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Old 1st May 2008, 09:31 AM   #421
tinitus is offline tinitus  Europe
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Old 1st May 2008, 10:49 AM   #422
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Originally posted by kstrain

There is either misunderstanding of the physics here or more likely confused wording.

I think I should just give up.
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Old 13th January 2010, 05:36 AM   #423
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Default mdf or ply? who cares theyre not all that different

the difference as far as i can see between MDF and decent ply, as far as speaker boxes go, is NOT the stiffness difference between them. Sure good ply is about15% stiffer perpendicular to the (again perpendicular) grains, due to wood grain tension, but weaker in compression. Also this introduces a 'springiness' to the ply that MDF, with its lossy fibrous structure does not possess in equal measure. This is a plus for MDF IMHO. shorter spurious vibration and all that. besides that when weighing up both compression AND tension forces on a board, which will be equal or thereabouts; I dont see any real significant difference between the two. MDF may be better, SLIGHTlY, when used in identical constructions, due to the more damped 'springiness' of the media. This means, to me at least, that MDF exhibits a more wideband lower amplitude vibrational resonance-low Q low F-and if braced well, or used in thr right way should be far better than ply. Real wood would be great to use, i just cant get over the fact that solid wood will always add tone and colouration to the sound. thats fine for music PRODUCTION, but not REPRODUCION, as far as im concerned.

maybe i will use a 'sandwhich' of 5mm MDF/HDF, 10mm sand/cement/concrete/rubber compound, with 20mm MDF on exterior. That should be stiff enough when braced sufficiently, and better damped than either of the two media on its own.

OR....maybe i will go solid wood route, and build oversize thickness, layering with MDF, or perhaps GRPing the whole inside of the constructed box to a good thickness to increase the rigidity....hmmmmmmmmmmm
Balancing the things I must do, with the things I'd like to do...This is a skill (or a luxury) amongst many that I do not possess.

Last edited by mondogenerator; 13th January 2010 at 05:41 AM.
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Old 13th January 2010, 12:57 PM   #424
gedlee is offline gedlee  United States
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Originally Posted by mondogenerator View Post
OR....maybe i will go solid wood route, and build oversize thickness, layering with MDF, or perhaps GRPing the whole inside of the constructed box to a good thickness to increase the rigidity....hmmmmmmmmmmm
Wow, how did this thread get revived?

I think that the fabrication differences between Plywood and MDF outweigh any performance differences. MDF is simply not a good material to finish. It is not stable enough. The better grades of Ply are much better in this regard - but much more expensive as well.
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Old 14th January 2010, 06:18 AM   #425
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What about OSB?

My office building uses this for door jams and such. Apparrantly the lumber was manufactured by a specialist using wood gutted from the building when they started renovation. It's thicker than the OSB I've seen at lowes et all, about 2", and finished with a thick resin/plastic that makes it really quite attractive. That plus its low cost got me thinking about using instead of MDF for some CNC cut layered construction I'm going to try.
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