Yamaha C7 tuning instability

[Don Mannino]

Mark,

As you surmised, this problem has nothing to do with the piano, and
everything to do with the air changing the string's temperatures.

The best approach is to move the piano so that it is not in a drafty spot
during tuning, then move it back when you are done.  Make sure the studio
owners are aware of the draftiness problem - you can demonstrate it for them
using your tuning machine easily.  Simple zero out the display, then 'huff'
hot air on the strings while playing it - the display will begin to move
right away.  Well, at least it works well with my unusually large quantity
of hot air ;-)

This problem could possibly be solved by redirecting a heating vent, or
getting air deflectors for one or two vents that are blowing on the piano.

A blanket or cover draped over the piano could help during tunings, too.

Don Mannino RPT


-----Original Message-----
From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of Mark
Dierauf
Sent: Wednesday, June 16, 2004 7:27 PM
To: caut@ptg.org
Subject: Yamaha C7 tuning instability



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?

- Mark



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