questions, etc.

[Ron Nossaman]

> 2)  Question one:  is a pitch lowering likely to be less stable than a pitch
> raise, in your experience?  I have observed that when I have to lower the
> pitch on a piano (because of environmental moisture), it's more likely to go
> back sharp again, regardless of whether I tune it once or thrice.  My
> hypothesis is that the string tension is keeping the piano from swelling as
> much as it could -- and so lowering the string tension allows/encourages the
> piano to swell more, thus raising the pitch again.  It's like taking off a
> pair of shoes that're too tight -- your feet swell up in response.  So, am I
> hallucinating?  Has anyone else noticed this?

As far as I can ascertain, pianos aren't much like feet, and 
don't swell unless you get them wet. Here's what I think is 
happening. Raising pitch, the speaking length has more tension 
than the back scale, so when you whack it, some of that 
tension difference equalizes as the test blow further raises 
the string tension and pulls wire through the bridge pin 
stagger. Lowering pitch, the back scale is higher tension than 
the speaking length, so the test blow does nearly nothing to 
equalize tensions on either side of the bridge, and the tuning 
goes sharp slowly as the higher tension back scale pulls wire 
out of the speaking length - raising it's tension and 
therefore it's pitch.
Ron N