On Feb 20, 2009, at 9:33 AM, Daniel Gurnee wrote: > My measurements of pin movement by block expansion/contraction > indicated mid performance with the effect of audience moisture that > the right pin of a unison moved farther from the capo/agraff than > the left pin. The measurement taken by michrometer was assumed to > be pin block expansion which may have been caused by humidity or > temperature. I am intrigued by your description. How exactly did you make this measurement? What was the magnitude? Magnitude of difference between one pin and another? I guess there are different designs of micrometer, but I haven't seen one that could do this. In any case, I don't find a difference in behavior between Steinway D and B, in spite of the difference in tuning pin array (my earlier post, I was confused - it is B and A that have those alternating offset groups for each unison, not D). So while it may be that the pins move relative to termination (ie, are moved by the expansion/ contraction of the block), and that the right pin moves more than the left, this model for the unison skew comes up against the contradiction of alternating unisons not moving similarly - that is, the pitch doesn't seem to move in accordance with what the model would predict. About hall heat and humidity, in my own experience at our venue, with a pretty efficient HVAC (with the pluses and minuses that presents), the only effect that seems to be significant at concert time is lights. Ours don't put out that much radiant heat (ie, directly radiating on the strings), and the HVAC keeps the temperature change down to about 4 degrees rise or so on stage. RH drops accordingly by about 1-2%. We have had several faculty who have tried to keep RH higher in their studios using a humidifier, and the HVAC flushes it out as fast as the humidifier produces it (I have measured: within a few feet of the devise there is a small effect). I don't believe the audience causes a rise in temp and RH, or at least not a significant one (the system flushes it out as fast as it occurs). Older buildings without the "blessings" of modern HVAC will no doubt have different issues, maybe including humidity rise due to audience breathing and perspiration, as well as heat rise. And facilities with humidity "control" may have their own special issues where the calibration is such that they create pretty wild seesaws (like Jeff Tanner describes). Regards, Fred Sturm University of New Mexico fssturm at unm.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut_ptg.org/attachments/20090220/0924a3b4/attachment.html>
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