Neg. Inhrmncty-What to do?

[Jim]

Hi Again Allen:

I have observed negative inharmonicity in pianos, but never on F3.
If I ever should, I would do this: Pluck the F3 string between the
strike point and V-bar at both F5 and F6. The normal
strike point of the hammer does sometimes interfere with the display
of the 8th partial - somewhat similar to the kind of display we get
when tuning a wild string which has two frequencies going at the same
time. If this still shows negative Inh., then measure F#3 or E3 as
tho' it were F3 (assuming it to be the same kind of string, ie wrapped or
plain). The rationale for this is that you wouldn't want one odd-ball
string to control the tuning of so many others.

In this particular case (Knabe Console) the F3 is probably a wrapped
string. Normally if a wrapped string has extremely long unwrapped
portions in the speaking length of the string, this will make the
inharmonicity higher.  The only thing I can think of which would make
the inharmonicity lower would if be if there is added weight in some
spot on the string.  I have observed glue spots on strings (sloppy
gluing of the dampers) which can play havoc with inharmonicity. Some
European and Japanese pianos have had the end of the copper over-wrap
itself about 1 inch to give better security, but it also plays havoc
with the inharmonicity (usually in lowering some of the lower partials.

Jim Coleman, Sr.


On Fri, 24 Jan 1997 Gilreath@aol.com wrote:

> In a message dated 97-01-23 16:35:52 EST, you write:
>
> <<   The string in question may very well have negative inharmoncity for some
>  partials, but it is not clear from your description that this is what you
> have.
>  When you say that you find F6 to be a little flat, do you mean F6 as the
>  8th partial of F3? or F6 as the 2nd partial of F5?  And flat compared to
> what?
>
>     -Bob Scott >>
>
> Sorry for any ambiguity in my original post.  When playing F3, tuned to F5
> then measuring F6, still playing F3,  I had to set the Accu-tuner to -1.6.
>  Hence, an obviously unusable, negative unharmonicity reading.  Also, thanks
> Ted for the Journal reference, I'll look it up first thing in the morning.
>  And thanks to Jim for the response, but I was in Tune mode, so this should
> have been a true reading.  I heard about the phenomenon but had never
> observed it.
>
> Allan
>
> Allan L. Gilreath, RPT
> Gilreath Piano & Organ Co.
> Berry College
> Gilreath@aol.com