested that I get something by OC called Quiet Zone. Does anyone have experience with that? It goes behind the sheetrock and acts as insulation (it's sold in 16" bails) and there's a link to it here, http://www.owenscorning.com/quietzone/p ... ducts3.asp but it seems like this is only to block noise from the rest of the house.

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Post by JWL » Sat Jan 05, 2008 1:45 pm

Hi Kento, I have no experience with that stuff. I looked at the data sheet; it looks like it's designed to reduce sound transmissions when installed in walls. Sadly, they don't publish any absorption specs that I could find quickly, and it also doesn't specify as to how it performs over the audio frequency spectrum.

What will you be using this for? If it's absorption in the room I'd stick to normal, proven materials. If they don't have 703 maybe they have rockwool?

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