<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 6.00.2900.2627" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#d8d0c8> <DIV><FONT size=2>I'm seeing some strange pitch drops in individual = strings, and I can't figure out why.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>First, the history.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>This is a 1974 Yamaha C3, in pretty good shape, in = the large band room of a community college, with central HVAC.  No D-C on the = piano.  Three weeks ago, we moved it overnight to two different = off-campus locations for the spring concert series (half an hour ride in a pickup = truck each time -- yikes!  I covered it up, but still...).  It's had = five tunings in the last month, and I've recorded humidity each time.  I = use TuneLab Pro, and used the same stored tuning each time.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>The series ended May 1, and I tuned it just before = that concert.  It survived the concert sounding good; no slipped = unisons.  It's been in the same spot for three weeks, uncovered, lid = down.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>Now, the mystery.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>On Tuesday, they asked me to tune for a recording = the next day, mentioning that a few unisons were out in the top two = octaves.  I measured all the A's before I tuned (as is my habit).  A4 and below = were right on, except A1 and A2 were up about two cents (humidity is = rising).  A5 was up 3c, A6 down 6, A7 down 3.  I noticed that in many treble = unisons, one or two strings would be way off: either a string would be right on, = or off by a considerable amount (is it my string-settling technique?).  I = also noticed that many strings would move a lot if I pounded on them, before = touching the pin.  I worked hard on those top two sections of the plate, = making sure every string was well settled, and wouldn't move.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>Yesterday, they called me back to tune their other = piano, and also mentioned that the top two octaves were out on the Yamaha again = (!).  I checked it, and A2 and below were spot-on, as were A6 and above.  = But in the middle three octaves, a dozen notes had one, two, or three strings = off by two or three cents (A4 was down five cents!).  All but one were = flat.  Again, either a string would be exactly in tune, or off by a lot.  = I checked the pitch of every string before I began to tune, and = chalk-marked the tuning pin of each string that was out (for next time).  = </FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>They did mention that they turned off the A/C in the = room for the recording (because of noise), and then fired it up full blast during = breaks.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>Here's the temp/humidity record (graph = attached).  Humidity was lower in the two off-campus locations, and has climbed = steadily upwards.</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>4/10: 72F, 42%</FONT></DIV> <DIV><FONT size=2>4/17: 68F, 32% (off-campus)</FONT></DIV> <DIV><FONT size=2>5/1:   68F, 39-41% (back home; last concert)</FONT></DIV> <DIV><FONT size=2>5/17: 72F, 44-48%RH. </FONT></DIV> <DIV><FONT size=2>5/20: 72F, 55%</FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2> <DIV><FONT size=2>By the way, the other piano didn't exhibit this = symptom of individual strings falling, and others staying right on.  This is = really the heart of the mystery to me.  My experience with pitch swings = from humidity is that it affects strings evenly.  The other piano = is a D in a different room, with similar humidity, also last tuned 5/1.  = It was sharp a few cents evenly across the middle, dropping down to -10 in the = top octave.  </FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>Maybe it is my tuning lever technique?  I = usually finish a string by coming down to pitch, to make sure the pin has no = residual torque; maybe I'm leaving some tension in the front string segment that = settles back to the speaking length during play, or humidity changes?  In = writing this history, I notice that the top two sections that I worked hard on = Tuesday night were still fine; the problems I found yesterday were lower down.</FONT></DIV> <DIV> </DIV> <DIV>The other possible suspect is loose bridge pins.  Earlier I = had noticed a consistent drop around A6 on some strings, and found I could = slightly move a few leading bridge pins with screwdriver pressure.  How this = would lead to pitch drop, I'm not exactly sure...</DIV> <DIV> </DIV> <DIV>--Cy Shuster--</DIV> <DIV>Bluefield, WV</DIV> <DIV> </DIV></FONT></DIV></BODY></HTML>