Inharmonicity

[Sy Zabrocki]

>From Sy Zabrocki

When tuning aurally for many years I seldom seriously thought much about =
inharmonicity. When tuning a good piano the temperament beat rates, =
tests etc. came out good and you were aware the piano had low =
inharmonicity. When on a "funky junky" the beat rates needed compromise =
all the over the place and you were aware of high inharmonicity. When =
learning this work we all receive the usual dose of information =
concerning inharmonicity and live with it the best we can.

Six years ago I purchased a Sanderson Accu-Tuner (SAT). Now we are =
accurately measuring for stretch factors, intervals, octaves etc. You =
began to become more aware of inharmonicity. About nine months ago I had =
Sanderson update my SAT to the FAC feature. During the last few months =
I've become even more curious about certain aspects of inharmonicity.=20

During this post I would like to talk about only the (F) number and not =
the (A) or (C). The stretch number of F3 is defined as the difference =
between the fourth and eighth partial. This number can vary from #4 to =
#25,  more than the A and C.

Consider the F3 stretch numbers I've found on the following pianos =
recently.

No. 1--Baldwin Studio 243      Built 1976       Stretch #25.5
No. 2--Baldwin Studio 243      Built 1976           "        21.5
No. 3--Everett Studio              Built 1979          "        11.0
No. 4--Baldwin Studio 243      Built 1955           "        11.0
No. 5--Acrosonic Spinet         Built 1954           "        11.0

I'm not sure these numbers are constant on all of these models. These =
are some I measured the last week or so while thinking about this topic.

I became curious why the newer Baldwins have a higher number than the =
1955 model. Can we assume the older scale was a better scale? The string =
length couldn't have changed much. String length on the Baldwin and =
Everett would be about comparable. Why would the Everett have a lower =
number? Why would the older Acrosonic have a lower number then Baldwin =
studios?

Consider the older and new Baldwin which would probably have the same =
string length. What factors would cause so much difference? Wire size =
and tension difference could probably cause this difference. Only the =
Acrosonic has wrapped strings on F3. Wrapped strings I believe have =
lower inharmonicity in this area.=20

As stated above, using the SAT causes you to become acquainted with =
various pianos and their amounts of inharmonicity. It causes you to =
think about inharmonicity more often. It's amazing how the SAT can do a =
pretty good job on one of the funky junkies. You know it jumbled up =
those beat rates as best as anyone could do and you're glad you didn't =
have to do it. I treasure that little blue box.

Sy Zabrocki RPT
Billings, MT