why does a string go out of tune?

Sy Zabrocki only4zab@imt.net
Sat, 10 Apr 2004 20:23:24 -0600


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Wm:
I too have experienced slipping unisons which seem difficult to explain. =
I've thought about it for years. I have a theory which I call =
"SOUNDBOARD SHAKING" for lack of a better term.

We strike the keys hard during tuning to settle the segments of the =
string. Maybe there are still tidbets of friction left as the string =
snakes through the bridge pins. Just striking each individual string =
isn't enough to free the friction. Later during hard playing the =
soundboard and bridges are SHAKING more intensely and these bits of =
friction surrender and the unison goes out of tune. Maybe there is more =
friction in the bridge pins than the agraffes, upper bearing and capo =
bar.=20

It's just a theory. How can one prove it?

Sy Zabrocki
  ----- Original Message -----=20
  From: Wimblees@aol.com=20
  To: caut@ptg.org=20
  Sent: Saturday, April 10, 2004 12:22 PM
  Subject: why does a string go out of tune?


  OK, what exactly is happening when a string goes out of tune. I know =
about climatic changes that effect the soundboard. This causes the who =
piano, or at least whole sections to go out of tune. I can accept that. =
But I pride myself on setting the string and the pin. I am a pounder. On =
new pianos, (at least new to me), and especially concert instruments. I =
beat the daylights out the notes to get them to stabilize. But there are =
still strings that go out. That is why we tune concert instruments =
numerous times, with strings still going out.=20

  I tune a D for a church once a month. I pound until my fingers hurt =
but I leave the string with the lights standing absolutely still. But =
every time I tune it, the piano is "in tune" in that it hasn't changed =
pitch over all, but there are at least 2 dozen strings that have =
"slipped." They are 2 or 3 cents off. I'm not talking notes, I am =
talking string. The right string of one note is 3 cents low, or the left =
string of another note is 2 cents flat.=20

  Why is that? Why do just these strings go out, and not the other ones? =
Am I still not pounding hard enough, or is the combination of slight =
variations in temperature, combined with strings that maybe weren't set =
right, causing this? Inquiring minds want to know.

  Wim
  Willem Blees, RPT
  Piano Technician
  School of Music
  University of Alabama
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