<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 10 (filtered)"> <style>  </style> </head> <body bgcolor=white lang=EN-US link=blue vlink=purple> <div class=Section1> I see my spread sheet date didn’t come out too well.  Let’s try that again with all the corrections.      <div> David Love davidlovepianos@comcast.net www.davidlovepianos.com </div> -----Original Message----- From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of David Love Sent: Monday, June 11, 2007 6:58 AM To: 'College and University Technicians' Subject: Re: [CAUT] pre-stretching new string?       In Robert’s book “The Calculating Technician” the formulas are given and you can program your own spread sheet.  The original claim was that when comparing the degree to which two strings will go out of tune with a change in length, the break point percentage was an indicator of which string would go out of tune more.  The other statements below came about as a discussion of the math.  If you do as I said and compare two strings which start out with different BPPs and calculate the change in tension for a given change in length (say 5 mm) and then see how that translates to a change in frequency, you will see that the one with lower BPP will have a greater change.  You have to reprogram your spreadsheet to make that calculation or just do the calculations separately since the spreadsheet is not generally set up to have Frequency as a dependent variable.  First determine the change in tension for a given change in length.  Then calculate the change in frequency for a given change in tension at the new length.  Then determine which frequency changed more.      Note            Length             Diam            BPP                  Tension                  Frequency               A – 7             70                    .032               76%                 138.64                    3322.44             A – 7             60                    .032               56%                 256.85                    3322.44   <div> David Love davidlovepianos@comcast.net <a href="http://www.davidlovepianos.com/">www.davidlovepianos.com</a>         </div>       </div> </body> </html>