Whacking

[Yardarm103669107@AOL.COM]

Bill:
While the pin might be very stable, the segments of string from the tuning 
pin on out to the waste length are under less and less tension if the pitch 
is being changed upward; the reverse is true in pitch lowering. The string 
system is unstable until an equalizing force is used to attempt to overcome 
friction at terminations and get the tension to equalize. I personally doubt 
that a string system left unaltered is stable enough to leave for very long. 
On the other hand, a stiff blow which is allowed to linger rather than 
stacato damped will go a long distance in stabilizing the string system. 
Overhard blows can indeed destabilize the system in the reverse direction.

A good test of this phenomenon is to try this. The next time you have to 
raise the pitch on a piano more than 20 cents, pick a string in the middle 
register and after pulling it up to where you want, take a brass punch and 
give the waste length of string on the other side of the bridge a tap in the 
opposite direction of the bridge pin, i.e. as if you were unseating the 
string; you will immediately notice a drop in pitch in the singing length as 
tension is released around the bridge. If you did not give the string a stiff 
blow to equalize out tension, then that residual unequal tension would 
gradually detune the piano. More thoughts? Is this clear? Again, I'm not 
advocating damaging blows (either to the piano or to self).
PR-J