Owens Corning 701, 703, 705

knightfly · Post by **knightfly** » Thu Aug 14, 2003 1:25 am

Carl, to answer your questions on 700 series fiberglas -

The "3" in 703 refers to density. In that particular case, the stuff has a density of 3 pounds per cubic foot. Carrying that out to it's (wishfully) logical conclusion, you would think that 705 would be 5 PCF, but it's not - neither is 701 = to 1 PCF, but they are kinda close - in actual fact, 701 is 1.5 PCF - here is a chart of the range

Type 701: 1.5 pcf (24 kg/m3)
711: 1.65 pcf (26 kg/m3)
702: 2.3 pcf (37 kg/m3)
ASTM C 303 703: 3.0 pcf (48 kg/m3)
704: 4.2 pcf (67 kg/m3)
705: 6.0 pcf (96 kg/m3)
707: 7.0 pcf (112 kg/m3)

and here is the entire pdf for the 700 series, from OC's site

http://www.owenscorning.com/comminsul/d ... Series.pdf

Sorry about the wait... Steve

Ethan Winer · Post by **Ethan Winer** » Thu Aug 14, 2003 2:42 am

Carl,

> The number like 703 does not apply to the actual thickness of the material, just the model? <

Yes, exactly. You can buy 701, 703, and 705 all in various thickness. The model number refers to the density of the material, not the thickness. 703 weighs about 3 pounds per cubic foot, and 705 weighs about 6 pounds.

--Ethan

knightfly · Post by **knightfly** » Thu Aug 14, 2003 3:14 am

Right, Ethan - the PDF covers all that, including what's standard, what's special order (forget it, you're not rich enough) and which versions are available in what thickness... Steve

feni · Post by **feni** » Thu Aug 14, 2003 4:05 am

Hi Eric
Sorry !

Here are the links :

http://www.basf.de/basf/html/plastics/i ... t_Br_e.pdf - Basotect Catalog, Pls checkout Page 8,9 and 10

http://www.primacoustic.com/Australis.html - Corner trap cliamed effective down to 45Hz. too good to be true ?

The question is not necessarilly. Is this a good absorber (you can make panel/membrane absorbers in lots of ways), but what do you need.

Bingo! Yes ! i need a bass trap that without any or with minimun side effect as u mentioned somewhere, a modular type and can be stand alone ! Pls !

You'll notice in the group that Helmholtz slat resonators are used a lot.

Yeah ! i made a corner trap 4' tall, and thanks steve for his help ! but i think i brought the wrong type of slats, white oak instead of pine, may be too hard for slat resonator, then i made a 2' tall with 1" 703 infront of the wood panel ( about 1" air gap ) then cover with burlap, on top of the slat. i can't test them, they mainly for my home setup. still have a lot of problems will post some later, can't express myself in english within one GO !

To check if you have open cell foam, just blow trough it. If you get a blown-up red head while trying it's closed cell foam.

I will un zip the cussion of the sofa first then blow them with a hair dryer if air passed through !, i will stick them on the corner use my shouting test menthod to verify the efficents, will post result later, and i hope all of us should do the same test. and see which is the best !

Very nice to chat with u all !
Feni. time reset my system again ! Thanx again Eric !

dbluefield · Post by **dbluefield** » Thu Aug 14, 2003 4:38 am

Interesting post.

Owens Cornings own test figures from their Noise Control Design Index only showed measurements to 4" of 703.

The late Malcolm Chisholm postulated from experience that a full 6" of 703 provides about the best broadband absorption you can readily make yourself, which appears to correspond with your figures.

I've built about a dozen or so boxes of 6"703.

Best,

Dave

Eric_Desart · Post by **Eric_Desart** » Fri Aug 15, 2003 1:27 am

Hello Feni,

Both are interesting links.

The BASF document: I hadn't seen it yet but knew that the FRAUNHOFER Institute in Germany had designed such a broadband absorber.
They have a license with some company (should have to look for the name).
You can be sure that they work perfect.
FRAUNHOFER is about the largest research institute in Germany in ALL kinds of acoustics.
Those absorbers are designed also as space saving substitutes for the traditional Anechoic room wedges, having extremely stringent specs they must comply with.

Basically it's a combined membrane absorber with open foam on top (so membrane sits in-between, where bottom is spring for membrane and top foam takes care of all the rest)

The other link are standard polyurethane foams, but the corner absorbers have a good and logical design.
If you should put them further away from the corner (e.g. first 4" foam before placing corner trap) they become better.

This number down to 40 Hz doesn't tell much about exact numbers.

Basically putting a OC 703 or 705 accross the corner will give about the same effect (not speaking in exact numbers now).

But when you want to use foam for allergenic reasons, the links you found give a good picture (lacking numbers at the 2nd link)

Best regards
Eric

Ethan Winer · Post by **Ethan Winer** » Fri Aug 15, 2003 1:43 am

Steve,

> Right, Ethan - the PDF covers all that <

I replied before seeing that you already gave a perfect answer ... on the next page!

--Ethan

Ethan Winer · Post by **Ethan Winer** » Fri Aug 15, 2003 1:48 am

Feni,

> [Australis] Corner trap claimed effective down to 45Hz. too good to be true ? <

Probably. A piece of tissue paper absorbs down to 45 Hz too. The question is how much? Since they don't give any data supporting that claim you should be very skeptical.

--Ethan

feni · Post by **feni** » Fri Aug 15, 2003 7:58 am

Hi Eric
Thanx for yr reply

They have a license with some company (should have to look for the name).

You can be sure that they work perfect.
Yeah ! is called something like PLA or PAL , can't find the link now !
Infact they did Emailed me the contact of thier far east distributor for these low absorber, lost as well, due to a computer crash ! should get it back !

Basically it's a combined membrane absorber with open foam on top (so membrane sits in-between, where bottom is spring for membrane and top foam takes care of all the rest)

Like a sandwhich, Right ! seems i read somwhere, the foam is sticked directly on the metal sheet, no air gap needed. a neat and simple design not sure !

The other link are standard polyurethane foams, but the corner absorbers have a good and logical design.

For me it's the smarter in shape design than Pro corner (RPG) or Aularex, but man! costing 4 times more if ship from England ! already over price by itself.

Basically putting a OC 703 or 705 accross the corner will give about the same effect (not speaking in exact numbers now).

What different it make if a 4" 703 warp with burlap only and boxed (1/4 plywood, front with burlup) 4" 703, Placed accross the corner ? and what if a 4" flat foam ? they may be more or less a promised boardband with bonus on 100hz ? my 703 are all boxed !

But when you want to use foam for allergenic reasons, the links you found give a good picture (lacking numbers at the 2nd link)

Infact not only for allergenic reason, i do think foam will have protential to be a very good accoustic material, it's cleaner and easier to handle or shape.
if i know the formular of the open cell foam, i am sure i will find some small pillow or cussion manufatory, to make me some 2lb/cu.ft foam for fun and do some experiment with them ! found some infor at Mike Shea book, but not much help !
OK! thanx a lot Eric !
by the way barefoot has posted a very very nice panel trap here ! He is one of those person that know how to build anything or at least some ideas in his head ! Hate him !

OH! also thanx Ethan for yr advice too !

Eric_Desart · Post by **Eric_Desart** » Fri Aug 15, 2003 10:15 pm

Hello feni

What different it make if a 4" 703 warp with burlap only and boxed (1/4 plywood, front with burlup) 4" 703, Placed accross the corner ? and what if a 4" flat foam ? they may be more or less a promised boardband with bonus on 100hz ? my 703 are all boxed !

I can't answer that exactly. It should be compared by measurements.
Problem is making correct absorption measurements below 100 Hz (the lower freq the worse repetetivity).
So just thinking out loud:
I did measure (in lab) rockwool accross corner thickness 120 mm, boards were 1200 * 900 mm. Results down to 100 Hz extremely good. Lab had cutoff of 80 Hz. So it's difficult to study to very low frequencies.

With the plywood front it becomes a paneltrap. So the response is more defined by the sizes (enclosed air volume versus panel weight).

Comparing Melamine to wool will give some advantage to wool (Melamine has lower gasflowresistance).
Comparing with polyurethane think still some advantage for wool. However it responds differently than Melamine.

In the yahoo group there is now a consensus to use wool, but also add some wool to the wall behind. This isn't really measured/compared but is done as safety in analogy with the original patented corner (diagonal) absorption design (belonged to a Sweed but is expired now).
But you can as well use an analogue principle with foam.
And if one isn't sure, just make the foam somewhat thicker.

by the way barefoot has posted a very very nice panel trap here ! He is one of those person that know how to build anything or at least some ideas in his head ! Hate him !

It's indeed very good to get advice from knowledgeable people as barefoot.
So I 100 % agree since the hate part is meant in funny way.

Best regards
Eric

feni · Post by **feni** » Sat Aug 16, 2003 4:28 am

Many Thanx Eric !
Got u later !
Feni