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
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