Duplex Noise

Michael Wathen Michael.Wathen@UC.Edu
Thu, 15 May 1997 08:46:23 -0400 (EDT)


There are many things one can do to eliminate the sizzle on a quick fix.  I
am not adverse to placing a small mute between two of the strings in the
front duplex.  It deadens the overall sound a little.  Voicing is another
possibility.  The trick with the glue I tried many times.  The results were
not convincing so I don't do it anymore.

The long range fix is a complicated venture.  Redressing the capo and
restring, as far as my experience, is not likely to fix the problem.
Recapping at this point seems to provide the greatest relief so far.  The
problem still resurfaces after it has been played in.

I suspect that the "noise" really has to do with a coupling that is too
strong between the string and the bridge soundboard system. There is always
a certain amount of noise that comes from the string do to the physical
nature of the system.  The wave form imparted to the string from the hammer
takes time to travel between its boundaries, the bridge pin and capo.  The
strongest shock at reflection is initially, before the energy in the pulse
traveling down the string has had a chance set up a standing wave.  This
means that the movements caused at the boundaries due to the pulse will not
be harmonic entities of the note, they will be noise.

Voicing down the hammer means that there will not be an energy overload in
the string enough to make the sizzle audible.  Another trick is to take a
punch and reduce the slant of the terminating bridge pin.  This decouples
the string from the bridge slightly.  You will also notice an increase in
sustain when you do this because that initial energy is not given away to
the soundboard as quick as it was when it had a stronger coupling.  You can
follow up with a shot of CA glue to take care of the oblong hole in the bridge.
****************************************************************************

Michael J. Wathen			Phone:	513-556-9565
Piano Technician			Fax:	513-556-3399
College-Consevatory of Music		Email:  Michael.Wathen@UC.Edu
University of Cincinnati
Cincinnati, OH 45221-0096

http://www.uc.edu/~wathenmj






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