Ready 2 buy... final mineral wool q's

[DaVinci]

Had to wait for tax return, but finally purchasing mineral wool, and I have called all local distributors I could find.

Basically, I have only been able to locate 4lb and 8lb densities. It's all local with no minimum, so I could do combo, so wondering if I should do 4lb for all major areas, but 8lb in corners, et?

Just go with one or the other? Best deal price wise is the 4" thick 4lb which I can do for 2/3 the price of going witht the 8lb.

Also, I have not been able to find specs on particular brand name... anyone have any info as to whether IIG's "Safing" is a good choice accoustically? It looks a bit soft to work with, but at the price, I'm not concerned about that.

[PaulP]

Originally Posted by CallMeAl

Basically, I have only been able to locate 4lb and 8lb densities. It's all local with no minimum, so I could do combo, so wondering if I should do 4lb for all major areas, but 8lb in corners, et?

It's the other way around. The thicker the insulation the less dense it should be.

At 4" thick you're better off with 4 lb stuff.

Paul P

[DaVinci]

Sorry, shoulda also said the 8lb comes in 2 inch... only the 4lb comes in 4"

I was planning on doing all 4lb all the way around, for ceiling cloud, superchunks, corner traps, broadband panels... just thought I'd check to see if there was a benefit of swapping a few of those pieces out for the 8lb.

[avare]

Originally Posted by CallMeAl

just thought I'd check to see if there was a benefit of swapping a few of those pieces out for the 8lb.

+1 to what Paul wrote. Use 4lb/ft3.

Andre

[Glenn Kuras]

I have a ton of respect for Avare, but I still think that 8 pound up to around 6" will out preform 4 pound. Call me crazy. lol lol Needless to say that either way you go it would not be "wrong" and considering 4 pound is less money you can buy a lot more which will over all yield better results.

[DaVinci]

ok, well, unless there is a clear and definite benefit for certain panels, $ wins.

[Glenn Kuras]

Originally Posted by CallMeAl

ok, well, unless there is a clear and definite benefit for certain panels, $ wins.

thumbsup

[avare]

Originally Posted by Glenn Kuras

I have a ton of respect for Avare, but I still think that 8 pound up to around 6" will out preform 4 pound.

No lack of respect taken. I am human, just like most people that post here, and make mistakes. Not to mention always learning.

4 lb/ft3 fiberglass has an air resisitivity around 15,000 mks Rayls. 8 lb/ft3 I don not even know the value for. However 6 lb/ft3 has around 30,000 mks Rayls. for a bit more on relating to various materials see Floating Floors and Mineral Wool...Extrapolate to 8 lb/ft3 and plug those values into a gas flow absorber absorption coefficient calculator with a thickness of 4" and the better performance is shown.

World class designers have used ~15,000 mks Rayls materials with a thickness of 4" and gaps slightly over 8" in world class facilities.

It's not intuitive, it's acoustics!

[Glenn Kuras]

Next time we are at riverbank maybe we could give 4 pound a try straddling corners. Might be fun to see the results. thumbsup

[avare]

Originally Posted by Glenn Kuras

Next time we are at riverbank maybe we could give 4 pound a try straddling corners. Might be fun to see the results.

+1. Real world results are what counts. As someone once wrote "the difference between theory and practice is that in theory there is no difference and in practice there is."

Andre

[DaVinci]

Purchased:

60 2x4 x 4 inch sheets of 4lb IIG "Safing" mineral wool for $375 including tax.

$6.25 per sheet... quite happy with that. Amazing what a difference from distributor to distributor... well worth the time spent calling around. I could swear the stuff is twice what will fit in the room... but I decided to go with covering everything, plus superchunking corners, and that's what the calculator gave me, so we'll see...

Thx, guys... will do a build thread when I get a chance.

[ocdstudios]

ok, so I bought the 2" and 4"... but was wondering the same thing. was going to buy 703 but the mineral wool in 2" 8lb was cheaper. the 4" 4lb was REALLY cheaper. But i am wondering if the 8lb is going to reflect too much of the higer frequencies back?? and ideas? i know that the 2" thinkness will not "catch" as many waves as the 4" but being denser it should absorb better. Just wondering if it is too dense. Also, given the two, which would you put in a cloud and which would you use on the walls (in boxes prob. spaced 4" off walls and of varying depths)? I am also wondering, as my room is only 11X20 how much absorbtion vs diffusion should i use? Ideas on this please!! the room is very hard and fluttery now - not very pleasant sounding on the short reverb that's there...

I have bad flutter, which I need to solve with diffusion. I was thinking of building a slat type diffuser for the rear wall and maybe using some pleated curtain panels. Whould the curtain panels (medium weight) dampen as well? especially if they were hung 6" or so from the wall? I was also thinking of curving the curtain around the corners to hide the bass trap materials in the corners?

Any ideas, suggestions? I am on a very tight budget but can definitely build things that look nice... I just want them to work!


Thanks for the comments/suggestions.

Matt

[DanDan]

Wow a question cluster.
Thicker is better. You can glue two 2's to make a 4.
Do your cloud with 8 Lb. 4Lb would probably sag. Neither will reflect HF.
Curtains will kill flutter but little else. Hang them pleated to create a fake thickness. Tight budget and diffusion don't seem to really jibe well together.
DD