temp change=how much pitch change?

[Diane Hofstetter]

Tuning it 4 cents flat was the backup plan if I couldn't tune it the night 
before at concert time and the auditorium didn't stay heated all night.

The reason was that the relative humidity would change so radically from 
about 1:00pm when it would be hot and dry in the auditorium until  the 
concert started at 8:00pm when the Monterey Bay fog had rolled in,  that the 
piano would be sharp if I didn't tune it flat in the afternoon.



Diane Hofstetter




----Original Message Follows----
From: "John M. Formsma" <john at formsmapiano.com>
Reply-To: Pianotech List <pianotech at ptg.org>
To: Pianotech List <pianotech at ptg.org>
Subject: Re: temp change=how much pitch change?
Date: Sun, 11 Feb 2007 20:56:22 -0600

Thanks for this, Diane. Good stuff, especially about the graphs. People can 
understand better when they're looking at some real data.

One thing I didn't understand is the following: "The only ways to have that 
piano at A=440 at concert time, were either to tune it at concert time the 
night before and have them keep the heat on all night (usually they don't), 
or to tune it in the afternoon, after the auditorium warmed up and tune it 
4cents flat! "

I don't follow why you'd tune it 4¢ flat if it's at the temperature it was 
tuned the previous night. Could you explain?

JF

Diane Hofstetter wrote:
>
>John asked:
>
>What do you guys do? Do you not worry about where the temperature is? If 
>you think it will be different at performance time, do you set the pitch 
>accordingly, and hope it changes in your favor? Or do you simply tune it to 
>A440 and don't worry about it?
>
>
>What we did was:
>Measure, measure, measure.  Get to know the piano.  Do more tunings than it 
>needs in the beginning until you know that piano.  Get to know it's 
>conditions. Get to know the people who have some control over it---become 
>their friend!  (It may be the janitor.)
>
>Work out a plan together with those who control the piano's conditions (it 
>has to be a plan that works for both of you) , and a contingency plan for 
>when that still doesn't work, for whatever reason.
>
>My partner and I tuned a Baldwin SD-10 for almost 20 years.  Did graphs of 
>the tuning before each tuning.  Measured temp & RH before every tuning.  
>Measured the same at concert time.  Adjusted procedures until we knew what 
>made it stable.  Piano had three 25 watt DC rods, a dehumidifier tank and a 
>cover, but the conditions in the "auditorium" were almost like it was 
>outdoors.
>
>The only ways to have that piano at A=440 at concert time, were either to 
>tune it at concert time the night before and have them keep the heat on all 
>night (usually they don't), or to tune it in the afternoon, after the 
>auditorium warmed up and tune it 4cents flat!
>
>Good luck with your concert venue!
>Diane
>
>
>
>