humidity and unisons

[Fred Sturm]

Newton Hunt wrote:
> 
> > So the bridge "rolls" (speaking length
> > side rises more than back side).
> 
> I am beginning to disbelieve in bridge rolling and more in
> bad soundboard installation.  I think Del pointed me in this
> direction.  Mechanically it make far more sense.
> 
Are soundboards installed badly in all pianos? This is a phenomenon that
occurs in all Steinway Model B, D, M and L under my care, as well as
Yamahas of various models. And uprights as well as grands. I bought the
notion it was caused by pinblock movement at first, but over the years
one piece of observation after another has led me to believe the
pinblock plays little if any role in it. 
	I definitely believe in bridge distortion in several directions. There
is a marked tendency, for instance, for a big difference in pitch change
on either side of a break, where the bridge has a curve. Makes sense
that the bridge has tilted one way or another.

Regards,
Fred Sturm
University of New Mexico