Unstable Yamaha C7

[Farrell]

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Agree. And on an upright with a DC installation, I make sure to keep the =
kneeboard in place while tuning. I have noticed pitch fluctuations in =
such a case when it has been removed.

Terry Farrell
  ----- Original Message -----=20
  From: Paul McCloud=20
  To: Pianotech=20
  Sent: Thursday, June 17, 2004 7:33 AM
  Subject: RE: Unstable Yamaha C7


  Mark:
      I think your problem is definitely the temperature fluctuation.  I =
always ask the customer to close the door/window to eliminate any breeze =
over the piano.  I also ask them not to change any climate control that =
they normally use when I'm not there.  (Sometimes they'll turn the air =
cond. to make me comfortable).   I've found that any change in =
temperature around the piano affects my tuning, and the strings are =
vulnerable to temperature changes especially when the cabinet is opened =
for tuning (uprights).  =20
      Hope this helps,
     =20
      Paul McCloud
      San Diego


    ----- Original Message -----=20
    From: Mark Dierauf=20
    To: pianotech@ptg.org
    Sent: 06/16/2004 6:28:04 PM=20
    Subject: Unstable Yamaha C7


    I take care of an older Yamaha at a recording studio that has a =
tuning instability problem that I've never encountered on any other =
piano - the pitch fluctuates by as much as 3 or 4 cents over the course =
of only a few minutes. It took me quite a while to realize that this =
fluctuation ran in sync with the forced hot air heating system. Now that =
it's summer, the air-conditioning from the same vents is having the same =
effect. The piano has a complete DC unit installed with a bottom cover, =
is tuned at least 20x annually, and is very pitch-stable in the long =
term. It is not located in direct sunlight and the temperature doesn't =
vary much, certainly not within seasons. In the winter there is a =
humidity control system adding moisture through the hot air ducts. The =
studio is in an old New England barn that had several hundred thousand =
dollars worth of renovation, and so is very well finished and insulated, =
but in the time that it takes me to work through the temperament the =
first notes tuned have already moved substantially. Once after chasing =
the pitch all through a tuning I repeated A4 for several minutes and =
watched the pitch rise about 2 cents above the starting point then fall =
about 2 cents below. This cycle kept repeating as I watched. Has anyone =
ever seen such a problem? Did you find any solutions?

    =20

    - Mark

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