soundboard grain

[Delwin D Fandrich]

Dennis Benson wrote:

> What is the general opinion of the list on the value of tight grain on a
> soundboard. Is it necessary, preferable or insignificant?
>     Dennis

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Dennis,

I expected that by now there would be all kinds of comments in favor of the "tight grain"
concept of  soundboard construction. Since there isn't, I might as well be responsible for
getting the tar pots all fired up again, and for causing a few more chickens to get their
feathers plucked.

The short answers are no, no, and no. But I suppose you were hoping for more than that.

First, what are the characteristics of close, or tight, grain wood compared to wide, or
loose, grain wood? Basically, it is a question of stiffness and mass. The close grain wood
is both stiffer and heavier than is the wide grain wood. It was long thought that only
close grain wood was acceptable for piano soundboards. (Although Stephen Birkett will be
quick to point out that this was not always the case. In fact, he has said that the early
builders didn't really pay that much attention to the grain characteristic of the wood
they used in their soundboards. This whole concept seems to be of fairly recent origin. I
would guess from about the time builders started constructing soundboards in a manner that
proved to be often self-destructive. The early builders did not do this, the later ones
did.)

1)    Is close grain lumber necessary? No. Not really. I was originally taught that tight
grain wood should be used in the treble section so that the soundboard would be "stiffer"
through this region. Realistically, though, the bridge is so close to the inner rim and
the belly rail that stiffness is not really a problem. In fact, some manufacturers, most
notably Steinway, thin their boards out quite a lot in this region to reduce stiffness
(and mass) deliberately.

2)    Is it preferable? Well, if close grain wood is not necessary in the treble, what
would be the consequence of using it anyway? Follow the grain line of the individual board
that runs under the top end of the treble bridge down to the other end of the piano and
see where it ends up. In most pianos shorter than concert size it roughly follows the path
of the bridge and ends up along the back edge of the rim somewhere. Now notice the
location of the bass bridge in relationship to this board. Remembering that we really want
a fair amount of mobility in the bass bridge -- especially at the low end of the bass
bridge -- consider what affect stiffer wood will have on the ability of the bass bridge to
move. In other words, if we choose a stiffer wood to help us out in the treble section, it
will usually end up hurting us in the bass. Again, most companies will thin out the
soundboard panel along the bass edge to make the soundboard assembly somewhat more
flexible and, by so doing, allow the bass bridge to move a bit more freely.

3)    Is it insignificant? No. The grain characteristic of the wood used in piano
soundboards is not insignificant. As I mentioned earlier, this grain characteristic does
have a affect on the stiffness and the mass of the wood, and hence, the soundboard.
Soundboards can be too stiff and heavy, however. Just as they can be too flexible and
light. In our own experience, we have found that when using very close grain wood we have
to thin out the panel much more than we feel comfortable with to get the mobility we are
after.

The consistency of the stiffness and mass characteristic is more important in soundboard
construction than is any absolute grain density. We have settled on a grain characteristic
of from 8 to 12 grains per inch as our standard. When selecting the lumber for a specific
soundboard we look for reasonable uniformity of grain, color and "freedom from defects."
The latter two of which have precious little to do with the performance of the piano, but
much to do with its appearance and the perception of "quality." I have more to say on this
issue, as well. But, perhaps, it will best be saved for another day.

Hope this has done more to answer you questions than it has to confuse you further.

Regards,

Del