Inharmonicity & Capo Bar

[Richard Brekne]

List:

The recent thread pertaining to this has got me off and running again. I
must admit I have been frustrated by the seeming lack of information
that directly addresses this point. Lots of hints and physics pertaining
to terminations in general.. a few declaratory statements in a couple
books without any hard science to back them up.. etc. The reading leads
me to believe that McMorrows statement is true enough.. but just how
significant it is, is another matter.

So... as soon as I get my handy dandy portable puter back.. which has
been down for a couple weeks now (repairs of such things here in Bergen
is slow). I am going to do the following little experiment and post the
results to the list for anyone who may be interested.

I intend to take inharmonicity readings from the tenor / treble break
upwards on a piano I have at my disposal. This piano has a very sharp
v-bar configuration with pressure bar behind. The V ends at about 0.3 mm
(no kidding), is just very slightly softened (rounded) at the edges of
the V.. just enough to take the cutting edge off so strings can survive.
It is a non-hardened termination in a old style green sand cast. Low
tension scale (probably a neccessity for the configuration to work).
After taking the inharmonicity readings I will remove the strings from
this section and widen the termination gradually to reach 1mm at the
very top. This is off course going to increase downbearing, but this is
an old piano (110 cm high) with a board that has flattened out a good
deal and I do not anticipate that the increase in bearing will cause
problems. In any case the effect of increased downbearing will not
influence the results I am looking into. After widening the termination
I will then reset the same strings (for controll purposes) and take new
inharmonicity readings and compare the two sets.

This should give a pretty good indication as to whether there is to be
expected any significant change in string inharmonicity by use of said
proceedure. Should be fun, and I am definately going to learn something.




--
Richard Brekne
Associate PTG, N.P.T.F.
Bergen, Norway