Well, here's another can of worms. Last night I was fooling around trying
to pin down the reason for the "nasty" notes. I started poking various
places with the narrow bottom end of a Burton jack, minus the adjusting
screw of course, and this is what I observed: pushing lightly on the bridge
or the pins where this string crosses the bridge does not have much effect
on the sound, but it is possible to find a spot on the soundboard where
pressing down with the probe does have a relatively large dampening effect.
This spot is a couple of inches away from where the string crosses the
bridge, and is of fairly large lateral extent.
This is what I think must be happening: because of the mass and stiffness
of the bridge, energy is transferred from string to bridge fairly
inefficiently. But once the energy gets into the bridge, it can travel
efficiently along the bridge until it "finds" an antinode to resonate with
at the appropriate frequency.
A couple of years ago when I was fooling around with an oscillator and
Chladni patterns and all that jazz, I noted that there are a large number of
resonances in the treble, corresponding to various antinodes. I also
remember stumbling across a theorem stating that although you can't change
the number of resonant modes in a membrane system, you can do things to move
them around and change their relative prominence.
What I think must be happening is that the nasty note corresponds to a
relatively easily excited resonant mode associated with the antinode that I
located with the probe (you don't need to do Chladni patterns to find
these!). As Owen noted a few days ago, I forget whether on or off list, one
of the purposes of thinning the sb is to spread out and even up these
responses, or words to that effect. I think it must be true that the good
experienced builders have developed an intuition, or even methods for
details exploration, for how to do this, so as to avoid exciting these
Part of the picture must include the fact that the various partials of a
given note can excite different resonances, so in some cases a given partial
can be emphasized more than is desirable relative to the fundamental. It
also seems possible that a localized problem, such as a slightly loose pin
or a crack in the sb, could be exacerbated if it is associated with a
Does this make sense?