[CAUT] pre-stretching new string?

[Ron Nossaman]

> Would the pitch-change effect then be less, if not negated, by vertical 
> bridge pins.  

The pitch change would be less, because the string path length 
wouldn't change. You would also lose the clamping effect of 
the slanted pins.


>In other words, any guess as to how much of the bridge 
> affecting pitch change is due to the slant of the pins as compared to 
> the offset angles?  

The pin slant is what does it. Push a string up a pair of pins 
slanted away from each other, and the string path length 
increases, stretching the string and raising tension, therefor 
pitch. The big offset angle magnifies the effect, but the pin 
slant causes it.


>Has anyone who works with a Wapinized piano 
> observed greater tuning stability after the modification?
> 
> Alan Eder

The Wapin installation still has a pair of oppositely slanted 
pins in addition to the vertical one. I would, however expect 
the Wapin configuration to show less long term compression 
damage at the speaking length notch edge because of the 
vertical pin.
Ron N