Inharmonicity

[Jim]

Dear Sy:

When I worked for the Balswin factory, I saw various models of the
hamiltons 243 scale where they had changes the scaling radically from
time to time.  They tried one version with no wound strings on the
treble bridge.  The versions which have the hockey stick like shape to
the bottom of the treble bridge have a fore-shortened string length, hence
greater inharmonicity.  You may have seen one of those which had a
straighter treble bridge when you found lower F3 inharmonicity.  Most all
of the 36" spinet Acrosonic pianos had very fore-shortened strings in the
area of G3, but the F3 had wound strings which always had much lower
inharmonicity.  One of the tricks which are in the current SAT manual
show the procedure for using a separate page of memory for tuning the
plain strings on a such a piano, but using another page of memory for
tuning the wound strings.  I could spell that out for you if your
manual doesn't have that dual method which I wrote for them.

Jim Coleman, Sr.



On Sun, 5 Jan 1997, Sy Zabrocki wrote:

> >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 ra
tes 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.
>
> 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 wou
ld 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. Wrappe
d strings I believe have lower inharmonicity in this area.
>
> 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
>