More responses needed

[Delwin D Fandrich]

----- Original Message -----
From: "Wallace Scherer" <p003520b@pb.seflin.org>
To: <pianotech@ptg.org>
Sent: May 03, 2001 9:41 AM
Subject: More responses needed


> Dear list members,
>
> A recent discussion I started about applying epoxy to cracks in the
> soundboard of an old Winter piano which had strings and tuning pins
> replaced by another technician about 5 years ago, led to the conclusion
> by about 5 or 6 people who responded that repairing cracks in soundboards
> is mainly for cosmetic reasons and will not affect the tone significantly.
>
> To me this goes against the whole purpose a soundboard exists!

That may well be, but it doesn't alter the physics of the situation.

Regardless of what some of my esteemed colleagues have had to say here,
there is no repair method that has been described here yet that will result
in any lasting improvement in the acoustic performance of soundboard that
has been damaged by compression set. That is, the soundboard panel that was
crowned by what I have labeled the 'compression-crowning' technique. And
that includes most of the soundboards in existence that are exhibiting
multiple cracks and collapsed crown. I've already gone into the reasons why
this is so in a Journal article or two and have no desire to repeat all of
that here.

Yes, the piano can be made to sound better by doing all of this work. But
then, the piano would have sounded better by simply restringing the thing,
resetting the plate, putting on the new hammers, etc. And, yes, I realize
that once we've done all of that work we really want to believe that what we
did to the soundboard made a difference. Even though it didn't. Certainly
not for any appreciable length of time.

Yes, you can give yourself -- and perhaps your customers, at least for that
brief period of time -- nice warm fuzzies by doing all of this soundboard
patching and looking at the 'new' crown you have induced until you place
even a moderate load on the thing and watch all that new crown disappear
before your very eyes. Face it, the only new stress member you have
installed is the new wood and/or epoxy in the crack. Seriously now, how long
do you expect that 1, 2, or even 5 or 6 mm of new wood to support any
significant stress interface between the soundboard panel and the rib set?
Minutes? Hours? Go ahead, be brave and unrealistically confident and give it
a couple of weeks. Remember, there is no stress interface between the
original soundboard panel and the ribs any longer. That has dissipated years
ago. That new crown -- assuming you were able to measure any at all --
cannot last! No matter how much "tension" we envision in the soundboard
panel. (Tension, indeed! Tension, as in, "A pulling force. A force that
pulls or stretches something." It was tension within the soundboard panel
that caused these cracks to develop in the first place.)



> Take the
> analogy of a speaker cone:

OK. But, let's not take it too far. Speaker cones ain't piano soundboards.
They don't depend on expanding wood cells to form and maintain crown. And
they don't depend on that crown being placed in compression for added
stiffness to make them work properly.



> Lets say that we have a radio or other sound producing device whose sole
> output is through a 15" woofer loudspeaker. If we then take a razor blade
> and make a series of randomly spaced  slits about 2" to 3" long around
> the sides of the speaker cone, wouldn't we expect the tonal quality of
> the speaker's output to be diminished considerably? And if, then, we
> proceeded to seal those slits in some manner so as to come close to
> having the speaker cone intact again, wouldn't we expect an improvement
> in the sound from when the cone had the slits in it?
>
> The reduction in sound (volume, tonal quality, etc.) of the speaker with
> the slits is due to its not being intact - the movement of the cone does
> not faithfully reproduce the sound it is supposed to make because its
> surface area does not respond uniformly.

This analogy makes the same mistake Wm. Braid White made some decades back
when he wrote his famous piece on soundboard cracks. It isn't the cracks
that are the problem. It is the failure of the wood cells to support crown
and, through the mechanism of that crown working against the string load
(downbearing), to provide the required stiffness to the soundboard panel.
The cracks have nothing to do with the problem. Go back and read the
articles.



> In like manner, especially in the lower frequencies of the bass notes of
> a piano, when the larger area of a soundboard must faithful reproduce
> those lower frequencies and transmit them to the air without
> interruption, if the surface area is broken up by cracks, the movement of
> the soundboard is impeded, therefore greatly reducing the volume of the
> sound reaching the hearer.

Again, it ain't the cracks. Go back and read the articles.



> Because of the basic physics of sound production, it therefore does not
> make any sense to me that repairing the cracks of a soundboard (assuming
> that the bridge, ribs, strings, etc., are all in good condition) would
> not somewhat improve the sound of the bass section.

Wrong physics. Go back and read the articles.



> Since so few of you responded to this, I would like to ask more of you to
> respond, especially those who have had considerable experience in
> repairing cracked soundboards.
>
> The question is this:
>
> Assuming that the ribs, bridge, and strings are all good, would only
> repairing 10 fine, but rather long (10" or more) cracks in a soundboard
> make a noticeable difference in the bass section of a piano? (Let's also
> asume there is little or no crown.)

I do have considerable experience in repairing cracks in piano soundboards.
Did it for many years. Did a good job, too. My work on the repair of a S&S D
soundboard was featured in a Journal 25 years (give or take) back. I've done
shims by 'V-ing' the cracks. I've done shims by routing -- the 'Spurlock
method' ten years before Spurlock came along. And I've done it using epoxy.
I've glued shims in with just about every adhesive known to man or woman.
And the result of all of that experience is that I now replace soundboards
in most of the pianos that come through our shop today. I got tired of doing
all that work and going back to the pianos six months or a year later and
being disappointed in their sound. And this in Portland, Oregon -- a climate
that is a whole lot easier on soundboards than yours is. I hope all of that
experience qualifies me to respond to your question. If not, you can freely
ignore both the preceding and the following.

No. It will not make a noticeable difference in the bass section of a piano.
Not for any of the reasons you've given nor for any of the reasons others
have given. The problem is not in the cracks. It is in the other things that
have happened to the internal structure of the soundboard panel over many
years of degradation. Filling the cracks, regardless of how it is done is
not going to change this. And, no amount of wishful thinking is going to
change it either. Sorry.

Besides, you keep emphasizing the bass here. It's not going to be the bass
that is either hurt or helped by the collapse of the soundboard. At least
not by all that much. In this case -- if my short-term memory is not
altogether shot like the soundboard in question -- we've been discussing a
rather short Winter piano. The problem with the bass tone production of this
piano does not lie with the cracks in the soundboard, it lies with the
design of the piano itself. Now, there are things you can do to improve the
bass performance of these pianos, but they do not include shimming shot
soundboards and they are not things I'm going to go into here. Come to my
class in Reno.

Regards,

Del