Acoustical Treatments Master Thread - Page 285 - AVS Forum
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post #8521 of 10377 Old 01-19-2012, 05:51 AM
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Acoustic Performance

Acoustic Performance

Random incidence
absorption coefficient
acc. to EN ISO 354 125 250 500 1 000 2 000 4 000

at 10 mm 0.02 0.04 0.08 0.19 0.53 0.44

at 32 mm 0.08 0.17 0.51 0.56 0.25 0.24

This is the absorbtion table (i think) from the armaflex website that my local SPI insulation warehouse manager recommended. It's supposedly nice and rigid, requiring no frame, and is fairly cost competitive with other options. Can anyone evaluate this table an comment on the effectiveness of this product???

Sorry that the table is out of alignment, at 125, the 0.02 and 0.08 should be directly underneath
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post #8522 of 10377 Old 01-19-2012, 08:12 AM
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Quote:
Originally Posted by Docj04 View Post

Acoustic Performance

Acoustic Performance

Random incidence
absorption coefficient
acc. to EN ISO 354 125 250 500 1 000 2 000 4 000

at 10 mm 0.02 0.04 0.08 0.19 0.53 0.44

at 32 mm 0.08 0.17 0.51 0.56 0.25 0.24

This is the absorbtion table (i think) from the armaflex website that my local SPI insulation warehouse manager recommended. It's supposedly nice and rigid, requiring no frame, and is fairly cost competitive with other options. Can anyone evaluate this table an comment on the effectiveness of this product???

Sorry that the table is out of alignment, at 125, the 0.02 and 0.08 should be directly underneath

You are going to want to make those no less then 100mm thick and straddle corners if you want to use them as broad band bass traps. Honestly I would recommend thicker then that if you can.

Glenn Kuras
GIK Acoustics

http://www.gikacoustics.com

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post #8523 of 10377 Old 01-19-2012, 08:17 AM
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Quote:
Originally Posted by robc1976 View Post

Figured I would update with some pics, I have 4 QRD's to be ordered and placed or rear side walls to complete the room.




Right MLP:




Left MLP:




Rear wall:




QRD diffusor:


Wow I need to get these up on our face book page (and our website on the next update). If you are on face book would you mind posting them over on our page?

Glenn Kuras
GIK Acoustics

http://www.gikacoustics.com

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post #8524 of 10377 Old 01-19-2012, 09:44 AM
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Quote:
Originally Posted by myfipie View Post

You are going to want to make those no less then 100mm thick and straddle corners if you want to use them as broad band bass traps. Honestly I would recommend thicker then that if you can.

Given that Reply, I surmise that these are NOT as effective as OC703/705 at the same 1" thickness.
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post #8525 of 10377 Old 01-19-2012, 10:43 AM
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No, not as good - does that material have a paper facing? Not sure why else the absorption would be so bad at the top end.

703 1" (25mm) on wall 0.11 0.28 0.68 0.90 0.93 0.96
Armaflex 32 mm (1.26") 0.08 0.17 0.51 0.56 0.25 0.24

I think myfipie's comment applies regardless of the material - 4"+ and air space behind at a minimum for bass trapping.
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post #8526 of 10377 Old 01-19-2012, 11:15 AM
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Quote:
Originally Posted by Brad Horstkotte View Post

No, not as good - does that material have a paper facing? Not sure why else the absorption would be so bad at the top end.

703 1" (25mm) on wall 0.11 0.28 0.68 0.90 0.93 0.96
Armaflex 32 mm (1.26") 0.08 0.17 0.51 0.56 0.25 0.24

I think myfipie's comment applies regardless of the material - 4"+ and air space behind at a minimum for bass trapping.

Got it. I don't think there is a paper facing. The website is Armacell.com, and under products, you will find the Armaflex rolls and sheets. There is full description there.

looks like it's going to be Plan A--combination of mineral wool to line the corners where the tower speakers are as I can simply stand them up and use the speakers themselves to hold them in place, and OC703 panels (for rigidity) hung in various wall locations.

Should be better than nothing, which is what I have now...
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post #8527 of 10377 Old 01-19-2012, 02:02 PM
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Mineral wool works well for bass trapping, and is usually cheaper then rigid fiberglas - but of course, it takes a different approach to mount.
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post #8528 of 10377 Old 01-19-2012, 02:20 PM
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post #8529 of 10377 Old 01-19-2012, 02:45 PM
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Quote:
Originally Posted by pepar View Post

More volume, too, right?

Do you mean you'd need more volume of mineral wool? My understanding is that that's more impacted by density than the material type - i.e. ~3 pcf mineral wool performs similarly inch for inch compared to ~3 pcf rigid fiberglas. Maybe you meant lighter density, like pink fluffy?
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post #8530 of 10377 Old 01-19-2012, 03:02 PM
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Quote:
Originally Posted by Brad Horstkotte View Post

Do you mean you'd need more volume of mineral wool? My understanding is that that's more impacted by density than the material type - i.e. ~3 pcf mineral wool performs similarly inch for inch compared to ~3 pcf rigid fiberglas. Maybe you meant lighter density, like pink fluffy?

Yeah, that's it.
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post #8531 of 10377 Old 01-19-2012, 03:33 PM
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Docj,
do you have any photos of your space you're willing to share? would assist with recommendations on placement and approach -
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post #8532 of 10377 Old 01-20-2012, 09:16 AM
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Quote:
Originally Posted by localhost127 View Post

Docj,
do you have any photos of your space you're willing to share? would assist with recommendations on placement and approach -

Actually, I will likely snap some digital pics this weekend to post here. The only reason that I haven't done so already is because I am having a carpenter come and lower the mantle shelf above my fireplace (gas, and NEVER even turned on) so that I can mount my Sharp 70" LED above it.
This will, of course, change my speaker layout and therefore my acoustic treatment placement as well.

I will likely go today to buy a bundle of mineral wool panels to have ready, and then get whatever else I need once the room is rearranged.
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post #8533 of 10377 Old 01-20-2012, 05:40 PM
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Well, I got a 6-pack of 2'x4x1.5"', and a roll of burlap to cover it...

HATE the mineral wool. $30 for the panels,and $60 for the burlap = lessoned learned about the mineral wool.Too floppy and easily torn/damaged.

I'll end up keeping the mineral wool for odds and ends, and getting some 703 instead.
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post #8534 of 10377 Old 01-23-2012, 05:30 AM
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Quote:
Originally Posted by Docj04 View Post

Well, I got a 6-pack of 2'x4x1.5"', and a roll of burlap to cover it...

HATE the mineral wool. $30 for the panels,and $60 for the burlap = lessoned learned about the mineral wool.Too floppy and easily torn/damaged.

I'll end up keeping the mineral wool for odds and ends, and getting some 703 instead.

Yes with mineral wool you really do need to use a frame when making panels, but can be nice when cut into triangles and stacked in the corners.

Glenn Kuras
GIK Acoustics

http://www.gikacoustics.com

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post #8535 of 10377 Old 02-02-2012, 11:14 AM
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A couple of my corners can only be 24" face corner traps, due to space limitations. Using the Whealy calculator, I tried a few different depths. A 24" face corner trap has a maximum depth of 24 inches (if sound were to enter at a very oblique angle almost parallel to the large 24" face). But that's only at one point. At two other points it has has 17", 8", and 6" of depth, etc. [EDIT: Removed mean and average calculated depth stuff]

So I decided to graph the absorption curves for several low bass frequencies, by inputting into the Porous Absorber Calculator the depth in mm of each half inch slide: 24", 12", 11", 6", etc. for each of seven frequencies.



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post #8536 of 10377 Old 02-02-2012, 07:09 PM
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They may be a stupid question but I used this DIY method to make some cheap acoustic panelling:

http://www.amateurhometheater.com/di...ic_panels.html

I used pretty much the same duct board. Obviously, fiberglass isn't good for you and every time I handled it, there is usually a slight irritation if it comes in contact with skin.

Now that the project is done and the panels are up, I'm beginning to worry that this may not be good to breathe in and if there are any asbestos type concerns. I know it would be a huge waste of time and money if I take these down and throw them out but health is first. I'm assuming that because they are covered in speaker cloth, they should be fine.

Any re-assurance or warning bells?
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post #8537 of 10377 Old 02-02-2012, 07:12 PM
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Quote:
Originally Posted by HKman View Post

They may be a stupid question but I used this DIY method to make some cheap acoustic panelling:

http://www.amateurhometheater.com/di...ic_panels.html

I used pretty much the same duct board. Obviously, fiberglass isn't good for you and every time I handled it, there is usually a slight irritation if it comes in contact with skin.

Now that the project is done and the panels are up, I'm beginning to worry that this may not be good to breathe in and if there are any asbestos type concerns. I know it would be a huge waste of time and money if I take these down and throw them out but health is first. I'm assuming that because they are covered in speaker cloth, they should be fine.

Any re-assurance or warning bells?

I didnt use fiberglass for this reason.
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post #8538 of 10377 Old 02-02-2012, 07:40 PM
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Quote:
Originally Posted by nezff View Post

I didnt use fiberglass for this reason.

http://www.gearslutz.com/board/bass-...rs-review.html
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post #8539 of 10377 Old 02-02-2012, 07:57 PM
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So....get rid of it???

That double sided tape is going to mean some re-painting as well.
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post #8540 of 10377 Old 02-02-2012, 08:00 PM
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So blue jeans and newspaper shouldn't be in our homes but metal slag and glass fibers are ok because they will break down.
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post #8541 of 10377 Old 02-02-2012, 08:45 PM
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Is the fact that the the surface of the fiberglass has been spray-glued (to fix to the speaker cloth) and is fully covered by speaker cloth make any difference?
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post #8542 of 10377 Old 02-03-2012, 04:26 AM
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Quote:


Using the Whealy calculator, I tried a few different depths. A 24" face corner trap has a maximum depth of 24 inches (if sound were to enter at a very oblique angle almost parallel to the large 24" face).

Good stuff but
When you straddle the corner it is much more effective then what you posted. I did a quick test of our lab/test room with 8 Monster traps. 3 corners floor to ceiling and 2 on the back wall. Pretty much follows the results we got from Riverband Lab when we tested there. Which shows a great deal of absorption below 100 hz. Note I would want to put in even more treatment but it is pretty close to a 10 db window which is pretty impressive with a great deal of improvement at 67hz.


Glenn Kuras
GIK Acoustics

http://www.gikacoustics.com

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post #8543 of 10377 Old 02-03-2012, 05:36 AM
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Quote:
Originally Posted by HKman View Post

Is the fact that the the surface of the fiberglass has been spray-glued (to fix to the speaker cloth) and is fully covered by speaker cloth make any difference?

fiberglass is a porous material - it works by converting kinetic energy of the soundwave traversing through the series of porous ducts within the insulation into heat (friction). by coating the face of the insulation with a spray or glue, you are blocking the porous holes, restricting flow through the absorber - yielding unexpected results (reflection due to impedance change). you do not want to use spray or glue to coat the face of the insulation to bond fabric. maybe a small dab of 3M spray in the corners...
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post #8544 of 10377 Old 02-03-2012, 06:16 AM
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Quote:
Originally Posted by myfipie View Post

Good stuff but
When you straddle the corner it is much more effective then what you posted. I did a quick test of our lab/test room with 8 Monster traps. 3 corners floor to ceiling and 2 on the back wall. Pretty much follows the results we got from Riverband Lab when we tested there. Which shows a great deal of absorption below 100 hz. Note I would want to put in even more treatment but it is pretty close to a 10 db window which is pretty impressive with a great deal of improvement at 67hz.


I'm not sure what you're saying/showing. That 8 Monster traps with better performance in a room, versus one theoretical slice of 24" fluffy at 60 Hz?

I don't know if it matters, but using the same calculator, with a 4" thick material of 16,000 rayls (is this approximately the gas flow resistivity of a Monster trap?), with a 15" gap (the longest dimension air gap to the wall corner using a 2 foot-wide trap that isn't tapered to fit snug to the edges of the corner), I get .53 absorption coefficient at 60 Hz.

If the trap was had tapered edges to fit snug into a corner, then the longest dimension of air gap would be 17". Switching to 10,000 rayls yields .69 absorbtion.
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post #8545 of 10377 Old 02-03-2012, 06:42 AM
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Quote:
Originally Posted by nezff View Post

So blue jeans and newspaper shouldn't be in our homes but metal slag and glass fibers are ok because they will break down.

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post #8546 of 10377 Old 02-03-2012, 08:11 AM
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Quote:
Originally Posted by localhost127 View Post

fiberglass is a porous material - it works by converting kinetic energy of the soundwave traversing through the series of porous ducts within the insulation into heat (friction). by coating the face of the insulation with a spray or glue, you are blocking the porous holes, restricting flow through the absorber - yielding unexpected results (reflection due to impedance change). you do not want to use spray or glue to coat the face of the insulation to bond fabric. maybe a small dab of 3M spray in the corners...

Unless there is air gap on the back, does it make difference if sound waves hit glue or wall to reflect back? Also, if it is just meant for high frequency absorber instead of basstrap, the material should absorb all of it by the time it reaches back right?

I just want to clarify if the reason is not valid.
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post #8547 of 10377 Old 02-03-2012, 08:22 AM
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Is rockwool same as pink stuff? I read from localhost127 posts that it is best to absorb/pass waves.
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post #8548 of 10377 Old 02-03-2012, 09:33 AM
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Quote:
Originally Posted by sukumar View Post

Is rockwool same as pink stuff? I read from localhost127 posts that it is best to absorb/pass waves.

No, its not the same - pink stuff is made of fiberglas, rock wool (a.k.a. mineral wool) is made from stone fibers. Pink fluffy is lower density than most mineral wool (although I'm sure there are different densities available of both, just speaking of the most common stuff).
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post #8549 of 10377 Old 02-03-2012, 09:52 AM
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Quote:
Originally Posted by sukumar View Post

Unless there is air gap on the back, does it make difference if sound waves hit glue or wall to reflect back? Also, if it is just meant for high frequency absorber instead of basstrap, the material should absorb all of it by the time it reaches back right?

I just want to clarify if the reason is not valid.

if no air gap and the panel is flat against rigid boundary, then it will not make a difference. but by not utilizing an air-gap, you are eliminating your "free lunch".

what is your definition of a "high frequency absorber"? in the specular region, the lower frequencies have longer wavelengths with inherently more energy content. thus, attention for broadband panel absorbers generally needs to be with regards to the lower end of the specular region.
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post #8550 of 10377 Old 02-03-2012, 10:36 AM
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Quote:
Originally Posted by localhost127 View Post

if no air gap and the panel is flat against rigid boundary, then it will not make a difference. but by not utilizing an air-gap, you are eliminating your "free lunch".

With air gap it makes sense. Regarding air gap, I have question. If super chunk bass trap is made with oc 703, does it make difference if 24 inch deep oc 703 vs 12 inch oc 703 and 12 inch airgap? Since oc 703 is cheaper, it is easy to make 24 inch bass traps to stand stable.

Also if volume remaining constant, does filling pink stuff for the same volume more effective than oc 703?

Quote:
Originally Posted by localhost127 View Post

what is your definition of a "high frequency absorber"? in the specular region, the lower frequencies have longer wavelengths with inherently more energy content. thus, attention for broadband panel absorbers generally needs to be with regards to the lower end of the specular region.

I meant panels for first reflections need to be high frequency absorber. I remember absorption coefficient for 4 inch panels for high frequencies is close to or equal to 1. In this case, by the time sound reaches to the back, I thought they would have been absorbed.
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