Ludek:
Impedance is not the easiest to understand.
An object with high impedance has more resistance to being vibrated or moved. As a result the energy being imparted to the object will not be transmitted as quickly.
I usually lower the impedance of the upper registers because I personally find that the default settings permit the upper registers to vibrate too long (the sound holds longer than I think a grand piano does). OR - this may be because of my playing style.
At first Impedance seems counter intuitive - but it's not:
By lowering the impedance of the high notes, the energy is transmitted more quickly from the strings to the soundboard. Since the same amount of energy is being transmitted, this results in the energy being sent in a shorter period of time, and the notes have a quicker decay.
I believe the impedance (for example) can only be changed note by note in the Pro version. Fortunately I have this version so I can make my piano sound the way I want.
As an aside to this, I believe that if it was physically possible to make the treble strings longer (and have more sustain), piano makers would have done this. But to make a string longer and maintain the same pitch would require much higher tension in the string. There are two problems here - the piano frame would have to be much stronger to resist the forces, and there comes a point where steel simply cannot be made strong enough to withstand the tensile forces. One might say, "well make the strings thicker", but obviously this fails as thicker strings vibrate at a lower frequency.
There is another property of steel that Joe Felice can explain better than I: Steel under constant stress exhibits "stress relaxation". If you tension a steel string (or a strand in pre-stressed concrete), and measure the tension, then after a period of time, measure the tension in the string again, you will find that the tension has dropped - the steel has "relaxed" - it has deformed under the high stress. In a piano, this would require constant tuning.
The modern grand piano is a miracle of compromises with everything pushed to the limit.
Glenn
__________________________
Procrastination Week has been postponed. Again.
