Mistery Pitch Swings

[JElving@aol.com]

Dear Fellow Techs -

Today I was tuning in a church (Oh! Another church story!) and had a very
unusual occurrance and am looking for some help in explaining it to myself.

To preface the story, I was at the same church to tune 2 pianos in August of
this year. One piano, an *inexpensive* grand, I had been servicing since it
was new, and it is fairly well settled in. The 2nd piano was new to me
(recently donated, I think). It is a Wurlitzer 41 in. console, 1980's
vintage. On that service call I did a pitch raise of 34.3 cents (according to
my SAT), and tuned it to A440. The Temperature was 77 and Relative Humidity
was 46%.

Today when I returned for another tuning, I expected the pitch to have
dropped some, as is usual, and be out of tune with itself. But what to my
wondering ears should appear, but a piano that was slightly flat in the bass
(as expected), and from the bass break up 24.9 cents sharp. The humidity was
58% (not a wide varience), but the temperature in the room was 60 degrees.

Now the grand was in a different building, but also without heat. (T=59,
RH=53%) This piano was slightly sharp, mostly in the extreme treble, but not
to the degree that the console was.

I should also say that both piano were tuned on the same days, using the same
SAT and set of ears.

My question is: What would cause this wild raise in pitch in the console,
especially above the bass/tenor break? My curiosity is really piqued. I would
appreciate any ideas from any of you.

John Elving, RPT