Modal Analysis (was Negative bearing (long))

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: December 04, 2001 5:42 PM
Subject: Modal Analysis (was Negative bearing (long))


>
> I'd like to put in my two cents worth if I may.  In my opinion what we
should be hoping for from modal analysis is a way of relating the behavior
of the unloaded (and perhaps even uninstalled) soundboard to its final
behavior in the piano with the strings on it.  Understanding the built up
configuration is only part of the picture.  Until we can relate this back to
design or construction parameters for the piano itself then this information
is interesting, but essentially useless.  But if you can test and analyse
individual components and determine a way of relating their behavior to the
behavior of the whole then you can start to make changes to the components
that will affect performance of the whole.  Violin makers have been doing
this for centuries.
> Old makers spent years learning to feel top and back flexibilities that
were necessary for the completed violin to function well.  In our own time
these flexibilities have been quantified through modal analysis and
practical methods useful to the modern builder have been developed to aid in
the process so that he or she doesn't have to rely on years of 'getting the
right feel'.  Other parameters such as air modes, neck stiffness, etc. have
also been quantified and related to the performance of the completed
instrument.  These are very useful tools available to the modern violin
maker.
> The piano maker has no such tools.  Modal analysis is one of the things
holding some promise to provide us with these tools.  It would be a huge
research project but, as Del pointed out, a company which depends on piano
sales for their large income should be spending money on R & D and this is
just the sort of thing they ought to be spending it on.
>
> Phil
------------------------------------------


Well, as I've said, I have limited experience with the technique. But that
was on a new grand piano I had designed and built. So I was at least
intimately familiar with the instrument and with what the designer intended
to achieve with the design. I learned more about the design during the few
days I was able to work with an engineer from B&K on the modal analysis
project than I ever expected. It gave me insights into the functioning of
the soundboard I doubt I'd have gotten any other way.

We've lived with the old model of soundboard function for centuries. It's
really time to move on. For me, at least, that was just a beginning...one
small step. And there are so many more to take.

Del