was flat facts

[Terry]

I don't really buy into the "tuning pin turns" theory.

How they can one explain a 100 year old Kimball upright (real beater - all
original) I have tuned twice - both times in the summer when AC is running
and humidity is very constant in homes. This piano had moderate-to-minimal
tuning pin torque (no pins were real snug/tight). The first tuning was
August 2001. I raised the pitch 200 cents and tuned it. The second tuning
was August 2004 - I only tuned it because the piano was right up to pitch!

Terry Farrell

> I've read the comments that have been thoughtfully posted, but I have a
> very hard time believing that bridge grooves, string stretching, etc.,
> will take a piano 50 cents flat in 10 years--especially if it's an old
> beater that has been crushing and stretching  for 75 years.
>
>     I've seen pianos go 100 cents flat in 5 years.  Newer pianos, now,
> not old beaters. But I would not be surprised if I raised pitch to A440
> on an old piano that should have already done most of its stretching,
> then came back 10 years later to find it 50 cents flat.  In fact, I
> think it's happened to me several times.  Even on an old one that's had
> 75 years to crush and stretch, if you raise pitch, you're adding more
> tension to the strings and more pressure to the top of the bridge.  It's
> gonna react because it's wood and stretchable metal, not concrete.
>
> I agree with Sarah Fox; I think those pins are s-l-o-w-l-y turning;
> unwinding, if you will.
>
> It's the only explanation that, to me, could account for such huge
> changes. If the strings were stretching, they'd be getting thin and I've
> measured enough old strings to know that, except when abused, they don't
> change /that/ much.
>
> No, not that much, but they can decrease in size by a thousandth of an
> inch, which is one string size.  And yes, if the pins are a bit loose, I
> suppose they can unwind a bit, but I don't think it's the main factor in
> causing a piano to go flat.
>     Ever seen the becket sticking out of a pin a little too far, so you
> squeeze it in?  Does the pitch drop by just a few cents?  NO!  It drops
> WAY down!  It just doesn't take much at all to make a string go flat, so
> all those reasons above combined (string grooves, pins settling, etc.)
> are plenty to explain the pitch drop, even if the pins don't unwind at
> all.  It's an exponential, not a linear function, right?  Isn't pitch
> related to the square of the tension?  (IMHO)
>     --David Nereson, RPT
>
>
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