String tension (was : Birdcage pitch raise)

[Philippe Errembault]

Frank and Stéphane,

Why wouldn't it be desirable to reduce inharmonicity ? Isn't it the reason 
why one expect a full length grand piano to be better than an upright type ?

I also don't understand why higher tension shortens the sustain. I would 
have expected the resonance factor to be more important in comparaison with 
the losses by transmitting it's energy to the air or in the metal itself. 
So, shouldn't it lenthen the sustain instead of shortening it ?

Also, about the power... Am I correct, if I say that it give more energy for 
the same amount of vibrations, and so you may have a louder sound, on the 
condition, that you have more weight in your hammer (so your keys will be 
harder) ? I observed that on my piano, the keys are much lighter than on 
some modern pianos.

Or may be, is the louder sound related with the shorter sustain, the weight 
in the hammer having nothing to do with that ?

Philippe


----- Original Message ----- 
From: "Frank Emerson" <pianoguru at earthlink.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Friday, July 13, 2007 8:56 PM
Subject: Re: String tension (was : Birdcage pitch raise)


Stéphane

> 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).

You are correct.  If you tune a string to a higher frequency, all else
remaining the same, you decrease the inharmonicity.  On the other hand, if
in the scale design, you increase the diameter of the plain wires (and core
wires of the wrapped strings), tuning the strings to the "correct"
frequencies, all else remaining the same, you increase the tension, as well
as the inharmonicity.

Frank Emerso