Mineral wool vs. Fiberglass for absorbers

Vagabond · Post by **Vagabond** » Sat Aug 19, 2006 9:02 am

Hi everybody,

I see lots of people using OC703 for broadband absorbers. From looking at mineral wool and it's NRC values, it seems a little better at low frequencies but I hear is a good bit nastier to work with. Also does it have a smell at all? I read a post somewhere where someone said theirs had a smell. I just wondered why I don't see more people using mineral wool, if there was some downside besides being nastier to work with that I wasn't catching.

Thanks for any help!

Eric_Desart · Post by **Eric_Desart** » Sat Aug 19, 2006 4:48 pm

Vagabond

Rockwool and glasswool (fibreglass) are interchangeable.
Look at Bob gold's page:
http://www.bobgolds.com/AbsorptionCoefficients.htm

Knightfly has entered this link here somewhere in the stickies too I think.

One is a bit more itchie to work with than the other, but both cause this.
There really is no reason to choose one over the other for mechanical or chemical reasons, unless glassfiber boards are a bit more elastic and rockwool a bit more brittle (The types and brands I know).

Summary: you can use both as good.

Eric

TomM · Post by **TomM** » Tue Aug 22, 2006 4:11 am

There are several places on the web to buy owen's corning, but are their any sites that ship Rockwool? It's so much cheaper...

knightfly · Post by **knightfly** » Tue Aug 22, 2006 4:32 am

Tom, tried these guys?

http://www.spi-co.com/servicecenterdire ... ?detail=56

the branch near me has more mineral wool than fiberglass, call 'em and see what they have in 3 PCF range... Steve

Vagabond · Post by **Vagabond** » Tue Aug 22, 2006 6:29 am

Most mineral wool I see comes in 4,6,8pcf I think - is one preferable to the other or should I just look at published NRC values?

Also any comments on the smell issue?

z60611 · Post by **z60611** » Tue Aug 22, 2006 11:17 am

Also does it have a smell at all?

My rockwool doesn't smell at all -- and I've got a bunch of it hanging above me, and a bunch open scattered around the walls at the floor.

The grey/green stuff is Roxul RHF80 rockwool: http://www.bobgolds.com/SpeakerTests/20 ... G_0953.jpg

Here's Roxul SafeNSound in my ceiling: http://www.bobgolds.com/AbsorberCeilingJoist/

http://www.bobgolds.com/InsulationContractors.htm

Post by **John Sayers** » Tue Aug 22, 2006 5:42 pm

I'm haven't used rockwool or fiberglass in the Tullebudgera studio we have almost completed.

It's all polyester dacron.

cheers
john

Vagabond · Post by **Vagabond** » Wed Aug 23, 2006 3:23 am

I was looking at the Roxul products but I'm too far south to get any - I'd have to order a truck full of the stuff from Canada. I'm looking at Fibrex and IIG and Owens Corning 700 series at the moment. One requirement is that I need to get it in 16" widths and according to the data sheets Fibrex SAFB is the only one that does that, the Fibrex FBX series and the IIG 1200 series (which look to be exactly the same product, perhaps resold by one company and manufactured by the other - NRC coeffs are the same) are only listed as coming in 24" widths.

knightfly · Post by **knightfly** » Wed Aug 23, 2006 4:46 am

I'm too far south to get any

We would know that if you could follow the "don't even think about..." thread at the top of the forum - specifically the part about editing your profile to include a location

Thanks... Steve

Vagabond · Post by **Vagabond** » Wed Aug 23, 2006 6:41 am

Sorry, I generally like to remain as anonymous as possible on the internet. Will modify location per forum guidelines. Also since forum guidelines want room details here we go:

Added information: These will be for broadband absorbers meant to kill first reflections in a music listening environment. I live in an apartment and move every few years, but my current listening room is 12'x17'. I listen on one side of the 17 foot dimension so the listening room/setup is assymetric, and I only really have to kill the reflection off the right 12' wall (no windows). I also might want some absorption perhaps on the back wall for slap echo and perhaps on the ceiling for its first reflection point. I would like 16" wide panels for aesthetic reasons.

amistybleu · Post by **amistybleu** » Wed Aug 23, 2006 8:11 am

Sorry

amistybleu · Post by **amistybleu** » Wed Aug 23, 2006 8:16 am

Ok, my sketch is .bmp and it wont work.

z60611 · Post by **z60611** » Wed Aug 23, 2006 9:35 am

I'm a home theatre guy (think 5.1 control room with big video), and not a musician (well, I play clasical guitar and piano and saxaphone but so poorly the 'not a musician' applies)

1) Bass traps, OK where, I am thinking far end of the room, what then behind speaker cabs, ie: bass & guitar, looking at Jon Risch's Tube bass trap plans.

If you have nothing else in the room (no carpet, no false ceiling, no couches) then any of the 12 corners would be fine (4 wall-wall, 4 wall-ceiling, 4 wall-floor) -- all modes are active in tri-corners. May as well take a bite out of them.

I read recently about a hip-hop engineer who always made his mixes with way too much bass -- because his chair was in a multi-modal null.

would a 4" deep x2'x4' pine frame with 4" of thermafiber work well

Sure. That'd make an excellent first reflection point absorber.

You can make them out of anything found here
http://www.bobgolds.com/AbsorptionCoefficients.htm
but you might find a link to someone who sells 703 in your area here
http://www.bobgolds.com/InsulationContractors.htm
Not that 703 is any better -- just find something on
http://www.bobgolds.com/AbsorptionCoefficients.htm
with absorption coefficients similar to 703 or slightly lower if you're building superchunks as opposed to diagonal Corner absorbers.

Before you start have a look at this page:
http://www.bobgolds.com/AbsorptionCoefficients.htm
at the links between "Jon Risch's Absorbers" and "Vshine's Wall Absorbers"
and this page
http://www.bobgolds.com/
at the links between "ChristianG's Corner Traps" and "TrevorMag's Slotted-For-Aesthetics Corner Absorbers"

There's also the easiest of DIY bags from
http://www.readytraps.com/products.php?cat=10
http://www.modularacoustics.com/teabagz ... ctions.htm

As a "rehearsal space" you probably want to keep the room live -- so perhaps portable absorption (gobos, variable absorbers) and diffusers might be good.

knightfly · Post by **knightfly** » Wed Aug 23, 2006 10:32 am

Ok, my sketch is .bmp and it wont work

bmp's end up too big a file size; open it in paint and re-save as .jpg, make sure it's under 750 pixels wide, and it should fly... Steve

amistybleu · Post by **amistybleu** » Wed Aug 23, 2006 1:13 pm

Thanks z60601 & Knightfly, My bad on posting that here as I totally hijacked this guys thread, I have reopened an appropriate thread and will review z60601s suggestions. my new thread is bass traps and acoustical panels.

Cheers

Mike

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Mineral wool vs. Fiberglass for absorbers

Mineral wool vs. Fiberglass for absorbers

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