Key Leads and Inertia

[Delwin D. Fandrich]

----- Original Message -----
From: "Sarah Fox" <sarah@gendernet.org>
To: "Pianotech" <pianotech@ptg.org>
Sent: Tuesday, April 29, 2003 4:16 PM
Subject: Re: Key Leads and Inertia
>
> We can see from these conceptual experiments that greater mass in a key
> results in greater energy wastage at higher key velocities.  The lower a
> key's mass is, the more of the pianist's effort that can be put into
moving
> the hammer.

Only up to a point. And that is my point. For every real-world action there
is a point at which no matter how much more energy is put into the key the
motion of the hammer does not change. This point is called action saturation
and is a function of the various key and action component compliences. Once
the point of action saturation is reached the pianist can be replaced by an
800 lb gorilla and no more sound is going to come out. At least not out of
the piano. Well, maybe the sounds of things breaking....


>
> There are other issues at play as well.  If the hammer (barely) moves
before
> the key hits the punching during a hard blow, there is an important
ceiling
> effect to consider.  I'm rather surprised at this assertion, by the way,
but
> I certainly take your word for it.  I tried depressing a key somewhat hard
> while holding the capstan end in place and produced about 1/8" of dip from
> flexion.  Wow!  I guess the remainder is flexion in the action, which can
> certainly be tested statically by depressing the key while holding the
> hammer in place.  What sort of force is required for such a thing?  (I'm
not
> willing to try it on my piano. <grin>)  Anyway, I digress...

It varies from piano to piano. Or from action to action. Actually from key
to key. Due to their shorter keys there is considerably less overall
complience in an action typical to a short piano. Older concert grand pianos
often had key bottom plates, key top plates and long hardwood buttons all to
increase the height of the key lever making them stiffer. Obviously, those
things cost money and with the price of today's concert pianos being only in
the $75,000 to $150,000+ range you can't really expect them to continue
throwing away money like that.


>
> If this effect does in fact occur, even an 800 lb gorilla with a sledge
> hammer couldn't produce a louder note than someone capable of bottoming
out
> the key without the hammer moving (much).  The maximum amount of energy
that
> can be delivered into the action is, again, force times distance -- the
> integral sum of the force applied against the key at each given position,
> times the tiny distance increment traveled -- with the hammer held
> stationary.  To hear this "loudest" note, just lock the hammer in place,
> depress the key completely, thereby "winding up" the system, and release
the
> hammer.

As I said, in every real-world action there is a point....


>
> Could Mr. Olmsted (COWABUNGA BACK, DUDE! ;-) achieve a higher hammer
> velocity and louder note, given that he does a ff workout 1 hr/day?
Almost
> definitely.  However, someone is going to have to design him a stiffer
> action.  Could an amateur such as myself, similarly, produce a louder ff?
> Probably, but someone is going to have to reduce the mass of my keys and
> action parts and increase the mass of my hammers.  (And do we REALLY want
to
> do all this ear-splitting banging anyway?  With all all respect to your
> feelings about "LOUD" pianos, many pieces do legitimatelly require some
> banging.  Sorry, Del! <grin>)

What they legitimately require, I would suggest, is a broad dynamic range.
That is different than LOUD and less loud. It means giving the pianist
control over the bottom end such that the tonal quality as well as the
absolute volume changes. With improved control over the bottom end the
pianist has the ability to develop the full range of the music without the
need to overdrive the piano.

Some years back we were manufacturing a vertical piano with an exceptionally
broad dynamic range. Mostly, partly due to its overall acoustic design and
partly due to its action design, it had an excellent and very controllable
pianissimo. It also had reasonable power. People who played on these pianos,
however, often came away with the perception that they were much more
powerful than they actually were. What I noticed over and over again was
that these were the folks who had discovered how to play softly with good
control. They were exploiting the instruments' broad dynamic range and had
convinced themselves it was really a very powerful instrument.

My point being that if you give your piano an excellent pianissimo voice,
power will take care of itself and you won't have to destroy your fingers,
muscles and joints--or your piano, for that--to get it.


>
> Why force and not velocity???  Putting on my neurobiologist hat for a
> moment, I think there is a very good reason for this.  (Those with
headaches
> can skip this paragraph and the next one.)  Controlling key velocity is a
> slow process.  It requires proprioceptive input to the brain (i.e. finger
> position information), which must be coordinated with motor output through
> the basal ganglia -- a slow, neurologically "clumsy", and inherently
> inaccurate process.  Did I mention SLOW?  I can't overemphasize this.
When
> I'm playing something that has a lot of fast pp stuff, there's simply no
> time for nerve impuses to make the round trip in order to regulate key
> velocity.  (Yes, I've calculated!)  However, there is time to "regulate"
the
> amount of force I apply against a key.
>
> Regulation of force against a key is an output-only process.  It relies on
> output from the cerebellum, which is the part of the brain that learns
> complex and elaborate movements, such as are required for learning piano
> fingerings.  The force applied against a key is directly proportional to
the
> strength of muscle contraction, which is directly proportional to the
number
> of nerve impulses (action potentials) reaching the muscle.  (A bit of an
> oversimplification, but roughly accurate.)  Therefore, relative force is
> directly controllable from the brain without *any* proprioceptive or even
> tactile feedback.  It works as fast as I can move my fingers (which is
> actually as fast as my brain can send bursts of nerve impulses, barring
> tetany.)  What feedback does occur (tactile, proprioceptive, auditory,
> visual) is still important, of course, but it is incorporated into "fine
> tuning" the motor program, much like a machinist on a factory floor tweaks
> an adjustment on a running machine to shave another 1/1000" off of the
parts
> that are shooting through it.

Yes, that's probably what my neurosurgeon friend/client/pianist was trying
to explain to me, lo, these many years ago.


>
> Sorry for the digression.  I think I would really love working with some
> team to redesign the piano action.  There are so many things that could be
> done with modern materials, acceleration optimization through jerk
> reduction, etc., etc.

Not much chance of that. We'll never reduce the jerks....

Del