temp change=how much pitch change?

[John M. Formsma]

OK, that makes sense now. You're anticipating your local weather 
conditions, which are totally unlike this situation (dry lander). I get 
it now. :-)

JF

Diane Hofstetter wrote:
> 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
>>
>>
>>
>>
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