corrections

[Michael Wathen 556-9565]

I've been misquoted twice this week.  Ron Torella: I never
advocated a Sharp "V" for the shape of the capo bar.  Read
February "Journal".  Bill Ballard: I don't ever recall saying
anything about the hammershank "whip"...somebody else.  I will
say that Baldwin made a similar type film back in the '70s where
you could very clearly see this effect.  Maybe Kent Webb would
know where this film is.

I believe the "zing" comes from nearly harmonic lengths in the
capo section.  See February "Journal" where Harold Conklin talks
about this.

Stability....

The steeper the angle going across the capo bar the greater the
friction.  Most mathematical models assume uniform tension
throughout the speaking length of the string.  This is assumed
for ease of calculation.  If nonuniform tension is the assumption
then it is nearly impossible to find the function that will
describe the motion of the string.  The initial shape of the
string upon impact, in reality, would indicate nonuniform tension
that would be both a function of time and position.  To make a
long story short, as the initial pulse travels to the capo bar it
would attempt to grab tension from the non speaking portion on
the other side of the capo bar.  The result would be a lowering
of tension and frequency in the speaking length provided that
friction at the capo bar was small.  Each reflection would find
the same thing occurring until finally when the string was fully
dampened (not moving), forces would seek equilibrium and the
speaking portion of the string would return to its higher pitch.

I'm not sure that this is the correct model either.  It is just
what I'm thinking right now.  I just started my second quarter on
Partial Differential equations and Fourier Analysis and this is
the sort of stuff it deals with.  Hopefully, in the summer I will
be able to apply some of this knowledge when I have leisure time.

It has been a long time since I have seen or tuned a Steinway
Upright but I'm willing to bet that the problem lies in too
little friction at the capo bar or what ever that thing is.


Michael Wathen
College-Conservatory of Music
University of Cincinnati