Auralex aint got nothin on roxul safe!

[Diffusion]

I just found this new Roxul Safe (not Safe 'n Sound) insulation and was reading its NRC ratings... check them out...

http://www.roxul.com/graphics/rx-na/canada_us/products/safe/Safe_tds_USA.pdf

The 4" thick stuff has a minimum NRC of 1.03! (at 125kz) Also, its melting point is at 2150°F! I still waiting on a quote for this stuff but my guess is it shouldnt be much more than Roxuls other already cheap insulation products.

heres another link:
http://www.roxul.com/sw34143.asp

So what do you guys think of it's NRC ratings?

 

[bpape]

Just understand that the NRC is an average of the specs from 250-2k(might be 4k - kind of late). I can show you lots of stuff that has GREAT NRC numbers and does jack in the bottom end.

Look at the individual coefficients at specific frequencies as you did to determine what it's really going to do for you.

Just for comparison, take a look at these numbers:

125Hz 250Hz 500Hz 1KHz 2KHz 4KHz NRC
0.97 1.37 1.23 1.05 1.00 1.01 1.15

This is for 3.5" Acoustical Cotton. Higher NRC, much better at 250 and 500Hz - a little less at 125Hz. This is a perfect example of why you basically ignore the overall NRC number and look at what you need in the individual numbers. It's a great material to work with but if you ONLY looked at the NRC, you'd never know to expect the hump in absorbtion at 250 and 500Hz.


Back on topic though - the Roxul will do a fine job if you select the appropriate thickness and density for the task at hand for a very reasonable price.

 

[Diffusion]

Just understand that the NRC is an average of the specs from 250-2k(might be 4k - kind of late). I can show you lots of stuff that has GREAT NRC numbers and does jack in the bottom end.

I know... but take a look at this stuffs specs they are all above 1.0 and are very close numbers... it doesnt have the huge gap from the 125Hz to 4KHz that most other absorbtion materials have... almost every other absorbant material I have seen has a 125kz NRC of around .10 to .40, which gradually increases with the higher frequencies... this stuff has a NRC of around 1.0 for each frequency... seems to me that this stuff will absorb better than most expensive acoustic foam that you'd see in many studios...

 

[arnorhs]

Just curious... don't know much about this stuff... What does NRC 1.10 mean? is it something like 3X or 4X?

 

[bleyrad]

Ialmost every other absorbant material I have seen has a 125kz NRC of around .10 to .40, which gradually increases with the higher frequencies....

That is because the other material you're looking at isn't spec'd at 4" thick.
Obviously this stuff is better than Auralex, but it's about average for any sort of compressed mineral or glass fiber product.

 

[Diffusion]

Average? Compare Roxul safe to the 'highly acclaimed' 703...

703 Rigid Fiberglass:
125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz NRC
.53----1.19--1.21---1.08---1.01----1.04----1.01
Roxul Safe
125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz NRC
1.03---1.07--1.12---1.04---1.07----1.08---1.10

Notice the huge skip in the 703 ratings from the 125Hz to 250Hz? The Roxul safe doesnt have that... the roxul safe also has better high freqs, and a better overal NRC... not to mention this stuff will only burn at 2150 degrees Farhenheit... its prolly cheaper than 703 too...

 

[bleyrad]

Look, I'm all for Roxul - my studio is covered in the stuff - but have you checked the testing methods for both of these?
Perhaps the Roxul was measured away from a wall while the 703 was measured right up against one.
The idea is that all these materials are basically the same, absorption-wise. I cannot imagine Roxul of a similar density being TWICE as effective as 703.

 

[bpape]

Here are the specs straight from Owens for 4" 703

0.84 1.24 1.24 1.08 1.00 0.97 1.15

The Roxul Safe is also a 4.5lb product vs a 3lb OC product. Here are the numbers for the Roxul 2.5 lb.

0.86 1.11 1.20 1.07 1.08 1.07 1.10

Again, apples to apples, density to density, they're almost the same. In fact, since many rooms end up a bit on the dead side on the high end, the lower numbers at 2k and 4k can be a benefit for the 703.

To go to 3.5lb Roxul (RHT 40)

1.07 1.01 1.07 1.06 1.07 1.16 1.05

In reality, there is no 'better'. There is simply what's more suitable for what YOUR room needs.