[CAUT] temperature and pitch

[David Ilvedson]

I think it is the difference between how the piano wire and plate are affected by temperature changes?

David Ilvedson, RPT
Pacifica, CA  94044

----- Original message ----------------------------------------
From: "David Love" <davidlovepianos at comcast.net>
To: caut at ptg.org
Received: 12/11/2009 3:07:46 PM
Subject: Re: [CAUT] temperature and pitch


>Can't comment on the amount of change per unit of temperature but the speed
>with which it happens is fairly quick.  Started tuning a piano in a church
>this morning with the temperature about 50 degrees at the start.  Pitch was
>about 2-3 cents sharp in the tenor section.  Tuning up from there by the
>time I got to C5 (20 minutes or so) the temperature had risen to 70 with the
>heat on and a remeasure of the tenor section showed that the pitch was about
>2 cents flat--pretty uniformly.  Steinway D.  It does show that there are
>clearly two aspects to pitch swings.  Temperature in which probably the
>metal parts are affected, and humidity in which the wooden parts are
>affected.    

>David Love
>www.davidlovepianos.com


>-----Original Message-----
>From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Fred
>Sturm
>Sent: Friday, December 11, 2009 8:17 AM
>To: College & University Technicians
>Subject: [CAUT] temperature and pitch

>	This morning I had the opportunity to see a pretty precise picture
>of  
>what temperature change does to pitch. I tuned a Steinway A (old,  
>rebuilt) yesterday in a performance space, and came back this morning  
>to tune it again (two night show). The temperature today was about 10  
>degrees F lower than yesterday (heat turned down overnight). The  
>tuning was as expected for a next day (unison tweaking), but the pitch  
>was pretty consistently 2 cents sharp throughout. Tenor was maybe a  
>bit less (1 - 1.5), but otherwise quite consistent. The piano had  
>obviously cooled down slowly overnight, and was stable.
>	So there you have a field observation under more controlled  
>conditions than we usually see, for the record. (I tuned it where it  
>was).
>Regards,
>Fred Sturm
>University of New Mexico
>fssturm at unm.edu