Experience with Constrained layers

Discussion in 'Home Theater Projects' started by DanielGM, Apr 7, 2004.

  1. DanielGM

    DanielGM Stunt Coordinator

    Joined:
    Jul 15, 2003
    Messages:
    116
    Likes Received:
    0
    Has anyone experimented with using some sort of constrained layer between two pieces of MDF when laminating to make a thicker enclosure? Is there a worthwhile improvement (particularly for a subwoofer application)? What type of materials would be suitable for this application?

    Thanks in advance
     
  2. RichardHOS

    RichardHOS Second Unit

    Joined:
    Mar 11, 2003
    Messages:
    454
    Likes Received:
    0
    IMO, constrained layer damping is the very worst method to deal with cabinet resonances for subwoofer applications. It has some merit for broadband enclosures where keeping modal frequencies out of the operating range of the drivers isn't easy or even possible, and damping the resonances is the next best approach.

    For subs, it's quite easy to construct a cabinet that has a first mode above the operating range using sufficient wall thicknesses and bracing. No resonances at all, and the added stiffness used to up the first mode will also work to keep non-modal forced vibrations to a minimum as well.

    Constrained layers in a sub enclosure will typically drop the resonant frequency of the enclosure compared to an identical design without the extra mass baggage the constrained layer adds.

    Remember kids... stiffness is key for sub enclosures. Damping becomes important only for high frequency and full range enclosures.
     
  3. Hank Frankenberg

    Hank Frankenberg Cinematographer

    Joined:
    Oct 13, 1998
    Messages:
    2,573
    Likes Received:
    0
    Richard is correct. That's why you can use plywood (solid core of course) to build sub enclosures. The density of MDF is not much use in a sub compared to the advantage of the STIFFNESS of solid core plywood. Speaking of stiff, solid core plywood makes better "H" braces in full range cabinets than MDF. Just MO.
     

Share This Page