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advertised absorption coefficient of foam
Old 12th June 2018
  #1
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advertised absorption coefficient of foam

hi Guys, could you have a look at this link and see if these numbers look exaggerated or not? I was thinking of making some bass traps with Roxul but having trouble finding the right type here in canada (best to absorb below 250k). I was surprised to see these foam traps having a rating of over 1.0 at 100hz. I also noticed Amazon sells a bunch of similar foam traps at a pretty cheap price. Wondering if it's worth it...

https://abbotsford.craigslist.ca/msd...597598967.html
Old 12th June 2018
  #3
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Foam works fine, if it's thick enough, the downside is it's expensive. You want thicker than the link you posted, so the cost will go up more, and at that point you would be better off just buying some commercial traps from a place like GIK.

For DIY what materials are available locally? I would imagine there is something suitable.
Old 12th June 2018
  #4
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Quote:
Originally Posted by johnnyc View Post
Foam works fine, if it's thick enough, the downside is it's expensive. You want thicker than the link you posted, so the cost will go up more, and at that point you would be better off just buying some commercial traps from a place like GIK.

For DIY what materials are available locally? I would imagine there is something suitable.
I agree I think thicker would be better, but interesting read here:
Rigid fiberglass density tests
where more panels at 3" are better at LF diffusion than half the amount of 6" panels (between 40Hz and 200Hz)

as far as cost, I was surprised by the price (I thought foam would be more than quoted). 4 of these panels would be $100 at 1728 cubic inches (less $ if you buy more says the ad). a package of roxul is 2150 cubic inches at $53, but I still have to buy the wood, cloth, staples etc. plus the time to build them. Not sure if it's much of a savings if any.
Old 13th June 2018
  #5
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Your math is bit off for the pricing.

Let's use cubic feet:

For the foam:
1 x 1 x 2 x 0.5 = 1 cubic foot
So $25 per cubic foot

For the roxul, 12 panels of 16"x48"x3"
1.33 x 4 x 3 = 16 cubic feet
53 / 16 = $3.31 per cubic feet

Roxul about 8x cheaper

Also yes using more thinner panels has been shown better. Really you want a good deal of coverage, all corners, and then all first reflection points.

What is your budget? I used ultratouch cotton in my room, more pleasant than roxul and similar price if available at the hardware store.
Old 13th June 2018
  #6
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Quote:
Originally Posted by johnnyc View Post
Your math is bit off for the pricing.

Let's use cubic feet:

For the foam:
1 x 1 x 2 x 0.5 = 1 cubic foot
So $25 per cubic foot

For the roxul, 12 panels of 16"x48"x3"
1.33 x 4 x 3 = 16 cubic feet
53 / 16 = $3.31 per cubic feet

Roxul about 8x cheaper

Also yes using more thinner panels has been shown better. Really you want a good deal of coverage, all corners, and then all first reflection points.

What is your budget? I used ultratouch cotton in my room, more pleasant than roxul and similar price if available at the hardware store.
Of course! I stand corrected. I forgot to multiply the Roxul by the number of panels in one package. Definately a better price going with the Roxul for sure.

My budget? I would be happy if I could get my 10' x 18' x 6.10' high room treated for a couple of hundred.

and from what I've started reading it seems foam is the least effective as a bass trap compared to OC or Roxul.

I don't have access to OC or ultratouch cotton where I live. Safe and Sound seems to be my best option. Why is the cotton more pleasant?
Old 13th June 2018
  #7
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Quote:
Originally Posted by Bakelite View Post
I don't have access to OC or ultratouch cotton where I live. Safe and Sound seems to be my best option. Why is the cotton more pleasant?
Fiberglass is very itchy, and it can be difficult to get it out of your clotting even after the fact. I've also been in studios loaded with OC and found it unpleasant due to the air quality. Not much direct experience with roxul but have read similar issues.

Didn't have those issues with ultratouch. Though it should be noted a lot can be person dependent. Many work with roxul and OC without adverse effects. Wear appropriate protective clotting and seal in the fibers whatever you choose.

If budget is an issue maybe look into just stacking material in corners and sealing it, would save time and expense of wood frames. The low ceiling could be problematic necessitating more treatment.
Old 13th June 2018
  #8
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avare's Avatar
 

Quote:
Originally Posted by Bakelite View Post
was thinking of making some bass traps with Roxul but having trouble finding the right type here in canada (best to absorb below 250k).
Your joking, right? Best bang for buck is Safe N Sound. Best 703 like product is Rockboard 40.

Enjoy!

Andre
Old 14th June 2018
  #9
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Quote:
Originally Posted by avare View Post
Your joking, right? Best bang for buck is Safe N Sound. Best 703 like product is Rockboard 40.

Enjoy!

Andre
3" of Rockboard (at the typical measured frequencies)
0.63 0.95 1.14 1.01 1.03 1.04 1.05

3" of safe & sound
0.52 0.96 1.18 1.07 1.05 1.05 1.05

doesn't seem that disparate. Plus, I don't have access to RB40 where I live.

edit: Hey Andre, I just noticed you're from ON. I'm in BC. Can you buy RB40 where you are?
Old 14th June 2018
  #10
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avare's Avatar
 

Quote:
Originally Posted by Bakelite View Post
I don't have access to RB40 where I live.

edit: Hey Andre, I just noticed you're from ON. I'm in BC. Can you buy RB40 where you are?
Rockbaord etc is sold through commercial/industrial suppliers, not Home Depot etc. Look up insulation, HVAC suppliers, Air conditioning suppliers etc in the phone book, or your favourite search engine.

Enjoy!

Andre
Old 15th June 2018
  #11
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Bakelite, what is the size of your room?
I used Safe N Sound and very happy with the results. Strarted with 703 but then moved to Roxul. I was gradually adding absorption panels > measuring > listening > driving to Rona > adding pannels e.t.c
Just be patient, no rush.
Old 15th June 2018
  #12
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Quote:
Originally Posted by Flash R View Post
Bakelite, what is the size of your room?
I used Safe N Sound and very happy with the results. Strarted with 703 but then moved to Roxul. I was gradually adding absorption panels > measuring > listening > driving to Rona > adding pannels e.t.c
Just be patient, no rush.
Good to know Flash! Yeah based on the numbers it seems like the sound absorption is similar to Rockboard at least. The room is 11’ x 17’ x 6.10’ high (basement). The irony is I finished the room myself a few years ago and put safe and sound in the joists before drywalling. Now I’m wondering if I should just open chunks out of the ceiling and cover them with fabric instead of building cloud absorbers. As well as wall mounts I might build two gobo bass traps. How many panels did you end up with? how many bundles did you end up buying?
Old 17th June 2018
  #13
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Quote:
Originally Posted by Bakelite View Post
Now I’m wondering if I should just open chunks out of the ceiling and cover them with fabric instead of building cloud absorbers. As well as wall mounts I might build two gobo bass traps. How many panels did you end up with? how many bundles did you end up buying?
You don't need to open ceiling and make changes. The purpose of the existing isolation is exactly what it should be, to reduce the level of sound coming out of your basement room. And it is serving its purpose.
Now you want to improve acoustics. (right? )
The first step would be (in my opinion) to get a measurement mic and get familiar with a software like REW.

I have a similar room, except the ceiling is 2ft higher. If I tell you the number of absorption panels I have, it won't help that much, since I built them based on measurements and try&fail tests. There are 4 different sizes of the absorbers with different thickness that I had to built, based on measurement results. The number also depends on what is behind the walls (another room or a cement wall). In my case (and I'm pretty sure in your case as well) ceiling will be a big bummer to get rid of nulls bellow 250 Hz. I ended up covering the ceiling with cloud absorbers (9 inch thick) at the area between the front wall and a listening spot (but not over the listening spot). In your room it might be different. Here is a picture of the work in progress. Since then, I added few more small panels on the ceiling.

Back wall corners are covered with two triangular-shaped superchunks (from the floor to ceiling). The rest of the back wall is covered with 12 inch thick absorption panels.
The front area and the back wall are those that are mostly covered with absorption panels and corner superchunks.

Again, you will get better results if you have (and use) measurements along with adding absorption panels as necessary.
Also depends on your end goal... make a small improvement or go "head-to-head" with acoustics?
Old 17th June 2018
  #14
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Great info! Yes, I’ve got REW installed but haven’t tried it yet. My only omni mic is an AT4050. I think that might work for relative comparisons. So the takeaway from what your saying is likely I’ll need panels with different thicknesses. opening the ceiling in sections to expose the joists/insulation was just a thought to save some ceiling height. It’s just my wife and I in the house (and she’s a musician as well) so sound isolation is not as critical as absorption. Having said that maybe it’s better to keep the ceiling and put clouds up. My plan is to have a couple of feet between the front wall and desk so I should be able to beef up the absorption there. What cloud thickness did you end up with for the rest of the ceiling? I don’t think I could do more than 3” panels - or 2” with a 1” air gap (or both). Maybe above the desk I could go thicker/lower. I’m planning on making super chunks and a couple of 7-8” gobos, depending on the REW numbers. Do you track and mix in your room?
Old 19th June 2018
  #15
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Quote:
Originally Posted by Bakelite View Post
Great info! What cloud thickness did you end up with for the rest of the ceiling?
Do you track and mix in your room?
I was trying to eliminate two deep nulls under 250 Hz. Cloud absorbers helped to reduce the deeps by probably 40%. Superchunks in the front corners reduced another ~20%. Absorption on back wall gave another ~20%. Another 20% or more was achieved by experimenting with positioning of the speakers.
Again, it is my case. Don't take it as strict rules.

Yes, I mix in this room. It took about 3-4 months to get stable results after the acoustic treatment was installed. By stable results, I mean - to get used to the tonal characteristics of the room and to get mixes translate well to other systems.
Old 20th June 2018
  #16
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Quote:
Originally Posted by Flash R View Post
I was trying to eliminate two deep nulls under 250 Hz. Cloud absorbers helped to reduce the deeps by probably 40%. Superchunks in the front corners reduced another ~20%. Absorption on back wall gave another ~20%. Another 20% or more was achieved by experimenting with positioning of the speakers.
Again, it is my case. Don't take it as strict rules.

Yes, I mix in this room. It took about 3-4 months to get stable results after the acoustic treatment was installed. By stable results, I mean - to get used to the tonal characteristics of the room and to get mixes translate well to other systems.
thanks again from a fellow (ex) Winnipeger!
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