Plate Bushings - was Re: Bushing vs. bigger pin?

Ron Nossaman RNossaman@KSCABLE.com
Fri, 02 Jun 2000 23:10:44 -0500


>Just a question regarding piano design/construction. I thought a soundboard
>should idealy be fit snug to the outer rim.  Are not Steinways built like
>that? How else can the "sound be reflected back into the soundboard" if the
>soundboard is not snug against the outer rim? Do you think that in cases
>where there is a gap between the soundboard edge and outer rim, the gad
>should be filled? Just curious. I hear of this "sound reflected back" thing
>and wonder if some of that may be just bunk. Thanks for any thoughts.
>
>Terry Farrell

Well, I'd prefer "energy" reflected back, rather than "sound", because
sound is the result, not the medium. As to this energy reflection being
dependent on the panel contacting the outer rim exactly, then what's the
inner rim to panel glue joint for? If any measurable energy is leaking away
as a result of the panel not contacting the outer rim anywhere, then it's
because the panel's not glued down properly to the inner rim, in which case
there are going to be a few other somewhat less than minor tonal problems
to deal with. In practice, I haven't seen any evidence that it makes a
smidgeon of a hoot of difference. Total contact, a thousandth of an inch
gap, or a quarter inch, are going to sound the same because the impedance
sink of the inner rim begins at the inner edge of the rim, where the glue
welds the panel to the rim. Any gap resulting from a less than perfect fit
to the outer rim can be filled, as a cosmetic concern, but I haven't seen
any hint of it's being detrimental to sound production. The mass and
stiffness of the inner rim, however, is much more critical and receives
much less attention.
 
Ron N


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