[pianotech] Bridge agraffes FYI

[Jim Ialeggio]

Will,

Yes I was at Larry's but was focused on other things...I have a call in 
to him.

But my question was a basic phsyics question, not an applied physics 
question.  The "what I thought of the "xyz" piano" is premature .

Let me state my wonder from an different angle. The traditional belly 
systems we are familiar with empirically function within what we assume 
to be an apparent overall system wide impedance level. The impedance 
being determined by rib beam strength, panel compression, bearing and 
its associated string tension, hammer velocity/mass/density, etc. We 
also find emprically, in the traditional bridge pin termination system 
that there are impedance levels below which the board, as Ron O, 
mentioned...does not function musically.

In assigning impedance levels to various belly structures there is an 
implicit assumption, that assumption being that the relative efficiency 
of the pin termination, since its the only model we use in our empirical 
exercises, is not part of the impedance equation, or rather factored out 
because it is a constant. Its considered to be a "constant" because its 
the only model we use. So, my wondering was, if you take this "constant" 
in insert it into our impedance equation as a "variable", by using a 
different bridge termination system with efficiencies different than the 
pin termination, what effect does that have on the system wide impedance?

How much of the impedance equation is actually accounting for force 
needed to make sure the bridge pin termination functions at adequate 
efficiency?

Jim Ialeggio


-- 
Jim Ialeggio	
jim at grandpianosolutions.com
978 425-9026
Shirley Center, MA