Drifting Unisons

[Newton Hunt]

When the humidity goes from 15 to 85 percent every year for 10 years
the pattern becomes quite obvious even on Bs but, as you say, less so
mostly because the block in so well integrated into the case it's
movement is restricted.  Small pianos in the S&S line show more of the
pattern.  

Se, essentially, I beg to differ.

		Newton

"Fred S. Sturm" wrote:
> 
> Newton Hunt wrote:
> >
> > > There is a consistent difference between left and right
> > > strings, sometimes as much as 20 cents in mid to upper treble
> >
> > The pinblock shrinks or expands, gradually, with changes in humidity.
> > It can only expand a small amount from left string tuning pin to the
> > plate flange, a little more from center string pin to plate flange and
> > more from right string pin to plate flange.
> >
> > Simple answer but it took me years to understand it as well.
> >
> >                 Newton
> 
> That might be an adequate explanation except for the fact that Steinway
> model B grands don't show a big difference, if any, between adjacent
> unisons where the tuning pin pattern is offset (bigger difference in
> distance from agraffe to pin from unison to unison than between pins in
> one unison). Also, upright pianos show the same tendency (right tuning
> pin shows more movement), and the distances are reversed from that of
> grands (right pin closest on upright, farthest on grand).
> 
> Regards,
> Fred S. Sturm, RPT
> University of New Mexico