Best accustic insulation?

[robertbartsch]

OK, so I finishing up a pair of 15 inch 3/ways that I had a cabnet-maker construct.

What is the best insulation to use on the inside of the box?


Should I just use plain pink home insulation or is there something better?

By-the-way, exactly what does this stuff do; prevent the box from vibrating or is there some other purpose?

Thx...

[Rusnzha]

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=260-330&vReviewShow=1&&vReviewPage=2&vReviewRand=5792917

I've had good luck with acoustastuff from Parts Express. You need about a pound/2 cubic feet. It tightens up the bass giving it more impact while reducing boominess. If you put some in your midrange compartment, this can have a similar effect on the low end. The stuff has the same effect as adding volume or using a bigger box.

[robertbartsch]

It looks like this stuff is packed into the open cavity of the box rather than just placed along the walls of the box; right?

Wow; my boxes are 7 cubic feet each - so that would take two bags of this stuff at $35 each.

Is this worth it for large boxes or just for smaller bookshelf-type systems?



Thx...

[sourceoneaudio]

I use Dacron (pillow stuffing) or Jute. Jute is the underlying material used under carpet in the automotive industry.

Using both of these and not fiber glass keeps the glass particles of out the air you breath. (in ported applications)

[robertbartsch]

Yeh, I hate the idea of breathing pink insulation too. The stuff makes me itchy thinking about it. I suppose you could place a screen over the baffle ports; right?

Where can you buy dacron pillow stuffing; Martha Stuart's place; Sears, Bed Bath Beyond? Is this stuff placed in the box cavity too or just used on the inside walls of the box?

Thx...

[Valentin]

fiber glass semi rigid board 3lb/foot density (48kg/m) or mineral wool
1 o 2 inch thick

that's the best cost effectiveness and you can find it all over the world.

density is very important the normal home insulation does not have the correct density

visit http://www.bobgolds.com/AbsorptionCoefficients.htm

you will find different manufacturers and models numbers

[Hoerninger]

Closed box: fill the whole volume.
Bass reflex: attach to the walls only.

Lamb's wool by VISATON (Art.No. 5069) might be an alternativ, which I prefer.
____________
Peter

[robertbartsch]

Val:

Ok, I think I saw this hard board insulation at the Depo. It was very dense and was being sold in 8' x 4' pieces for about $20 per sheet. It was pink in color, I beleive.

Is this the stuff you are recommending?

Thx..

[Valentin]

if its the Owens corning it must be model 703 made of fiber glass not foam it is usually yellow normaly sold in 2 by 4 foot sheets

[Robh3606]

I use a combination of 3/4 inch fiberglass ceiling tiles and batting. Works for me. Just use a long sleeve shirt and scissors to cut it up. The tiles are about 2'X4' are inexpensive and are easy to cut to size and install.

Rob:)

[Mr. Widget]

What is the best insulation to use on the inside of the box?I am not a fan pink or yellow house insulation as it is so miserable to work with and it will usually over dampen the box anyway as it is so thick. I have found dacron batting to have limited damping ability... even using a ton of the stuff.

I like Wrap-On fiberglass batting. It is shed resistant and has excellent acoustic properties.

http://www.audioheritage.org/vbulletin/showpost.php?p=35394&postcount=7


Widget

[Valentin]

sorry to disagree

but the celling tiles plus home insulation don't compare in the amount of absorption done by the 3pcf density fiberglass or mineral wool with the same thickness

tiles work for you ok they do absorb

but it is not the best solution when absorption is too be taken into account

Robert i am sure you could find this type of material near you

[Valentin]

the semi rigid fiberglass board is very easy to work with you only need a cutter

easier than mineral wool sine fiberglass boards have a resin that makes them stiffer and easier to cut and preserve their dimensions once cut and stay in place in the box

it cuts with help of a ruler in easy fashion you will find different thickness 1 ,2 ,3 or 4 inch

normally only 1 inch is used

there is also a product made by johns mansville cald linacoustic which has a slite neopren covering that makes it resistant to air flow with out sacrifing too much

[Robh3606]

sorry to disagree

but the celling tiles plus home insulation don't compare in the amount of absorption done by the 3pcf density fiberglass or mineral wool with the same thickness

I think it's the same stuff

http://www.allnoisecontrol.com/products/CeilingTiles_ANC1010.cfm


Rob:)

[Valentin]

there are many types of celiling tiles not all af the comply

in the one posted the NRC are very good indeed for 1 inch and 11/2 inch

good data it is 6pcf density glass fiber with a backing

[Robh3606]

Yes but even the lighter tiles are at least 3 pcf. You can get those in almost any home center. They are thinner 5/8 so you may have to double them up. But yes the thicker more dense materials will always be better. And your right you need to know what the tiles made out of. As far as better? All I know is I can build a box, drop in the tiles, and have it end up within a 1hz-.5hz of my design spec. tuning frequency.

Rob:)

[Valentin]

But yes the thicker more dense materials will always be better


not really there are limit and types of materials some absorb some reflect
density is not the only factor

not all ceiling tiles are made of the same materials

JBL uses 1" 3pcf density fiber glass in their encousures at least in the LSR

[readswift]

someone has a link to Mr. Widget's "the next best thing" egg-crate-foam (thats costly)?

[Rusnzha]

Originally posted by Robert Bartsch
Wow; my boxes are 7 cubic feet each - so that would take two bags of this stuff at $35 each.


You would need 7 lbs of the stuff -- They also sell it in 1 or 2 lb quantities. I attached it to the sides and back of the cabinets with silicone glue. I use it in my 12 cubic foot box with a 2241h/720 watt Hypex Amp/Velodyne SMS-1. I spent a bunch on components, why skimp on box treatments. It sounds like a million bucks. You got a lot of replies to check out, I'm sure there are many good ideas. If you can do it for less, thats cool! Good luck.