Formulae for String Calculations

[Jason Kanter]

Re: Formulae for String CalculationsJD, can you please comment on hex core?

-Jason Kanter
  ----- Original Message ----- 
  From: John Delacour 
  To: Pianotech List 
  Sent: Tuesday, October 03, 2006 3:59 PM
  Subject: Re: Formulae for String Calculations


  At 11:25 am +0200 3/10/06, Ric Brekne wrote:


    My question is, whether or not spreadsheets and string calculation programs generally take into account these end lengths for basic scaling work ?  How important is it to gain the extra accuracy in taking into account these endlenghts, hex/round... etc factors ?


  So far as calculating tension etc., the matters I dealt with in the web page, not at all.  As I explained in the last paragraph, the tiny differences involved are not significant in the basic calculations.  But as regards the tonal quality of the string, inharmonicity etc. these things do matter.  We aim to start the copper about 8 to 10 mm from the bridge pin and leave about 15mm bare at the top bridge.  If I'm working from a rubbing I have taken myself then I will reduce these figures.  The first two pictures below illustrate "Erard whipping" and "Steinway whipping", both of which lend greater purity or clarity to the tone.  Unless we are asked for unwhipped strings, which we never are, we use the Erard or Bechstein style of whipping on all bichords and trichords.  The Steinway syle of whipping takes more time and we charge extra. Steinway stopped bothering to whip their strings some time before WW2 but Bechsteins have always been whipped.


  The third picture shows the end of one of our typical double-covered strings, which, as you see, has a shorter shoulder than is found on most makers' strings.  This also makes a slight difference to inharmonicity, as does the ratio of the two covers.


  So the answer in brief is that these things are irrelevant in your "basic scaling work" but in combination, including other factors too, make a huge difference to the quality of sound produced by the strings.


  JD








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