<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> No John He does not just use Pythagoras' theorem just as you did.  And if you stop up and look closely I am sure you will understand this.  When you change the deflection you change three things... its length, tension, and frequency. The new length you can calculate just as you did.  But that leaves you with two unknowns... the new tension and the new frequency. None of your formulas can calculate one without the other. Galembos formula does something entirely different.  It finds the change in the amount of tension in the wire cause by the change in string length. Once you have this figure... then you can calculate for frequency using your formula.  But you cant just change the length of the string and without further ado use the formulas you give... they dont deal with two unknowns.  I'll let you work it out... and find the error in the documents last line I pointed out to Alex when I first got it.... just a typo... but important to get right. Cheers RicB <blockquote> <blockquote>At 5:51 pm +0100 29/4/07, RicB wrote: >Unfortunatly, you can not calculate the change in frequency for >change in string deflection this way. Or so I am told by a few of >the worlds physisists.  Please see the following for what according >to these is a more correct way of doing this. </blockquote> </blockquote> <blockquote><a class="moz-txt-link-rfc2396E" href="http://www.pianostemmer.no/files/String%20deflection_files/brekne.doc"><http://www.pianostemmer.no/files/String%20deflection_files/brekne.doc></a> Your "world's physicist", in the file above, uses Pythagoras' theorem and no other principle, just as I did, to calculate the changes in length.  The only difference in his equations is that he takes into account a change in length behind the bridge, considered as a violin bridge and not a piano bridge.  Clearly some slight difference in the results will arise if that is added in, with corrections for the actual disposition of the string on a real bridge, just as the re-angling of the dogleg 1/2mm lower round the slanting front pin on a real piano bridge will make a difference, but I'm at a loss to understand why you consider your famous person's Pythagorean theorem so superior to mine and intrigued to see your worked example and results based on this document. If, for instance, you take C76 with a speaking length of 100mm, as I proposed, and take into account a back-length of 50mm, with an initial deflection of +1.5mm (i.e the soundboard bridge is 1.5mm above the straight line from hitch-plate bearing to top bridge), what exact results do you get, using your valued equations, when you force the string down 1/2mm into the wood of the bridge at the front pin? JD </blockquote> <div class="moz-signature"> </div> </body> </html>