Trying to determine the route to go for insulation in various Altec builds. I thought i had it determined that the Owens Conrning 703 unfaced 1" thick boards would be best, and they may, but I can't get it here. They require huge quantities. it appears to be available on Amazon, but shipping is not Prime and really expensive.
I can get the Roxul Rockwool AFB product 2" thick for $52.91 /bag. About $.55/sf
Rockwool still a viable option?
Hi Drugolf,
JBL does not recommend the use of Rockwool, but they don't say why... I assume its not enough soft, fluffy and absorptive.
See attached picture from page 6 of the JBL E series Instruction Manual. Regards,
Richard
I use wool for speaker projects. You can purchase it in "ropes" or roving, which are simply loose hair that has been wound but not woven into a long slender shape resembling a rope. They are very easily pulled apart to create quite the pile of fill. You want low bulk wool, not high. I purchase mine here:
http://www.customwoolenmills.com/woo...lation_rovings
They can advise based on what they have available. They ship to the States. The 5-7 pound bag would fill a normal-ish sized speaker cabinet. I think I've been using about a pound per cubic foot.
Quite a bit more expensive than fiberglass, but a pleasure to use and highly effective, imo.
I probably should have said I use wool, as in from sheep, not Rockwool.Originally Posted by rusty jefferson
Madisound sells carded wool... very old school and very good. Not cheap though.
Widget
I used that dense 703 compressed fibreglass in a pair of Augspurger monitors—contrary to what George Augspurger recommended. My (naive) thought was that the more completely the damping material absorbed the back-wave from the TAD drivers (which are crossed over at 800 Hz), the better.
My mistake. The 703 fibreglass sucks up too much of the sound and deadens the sound of the speakers. With two inches of much lighter Dacron, the speakers sound more dynamic and lively.
Just my experience.
I wonder if they are concerned about it being airborn or not. I have Rockwool in the ceiling joists as a barrier to the floor above and plan to have rockwool in the walls as an acoustic barrier (working on the room now). However, on the wall face itself, it will be less aggressive and more traditional fiberglass and/or duct liner.
Oh...one more downside to Rockwool in a speaker...you can only work with it once. Once you get to the second handling, it will start falling apart (which in a speaker would mean it would blow out of the ports).
Hi Drugolf and Sguttag,
Another place where JBL mentions the same not recommended for Rock wool, but this time "not" is in bold and underlined in the original document...
So they are pretty consistent! This one being JBL Enclosure Construction Manual, Page 6. Regards,
Richard
Hello,
Read the cancer warning on the bag.
Think about the fibers being pumped out of the reflex port for you and your children to breath.
Thanks DT
I don't believe those extruded fibers used for insulation are carcinogenic, however rock wool is far more irritating than glass wool. Also far more prone to being suspended in air. You can bet you'll have a steady supply flying out the ports of your speakers. Get that in your lungs and you'll be hacking for a week. I know since I'm in construction and around it often. I have to wear a respirator when rock wool is being installed, it's just everywhere. Contrary to what you may read about it, the fibers are way finer than glass wool, hence the heightened irritability. Mind you there is a variety of both on the market but this has been my experience. I would stay away from either and choose a stable alternative, ie: open cell whatever.
Hi DualTriode & gasfan,
Thanks for the input on Rockwool. Two interesting point of view.
As for me, I know Rockwool from seeing it all the time front row insulation at the local Home Depot store, but never used it in the house nor in my DIY boxes.
In the past I always used insulation type fiberglass in speakers. However, sometime ago I started purchasing polyester instead.
Insulation type fiberglass seems to have too many fibers flying in the air when manipulated or vent passing a good amount of air, unless its wrapped loosely in one layer of cheesecloth before tacking it in place or sprayed a little with some spray paint. Polyester doesn't appear to have that fiber issue.
So I'm slowly replacing the fiberglass in all my DIY boxes with 1-1½" polyester sold by Solen as well as others. Regards,
Richard
In my experience polyester does not work nearly as well as fiberglass or the blue denim cotton batting you can get as house insulation. When I use fiberglass I use 1” non-shedding insulation. Standard wall insulation is horrible to work with.
Widget
I finally found some of the OC 703 fiberglass. Tracked some down through a local insulation contractor instead of a direct supplier. He had to order it for me, but he does on occasion anyway. Knew exactly why since they have helped a couple local venues with their acoustical panels for live music etc.
dubkarma, how much of the 703 did you use? This is probably why many of the designs call for only 3 walls to be lined.
I believe it was 2" thick panels. (Augspurger had recommended 2" of the regular pink fibreglass, but on all interior surfaces except the front baffle.)
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