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Should subwoofers have internal wadding?

Discussion in 'Subwoofers' started by morksbeanbag, Oct 23, 2005.

  1. morksbeanbag

    morksbeanbag
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    Hi all,

    i have a Sony SAWX900 sub which i'm very pleased with, however i looked inside the unit and there was no wadding whatsoever. I bought it half price and it looks as though someone else has taken the back plate/amp off to either replace a driver or maybe even replace the amp, not sure but what i did notice is that on the side panels they were two small black patches of material that were stapled on. From what i've seen before this is usually done to hold wadding in place so i am thinking that perhaps the wadding (if there ever was any) was once removed and never put back.

    Does anyone have any ideas, or are prepared to look inside they're own subs to see if they have wadding?

    many thanks

    Ben
     
  2. Jase

    Jase
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    Might vary from Sub to Sub but the inside of my Velodyne DD15 has wadding.
     
  3. morksbeanbag

    morksbeanbag
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    might try fitting some and see if it makes any difference. i'm also thinking of making some bracing for it. I really like b&w's matrix bracing. I'm thinking of making a simple version of that to fit.
     
  4. eL-ZilCHo!

    eL-ZilCHo!
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    i know the last post was a week ago, but thought i'd add my 2p's worth. Wadding essentially fools the driver into thinking it is in a larger enclosure. it does this by slowing down the movement of air inside the enclosure. you could always give it a go an see which you think sounds best
     
  5. morksbeanbag

    morksbeanbag
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    thats what i think i'll do when i get time to take off the 30 odd screws holding the back plate on. takes forever to remove. i think some good bracing would be more of a help than wadding to start off with.
     
  6. Nimby

    Nimby
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    Wadding reduces efficiency by absorbing sound that would otherwise be radiated by the driver and/or ports. If you are rolling off at 80Hz then is may be that no signal is reproduced at a frequency and level that would be affected by the limited amount of wadding that can be fitted into a box.

    Bracing reduces internal box volume. Possibly affecting tuning in a reflex ported enclosure or raising the resonance point of a sealed box. Again the subwoofer is usually rolled off at 80Hz. Which makes one wonder whether the panels are able to resonate at a frequency which would be audible without the bracing.

    I would not suggest the removal of wadding or bracing from an existing sub. But might question the purpose of adding it to one that hasn't either.

    It might be that the panels resonate at precisely the correct frequency and level to fill in an important gap in the response. And of course a crossover or roll-off filter isn't a brick wall against higher frequencies.

    I would just ask yourself what you hope to gain by modifying a subwoofer. Keep your eyes and ears open to the possibility that it will actually makes things worse rather than improve things.

    Test tones and an SPL meter can tell you a lot about the problem areas before you even start. It would not be difficult to find the resonance point(s) of your sub's panels using test tones for instance. Now try the same thing via your usual roll-off filter to see whether the panels ever get excited by normal programme material.

    Nimby
     
  7. andyturner28

    andyturner28
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    I put wadding in my sub and it did improve the sound quality. Before i could hear the cabinet resonating at i would guess about 70 or 80 hz. After inserting the wadding the bass was much deeper and more controlled.

    If you havent tried this already don't go through the back because you don't know what is behind there. Sometimes the wires are as short as humanly possible and there is a danger of ripping them out of the terminals. Remove the driver and insert wadding through the front. I used double sided tape and 1/2inch thick sheets which i stuck on the sides of the cabinet several layers deep.
     
  8. Nimby

    Nimby
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    And hopefully your sub was out of guarantee? Well it is now. ;)

    Nimby
     
  9. andyturner28

    andyturner28
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    It's only a cheapy £150 Kenwood sw501. Was all i could afford at the time and i tried everything to improve on the crap sound. After 5 years with this piece of crap i cant wait to get an xls200 or monolith.
     
  10. Nimby

    Nimby
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    You could try cutting some 10-12mm dowel and pressing a length in between any two sides to damp the opposing panels. You want a tightish fit so they stay in place by friction. But not tight that so you end with the sub skewered like a pig at a barbecue. :devil:

    Don't damage anything inside while trying this will you?

    Nimby
     

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