Overshoot -- Pitch Raising

[Ron Nossaman]

>Ron,
>
>Interesting comments.  Now, I haven't tuned any pianos in, probably, 15
>years and memory fades -- mercifully -- over time but I've a question here.
>And even when I was tuning most everything was a grand of some sort.
>
>Now, I've also heard the theories about plate compression during pitch
>raises and have wondered... What is your experience pitch raising pianos
>such as the Baldwin Hamilton? These have to be the lightest plates in the
>business. Still, I don't hear many horror stories about either tuning them
>or pitch raising them. What say you?
>
>Del


Hi Del,
I was talking about grands here too, but it should apply to verticals as
well if it's valid at all. I don't have any characteristic pitch raise
problems with the Hamiltons, so I can't say for sure. I believe the plate
compression theory, in general, because the soundboard deflection from the
increased tension from the pitch raise doesn't, according to my
calculations, shorten the already tuned strings nearly enough to account
for the pitch drop. Something else is moving, and plate compression, or
more accurately deformation, seems like the only thing left that could move
enough to produce that pitch drop - unless I'm missing something obvious. I
suspect too, that there is some racking, bowing, or deflection off plane
going on in some plate configurations, more so than in others that accounts
for some of the differences between pitch raise characteristics in pianos
with lighter plates. As a casual observation (otherwise unqualified), I
seem to get less pitch drop in thicker, heavier plates in grands than in
lighter ones. Since mounting and internal stress balance wouldn't be as
critical in a heavily overbuilt plate as in a more reasonably adequately
built one, it seems to me that I'd statistically see less pitch drop with
heavier plates, though not necessarily more in lighter ones. And that's
what I find. 

Nothing really definitive, with no real research behind it, but a general
trend I've noticed. 

I wonder too, while we're at it, how much of the difficulty in getting an
S&S D to calm down with a pitch adjustment is plate flex related.


Ron N