particle board

[Don]

Hi all,

My understanding of the use of MDF in high end speaker cabinets is that it
has *no grain* and therefore has a resonant frequency that is not a problem.
Where as *plywood* and regular wood have a grain. If there *is* a resonant
frequency, then the sound is *colored* as that frequency is absorbed. 

At 09:54 PM 9/20/97 -0400, you wrote:
>Dear List,
>     Another aspect of MDF use in speakers - It's a good base for the
>application of veneers and laminates - much better to work with than
>plywood.
>
>----------
>> From: Delwin D Fandrich <pianobuilders@olynet.com>
>> To: pianotech@ptg.org
>> Subject: Re: particle board
>> Date: Saturday, September 20, 1997 9:29 PM
>> 
>> Alex Thompson wrote:
>> > 
>> > Dear particle board critics and everyone else,
>> > Particle board/MDF is not the inferior product some of you claim it to
>> > be. It is by far the best material acousticly. You want proof? Tear
>> > apart any high quality loudspeaker, I dont mean a cheepie pioneer I
>mean
>> > a something comparable to a Bose or Infinity. (the cheapies use
>particle
>> > board too) They all are constructed out of particle board/MDF. The
>> > reason is because particle board/mdf is incredibly dense and it absorbs
>> > sound rather than vibrating like solid wood adding unwanted coloration
>> > to the sound. So the result of using particle board is: the sound you
>> > hear is the sound from the speaker not the sound of the cabinet
>> > resonating.
>> > So as long as particle board is not being used in soundboards pinblocks
>> > or any important structural part of the piano, don't complain it may
>> > actually be <improving> the quality of the instrument.
>> > 
>> > A
>> -------------------------------------------------------
>> 
>> MDF is used in high-end speaker cabinets because it is acoustically
>> dead--well, relatively so, anyway--not because it has any outstanding
>> acoustical properties of its own or because it is particularly strong.
>> It's obviously strong enough for speaker cabinets. But then there is
>> essentially no structural load on a loudspeaker. Pianos have different
>> needs from its cabinet parts.
>> 
>> The key words you've used above are "any important structural part." I
>> think that one of the things that has given the material a bad name in
>> the piano industry is its mis-use early on. Before piano engineers
>> learned about stripped out screws and its lack of long-term structural
>> stability. (Actually, some of the first man-made materials used in piano
>> cabinets was particleboard. MDF came later and, for pianos at least, is
>> a far better material.) I'm not up on the current usage of the material
>> in pianos, I just know that it should be possible to use it without ill
>> effect in many parts of the cabinet.
>> 
>> --ddf
>
>
Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.
"Tuner for the Centre of the Arts"
drose@dlcwest.com
3004 Grant Rd.
REGINA, SK
S4S 5G7
306-352-3620 or 1-888-29t-uner