[CAUT] temperature and pitch

[David Love]

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