# Fiberglass Insulation, Fiberfill, or Acoustic Foam for Sealed Box?



## BowDown (Sep 24, 2009)

Ok.. used to use R11 fiberglass insulation in my enclosures because that's what I had. Then after reading something on Egg Crate foam I started using that with mixed results.. Now fiber fill (like pillow stuffing) seems to be the poison.

What do you use and why...


----------



## XtremeRevolution (Dec 3, 2010)

Fiberglass insulation has been tested to be superior with regard to absorption of sound waves to nearly all of the acoustic foams readily available, with polyfill coming in with the worst levels of effectiveness.


----------



## TheDavel (Sep 8, 2006)

I combine a few methods... Typically a layer of deadner followed by egg crate foam then finished off with an polyfill or attic insulation (usually wool based)... In addition I always off set my sub in sealed boxes, try to incorporate an angle and will place bracing inside which all help with internal issues...


----------



## UNBROKEN (Sep 25, 2009)

Any thoghts on lining a sealed enclosure with say 1/2" thick closed cell foam? Dimensions adjusted accordingly for the foam of course. 
That plus some mineral wool fiber ?

Just thinking out loud....


----------



## XtremeRevolution (Dec 3, 2010)

TheDavel said:


> I combine a few methods... Typically a layer of deadner followed by egg crate foam then finished off with an polyfill or attic insulation (usually wool based)... In addition I always off set my sub in sealed boxes, try to incorporate an angle and will place bracing inside which all help with internal issues...


No real need for an angle. The frequencies subs play in relation to the internal dimensions of the box make angled boxes only necessary for car-specific installs.



UNBROKEN said:


> Any thoghts on lining a sealed enclosure with say 1/2" thick closed cell foam? Dimensions adjusted accordingly for the foam of course.
> That plus some mineral wool fiber ?
> 
> Just thinking out loud....


Not sure if closed cell foam will do much. I've never used it. I don't think there will be any difference. If anything, it may cause some negative effects given it will act as an additional air spring on top of what's already inside the box. Wouldn't hurt to try. 

What kind of mineral wool fiber are you referring to?


----------



## trojan fan (Nov 4, 2007)

Fiberglass wall insulation is fine.....sounds like your're trying to split hairs here


----------



## trojan fan (Nov 4, 2007)

XtremeRevolution said:


> Fiberglass insulation has been tested to be superior with regard to absorption of sound waves to nearly all of the acoustic foams readily available, with polyfill coming in with the worst levels of effectiveness.


x2...that is exactly right and is not subjective


----------



## trojan fan (Nov 4, 2007)

TheDavel said:


> I combine a few methods... Typically a layer of deadner followed by egg crate foam then finished off with an polyfill or attic insulation (usually wool based)... In addition I always off set my sub in sealed boxes, try to incorporate an angle and will place bracing inside which all help with internal issues...


wool based, where do you find that


----------



## UNBROKEN (Sep 25, 2009)

Mineral wool is just a product description. It's a mineral based fiber insulation....not actually wool.
Rockwool and Roxul are 2 of the big mfg's if you wanna google some info.
I have that crap literally by the 18 wheeler load at my shop....since I'm in that industry.

I wonder where and how density comes into play?
I have 3 pound and 8 pound on hand....hmmm....


----------



## XtremeRevolution (Dec 3, 2010)

UNBROKEN said:


> Mineral wool is just a product description. It's a mineral based fiber insulation....not actually wool.
> Rockwool and Roxul are 2 of the big mfg's if you wanna google some info.
> I have that crap literally by the 18 wheeler load at my shop....since I'm in that industry.
> 
> ...


Ah, I know what you're talking about now. I've seen it around at home improvement stores. Should be fairly similar to fiberglass insulation. Compare the weight of the two. I imagine it might be a slight bit less effective (possibly inconsequential), but certainly more effective than polyfill.

If I had it by the truckloads, I'd use.


----------



## UNBROKEN (Sep 25, 2009)

So are we talking lightly fill an enclosure or stuff it full ?
The 8lb density stuff is 8lbs per cubic foot of material....polyfill is recommended at 1lb per cubic foot of enclosure volume....so use the same 1lb per cu/ft ? That wouldn't be much material.


----------



## The Baron Groog (Mar 15, 2010)

I'd go with polyfil or natural fibres. Fibre Galss loft insulation breaks easily, those pescky bits that get in your fingers/back/socks, and it would always concern me that it's ending up in the motor.

Wool is advised in lots of articles i have read, or you could try activated carbon as KEF do in their new range of speakers:

http://www.kef.com/resources/whitepapers/ace.pdf

Available from aquatic centres and you just fill up some socks or stockings to house it in your enclosure.


----------



## XtremeRevolution (Dec 3, 2010)

The Baron Groog said:


> I'd go with polyfil or natural fibres. Fibre Galss loft insulation breaks easily, those pescky bits that get in your fingers/back/socks, and it would always concern me that it's ending up in the motor.
> 
> Wool is advised in lots of articles i have read, or you could try activated carbon as KEF do in their new range of speakers:
> 
> ...


Fiberglass has been used for decades and in some quite expensive diy designs like the statements, mini statements, and statement monitors. I'm building the monitors and $650 for parts alone is no joke. These guys know what they're doing a lot more than I do, so when they all recommend fiberglass, chances are they've thought it through. Those pesky bits are handled with gloves and stay inside the speaker/sub once built.

Not trying to be an ass, just saying that your concerns are a non-issue. That stuff holds together pretty well.

Sent from my HTC Awesome using Tapatalk


----------



## sqnut (Dec 24, 2009)

Can you hear a difference between the different materials? In a car?


----------



## XtremeRevolution (Dec 3, 2010)

sqnut said:


> Can you hear a difference between the different materials? In a car?


Can you hear a difference installing them or not installing them? 

If so, the answer is yes. If anything, you'd have to use less of one material to get the same effect. 

My _research _indicates that fiberglass insulation is the best for this purpose. However, my experience is only partially relevant as the effects I experienced had to do with home theater speakers at significantly higher frequencies. 

Regardless of frequency though, I do think you will hear a difference between the materials used.


----------



## The A Train (Jun 26, 2007)

I agree with XR, as I normally do. Home audio isnt too far of a stretch from mobile audio. First off I would rule out CCF for that affects higher frequencies. I have used pillow stuffing, fiberglass, and 1.5" mattress topper. Pillow stuffing was horrible. My assumption is that it was kinda dense. Fiberglass worked great, but I used it in a ported enclosure that didnt even reach subwoofer frequencies. From my research, it seems to be the cheapest ($15 for a roll that would last for a gazillion boxes) and most effective. I did like how the mattress topper worked. It was thick and was contoured. I used it in my boombox build which actually reached frequencies into the 40's. It doesnt have that 'hollow' sound to it, nor did it 'ring.' One build that comes to mind is Minibox's build in his M5. http://www.diymobileaudio.com/forum/diyma-member-build-logs/65151-06-m5-build-8.html


----------



## ecbmxer (Dec 1, 2010)

I switched from polyfill to pink fiberglass insulation and noticed an improvement in smoothness and low end.


----------



## Chaos (Oct 27, 2005)

Fiberglass works, but I change enclosures/subs around too often to deal with the hassle of cleaning up afterwards. Polyfill, (aka pillow stuffing) doesn't seem to have much effect, at least with subs, so I tired acusta-stuff from PE and it seems to do the trick.


----------



## The A Train (Jun 26, 2007)

ecbmxer said:


> I switched from polyfill to pink fiberglass insulation and noticed an improvement in smoothness and low end.


Ah i think the pink is the itchy and flammable kind. And bad to breathe in. Try the white


----------



## BowDown (Sep 24, 2009)

It's not flammable... but it is itchy. Just use gloves when installing it. If it's a ported box I would use some alternative stuff tho.. just to make sure it doesn't become airborn outside the box.


----------

