#3 or #6 density fiberglass from SPI?

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Seeker of Rock

Seeker of Rock

Let us be unburdened by that which has been ?
SPI on their "order" form has 'fiberglass board' listed by a choice of 4 manufacturers, in #3 or #6 density. I wish they just listed 705 rigid fiberglass, but I didn't see that option. Anyway, I'm assuming #6 would be more dense, so I asked for a quote on that. It is $173 for 210 sf of 2" and $273 for 230 sf of 3". Any thoughts on the price and did I do right in asking for #6 density?
 
Sounds like a very decent price to me. I would choose the 6 over the 3 for better bass absoprtion, too.
 
Those are good prices.
Now for the confusion : If "space permits" it better to have fluffier stuff in larger quantities (less dense) than denser product. I personally have not tested it, but some gurus state that the gas flow resistance is better with thicker material in lower density. I can't wrap my head around that statement, but who am I to say :D

T
 
I believe the denser stuff is good for bass traps, the lighter is better for broadband absorbtion. The fluffy pink stuff is almost usless.........

I know the 6 and 8 lb stuff will be fairly reflective in the upper freq's.
 
NL, I thought so too! Pink stuff?... meh

Got the meat of a thread:
for rockwool/mineralwool use 2.5-3.5pcf for at least 6" thick vs. 4.5- 6 or more pcf for thinner 4" and below. Seems its a matter of price point.

So for 705, it'd be good for thin absorbers 1-2". 703 you should be able to use in 2 or 3'

Thats if we're talking BB coner straddling absorbers.

Anyone try some scrim in front of BB panels for better HF content instead of the price point of FRK? I'll be doing that soon, since some diffusors won't work in my small space-or so it seems.

T
 
Forgot to add, for Roxul MF:
Best bet @4" in 125hz coefficent:
RXL40 - 103
SAFE - 103
RHT40 - 107

suprisingly the RHT is the lowest density of the three??? Must be the grazing effect?

I have supplier in town that has the SAFE 4.5 pcf.3 sheets 24sf for 24$ plus tax. Recently got a few bales to put up some presonal test panels. Gonna be fun.

T
 
Tonio said:
for rockwool/mineralwool use 2.5-3.5pcf for at least 6" thick vs. 4.5- 6 or more pcf for thinner 4" and below. Seems its a matter of price point.
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Nope.

It's a matter of the right material for the job. The denser RW or RF will reflect the higher frequencies - not good for broadband absorbers. If you are making sealed bass traps, I believe the thicker stuff is OK.

edit - i actually puchased 8lb RW for LESS than the 3lb OC stuff. Then found out it is no good for BB absorbers.
 
Shit man, my happy bubble has been burst. The number totals are $1.79/sf for 2" and $2.59 for 3". That puts me into a lot of money. I can see using this stuff inside to build aborbers, but I had the nice idea of placing it between the drywall and block structure all the way around inside my walls. Don't think I can afford that, and will have to go with loose fiberglass (fluffy stuff) instead. I'll be able to order enough to build some panels for the back/front and bass traps, though :) :)
 
Edit: I talked to my local SPI rep, Hank, and he said that was the 705, which they didn't list by that title, just by manufacturer and density, but said the 705 was OC's #6 stuff.

What the hell, and while I'm already bitching....I'm hiring someone to do my exterior stucco. Priced it out with some contractors...pffffft. $1500 my ass to stucco approx. 350 exterior sf. So I'm on my way to Home Depot and my neighbor, who is getting ready to do a 3rd bedroom extension onto his house, tells me his parents have a neighbor that does remodeling, interior and exterior, and did new bathrooms, kitchen, and exterior finish on their house. $700 materials included, about 2 days to complete. I had to take the offer. He is supposed to start either tomorrow or Thurs. I'm tired at this point :( :( Plus I still have the wood ceiling/door/drywall/insulation/finishing details to do.

Dani Pace, if you're reading....I can't remember whether you mentioned this when you were giving advice to the newbie that was wondering what they should figure in building a studio....aside from twice as many outlets as you think you will need, four times as much money :( :(

At least it is coming along, though, my only solace :)
 
For reflection panels, stick with 2" of 703 (3lb density). For bass absorbers, do yourself a favor and save some money. You can build 6" thick bass absorbers from 3lb for 75% of what 4" thick 6lb absorbers will cost - and the 6" thick ones will perform better.

In fact, by the time you get enough material to do 6" thick, you can actually cut it up into triangles and make a solid 'chunk' style corner absorber that takes up LESS space in the room but is approx 12" thick in the center.

Bryan
 
For panels it won't be a problem, I can afford it. I was going to use it in between all of my studs in hopes of absorbing any low frequencies that got through the drywall, keeping them from transferring to the concrete block exterior structural walls. I think I'm going to have to use soft fiberglass insulation between the studs instead, not for absorbing sound, but for thermal insulation and just treat the interior with panels when the time comes.
 
I checked out the 'acoustics 101' on the Auralex site. Haven't really paid much attention to Auralex yet, but it was a good, seemingly straightforward 'Cliff Notes' version of acoustic treatment. I don't feel so bad about the soft insulation between the studs now, though I'm sure the 705 would have been better.
Just a little update. :)
 
S.O.R. - I'd check out John Sayers sight and Ethan Winers. BEFORE you start building ANYTHING.

:D
 
bpape said:
For reflection panels, stick with 2" of 703 (3lb density). For bass absorbers, do yourself a favor and save some money. You can build 6" thick bass absorbers from 3lb for 75% of what 4" thick 6lb absorbers will cost - and the 6" thick ones will perform better.

In fact, by the time you get enough material to do 6" thick, you can actually cut it up into triangles and make a solid 'chunk' style corner absorber that takes up LESS space in the room but is approx 12" thick in the center.

Bryan
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So I was close no?


SOR don't waste money on the inside of a wall, you can use fluffy inside. Just need to damp the drywall. GG on inner side mucho bueno!! But pricey :mad: Just be sure to use some for firestops(between inner /outter wall) if you decide a RIR (room in a room ), but don't ask what type ha! Best go to JS' for that.

T
 
NL5 said:
S.O.R. - I'd check out John Sayers sight and Ethan Winers. BEFORE you start building ANYTHING.

:D
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I appreciate your response, but it's a little late. https://homerecording.com/bbs/showthread.php?t=217410

I went to John's and Ethan's and most recently, Auralex's 'acoustics 101', not expecting much but peddling of their product at first, but found it good reading. Studied the posts on here as well. I've got a decoupled room minus the ceiling, which I improvised on. The other construction is inline with the concepts here except the ceiling, and for that part we'll just have to see how my improv sounds when I'm done. :) :)

NL5, I sent you a PM btw, a week or so back.
 
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It is correct that the denser stuff is better for bass absorbtion and the lighter stuff is better for midrange absorbtion. However once you get much less dense than about three it stops being all that good at all. What that might mean in practice though is that a three inch panel of 705 might do as well as a four inch panel of 703.

But here is the kicker. Because the 705 contains more fiberglass and less air it is more expensive.

Also some have shown that FRK is better for bass but worse for midrange.

Also you can never buy less than a full bale.

So the buying strategy for a do it yourselfer doing his first and most likely last room treatment project is different than a trap manufacturer who will certainly find use for leftovers.

So my recommendation for the do-it yourselfer is to buy a bale of unfaced 703 in one or two inch panels. Start by using it to stack up four 4-inch corner traps and four two-inch side-wall traps or clouds. Play around with placement and possibly making more or fewer of the corner or wall/ceiling traps. The fact is that it would be a rare home recording room that can't be tamed with one bale of unfaced 703 inteligently placed.
 
NL5 said:
I replied, but your inbox is full. :D
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Oops, sorry about that. I'm going to clear it now.
 
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