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Acoustic stuffing differences , any ideas ?

Discussion in 'Speakers' started by bob s, May 15, 2018.

  1. bob s

    bob s Active Member

    Messages:
    179
    Location:
    Michigan's Upper Penninsula
    I have dismantled some loudspeakers that had badly damaged boxes. I saved the stuffing material for future use. The material out of the AR-14's is coarser in texture. The material from the Infinity's is a much finer in texture, almost silly feeling. I am wondering which would be superior for stuffing some bookshelf speakers, like my Optimus LX-5's, or if it matters. Some folks swear that plain old fiberglass is the best, but it is so dogone itchy, I want to stay away from it if possible. Any thoughts ?

    Bob S
     

     

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  2. quiet

    quiet AK Subscriber Subscriber

    Messages:
    1,823
    Location:
    arkansas
    The move away from fiberglass was for the reason you just said. Day in and day out was a discomfort for the speaker makers. It was the most common at the time.
    And of course the material used has a big effect on the sound as you said. For your limited use with gloves it may be a good option.
    Good luck.
     
  3. gdmoore28

    gdmoore28 Super Member

    Messages:
    2,809
    Location:
    Central Arkansas
    Fiberglass still reigns supreme, but Parts Express has AcostaStuff. I've had very mixed results from polyester pillow stuffing.
    GeeDeeEmm
     
  4. swechsler

    swechsler Frog Whisperer

    Messages:
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    Location:
    7th row center
    Infinity's been using the polyester-looking stuff since at least the 1980s, for whatever that's worth.
     
  5. zieglj01

    zieglj01 Member

    Messages:
    73
    Location:
    Tenessee
    Put gloves on and use fiberglass -- still one of the best
     
  6. bob s

    bob s Active Member

    Messages:
    179
    Location:
    Michigan's Upper Penninsula
    So the parts express acousta stuff is different than polyfill? I think that is what was in the Infinities, its real soft and silky feeling. I suppose I clubs stuff one speaker with one material and one with the other and see if I can discern the difference.
     

     

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  7. JimPA

    JimPA Distinguished Member

    Messages:
    3,161
    Location:
    Grover's Corner PA.
    This should answer your question.
    index.php
    index.php
    /
     
  8. bob s

    bob s Active Member

    Messages:
    179
    Location:
    Michigan's Upper Penninsula
    I read the linked article, still not sure if I totally understand the concepts, but I'm no engineer so can't argue the point. Without sophisticated test equipment it would be hard to really pick apart any small changes the various materials make. I guess I'll just stuff em and see what happens.
     
  9. kfalls

    kfalls Super Member

    Messages:
    1,076
    Location:
    Dennison, Illinois
    I've heard many use Rock Wool which is also a fiberglass.
     
  10. woodj

    woodj Super Member

    Messages:
    3,461
    Rock wool (unless it has been refined considerably) contains chemical contaminates.
     
  11. hjames

    hjames dancing madly backwards ... Staff Member Moderator Subscriber

    Messages:
    12,056
    Location:
    VA near DC
    You can get bags of polyfill (polyester filler) pretty cheap ($7-10 bag) at places like Michaels. Its used for creating/stuffing pillows and such and is a readily available and safe media. I had heard some car audio folks stuff their cabinets with it.
    Yellow building insulation fiberglass is real nasty stuff and recommend NOT putting it in ported speaker boxes where broken bits of the fibers can be expelled when bass is played. YUCK!

    I have been modding a pair of Heathlkit Valencia type speakers recently. The cabinets have sheets of, I presume, Rock wool stapled to the sides and back of the cabinet. I installed a sheet of stiff fiberglass between the bass area and the horn area. An audio guru I am working with gave me a large box of raw lambs wool, with details on pulling the fibers apart for the most expanded use as stuffing inside. Its got a nice feel (lanolin in the fibers) smells pleasant, and the (ported) boxes have a nice bass response now. The little flecks of white are some polyfill media I had tried before.
    This shows maybe 6-8 ounces of lambswool really pulled apart and fluffed up in air.
    There is a 15 inch woofer underneath.

    You can buy it lambs wool on ebay (cheap!) - https://www.ebay.com/bhp/raw-wool


    Woofer-lamb-fluffed_6563.jpg woofer-Area-B4_6561.jpg Woofer-screened_6562.jpg

    This is a picture from one of the ebay ads - looks just like what I have at home,
    before I pulled all the strands apart and fluffed it up!

    eBay-lambswool-l1600.jpg
     
    Last edited: May 17, 2018
    darkblue94 likes this.

     

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  12. gdmoore28

    gdmoore28 Super Member

    Messages:
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    Location:
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    We've discussed Rockwool before, and my personal opinion (ie, likely worthless) is that while it does function as intended as a sound barrier/insulator for home use, it's not good for the qualities that are generally sought by speaker builders. This is because Rockwool (compared to fiberglass) is very dense and minimally air permeable - ie, air movement thru it highly restricted. I think it would be impossible, for example, to use Rockwool in a transmission line the same way as fiberglass or Fiberfill simply because it will not allow air waves to move throughout the enclosure unimpeded.

    Additionally, it weighs 2.5 lbs per square foot! ("ROCKWOOL insulation is a rock-based mineral fiber insulation comprised of Basalt rock and Recycled Slag.") That means that, whereas fiberglass will actually "fool" (for lack of a better term :dunno:) the woofer into seeing a larger (sealed) enclosure volume as it is added to the box, Rockwool will instead occupy space and thereby decrease enclosure volume.

    https://cdn01.rockwool.com/siteasse...fing-Insulation-Techdata.pdf?f=20180419081800

    JMO, you understand. ;)

    GeeDeeEmm
     
    CT Jim likes this.
  13. woodj

    woodj Super Member

    Messages:
    3,461
    Rockwool was widely used in speakers when fiberglass was less available and more expensive.
     
    Retrovert likes this.
  14. bob s

    bob s Active Member

    Messages:
    179
    Location:
    Michigan's Upper Penninsula
    I worked 35 years in a power plant where they used rock wool as high temperature insulation. It's really nasty stuff, very irritating, so I'll stick with the fiberfill and similar materials. Lambs wool sounds interesting, and we have friends that have sheep ( same critter I suppose ) Maybe we can talk them out of a few handfuls come shearing time.
     
  15. Retrovert

    Retrovert AK Subscriber Subscriber

    Messages:
    3,595
    Location:
    New York City, NY
    You likely don't want to do that. Raw sheep wool is covered in lanolin (grease), is filthy, and it stinks. This is why all those jokes about sex with sheep are somewhat misplaced. As an Aussie I knew a long, long time ago once said to someone making jokes about sex with sheep, "You ever smell a sheep, mate?" Anyway, it will be a dense, greasy, dirt mass.

    The speakers with wool stuffing use the cleaned and carded variety, with long fibers, which fluffs up a lot better. I believe it was Bailey who first introduced this for transmission-line stuffing. You'll see this called "long fiber" which means the fibers are (IIRC) about six inches long. Much of the wool sold as batting or padding is shorter fibers twisted together which doesn't matter for upholstery, but it does matter for speakers.
     
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  16. DavidF

    DavidF Active Member

    Messages:
    338
    Location:
    San Jose, CA
    At the end of the day I would just use Acousta-Stuf but it doesn't hurt to bag up the fill you mentioned for other uses. The advantage of Acousta-Stuf is that will resist settling over time. There is a need to keep the filaments spread in the material to work as intended in providing resistance to the air flow.

    Fiberglass is better for lining cabinet walls to target the high pressure areas that build up against the interior walls. I don't have a big concern for the loose fibers but the cautions above are well founded. Rockwool is best used for acoustic absorption for treating walls/ceilings or in acoustic panels. I certainly wouldn't go there for speaker cabinet uses.
     

     

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  17. Retrovert

    Retrovert AK Subscriber Subscriber

    Messages:
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    Location:
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    Cotton batting is superb for lining the interior walls. That's what Bozak used.
     
  18. highend64

    highend64 Well-Known Member

    Messages:
    626
    Location:
    Central CA
    Well believe or not used some memory foam used for bed I had laying around and it work great for my DIY speakers.
     
  19. bob s

    bob s Active Member

    Messages:
    179
    Location:
    Michigan's Upper Penninsula
    Good point about the raw lambs wool, ick.....acoustastuff or equivalent will likely work fine. I have seen folks use the eggcrate foam to line enclosure walls, then stuff the insides with other fibers. The foam they make mattresses is probably too dense and would act to reduce the interior volume of the enclosure, just the opposite of the intention.
     

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