[CAUT] pre-stretching new string?

[reggaepass at aol.com]

Ron,

Would the pitch-change effect then be less, if not negated, by vertical bridge 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?  Has anyone who works with a Wapinized piano observed greater tuning stability after the modification?

Alan Eder


-----Original Message-----
From: Ron Nossaman <rnossaman at cox.net>
To: College and University Technicians <caut at ptg.org>
Sent: Thu, 7 Jun 2007 9:15 am
Subject: Re: [CAUT] pre-stretching new string?


 A little trig, a little Pythagoras, and Sanderson's scaling formulas answer a lot of questions. Downbearing deflection angles in pianos are so small, that soundboard rise and fall would have to be enormously more than we observe in actual pianos, to account for observed pitch changes. Dimensional changes in bridge caps, moving strings up and down bridge pins slanted at 15-20° in opposite directions with bearing offset angles around 10°, produce string length changes ten times that of soundboard rise and fall. 
 


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