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<div>Kevin,</div>
<div><br></div>
<blockquote type="cite" cite><font face="Arial" size="-1">
This is a Steinway M from 1995. Looks brand new; no string grooves to
speak of, knuckles perfect, case perfect, I suspect it saw light
playing infrequently for most of it's life. Wasn't Susan's article
about an SD-10?</font></blockquote>
<div><br></div>
<div>Susan's article was about an SD-10, but front duplex problems are
the same regardless of the manufacturer. There are pretty new pianos
out there which don't sound too pretty, with noises aplenty.</div>
<div><br></div>
<div>Duplex bars which are:</div>
<div>* larger radius</div>
<div>* softer than the wire</div>
<div>* close to in-tune with a harmonic of the speaking length</div>
<div>* too long</div>
<div>are all factors which contribute to string noise.</div>
<div><br></div>
<div>Ideally the front duplex should be:</div>
<div>* a small radius (these days we are setting to 1mm or slightly
less)</div>
<div>* harder than the wire (when rebuilding we harden the cast in
bar)</div>
<div>* shorter, 40 mm is too long, under 30 is preferable though
often impossible to achieve.</div>
<div>* set to a detuned length, ie. to a length mid way between two
harmonic lengths</div>
<div>* set to a height for a string approach angle of not greater
than 15 degrees (or the wire will be cut by the non-deforming
small-radius duplex bar).</div>
<div><br></div>
<div>The 'glue on the duplex length' trick (thank you Jim Coleman
snr), to increase mass and therefore to detune, is a very effective on
the road fix.</div>
<div><br></div>
<div>We nickel plate our front duplex bars (after hardening) to
improve string rendering and to prevent corrosion.</div>
<div><br></div>
<div>Ron O.</div>
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<div><font face="Times"
color="#000000"> OVERS
PIANOS</font></div>
<div><font face="Times" color="#000000">Grand piano
manufacturers</font><font color="#000000"></font></div>
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http://www.overspianos.com.au</font></div>
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