Capo Bar noises

[Michael Wathen 556-9565]

Please excuse me for posting in an untimely manner.  Below I quote a part
of a post from Dennis Johnson about the Capo Bar situation.

\ Absolutely!  Voicing can usually take away or minimize the noise
\which remains even after shaping and cleaning the bar. But I am convinced
\the real problem is that the duplex segment sympathetically resonates with
\the speaking length on these problem notes.  Compare the angle of string
\termination lengths by the front bridge pins with the angle of the duplex
\string rest.  Ideally, the duplex should be just the correct tension and
\length not to be activated audibly by the speaking length, but these duplex
\lengths are approximated and cast into the plate.  That is why some notes
\are problems and others aren't.  I believe that the real function of the
\duplex is to enable the wire to vibrate more completely at the bar, as Ed
\McMorrow described, giving more power and sustain, and less Inharmonicity.
\These noises are a by-product of that objective when the length and/or
\tension is not ideal.

After having read the post of Mr. Conklin on how Baldwin termination
bars should work I have now been dissuaded from my original belief that
the string lengths of the duplex should correspond to one of the partial
lengths of the string. Mr.Johnson's post is much closer to the mark
than I had thought when I had first read it.  Webb's trick works because
the glue changes the mass of the string in the duplex and thus the frequency.

Why have a duplex at all?  Without it there is a tremendous
energy loss.  Ideally, a perfect termination would be one that
provides a boundary for each an every molecule at the same cross
section location.  We know by Newton's Laws that forces come in
pairs.  If you throw a ball at a hard surface the surface will
literally throw the ball back in the opposite direction.
Likewise, with a piano string the mass at the capo bar reflects
(throws back) the energy, but only on one side of the string
while the other side continues to send its energy to the other
side of the capo until it hits the counter bar on its side of the
string.  At the counter bar it is reflected to the other side of
the string and moves towards the capo bar.  Now, at the capo bar
the energy is reflected on one side and on the other side the
energy moves past the capo to the main speaking length on the
other side, so on and so forth.  In essence the energy is
returned to the string and it is not allowed to be given up to
dampening in the felt, tuning pin and wood.

Michael Wathen
College-Conservatory of Music
University of Cincinnati