Roxul RHF 80

Riad · Post by **Riad** » Mon May 03, 2004 11:34 pm

In lieu of OC-703 I'm looking at Roxul RHF 80 (8lbs/ft3) it has acoustical properties of:

125Hz == .43 Co-Effecient
250 == .78
500 == .90
1000 == .97
2000 == .97
4000 == 1.00
NRC == .90

Can someone explain to me what those numbers represent?

Much appreciated. Thank you.
Robert

AVare · Post by **AVare** » Tue May 04, 2004 12:29 am

The numbers with numbers beside them represent how much of the sound that strikes the material, when mounted flush against a hard surface, is reflected back at the 1/3 octave frequency in the first column. The NRC is the arithmetic average rounded off to 0.05.

Looking at the figures you are looking at 2" thick material. I strongly suggest looking at thicker. Thicker gives more low end absorption.

Also ask about other companies products. Ask for 3.0 pcf fiberglass and 4.0 pcf rock wool. Certain Teed, Knauf, Delta, Fibrex, all make products in that range. Even Roxul with their RHF 40 There is no significant difference between the companies' products and within the criteria I wrote at the beginning of this paragraph.

Prices vary wildly in different regions. Check on the prices as well as the availability.

I feel that you already have a good lead on where to look, so this more for new people reading this post. The products we are talking about are NOT stocked at Home Depot etc. Look up "insulation" in the yellow pages. Commercial contractors, industrial companies are all good leads.

Good luck with your project!

Riad · Post by **Riad** » Tue May 04, 2004 12:43 am

Thanks for the response. I have a distributor, SPI (I posted the contact information in the where to buy section) and all they have is the 2" 80 so I'm going to go with that. I will be using a couple of bundles of 4" Roxul AFB (24" and 16") I have left over to round off the low ends.

The price I was quoted was .46 sq/ft so it's not that expensive.

Thanks,
Rob

brandondrury · Post by **brandondrury** » Sat May 15, 2004 1:07 pm

I just read a different forum ( I believe it was at prosoundweb.com's forum) that quoted one of the Allen Everest books. The concept involved the absorbtion of lower frequencies.

He said that a 3 inch thick piece of 703 placed 3 inches from the wall would outperform a 6 inch piece of 703 placed directly on the wall.

This is consistent to what Ethan Winer has told me on another forum. For optimum low frequency absorbtion make sure you mount your 703 or equivalent with an air space of at least 3 inches.

Then again, I'm just as new to this and lost as everyone else.

I hate acoustics!
Brandon

AVare · Post by **AVare** » Sat May 15, 2004 10:24 pm

I just read a different forum ( I believe it was at prosoundweb.com's forum) that quoted one of the Allen Everest books. The concept involved the absorbtion of lower frequencies.

He said that a 3 inch thick piece of 703 placed 3 inches from the wall would outperform a 6 inch piece of 703 placed directly on the wall.

This is consistent to what Ethan Winer has told me on another forum. For optimum low frequency absorbtion make sure you mount your 703 or equivalent with an air space of at least 3 inches.

Then again, I'm just as new to this and lost as everyone else.

I hate acoustics!

The name is Alton, not Allen. What you wrote is wrong. Here is a thread that gives the truth.

http://johnlsayers.com/phpBB2/viewtopic ... highlight=