Inharmonicity - so what actually causes it ?

[Jim Coleman, Sr.]

The Pscale program by Tremaine Parsons is excellent in showing the
effect of changing the various parameters listed below as far as the
strings themselves are concerned.

If you keep the pitch constant, changing or increasing:
the diameter    increases the inharmonicity and tension.
the length      lowers the inharmonicity and increases the tension
the tension     lowers inharmoncity and raises pitch

After the flood of Noah's day, a great deal of technology was lost (organs
and harps were built way before that time)

I don't know about hammer work hardening effects on strings.

I don't know how humidity affects inharmonicity because I don't know if
the string length changes with rising bridges.

Adding wrap to a string lowers pitch, increases tension and lowers 
inharmonicity. However, it does these things in irregular ways.

Adding a second wrap and the necessary step increases tension, lowers
inharmonicity in general, but the affect of the step is greater than 
expected (assuming a constant pitch)

On the note F3, lowering the pitch 25 cents increases the inharmonicity
by .3 cents between the 4th and 8th partials on a Baldwin SF10.

Conversely, raising the pitch will lower the inharmonicity if the length
stays the same.

I know that the FAC stretch numbers change from one season to the other.
I have not come to a conclusion as to how much and in which direction.

I don't know the effect of inharmonicity from bridge/string tapping. In
general I am opposed to tapping, it is only temporary and severe tapping
damages strings and bridges, all of this for only temporary satisfaction.
Better to fix the bridge.

A 25 cent pitch raise will in general lower the inharmonicity by a small
amount.

Jim Coleman, Sr. (flame suit is handy)


On Thu, 13 Aug 1998, Don wrote:

> Hi Folks,
> 
> I have a simple mind, so I will ask simple (I hope) questions!
> 
> How does Inharmonicity change (i.e. increase or decrease) when:
> 
> A. wire diameter increases
> 
> B. Wire length increases
> 
> C. Tension increases
> 
> D. The strings came over on the ark?
> 
> E. Hammers are *work hardened* (striking sparks, almost *grin*)
> 
> F. Humidity increases.
> 
> G. String is wound, single wrap
> 
> H. String is wound, double wrap
> 
> I. Pitch is NON standard (say flat 25 cents)
> 
> J. Pitch is NON standard (say sharp 25 cents)
> 
> K. Sound board impedance is high
> 
> L. Strings are *set* on the bridges by tapping.
> 
> M. Piano receive a major pitch correction (say 25 cents)
> 
> 
> Regards,
> Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.
> "Tuner for the Centre of the Arts"
> drose@dlcwest.com
> http://www.dlcwest.com/~drose/
> 3004 Grant Rd.
> REGINA, SK
> S4S 5G7
> 306-352-3620 or 1-888-29t-uner
> 
>