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  • box damping material

    What would be the best (and cheapest) material to use to dampen a ported speaker enclosure? Looking at egg crate foam, standard flat (about 2" thick) foam that you'd buy at a craft store, roll insulation, etc. Since its a ported enclosure I assume polyfill would be out as it would tend to get blown out the port (humorus to watch but irritating to clean up, especially whn your two year old finds it and scatters it all over the house.) I'm not against buying acoustic foam but am trying to keep the cost down as much as possible and put that money on components.

  • #2
    Re: box damping material

    Originally posted by bre's dad View Post
    What would be the best (and cheapest) material to use to dampen a ported speaker enclosure? Looking at egg crate foam, standard flat (about 2" thick) foam that you'd buy at a craft store, roll insulation, etc. Since its a ported enclosure I assume polyfill would be out as it would tend to get blown at the port (humorus to watch but irritating to clean up, especially whn your two year old finds it and scatters it all over the house.) I'm not against buying acoustic foam but am trying to keep the cost down as much as possible and put that money on components.
    Yup, mattress-topper from WalMart. Plus it's got really cool patterns on it.

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    • #3
      Re: box damping material

      Carpet padding can be good too. You could go to the store and ask for scraps, or if you know anyone who is getting carpet put in.

      I like this stuff. http://www.parts-express.com/pe/show...number=260-520

      It seems expensive, but by the time you buy padded foam, or carpet padding and a can of spray adhesive, the sonic barrier isn't really all that much. It's also easy to work with. Cut, peal, stick, done.

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      • #4
        Re: box damping material

        I've always preferred FB batting stappled down. It just seams to control back waves nice and keeps a lot of the midrange FR junk from coming out of the port.
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        • #5
          Re: box damping material

          I've always wondered if plasticine would be a good option. Actually, I used it on a pair of small MTMs, and it worked great. It damped the box perfectly well.
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          • #6
            Re: box damping material

            I'm pretty sure the most effective thing out there is rigid fiber glass with acoustically transparent material glued to it to prevent glass fibers from shedding and being blown out the port. Bang for the buck steers me toward the 3 lb/ cubic foot stuff as it is about 1/2 price of the 6 lb/cubic foot material and from what I understand is very similar as far as noise reduction coefficients go.

            Mostly people use Owens Corning 703 but Johns-Manville also makes a comparable product. Finding that stuff locally can be tough but I know GIK Acoustics will ship it to you.

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            • #7
              Re: box damping material

              Has anyone used recycled denim? I was watching a show once on TV that had to do with home improvement, but they were using the recycled denim and claimed it blocked more sound then fiberglass. I forget by how much. Maybe 25,30%.

              I checked awhile back and couldn't find a cheap source for it. Now it is available at Home Depot for $6 a roll 48"h,16"w,2"d, or a 6 pack for $36. Home depot links never work, but its Model # 60306-16482.

              At 2" thick, it might only be workable in a large sub box, but I was also thinking maybe DIY acoustic panels.

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              • #8
                Re: box damping material

                I use what Chris does (foam from walmart) then spray a light coat of car undercoat to turn it all black inside the box. Looks cool and sounds good to me.

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                • #9
                  Re: box damping material

                  Originally posted by Alex2507 View Post
                  I'm pretty sure the most effective thing out there is rigid fiber glass with acoustically transparent material glued to it to prevent glass fibers from shedding and being blown out the port....
                  +1 on the acoustic fiberglass. Armstrong #420 ceiling tiles with the plastic stripped off or Owens Corning #703 are what I use.

                  OT, but relevant: Regardless of what you do to the fiberglass, you won't get glass fibers blown out of the port. Think about it. How far does the air column in the port actually move before it reverses? Maybe 1/2"? And your port is 3-4" long? There is no transfer of air from inside the speaker to outside. Those cartoons of a guy siting in a chair in front of a speaker with his hair being blown back are pure nonsense.

                  I have never had yellow dust appear on the floor in front of a speaker.

                  [/rant]

                  Bob

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                  • #10
                    Re: box damping material

                    Originally posted by mramsay10us View Post
                    I use what Chris does (foam from walmart) then spray a light coat of car undercoat to turn it all black inside the box. Looks cool and sounds good to me.
                    Doesn't that turn the open cell foam pad into a closed cell foam (at least the boundry layer)?

                    Similar to what Bob does, I buy the 2' x 4' acoustic ceiling tiles that are made of fiberglass board and just peel off the thin plastic film.
                    Craig

                    I drive way too fast to worry about cholesterol.

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                    • #11
                      Re: box damping material

                      Right now I'm using some 1.5" egg crate foam but I don't have enough for both speakers and no one arround here sells egg crate foam. I'm checking around with the flooring stores and trolling for some scrap padding. I tried one speaker lined with the egg crate against the other empty... could hear any obvious differences.

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                      • #12
                        Re: box damping material

                        Originally posted by generic View Post
                        Has anyone used recycled denim? I was watching a show once on TV that had to do with home improvement, but they were using the recycled denim and claimed it blocked more sound then fiberglass. I forget by how much. Maybe 25,30%.

                        I checked awhile back and couldn't find a cheap source for it. Now it is available at Home Depot for $6 a roll 48"h,16"w,2"d, or a 6 pack for $36. Home depot links never work, but its Model # 60306-16482.

                        At 2" thick, it might only be workable in a large sub box, but I was also thinking maybe DIY acoustic panels.
                        The stuff I've seen comes about 4" wide and about 4" thick, not 2". I didn't know it came in 'sheets'. I'll be looking into that.

                        Later,
                        Wolf
                        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
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                        • #13
                          Re: box damping material

                          Originally posted by Bob Brines View Post
                          OT, but relevant: Regardless of what you do to the fiberglass, you won't get glass fibers blown out of the port. Think about it. How far does the air column in the port actually move before it reverses? Maybe 1/2"? And your port is 3-4" long? There is no transfer of air from inside the speaker to outside. Those cartoons of a guy siting in a chair in front of a speaker with his hair being blown back are pure nonsense.

                          I have never had yellow dust appear on the floor in front of a speaker.

                          [/rant]

                          Bob
                          That might be true for low xmax drivers with largish ports but have you ever played with a high xmax driver with a small port?

                          I've seen the tang band w6-1139 (6.5 inch driver, 13 mm xmax) in a small box with a 2 inch diameter port. At full blast, air velocity was so violent that it ruffled papers 6 feet away - and not because it was an awesome bass machine, it was port air at very high velocity, very much like a little leaf blower. I'm pretty sure that thing could hurl tiny loose fibreglass bits all over the room.
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                          • #14
                            Re: box damping material

                            Originally posted by diy speaker guy View Post
                            I've seen the tang band w6-1139 (6.5 inch driver, 13 mm xmax)
                            11.5mm Xmax, but I've also seen the effect you are stating.

                            Later,
                            Wolf
                            "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                            "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                            "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                            "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                            *InDIYana event website*

                            Photobucket pages:
                            https://app.photobucket.com/u/wolf_teeth_speaker

                            My blog/writeups/thoughts here at PE:
                            http://techtalk.parts-express.com/blog.php?u=4102

                            Comment


                            • #15
                              Re: box damping material

                              Originally posted by diy speaker guy View Post
                              That might be true for low xmax drivers with largish ports but have you ever played with a high xmax driver with a small port?

                              I've seen the tang band w6-1139 (6.5 inch driver, 13 mm xmax) in a small box with a 2 inch diameter port. At full blast, air velocity was so violent that it ruffled papers 6 feet away - and not because it was an awesome bass machine, it was port air at very high velocity, very much like a little leaf blower. I'm pretty sure that thing could hurl tiny loose fibreglass bits all over the room.
                              The port is clearly too small and port velocity is too high. Surprised you heard anything but port noise. I don't remember for sure, but I think I used a 6" port on my TB sub.

                              Just because you can make something do the unusual, it isn't normal for a sub to blow fiberglass around. I guess if you design it for that function, you might be able to make it work.

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