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Thread: Mdf vs bb vs pb question

  1. #1
    Senior Member bldozier's Avatar
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    Mdf vs bb vs pb question

    In my next incarnation, the 4344, id love to keep away from mdf, its just not fun and to demanding. Pb is not with in
    Reason, from my understanding, being the least dense,
    1" pb was used in early cabinets at this size, so would a 3/4" mdf or bb equate to 1" pb. I have not seen or read other then maybe once or twice it it being used in place of 1" material.

    I have to face glue my pieces my local wood distribution center has been closed. I can do 1/2(9ply)×2 or 3/4(13)+1/4(5) or 1/2+1/4 or 3/8(7ply)+1/2

    Can anyone explain the density of pb vs bb vs mdf, and could I use a 3/4 mdf combination for the 4344.

  2. #2
    J.A.F.S.
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    Wink My favorite laminate

    My favorite laminate for speaker construction is:

    1/2" Baltic birch plywood laminated to 3/4" MDF laminated to another sheet of 1/2" Baltic birch plywood. I use this for the tops and sides of the enclosure.

    for the front baffle of the enclosure I use 1/2" Baltic birch plywood laminated to 3/4" MDF laminated to another sheet of 3/4" Baltic birch plywood. The 3/4" Baltic birch plywood is on the inside of the baffle -- it gives strength and stability as a substrate from which you can attach TEE-nuts.

    The back baffle is the same as the front baffle. You choose which Baltic birch plywood plywood faces outward.

    Your cabinets will be acoustically dead -- but very heavy. Apply panel buttresses as you see fit. You can test for their necessity by the "knuckle rap" procedure on the box when it is finished.

    Some may say this is excessive, but when building your own cabinets, excessive is "just good enough."
    Amazed I'm still alive!
    Tim

  3. #3
    Senior Member bldozier's Avatar
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    Ok I will try it on both my jbl projects
    Brian

  4. #4
    J.A.F.S.
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    Laminate

    Quote Originally Posted by bldozier View Post
    Ok I will try it on both my jbl projects
    Brian
    Brian:

    The MDF acts as MASS to help move the resonant frequency of the panel out of the audio passband.
    The plywood adds dimensional stability and acts a nice substrate from which you can add veneers.
    Make sure to apply yellow woodworkers glue to the panels with a paint roller to get 100% coverage.
    I lay the panel on the floor and shoot drywall screws into them every foot or so to make sure the panels clamp
    down on each other tightly during the lamination process. After a day or so of glue dry, you can remove them.
    Laaving the drywall screws in the laminated panels will cause sawing to be a great hassle.

    Like I said, the resultant laminated panels will be HEAVY -- but they will be acoustically DEAD.

    Good luck with your construction project!
    Amazed I'm still alive!
    Tim

  5. #5
    Senior Member bldozier's Avatar
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    Thanks laoch711,
    Found some 1/4 & 3/8 for the 4315 project, the 3/8 will go in while the 1/4 out. 3/4 mdf is being used. ��
    The same seller also has 1/2 bb, which I will purchase later for the 4344 cabinets.
    Brian
    Im using a dado joint, fwiw.
    Im going to fix the edges with wood putty before gluing not just fill gaps, also saved some shavings from the Stanley 45 to help the gaps, on tops and bottoms. I will use pl premium upon completing that.
    More later.
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  6. #6
    Senior Member Lee in Montreal's Avatar
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    To keep these flat panels from vibrating, just brace them on at least on two axis.
    Proper bracing + 3/4" MDF + 1/4" finishing plywood will make you happy.

    As for the MDF, it is... Medium Density Fiberboards. You can also have High Density Fiberboards for extra $. Much heavier and denser.






  7. #7
    Senior Member Ed Zeppeli's Avatar
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    The Ace of Brace!
    DIY Array, 2242 sub, 4408, 4208, Control 8SR, E120 Guitar cab, Control 1, LSR305.

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