questions, etc.

[Annie Grieshop]

Ooooh, I see what you mean.  That's why I ask you folks these questions --
and you always have intriguing answers for me.  Thanks!

If I get what you're saying, the test blow can pull the wire past the bridge
pins when it's a matter of raising tension, but it can't push the wire back
the other way when lowering tension -- so the wire eventually equalizes the
tension on its own, raising the pitch again.  That makes sense.  And I have
noticed that pitch-lowered pianos are more likely to go sharp while I play
them (as part of the tuning) than pitch-raised pianos are to go flat, which
would also support your explanation.  Cool.

But these pianos are in damper-than-ideal environments, so isn't the
moisture playing a role?  Or is that not always such a culprit as I've been
led to believe?

Of course, my original question suggested there's a single-point cause, when
I know full well it's a complex system.  So nice to have so many topics of
contemplation while working.

Annie

> -----Original Message-----
> From: Ron Nossaman [mailto:rnossaman at cox.net]
> Sent: Tuesday, February 06, 2007 2:14 PM
> To: annie at allthingspiano.com; Pianotech List
> Subject: Re: questions, etc.
>
> 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
>