humidity and unisons

[Newton Hunt]

> Are soundboards installed badly in all pianos? 

Probably. Too few are installed in strictly controlled
conditions and many are just not designed properly.  As Del
about this sometime when you have lots of time.

Bridge roll is determined by putting a thread along side the
longest rib and observing the gap between thread and board. 
This can be done in several places.  If the gap is a nice
curve then there is no roll.  If the gap closes on one side
of the bridge then there is a problem which likely started
at installation.

		Newton


Fred Sturm wrote:
> 
> 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