temp change=how much pitch change?

[John M. Formsma]

Yeah, but the one I'm talking 'bout has a full DC system. 2 humidifiers, 
3 dehumidifier bars, undercover. It's been in since Jan '06, and working 
fabulously to control pitch. The only variable was the temperature 
change, as humidity was more or less constant.

It takes a while for the wood to react enough to cause pitch changes 
this large. I'd think a few days rather than a few hours. So it's gotta 
be the temperature alone. I was pretty amazed, but in subsequent 
thinking about how long those tenor strings are, that's a lot of pitch 
change potential from temperature change. I just didn't realize it at 
first because I don't tune concert pianos all that often.

JF

pianolover 88 wrote:
> Simple. If all concert pianos had full DC systems installed, the pitch 
> wouldn't change to any substantial degree, providing that the piano is 
> stabilized first, with regular tunings. The RH fluctuations will 
> obviously cause swings in pitch as the soundboard takes on/lets off 
> moisture. DC systems take this problem out of the equation. At least 
> in my experience.
>
> Terry Peterson
>
>
>
> ----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 21:45:01 -0600
>
> Huh? maybe a little more elaboration.
>
> JF
>
> pianolover 88 wrote:
>> Dampp-chaser.
>>
>> Terry Peterson
>
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