Temperature Change affecting pitch

[Farrell]

Now why would turning on the AC make a piano go sharp? The cooler temp.
would make the plate and case contract (albeit very slightly), thus lowering
pitch, and the lower humidity (because any properly operating AC unit will
remove water from the air, thus lowering relative humidity) would tend to
make the soundboard contract, again lowering the pitch. Why in the world
would it go sharp?

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com

----- Original Message -----
From: "pryan2" <pryan2@the-beach.net>
To: <pianotech@ptg.org>
Sent: Tuesday, March 28, 2000 11:02 PM
Subject: Re: Temperature Change affecting pitch


> I learned the hard way that temperature has a immediate effect on pitch.
> When I go into one of the showrooms to tune a piano, I click on the air
> conditioning (I'm in South Florida), proceed to strip mute a piano and
begin
> tuning middle strings with the SAT.  After getting half way through the
> piano, I go back to where I started and re-check my work. All the red
lights
> are spinning sharp now. What do I do now? Start over or let them go?
What
> I do now is turn the AC on in advance and let the showroom and pianos to
> cool down before starting.
>
> Phil Ryan
> Miami Beach
> -----------------------------------------------------
>
> ----- Original Message -----
> From: "Larry J Messerly" <prescottpiano@juno.com>
> To: <pianotech@ptg.org>
> Sent: Sunday, March 26, 2000 7:15 PM
> Subject: Temperature Change affecting pitch
>
>
> > Just for my own information, when I came into my store this morning I
> > took pitch readings on two grands at 61degrees F. then turned on the
> > heating system and raised the temperature to 68 degrees.
> >
> > The 6' Kranich and Bach dropped pitch 3.2 cents initially and then when
> > (I presume) the plate temperature rose ended up 1.6 cents flat of where
> > it had begun the morning.
> >
> > The 5'3" George Steck initially dropped 0.4 cents then continued to fall
> > to 1.2 cents from where it had been.
> >
> > They have not changed any more over the last hour.
> >
> > No real problem or question here, just thought it was interesting.
> >
> > Larry Messerly, RPT
> > Phoenix/Prescott
> >
>
>