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Dampening thickness matter?

Discussion in 'Amps and Cabs [BG]' started by Myth_103, Sep 21, 2008.


  1. Myth_103

    Myth_103 Supporting Member

    Hi, I'm almost at the stage of putting dampening material inside my 4x12. However, I don't really know what differences I'd get out of thicker material? What thickness would be best you think? It's has 4 deltalite II 12s tuned to 40hz. Should I put the material on every wall of the cabinet (all sides and top EXCEPT on the piece with the speakers)? Or should I just place it directly behind the drivers themselves? That's how it is in my ampeg cab...
     
  2. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    All you'll need is about an inch. A polyurethane mattress cover is cheap and works well.

    Cover all but the board with the speakers.
     
  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Every surface must be covered. Ideally the baffle as well, but that gets to the point of diminishing returns. Covering only one surface is a design defect.
     
  4. toobalicious

    toobalicious

    May 6, 2008
    triad, nc
    IMHO, the foamy mattress toppers are not enough. i feel like a couple of inches of poly batting works much much better. others on this forum will disagree, and i have nothing but personal experience to bolster my stance.

    think of it this way.... it is a complete waste of time (and a fire hazard!) to cover your studio walls with the stuff. there is just not enough thickness/mass to absorb anything but the highest frequencies. that doesnt include the midrange frequencies that should be the ones you are targeting by lining your cab. ever been in a studio with one of the aurelex roominator kits or whatever? makes for a dull and muddy mess. i cant imagine that bed foam (with much less density and thickness than even the aurelex garbage) will perform any better, even in an almost-sealed box.

    acoustic batting was made for speaker cabs. eggcrate foam was made for the top of your bed. again, IMHO.

    YMMV.

    no offense intended to anyone or their opinion, BTW.
     
  5. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    From an acoustic perspective they function identically. ;)
    From a price perspective one guess which two options cost two to four times what the other does. :eek:
     
  6. toobalicious

    toobalicious

    May 6, 2008
    triad, nc
    you say so man. i appreciate all of your knowledge and your contributions to this forum, and your designs, which i find very appealing. likewise the forum that (i assume) you host (or sponsor, or however that works). but i am going to have to disagree with you here, material cost notwithstanding.

    unless we arent talking about the same stuff, which i suppose is possible.

    shoot, the last eggcrate foamie i had was only 1 1/2 inches at its thickest---- the thinnest spots were more like 1/2".

    and perhaps room control is far removed from lining a speaker box, but i know for fact that foam that is as lightweight and thin as the average bed foam does NOT restrict sound waves much below the low cut-off of an average tweeter. used in a live room, the foam makes a muddy, boomy mess.

    OTOH, those properties may suit your applications. designs, and preferences perfectly. but to me, for a bass-range cabinet, it just isnt enough.

    on that note, i am certain that you would feel my cabinets are over-damped. and maybe youd be right. perception is a bi*ch.
     

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