Why do I want to use MFD over other types of material?

Discussion in 'Archived Threads 2001-2004' started by SteveSpoon, Feb 14, 2002.

  1. SteveSpoon

    SteveSpoon Stunt Coordinator

    Joined:
    Feb 12, 2002
    Messages:
    231
    Likes Received:
    0
    Would like to build a subwoofer cabinet, but can't figure out why people use MFD over other type of material. Went to Home Depot today to look at it and the stuff looks like nothing more than pressed paper/wood. Seems like something a little more dense would be better.

    Why do people use this material over others? Thanks.

    Steve
     
  2. Brian Hepler

    Brian Hepler Stunt Coordinator

    Joined:
    Jan 6, 1999
    Messages:
    63
    Likes Received:
    0
    Something more dense than MDF? Heh heh heh... did you try and lift that stuff?
    MDF is actually denser than plywood or chipboard. I think it is denser than most naturally occuring wood. It also doesn't have any grain to it, which is good for those of us who don't really go for wood-grain patterns on boxes. It is very nice from an acoustical point of view. My only real complaint about it is that it is a bit brittle, but since we're trying to eliminate flex, this is a good thing.
    Someone with more knowledge in acoustics and/or box construction can elaborate on this, but the short answer is that you won't find anything better for the price.
    Are you sure you were looking at Medium Density Fiberboard?
     
  3. Greg_R

    Greg_R Screenwriter

    Joined:
    Apr 9, 2000
    Messages:
    1,996
    Likes Received:
    0
    Location:
    Portland, OR
    Real Name:
    Greg
    Don't confuse MDF with particle board. Some people like using marine grade ply for their subwoofer projects. It's stiffer & lighter but costs $$$. MDF is fairly ideal except for the weight...
     
  4. Dustin B

    Dustin B Producer

    Joined:
    Mar 10, 2001
    Messages:
    3,126
    Likes Received:
    0
    If you never picked it up Steve I think a 4x8 sheet of 3/4" mdf weighs just under 100 pounds.
     
  5. SteveSpoon

    SteveSpoon Stunt Coordinator

    Joined:
    Feb 12, 2002
    Messages:
    231
    Likes Received:
    0
    I go right on by Home Depot on my way to work, so will swing in there again tonight. The stuff I was looking at was definately MFD (well, the sign said it was MFD). No, I didn't try and pick it up. Take that back, I tried to lift a corner of it and it didn't budge. Thought it was "glued" to the next sheet. You're right, it is very heavy stuff!!

    My concern with the material is that I saw a broken piece of it on top of the pile.....it almost appears as if you can destroy the stuff just by rolling it between your fingers. DEFINATELY would not want to have one of your drunk guests spilling a beer on it, since the material appears as if it would soke (sp?) up the liquid fairly quickly. Guess a little paint would take care of that problem, though. Or, better yet, kick the drunk people out of the house, first.

    Forget what the price was....something like 17 bucks. Have the memory of chicken.

    Steve
     
  6. Mark Krawiec

    Mark Krawiec Agent

    Joined:
    Jan 9, 2002
    Messages:
    49
    Likes Received:
    0
    check out these two threads
    mdf one
    mdf two
    wasn't aware HD carried MFD[​IMG]
    my 2 cents
    use mdf or ply. the commonly accepted wisdom is to use mdf in mains and mdf or ply is subs. the audioxpress article didn't really prove or disprove major differences between mdf, ply and particleboard for that matter.
    mdf and ply come in different grades. if you're really going to build a top notch project, it might be worth it to get a better grade of mdf or ply, which you won't find at HD. looks like good bracing, sandwiching/multiple layers, and some way of isolating the drivers also seem to help.
    does it chip-yes. and, yes, water and mdf don't do well together. unfortunately, real wood is generally difficult to use in speakers.
     
  7. Ellen

    Ellen Stunt Coordinator

    Joined:
    Jan 8, 2000
    Messages:
    142
    Likes Received:
    0
    Real Name:
    Ellen
    You might want to check out the MDF FAQ.
     
  8. Dave Poehlman

    Dave Poehlman Producer

    Joined:
    Mar 8, 2000
    Messages:
    3,813
    Likes Received:
    0
    The reason MDF is so popular is:

    1) it actually is pretty acoustically "dead"... not allowing a lot of vibrations to pass through.

    2) its density is very uniform, unlike particle board, plywood, or solid woods.

    3) its relatively cheap @ about $20 per 8 X 4 sheet.

    4) its pretty easy to work with... although messy. (be prepared for a lot of dust)
     
  9. SteveSpoon

    SteveSpoon Stunt Coordinator

    Joined:
    Feb 12, 2002
    Messages:
    231
    Likes Received:
    0
    Thanks a lot for the info and links. Very helpful. Off to Home Depot again!!!

    Steve
     
  10. Jeff Rosz

    Jeff Rosz Second Unit

    Joined:
    Sep 24, 2000
    Messages:
    335
    Likes Received:
    0
    a word to the wise about mostly dust fiberboard....when it comes time to run it thru your saw, DONT assume the the corners are square.
     
  11. Jeff_Hunt

    Jeff_Hunt Stunt Coordinator

    Joined:
    Mar 21, 2000
    Messages:
    57
    Likes Received:
    0
    MDF is very strong if used appropriately. Another good reason to use MDF is dimensional stability. Assuming you finish it right to keep moisture out, MDF doesn't warp as much as other woods. The other bonus is that the rigidity of MDF applies to all 3 dimensions. Plywood can be more stable than MDF, but only in one dimension.

    Also, MDF wins the game when it comes to uniform density. Even no-void plywood has voids, it just has less of them. Regular plywood is like using swiss cheese. I'm not dissing plywood, I love the stuff, but MDF is better for speakers.
     
  12. SteveSpoon

    SteveSpoon Stunt Coordinator

    Joined:
    Feb 12, 2002
    Messages:
    231
    Likes Received:
    0
    Nuff' said!! Just need to get one of my brother-in-laws to help me go get a sheet!! Thanks for the good info.

    Steve
     
  13. JimHal

    JimHal Stunt Coordinator

    Joined:
    Aug 15, 1999
    Messages:
    87
    Likes Received:
    0
    Make sure to pick up a dust mask when you buy that sheet.

    Cutting the stuff is almost like throwing a handfull of flour onto a fan. Very fine dust, made an awful mess of my garage.
     
  14. Brian Bunge

    Brian Bunge Producer

    Joined:
    Sep 11, 2000
    Messages:
    3,716
    Likes Received:
    0
    I second Jim's suggestion. I ended up with a sinus infection for the better part of 2 months last spring when I built my dual 12" subs. I didn't use a dust mask. I've since learned my lesson!

    Brian
     
  15. AjayM

    AjayM Screenwriter

    Joined:
    Aug 22, 2000
    Messages:
    1,224
    Likes Received:
    0
    Well, I've heard that you use a multi-layer void free ply for subs because the resonant frequency of the box will be higher than the area that the sub plays in. So you can create a very strong, well braced enclosure that you can still move around.

    MDF is nice because it's cheap, it's easy to do stuff with your router (round-overs, etc), and it's fairly easy to finish. And with the difference between using MDF and ply so small in terms of how it's going to sound, may as well use the easier and cheaper material.

    Andrew
     
  16. jeff lam

    jeff lam Screenwriter

    Joined:
    Jun 4, 2001
    Messages:
    1,798
    Likes Received:
    0
    Location:
    San Jose, CA
    Real Name:
    Jeff Lam
    I just picked up a sheet of MDF this past weekend. Be careful, sometimes people mistake Particleboard with MDF. HD has both. The MDF should not look like anything was pressed together, it should look like a solid peice of wood from the edge. Once my HD made the mistake of putting the particleboard in the MDF spot. Once you see both, you will be able to tell the difference.
     
  17. Rob Lloyd

    Rob Lloyd Stunt Coordinator

    Joined:
    Mar 22, 2001
    Messages:
    234
    Likes Received:
    0
    The HD's around me carry MDF in 2'x4' sheets. Makes it easy to carry and bring home in my car. Plus it's much easier to work with that size. I don't have room or the help to lift and safely cut a 4x8 sheet on the table saw.

    I think you pay slightly more for 4 sheets that way than a single 4x8 but it's well worth it.

    -Rob
     
  18. Brian Bunge

    Brian Bunge Producer

    Joined:
    Sep 11, 2000
    Messages:
    3,716
    Likes Received:
    0
    Rob,

    We have the same thing around here. That's what I always do. The difference is, sometimes they don't even charge any more for the smaller, pre-cut sheets!

    Brian
     
  19. JimHal

    JimHal Stunt Coordinator

    Joined:
    Aug 15, 1999
    Messages:
    87
    Likes Received:
    0
    Here, the difference between 4 small sheets and 1 large is about $10 CDN. Rip-off.

    You can buy the full sheet and have Home Depot cut it at no charge. I think they make up to 4 cuts before charging you.
     
  20. James Slade

    James Slade Second Unit

    Joined:
    Nov 20, 2001
    Messages:
    250
    Likes Received:
    0
    I just bought a full sheet at HD last night for $28 Canadian, so that sould make it about free at HD in the U.S.

    They made all of the cuts for me for a Shiva Adire Alignment except for the circles, for free. And to my surprise when I put a square to the pieces they were all good. Gotta love free cuts!!!!!!

    I live in apartment with no power tools, so this was really the way to go for me.
     

Share This Page