Key Leads and Inertia

[Delwin D. Fandrich]

----- Original Message -----
From: "Classic Touch Ent" <classictouchent@comcast.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Tuesday, April 29, 2003 5:53 AM
Subject: Re: Key Leads and Inertia


> Greetings Del,
>        Thanks for resurrecting key bend energy loss as an issue. Is it
> primarily energy lost or does it amount to energy delayed? Both? Is the
> 'delay' sufficient to amount to 'loss"? How quickly does the key
> 'remember' it s original shape?

It is mostly delayed. But, if it is delayed until after the hammer has
struck the strings it's a moot point.


> There's certainly an interesting
> difference in the timing  and efficiency of the transmission of energy
> in a slow velocity key blow vs. max velocity blow. How much does a key
> stick bend at full blow with 'no stack/no lead'? If we work to stiffen
> a key I suspect new challenges in the way of action
> fragility/durability will arise. As a pianist it has not escaped my
> notice that I don't always get a bigger/louder sound from maximum
> acceleration of my paw vs. say 'dropping' my paw from 6-12" above the
> keys.

My own work in this was fairly limited and my results consisted mostly of
pretty curves on a dual-trace storage oscilloscope. An almost identical
set-up was used by Harold Conklin at Baldwin with similar results. His study
was much more detailed and disciplined than mine but the specific results
and reports are/were proprietary to Baldwin and I don't have access to them
any longer.

One thing I did find was that to increase real acoustical power it was
necessary to increase the product of hammer mass times velocity. This could
not be done by simply increasing hammer mass--the bending and compressing of
the various action components would simply reduce hammer velocity. The most
direct and effective option was to increase key stiffness. But, herein lay a
problem. As key stiffness increases so does wear and tear on the pianists
fingers and joints. It seems there is a balance between action dynamics and
the human hand that cannot be ignored without some physical consequences.
The limitations of power lie not in the instrument but in the performer. In
the quest for ever-more massive levels of sound power the battle has been
won--by electricity. That being a given, perhaps it's now time to get back
to building piano-forte's.

And now, allow me, if you will, to toss out a little side issue here:
depending on the level of power desired by the performer, i.e., pppp to ffff
or whatever, there is a considerable variation in the amount of time delay
between the moment the key is initially struck and the moment the hammer
impacts the string. This time delay can amount to some several milliseconds
and it is not shared by most other orchestral instruments. Now, considering
that the human brain only has so much computing power and speed and the
pianist is generally exceeding that processing speed during fast orchestral
passages, what is the mechanism by which that performer compensates for this
varying and complex time lag so that the sound of the piano comes out just
right with the rest of the orchestra?

Del

Delwin D Fandrich
Piano Designer & Builder
Hoquiam, Washington 98550 USA
360.532-2563
360.532-6688
pianobuilders@olynet.com