Sound waves(The behavior of soundboards)

[Delwin D Fandrich]

----- Original Message -----
From: "Greg Newell" <gnewell@ameritech.net>
To: <pianotech@ptg.org>
Sent: December 19, 2001 9:18 PM
Subject: Re: Sound waves(The behavior of soundboards)


>     If the sound is the same on both sides of a piece of 1x1 maple
> outside of the piano however long it then follows that the soundboard has
> a great deal to do with the difference between top and or side of the
> bridge being struck. Have you any info about the grain direction of
> either bridge that you tested? I've not seen a recent Steinway with a
> good quarter sawn bridge cap. How much would this effect the differences
> in the sound you hear?

I just tried this on a Model O I'm stringing. As expected the tap on the
side of the bridge yields a higher pitch with considerably less volume.
Since the soundboard assembly has considerably more mobility in the vertical
plane it would be some distressing if this were not the case. As the strings
go on the pitch of the side tap gets even higher. Again, as expected. The
strings add still more fore-and-aft restriction to the bridge's motion.


>
>     Secondly can you establish or even theorize that the difference has
> anything to do with the glue joint between cap and bridge? I don't recall
> you saying which part, top or side, sounded better, stronger, clearer. Is
> striking the side thus eliminating or bypassing the glue joint a better
> sound? If every glue joint is an impediment to good tone quality then it
> would seem that experiments should be made to eliminate the use of wood
> for soundboards and bridges altogether.

There is no evidence that I'm aware of that indicates any tonal variation at
all that can be attributed to the glue joints. There is much to indicate
tonal variations attributable to bridge construction, i.e., as these relate
to the bridge's overall stiffness and mass.


>
>     What is it that we love about the modern piano? Is it the degree of
> control we derive from the action enabling us to achieve a high amount of
> expression limited mostly or only by our level of skill? Is it the fact
> that it is still an acoustical instrument? What trade - offs would there
> be to using different materials in the building of these cherished items?

As long as the physical characteristics of the object in question are met,
none. In other words, any material that matches the physical characteristics
of spruce can be used for the soundboard. Various composites have been used,
as has a foam core, aluminum faced 'sandwich,' all with acoustical results
varying from mediocre to excellent. The limitation is more a lack of
adequate research than one of materials. The traditional 'solid' wood panel
with cross ribs has hundreds of years of development behind it. To date
experimenters--more correctly, those funding the researchers--seem to expect
great results from one effort. It's not going to happen that way.


>
> Depending on how radical manufacturers might ever get in production and
> materials differences at what point would the product need to take on a
> different name?

When does a guitar with a composite soundboard cease being a guitar?
Consider the radical variations seen in the design and construction of
drums. I expect there will always be a demand for the 'traditional' piano
with its 'traditional' soundboard. But, if there is ever a company willing
to do the basic research needed to produce an acoustically superior
synthetic, or composite, soundboard/rib unit (the ribs will probably prove
to be unneccessary) I expect there will be a demand for that as well.


>     Forgive the silly musings of a sleep deprived compatriot. It is an
> interesting discussion that you folks are undertaking. I'm enjoying what
> I can grasp of it.

Off to get my morning coffee now....

Del
>