Re: Wire Size Calculation
By Douglas K. Rhodes
Greetings:
The Klepac chart from Travis' Guide to Restringing that Terry Smythe posted may be as good a place to start as any, if the piano in question has no strings and no other data is available. After all, this kind of *rule-of-thumb* approach is what many manufacturers used for years because they would not or could not spend money on their own research.
Just for fun, I plugged those numbers into my spreadsheet adaptation of Dave Roberts' formulas. I used Klepac's chart to modify and then evaluate an existing scale for a medium sized grand that I had rebuilt recently. The resulting *Klepac* scale would certainly be acceptable if no other data nor means of derivation were available. The piano would not implode from excess tension. However, the inharmonicity and loudness progressions are pretty sloppy without a whole lot of *fine tuning*, which the Klepac chart, of course, does not supply. And, Klepac's chart offers no assistance whatsoever in the matter of wound strings, nor the critical transition between wound and plain wire strings.
One can begin to appreciate that the higher quality pianos of yesteryear, the ones that sound good, are stable, and easy to tune, became so through a tremendous amount of experimentation at the factory. The scales were derived empirically, not by mathematical modeling, nor by simple adherence to rule-of-thumb scaling schemes.
When Travis first wrote his book, the *only* quantifiable factor available to him was tension, and that only for plain wire strings. Inharmonicity was certainly recognized, and at least partially understood, but accurate formulae for _predicting_ inharmonicity (nor any other quantifiable audible factor) did not exist until fifteen or twenty years ago. The rule-of-thumb approach will get you in the ballpark, but will not enable you to optimize the scale to any degree whatsoever. Where Travis' book _is_ invaluable is in the wire gauge data that he had gathered for so many American pianos. That data doesn't really exist anywhere else in such concentrated form.
Cheers
Doug Rhodes
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(Message sent Thu 25 Apr 1996, 19:14:00 GMT, from time zone GMT-0700.) |
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