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<DIV><FONT face=Arial size=2>Hi Mark,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Not sure if your post was directed to =
me or to
others. I do believe (and have argued before) that there are =
impedance
matching issues between a pianist's arms/hands/fingers and the keystick =
-- or
perhaps more accurately the entire action. I remember visiting a =
friend
who was interested to hear a piece I had been working on. I played =
it for
her -- on her spinet. The piano was apparently well tuned and
maintained. But as I was trying to play the thing, trying to eek =
more out
of it with each crescendo -- and as the keys were effortlessly =
bottoming
and the piano just WOULD NOT put out anything more -- well, there were a =
few colorful phrases floating around in my head at the time to =
describe the fine instrument I was playing. I'm sure the piano =
would have
been great for the average 4-year old, but for me, there was a pretty =
awful
impedance matching problem. (And yes, I realize there were also =
limitations
from the longitudinally challenged strings and the short-of-stature
soundboard.)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>There are likewise actions that are too =
massive for
me to play comfortably. If I were a huge person, on the other =
hand, I
imagine I would be able to play those actions with ease -- and my =
friend's
spinet would seem like even more absurd a tinker toy.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The difficulty is not when a note is =
played
softly/gently. That's merely a force issue. Any toddler can =
play a
note gently on any piano. Rather, it's an inertia issue that =
presents
itself during more forceful and rapid playing -- when lots of key =
acceleration
is required. Instead of simply resting one's finger on the key and =
depressing it, one must fly at the key and "punch" it, bounding off of =
it
towards the next key. *That* is where impedance matching =
would become
important.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Mind you, I don't really know how the =
mechanical
impedance of an arm would be characterized and how it would best be =
matched to
the impedance of the action, as referenced to the front of the =
key.
Perhaps our engineer friends could help us with that one. In the =
end, I
would think it important to have some degree of impedance mismatch, to =
aid with
the hand's rebound from the key. If the action's impedance is =
higher than
the arm's (which I would think would be an INCREDIBLY heavy action such =
as we've
not built), then the hand would spring off of the tops of the =
keys. If the
impedance is the same, then there would be little or no "spring," and =
there
would be a sensation similar to running in the sand -- maximum energy =
transfer
per note, but too much "bogging" on each note to have energy to put into =
the
next note. If the impedance is lower, then the key would bottom, =
and the
fingers/hand/arm would be able to "hop" off of the front rail. If =
the
impedance is too much lower, then there would be "nothing there" -- as =
with the
spinet -- and playing the piano would almost be the effortless
experience of "playing" one's dining room table -- or a toy =
electronic
keyboard. I suspect this all comes down to trial and error -- =
personal
taste. Perhaps some table of values could show average =
preferences, but
I'm sure much would depend on the individual.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>As for the center of percussion of the
keystick? New concept to me. The concept makes sense, but I =
don't
really know how to work with it. (Alas, Freshling Physics was the =
extent
of my education in mechanics.) I would think the effective center =
of
percussion of a loaded keystick (i.e. loaded with the top action) would =
be very
close to the capstan anyway. I doubt it would be possible to =
impart that
much energy to the top action by a mere "bonk" on the keystick, absent =
of any
other forces. Put another way if the action were floating in =
microgravity,
and if the key were not mounted in the keyframe, I doubt there would be =
much
"play" from "bonking" the key into rotation against the =
wippen. I'm
sure it requires a deliberate stroke, corresponding to a prolonged =
upwards force
of the balance rail on the underside of the keystick. Thus the =
center of
percussion of the keystick might be a moot point. Dunno... =
I'm
curious to hear what our engineering friends think.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Peace,</FONT></DIV>
<DIV><FONT face=Arial size=2>Sarah</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=mark.davidson@mindspring.com
href="mailto:mark.davidson@mindspring.com">Mark Davidson</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">Pianotech</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, December 18, =
2003 9:00
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Key Inertia</DIV>
<DIV><FONT face=Arial size=2></FONT><FONT face=Arial
size=2></FONT><BR></DIV><FONT face="Courier New" size=2>
<DIV>So what about impedance matching of the key and hand/arm? Or the =
center
of percussion of a key with leads, vs. without?</DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV>There must be some touch issues there also, especially with =
respect to
fast and hard playing. Wouldn't center of percussion move closer =
to
balance rail if springs replaced</DIV>
<DIV>leads? How would that affect touch?</DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV>Thoughts?</DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV>-Mark</DIV></BLOCKQUOTE></FONT></BODY></HTML>