<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>RE: capo buzz</title></head><body> <div>At 11:57 AM -0600 16/10/03, Fred Sturm wrote:</div> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>Lance,<br> <x-tab>  </x-tab>70's through early 80's there was quite a fad of filing capos "to a point," by people following McMorrow's book. Then lots of techs found that the wire shortly buried itself in said point (ie, created grooves while being tuned and played), with associated loss of clarity and power and return of noise. Then some folks got the bright idea of hardening sharpened capo. Which solved one problem to cause another - increased string breakage.</blockquote> <div><br></div> <div>Hi Fred and all,</div> <div><br></div> <div>We have done a lot of work on this problem over the years. Yes, if the bar is hardened without paying careful attention to both the bar radius and the string approach angle, string breakage will be a problem. However, if addressed appropriately, it is possible to use a small radius hardened profile bar without experiencing premature string breakage problems.</div> <div><br></div> <div>We have found that the following factors contribute to string noise;</div> <div><br></div> <blockquote> <blockquote>The radius or profile of the bar (both the capo and front duplex bars)</blockquote> <blockquote><br></blockquote> <blockquote>The length of the font duplex segment (shorter is better, longer is more prone to noise)</blockquote> <blockquote><br></blockquote> <blockquote>The accuracy of the duplex segment to a harmonic length of the speaking length (the closer the duplex segment is to a harmonic of the speaking length the greater will be the propensity to produce string noise).</blockquote> <blockquote><br></blockquote> </blockquote> <div>When rebuilding grand pianos with cast in front duplex bars we;</div> <div><br></div> <blockquote> <blockquote>* Remove the front duplex bars (with a small angle grinder) and build up the plate to enable the fitting of new 'de-tuned' front duplex bars.</blockquote> <blockquote><br></blockquote> <blockquote>* After measuring the string scale (before the piano is pulled down), using a spreadsheet which is designed for the purpose, we select appropriate front duplex lengths which will be as short as practical while at the same time set to a length which is out of tune relative to the harmonic lengths for each note.</blockquote> <blockquote><br></blockquote> <blockquote>* Manufacture new front duplex bars (which are also hardened - SAE 1040 key stock is a suitable and economical material from which to make the bars), varying the heights so that the string approach angle is uniform and between 12 - 15 degrees (preferably 12 - 14).</blockquote> <blockquote><br></blockquote> <blockquote>* Shape and harden the  capo bar (this is a once only job since there will be no grooving of the bar after hardening, so subsequent re-strings will be a simple matter).</blockquote> <blockquote><br></blockquote> </blockquote> <div>For those of you interested in hearing a recording of a piano fitted with this type of font duplex system, you can hear samples of our 225 (7'4") piano no. 3 at;</div> <div><br></div> <div>http://overspianos.com.au/samp.html</div> <div><br></div> <div>Best,</div> <div>Ron O.</div> <x-sigsep><pre>-- </pre></x-sigsep> <div><font face="Times New Roman" size="+1" color="#0000FF"><b>OVERS PIANOS - SYDNEY</b></font></div> <div><font color="#000000"><i>   </i></font><font color="#0000FF"><i>Grand Piano Manufacturers</i></font><font color="#000000"><br> _______________________</font></div> <div><font size="-2" color="#000000"><br> </font><font color="#000000">Web http://overspianos.com.au</font></div> <div><font color="#000000">mailto:info@overspianos.com.au<br> _______________________</font></div> </body> </html>