String tension (was : Birdcage pitch raise)

[J. Stanley Ryberg]

Hello, Stephane!
   
  I'm really only jumping in here to ask a question which may be appropriate at this point.  Is it not true that the increase in thickness/mass needed to raise the tension of a string at a given length also makes the string less flexible?  And is this not a factor in the increased inharmonicity which seems to be a characteristic of high-tension scales?  That has been my understanding, but I'd be happy to be corrected if that is not the case.
   
  Regards,
   
          Subject:  Re: String tension (was : Birdcage pitch raise)
  Hello Frank, Philippe.

I know that it wouldn't be the first time that I would have to change an idea that I have had for a long time, but I'm still thinking right now that everything else being the same, a string with more tension has less inharmonicity.

  Intuitively, you can hear the bell like sound (that is with partials much deviated from the theoretical geometric progression, so lots of inharmonicity) of a string whose tension you release.
That being said, to achieve a desired pitch with a string of a certain length, the thicker the diameter, the higher the needed tension.  I believe (uptil now) that it is the extra mass of the thick string (not the tension) that is capable of storing more energy from the (thicker) hammer, and through a well designed impedance coupling with the board, producing louder sounds.

  In my experience, when you raise the tension of a certain string, you raise of course the pitch of the sound, you lower the inharmonicity (which is not necessarily desirable) and you shorten the sustain (which is often not desirable).  No increase of volume, as far as I could hear.

  I did extensive what if tests with 19th century Bechstein pianos, and ascertained that the designer chose exactly the good tension figures in his scalings, achieving best sound, which is best inharmonicity pattern (gives nice colours and helps, yes helps tuning ET) and best sustain values, for wire equivalent of Röslau blue today and diapason of A4 = 440.

  According to controversial Roberts formulas, those tensions average between 30 and 45% of supposed breaking strain, with a drop in the low tenor plain strings, and higher figures in the wound bass strings.

This is what I think now, until someone makes me doubt, in which case I'll contemplate thinking twice.

Best regards,

Stéphane Collin.



Stan Ryberg 
Barrington IL 
jstan40 at sbcglobal.net
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