plate reaction was Re: Pitch Raising to A440.......Or Not?

[Graeme Harvey]

Ron wrote....

>Ok, here's one for you. I think I've demonstrated reasonably well that
>humidity swings push strings up and down bridge pins. With a 20° pin angle
>and 10° stagger, how much of the pitch increase with humidity increase is
>from soundboard rise, and how much is from the fact that the string is
>higher up the bridge pins and taking a longer path across the bridge
>(stretching as necessary to do so)?

Ron, do you think the string would remain part way up the bridge pin when
there is an increase in humidity causing a rise in bridge height? In other
words, what keeps the string up the bridge-pin when there are forces
attempting to bring it down?

I'm curious, with any amount of downbearing and the strings under tension,
when a force pushes against the strings increasing tension, wouldn't the
weakest link give in? Surely the string part way up the pin has less to hold
it there under these circumstances? Unless they've cut themselves a notch to
hold onto.
Having not followed all your theories regarding string climb on bridge pins,
though accepting this occurs, I'm wondering how much influence the vibrating
of the string itself has on this.

Could it be that the most flexible termination point in the vibrating
string's path, the front bridge pin, having the greatest string movement
occurring, and consequently first go at dampening the vibration, have enough
energy occurring for the string to lift off the bridge and climb the pin
regardless of pin angle and stagger angle?

Just throwing something else in to complicate things. ;)


>I'm beginning to suspect that we went through a lot of years not knowing
>squat about why and how pianos go out of tune.

Only beginning Ron?


Cheers

Graeme Harvey
New Plymouth
New Zealand