tapping strings

[Richard Brekne]

David Skolnik wrote:

> Downbearing as I view it has to be measured that way.  You already
> know the tensions involved... you need to know the angles you are
> subjecting the wires under these tensions to. If you measure an
> instrument that is already strung and up to tension...then you need to
> know how much the panel has been pressed down as well to really know
> what the actual downbearing is.  Knowing both is valuable anyways I
> might add.
>
> Just so that I'm clear, are you saying that it is not possible to take
> measurements with a gauge (and string under the 'panel') and make some
> conclusion about the downbearing present in the piano?

Hmm...... stricktly speaking the string and gauge under the panel gives
you information as to whether or not there is crown.... and nothing
more. I mean you could just as easily have the same readings on two
pianos... one that was strung, and one that was not. So if thats all you
have to go on... how can you say anything about downbearing ? Ok... add
to the picture that you can confirm positve bearing from strings with a
rocker gauge or something like that... you still dont know how much
downbearing there is... because you cant know how much the soundboard is
resisting whatever downward pressure there is.. so you cant figure it
out whatever angles you measure.  You can do that however when you know
what the upward pressure is... and of course when its zero.... that
makes things easy.

Since you have the paper copies of Journal reprints... read and re-read
all the articles on downbearing there are... I think there are several
different contributing authors who have written on the subject.  For
some reason this is one of those subjects a lot of folks get tripped up
on. Heck even today we find rebuilders who automatically assume that
increasing downbearing on an old panel automatically means improvement
of sound. It just isnt that simple. Its important to put what
downbearing is into the perspectives of what functions it serves in
piano construction / acoustics. These articles will help you understand
what you are after here.

>
> Thanks for the suggestion re: Gravagne's articles.  I just got the
> paper copies of the Journal reprints that the Guild is unloading.
> Good for ready while traveling about.
>
> Regards -
> David skolnik

Cheers !

RicB

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html