Is there a benefit to putting sound deadening material...

Discussion in 'OT Technology' started by GlocksRock, Nov 15, 2003.

  1. GlocksRock

    GlocksRock Glock > You

    Joined:
    Jun 15, 2003
    Messages:
    6,647
    Likes Received:
    0
    Location:
    North Carolina
    on the inside of your subwoofer box? I have heard of people doing this, but don't know what, if any, benefits there are to doing this. I have plenty left over from when I had my trunk and doors done, and I plan on building a new sealed box in the near future. Should I do it or not, I don't want to do it and find out that it makes no difference, or makes it sound like crap.
     
  2. 04

    04 Guest

    It won't hurt anything, but it wont do anything either.

    I once did the same thing when I was first getting into audio. Needless to say that was the last time I did that ;)

    Instead, I suggest filling it with around 1lb per cubic foot of polyfill or fiberglass if its going to be a sealed box.
     
  3. beef316

    beef316 New Member

    Joined:
    Nov 16, 2003
    Messages:
    2,473
    Likes Received:
    0
    Location:
    Holiday, FL

    It WILL make a difference. Whether you will notice it or not depends on how carefully you listen and if you even care about sound quality.

    It reduces standing waves that cause cone breakup (distortion) and also reduces enclosure resonances (vibrations). Short story: It helps allow you to play undistorted music louder.

    I would worry about getting the rest of the system in order before spending money on deadener for the sub enclosure. If you have your system in order (or you just have extra deadener laying around), then go for it and let us know how you make out. The wall behind the subs is the most important part to deaden. If you have extra after that, do the rest of the inside of the enclosure.
     
  4. 04

    04 Guest

    Uh, the sound quality will be unaffected at low frequencies. It wont reduce standing waves until MUCH higher frequencies, sub 100hz will be unaffected. Is your enclosure so poor that it vibrates in the first place?

    I have never heard of any regarded SUBWOOFER design that puts sound deadening material ie: dynamat on a subwoofer cabinet. Why not? Because it wont affect anything unless your subwoofer plays up into the midrange. There COULD be harmonic distortion and cone breakups from the woofer but if you fill the enclosure with fiberglass or other type of material, it will solve the problem.

    The reason people put sound deadening material on surfaces in the car is because it mass loads it and lowers its resonant frequency so buzzing and such is eliminated. You still get the same losses as before, just no nasty midrange buzz.
     
  5. twistid

    twistid Banged By Super Models Moderator

    Joined:
    Jul 15, 2001
    Messages:
    40,728
    Likes Received:
    81
    Location:
    The Kansass/Oklahomo Border
    we used a spray sound deadener in the enclosures at the shop for our demo units, and yes there are companies that make prefab enclosures with sound deadening sprayed inside. i'll get info on them tomorrow at work, though we've never sold any because they cost around $500/box.
     
  6. GlocksRock

    GlocksRock Glock > You

    Joined:
    Jun 15, 2003
    Messages:
    6,647
    Likes Received:
    0
    Location:
    North Carolina
    My whole system is already in order, and I do have extra deadening material lying around, so I figured I would ask about possible benefits because I heard of someone else doing this. I would rather not put it in there if it isn't going to be of much or any benefit, as I could possibly sell it to someone else.
     
  7. beef316

    beef316 New Member

    Joined:
    Nov 16, 2003
    Messages:
    2,473
    Likes Received:
    0
    Location:
    Holiday, FL
    You are correct, standing waves are not a problem in a dedicated subwoofer enclosure and probably not in this application.

    People do use sound deadening because it mass loads, but most can serve as great barriers as well. It is used in door panels, on the firewall and floor to serve as a barrier for road and engine noise.
     
  8. dbman96

    dbman96 Active Member

    Joined:
    May 25, 2000
    Messages:
    49,996
    Likes Received:
    6
    Just for kicks I made a box for my JBL 1500GTi entirely of dual sheets of 1/2" MDF "laminated" together with mastic (and clamped with screws every few inches).

    It was pretty solid. But then again... 3/4" MDF would have been pretty solid too. I just had too much time on my hands.
     
  9. lowfat

    lowfat 24/Mac/SciFi/PC Crew OT Supporter

    Joined:
    Oct 27, 2003
    Messages:
    63,949
    Likes Received:
    0
    Location:
    Grande Prairie, AB, Can
    I heard that putting sound deadner in between layers of fiberglass in a fiberglass enclosure will reduce resonation. So i did this. Did i just waste sound deadner?
     

Share This Page