Why?

[Roger Jolly]

Hi Clark,
         If you can solve the problem you win the $64,000 jack pot. Joking
aside, there are several reasons. But most common is the the loss of mass
due to the bridge notch, to accomodate the plate web, this reduces the
stiffness of the board in this area, and how the board responds to the down
bearing pressure.
Some designers will place a rib directly under the notch to try and
compensate for the loss in stiffness. I have rectified some pianos, by
gluing and screwing a maple block on the rear of the sound board, approx
equal to the mass removed.
Since the last string in a given section behaves differently,due to the
lack of down bearing tension on the open side.
Most grands do not exhibit the same problem, because the bridge is
continuous, however there is normally a change in string termination (
aggraffs to pressure bar) That results in a change of rendering. Frequently
the way you pin set in this register is a little different than the centre
section. ( Mason and Hamlin comes to mind)
Because there is more movement at these notches,due to climatic changes and
other factors, strings riding up on bridge pins is quite common, and more
false beats are noticed on these notes.
Similar instability can be noticed at the bass/tenor break, with the
addition of phasing due to the critical nature of angled hammers.
I'm sure others will add more reasons, but I would think this is the
primary cause.
Regards roger


At 05:41 PM 5/8/99 -0400, you wrote:
>I am wondering who can provide a definitive answer to the question of why
most
>pianos seem to go out of tune the most at the treble break.  I have heard
>several versions of answers, and would like to hear from the best.  I am
new to
>the List, and inquiring minds just have to know!    Clark Sprague  Greenwich,
>Ohio
>
>
Roger Jolly
Balwin Yamaha Piano Centres.
Saskatoon/Regina.
Canada.