String tension (was : Birdcage pitch raise)

[Ron Nossaman]

> Why wouldn't it be desirable to reduce inharmonicity ? 

Do you want a piano, or a pure tone generator? The degree of 
inharmonicity isn't particularly a problem. It mostly just 
defines the range of stretch in tuning. The problems come with 
discontinuities in inharmonicity levels at scale breaks, which 
affect tuning, rather than tone.


>Isn't it the 
> reason why one expect a full length grand piano to be better than an 
> upright type ?

No. It's the other 4,000 differences between the two.


> I also don't understand why higher tension shortens the sustain. 

I don't understand why either, because it doesn't. While the 
bass tension and overall tension in pianos I redesign and 
rebuild typically are somewhat lower than the original, the 
top two octave tensions are typically higher because I 
increase C-8 speaking lengths from the original 50mm, to 
53-54mm. Sustain at the top end typically improves not because 
of the tension change, but because the soundboard is built to 
accommodate the scaling.


> 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.

It's not any one thing. It's how everything works together.


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

Too hard a hammer, in a misguided attempt to get more "power", 
can certainly kill sustain.

Ron N