P.E. Acoustic Foam?

[dawg1161]

Hello to all again, I have read that there is something like this sold at the Home Depot? I have read it somewhere but i can't remember where and can't recall the name of the item. Any help would be great. Just trying to save some $ as a piece of the acoustic foam is $11 for 18"x 24" piece. (the gray foam ?).

Thanks in advance.

[MOState]

Hello to all again, I have read that there is something like this sold at the Home Depot? I have read it somewhere but i can't remember where and can't recall the name of the item. Any help would be great. Just trying to save some $ as a piece of the acoustic foam is $11 for 18"x 24" piece. (the gray foam ?).

Thanks in advance.

When I worked at Lowe's we sold nothing like acoustic foam

[kano32]

It might be similar to egg crate foam used as mattress pads. Other then that, I haven't seen anything at Lowes.

[warnerwh]

If you make panels with rigid fiberglass it will not only work much better but look better too. You can also buy acoustic foam off of Ebay for good prices. I used alot of acoustic foam behind, above and to the sides of my system. If I had it to do over again I'd use rigid fiberglass panels I made.

With the rigid fiberglass you can also build bass traps. These are very important also. Believe me when I say a room with good acoustics can make even a mediocre system sound as good as a high end system in a bad room. It can make a huge improvement and considering the cost is a bargain.

[Chris7]

You can buy various densities of carpet underlay at Home Depot. John Krutke discusses it at the bottom of this page:

http://zaphaudio.com/whispermat.html

Zaph suggests holding the chopped foam up to your ear to test if it's effective... that's a good suggestion, but I've found that it's difficult to do in the store. What works for me is I hold the foam up to a light (preferably sunlight)... if you can see spots in the foam where the sunlight shines through, it's not particularly good for audio use.

Also, if you go to an actual carpet supply place, they sell higher density chopped foam underlays than Home Depot does, for not much more. That stuff is quite good. You can also get higher end acoustic foam carpet underlays that aren't made of chopped material (typically for executive offices and luxury homes); those appear to be really good but I've never tried them because the price is roughly equivalent to the PE material.

Boat supply stores such as West Marine also sell Blackhole 5; it's marketed as an engine noise retardant, but it's the same stuff. Very expensive though.

[MOState]

If you make panels with rigid fiberglass it will not only work much better but look better too.

What do you mean rigid fiberglass? The only fiberglass that will be
rigid is the composite fiberglass (resin and mat) and I don't see how that would help the sound. Are you speaking of the rolls of fiberglass insulation, or rigid foam insulation? Or am I way off base here?

[Amphiprion]

Rigid fiberglass would be more accurately called compressed fiberglass. It comes in 2' x 4' panels and the most frequently used brand is Owens Corning 703. It comes in 1,2,3, and 4" thicknesses either unbacked or with a foil backer. It's density is something like 2-3 lbs/cubit foot.

It's not a stock item at Home Depot or Lowes, and I don't know if they can order it or not for you in small quantities. The cost is about $2 a square foot for 2" thick IIRC.

Another alternative is mineral wool, also called rock wool. It is essentially the same performance as compressed fiberglass, but maybe a little better at low frequencies. It is MUCH cheaper (I was quoted 0.88/sqft for 4" thickness material. Unfortunately it is not as easy to work with. It is made from basaltic volcanic rock that is melted and spun at high speeds in a steam system to produce fibers. The fibers are shorter than fiber glass which makes it harder to work with (more itchy) and it is a little harder on tools. It's appearance has earned it a less common moniker as "rottenglass" as opposed to fiberglass.

The best supplier I have found in Texas is Specialty Products Inc (SPI). You may see if you have one in your area. They are more than willing to deal in small quantities.

[Hank]

El Nino, when are you coming to Austin with your test gear?

703 data: http://www.owenscorning.com/comminsu...=&id=45e3341ea

BTW, type 705FRK is absorbs low frequencies better than type 703.

Here's a good source of acoustic materials and DIY items:

http://www.ethanwiner.com/acoustics.html

[---k---]

Are you guys talking about Apples and Oranges?

I thought:

Rigid Fibre glass such as OC 703/705 and Mineral Wool were great from room accoustics, and used in wall panels and such.

PE Acoustical Mats, Wispermat, BlackHole, Carpet Padding are great to use inside speaker boxes.

[Coby]

El Nino, when are you coming to Austin with your test gear?

703 data: http://www.owenscorning.com/comminsu...=&id=45e3341ea

BTW, type 705FRK is absorbs low frequencies better than type 703.

Here's a good source of acoustic materials and DIY items:
http://www.ethanwiner.com/acoustics.html

Looking at the spec sheet posted in the most recent thread, the 703FRK had higher absorbtion values than the 705FRK for the 2" thickness...that was kind of interesting.

[Amphiprion]

Hey Hank,

I should be making it over there not this weekend but next. I should warn you though that I won't be measuring any GR woofers as a matter of principle over recent events. But I'll still be up for the other stuff.

[Hank]

Are you guys talking about Apples and Oranges?

Could be. When I read dawg's post, I assumed he meant foam for lining speaker cabinets, but the thread turned towards room treatments so I thought my assumption was wrong.

[dawg1161]

It would be for lining cabinets. Today i was at Home Depot and i did come across some foam insulation sheets. They were pink seemed alittle stiff but looked like it might work? I think next time i will try carpet pad as i do have quite abit of it laying around?

[Kal Rubinson]

I don't know if you can make a distinction in application. The material either absorbs energy at certain frequencies or it doesn't.

Kal

[limulus]

I realize I'm about a week late on this post, but if you're talking about the 4x8 sheets of styrofoam insulation, don't use that. If you don't want to use Whispermat or something like that, just go to WalMart and buy an eggcrate mattress pad. I've used that stuff in several of my speaker builds. It'll cost you around $10.

Concerning acoustic panels for your room, you can definitely use rigid fiberglass panels. These are the fiberglass panels commonly used in the HVAC industry. They build the boxed sections of duct work with this. They also use the compressed (1-2" thick) version that comes in rolls to wrap ducts. This stuff is much more expensive than the rolls of OC fiberglass you'll find at HD or Lowes. Our house was being built and I obtained ours from the HVAC company. They delivered it right to the basement and it was several hundred dollars. Our home cinema used Certainteed Ultra Duct Gold on the walls. The entire front wall is treated from floor to ceiling. The side and rear walls are treated from the floor up to four feet. It's all covered with Dazian Expo Cloth. The other popular fabric choice is made by Guilford of Maine (GOM). I've attached a link that will give plenty of infor on absorption coefficients:

http://bobgolds.com/AbsorptionCoefficients.htm

It would be for lining cabinets. Today i was at Home Depot and i did come across some foam insulation sheets. They were pink seemed alittle stiff but looked like it might work? I think next time i will try carpet pad as i do have quite abit of it laying around?

[dawg1161]

Hello to all again. It has been awhile but i need some help. As my post states i am trying to save some cash by not using acoustic foam as it is $10.60 a sheet and i would need 2 sheets to complete my Dayton III towers i am finishing up. I will try and upload a picture of the carpet pad that i have and next to it is the same stuff that i put in my Sonosub. Could you (all) please tell me which you would use? Or should i spend the cash and wait a week and use the material that the design calls for? Thanks in advance.

[dawg1161]

Well i read the thread again so i went ahead and used carpet pad ?????? I won't seal the cabinet i'll use clamps and listen and compare to my other pair ? Wish me luck......

[Hdale85]

Your worried about spending 20 bucks versus 10?

[Jim Holtz]

Hello to all again. It has been awhile but i need some help. As my post states i am trying to save some cash by not using acoustic foam as it is $10.60 a sheet and i would need 2 sheets to complete my Dayton III towers i am finishing up. I will try and upload a picture of the carpet pad that i have and next to it is the same stuff that i put in my Sonosub. Could you (all) please tell me whih you would use? Or should i spend the cash and wait a week and use the material that the design calls for? Thanks in advance.

Rule of thumb is, if you can blow through it, it's acoustic foam. If you can't it's closed cell foam and won't work in speakers.

HTH

Jim

[Hdale85]

What about fiberglass the loose stuff? Isn't that supposed to be one of the best things? And rather cheap. I'm curious about this as well as I need to figure out what I'm going to line my cabinets with. But I want to know if its better the PE foam.

[Jed]

What about fiberglass the loose stuff? Isn't that supposed to be one of the best things? And rather cheap. I'm curious about this as well as I need to figure out what I'm going to line my cabinets with. But I want to know if its better the PE foam.

Zaph sums up all the differences between Sonic Barrier/whispermat/blackhole/fiberglass/ regular foam on his site. He uses different densities of Whispermat to line his speakers, and so does Jon Marsh. Use the thicker stuff on the back wall. Add a bit of poly fill midway to absorb a bit of the backwave reflections. For subwoofers, less fill is fine unless you are trying to achieve larger box volume by using fill. Sealed boxes require more fill usually as well, to absorb all the frequencies bouncing around in the box. For ported boxes, usually it is advised to keep the speaker lined and keep poly fill away from the port opening.

[ThomasW]

For a low buck fix NOTHING beats plain old fiberglass insulation it's much better than acoustic foam....

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

[dawg1161]

I thought that i was using the carpet pad for keeping the enclosure dead ? wouldn't insulation make the enclosure volume larger?

I should be able to listen to the speaker friday and then i'll decide if its a no brainer to spend 20$ vs. 10$..........

By the way if you were to have to choose between the 2 items i pictured which would you choose ?

Thank You for your replies.

[Jim Holtz]

I thought that i was using the carpet pad for keeping the enclosure dead ? wouldn't insulation make the enclosure volume larger?

I should be able to listen to the speaker friday and then i'll decide if its a no brainer to spend 20$ vs. 10$..........

By the way if you were to have to choose between the 2 items i pictured which would you choose ?

Thank You for your replies.

Bracing and solid cabinet construction make the cabinet dead. Acoustic foam or fiberglass are installed to kill the reflected back wave from the woofer.

I've used a lot of 2" foam on my projects but fiberglass is cheaper. Nasty to work with but it has the best absorption rates. If you want to use foam, Walmart sells a mattress pad that works well or you can go to a craft store like Hobby Lobby and buy a large sheet for around $10.

PE's works great too of course.

Jim

[ThomasW]

I thought that i was using the carpet pad for keeping the enclosure dead ?

Nope it takes something with weight (mass) to damp wall vibrations

wouldn't insulation make the enclosure volume larger?

Foam/fiberglass/polyfill/whatever are all going to do the same task. You're not using enough of any to effect the box tuning. All you're trying to do is absorb some of the rearwave.

[jmb]

I used a combination of PE's sonic barrier and fiberglass. I lined the front section, side walls and bottom, with the sonic barrier and on the complete back wall I used the fiberglass. About 1.5" thick at the top of the cabinet, and about 3" at the bottom. This is what I started out with, and haven't changed anything, because these sound SWEET. :B

[dawg1161]

Thanks....I'm pretty sure i get it now................I will try the carpet pad , then the poly batting i have and last i'll buy a mattress pad......

[ThomasW]

I will try the carpet pad

Unless it's an open-cell foam don't bother.

[69Stingray]

Bracing and solid cabinet construction make the cabinet dead. Acoustic foam or fiberglass are installed to kill the reflected back wave from the woofer.

1) Does "stuffing" and lining the walls have the same purpose, to absorb the sound waves inside the cabinet? I have made the observation that typically (not always) sealed enclosures have stuffing and porting enclosures have lined walls, why is this? Both have internal sound waves.

2) How does non-parallel wall work into this? I understand the prevention of standing waves, but by themselves do nothing to "absorb" the actual waves.

Sorry for hijacking. :B

[Jim Holtz]

1) Does "stuffing" and lining the walls have the same purpose, to absorb the sound waves inside the cabinet? I have made the observation that typically (not always) sealed enclosures have stuffing and porting enclosures have lined walls, why is this? Both have internal sound waves.

2) How does non-parallel wall work into this? I understand the prevention of standing waves, but by themselves do nothing to "absorb" the actual waves.

Sorry for hijacking. :B

Yes, stuffing and lining accomplishes the same purpose and everyone will have their own combination. I've used both and found I prefer to line the walls rather than stuff.

You don't want to have stuffing block the port so I again simply line the walls with 2" foam or unbacked fiberglass. Ported or sealed, I line the walls in the same manner. I try to cover all of the walls behind the woofer(s) the sound waves could be reflected from. Not too scientific but it works.

HTH

Jim

[dawg1161]

I used the carpet pad first.......ugh....then the poly batting like i used on my sonosub...quite the difference....i must've had closed cell pad? well any way they soumd great.....

[tpremo55]

Ok, so I've followed the thread and have run the numbers. It appears to me that standard fiberglass is still the clear winner for a good balance of cost and effectiveness. So, if you are used to working with it and the required precautions, is there any reason NOT to use it? I note a number of votes for specific acoustic attenuating materials, but don't see the numbers supporting the additional cost.

Goal: Absorbing back-wave from mid and woofer in ported enclosure. Assumed one layer lining walls.

Is there something I am overlooking? :scratchhead: