Cabinets - Construction & Resonance

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  • David Meek
    Moderator Emeritus
    • Aug 2000
    • 8938

    Cabinets - Construction & Resonance

    John, Thomas and all,

    Just out of curiosity (remember I'm a neophyte here ),

    When building the cabinet for a box-type speaker, the more rigid the cabinet the better, as long as non-resonant materials like MDF or HDF are used, correct? If that's the case, why not make a solid box of MDF and cut out conformal cavities to hold the various drivers and electronics? Wouldn't this be the best in a non-resonant cabinet - no large, reflective cavities to deal with? I realize the weight that would be involved could be excessive.




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  • Hank
    Super Senior Member
    • Jul 2002
    • 1345

    #2
    Hi David, I was about to shut down for a half-day vacation and go home to make some sawdust and noticed your post. The reason your idea would be impractical is that those conformal cutouts in the solid MDF block would have to be of sufficient volume to make the driver/enclosed volume "system" work, as in a regular speaker cabinet. Beyond those driver conformal cavity volumes, the extra solid MDF volume would make for a HUGE total cabinet cubic volume and you'd need to have access to a forklift for the annual rearranging of the furniture by the wife.

    BTW, I've never used HDF but would like to try it some day. Also, keep in mind that solid core (void-free) plywood is good for subwoofer cabinets. MDF's density wouldn't be of much benefit at those low frequencies, and the plywood cabinet would weigh less.

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    • David Meek
      Moderator Emeritus
      • Aug 2000
      • 8938

      #3
      Oh. I forgot all the posts I've read about tuning (subs anyway) via enclosure volumn and port size/length. Like I said, neophyte. :?

      - David -

      .

      David - Trigger-happy HTGuide Admin

      Comment

      • ThomasW
        Moderator Emeritus
        • Aug 2000
        • 10934

        #4
        IMO people tend to get too fixated on cab construction.

        First ALL materials resonate. The Fs varies depending on the mass/density of the material. So as long as the cabs resonant frequency (Fs) is out of the passband (frequencies the driver is playing) it doesn't matter too much what/how the cab is made within reason.

        Basically there are 2 ways to build a cab.

        High mass/ high density /high weight (MDF or HDF) or low mass/high strength/high ridigity (apple ply/birch ply/baltic ply/etc)

        Constrained layer damping (sandwiching with different density materials ie. ply and MDF, and or adding resonant damping materials between layers) doesn't really create all that much benefit given the added cost/labor/etc.

        Carving up a block of solid MDf/HDF isn't going to gain the builder anything over standard construction given the physical properities of MDF/HDF. Remember structurally it's just glue and sawdust. So as long as the cab has good air tight joints it's physically the same as if it were milled from a block of the stuff.

        If you want to go nuts laminate up a solid from one of the high quality plys and then machine that. It will be extremely strong and light. But will it sound better? I doubt it.

        So a solidly built cab (vs one built from a solid )with adequate bracing does the job. Heroic efforts (Avalon's 6" thick MDF front baffles) do make a difference. But you have to ask yourself if it's worth the effort?




        theAudioWorx
        Klone-Audio

        IB subwoofer FAQ page


        "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

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