Temperature Change affecting pitch

[Richard Brekne]

Unisons that go out of tune randomly... with no hint of a pattern are generally
not caused by changes in humidity. Humidity changes affect the soundboards
crown and generally changes in this will be seen in "chunks" or segments.
Typically the Bass section will be noticably higher or lower then the rest of
the piano in general, while the lower tenor will vary in similiar fashion to
the rest of tenor / treble in general. The area adjacent to the tenor / treble
break will also vary "chunkwise"... grin. Which way these move depends of
course on whether there has been a significant rise or fall in humidity.

I am unclear on how sunlight affects tuning in this regard.. tho at first
thought I would think it might lend itself more to randomness. Whenever I do a
tuning that is  unstable in a random fashion, I start worrying about my hammer
technique... grin. You are still pretty green Charly... this may be your
problem, and it would not be unusual or unexpected by any means if it is. Dont
worry about it tho... just work on it.. it will come.

As far as your observations in general.. I dont think I have ever met a tuner
who didnt express amazement at how mindlessly pianos are placed by panel ovens,
windows with lots of direct sunshine, fireplaces, airconditioners... you name
it. The more isolated the instrument it from any thing that can vary its
climatic enviroment the more stable the piano is going to be.

Charly Tuner wrote:

> I assume even a minor drop/rise in pitch, due to humidity changes will make
> perfect unisons go out randomly, so it will be out of tune the next day.
> This is the problem I have at the store where I work...NO hunidity control,
> big picture windows allowing sunlight/heat to focus DIRECTLY on SB's! So I
> have a real dilemma trying to keep these pianos, the vast majority of them
> new, in tune from one day to the next..and of course the store pays me to
> tune them/PR them, basically once.
>

Richard Brekne
Associate PTG, N.P.T.F.
Bergen, Norway