Briefly, the Welte recording methods described here recently will
not work.  The carbon rod does not reliably measure velocity.  Key
displacement is not always full travel, even at fortissimo.  All
observers of well regulated reproducing pianos are acquainted with the
phenomena of the keys just barely depressing when a very short note is
played. Actually, the key may get depressed further when a long soft
note is played.  To measure hammer velocity, which is what is really
necessary, the instantaneous rate of key movement from the _at rest_
position is necessary.  The systems previously described here cannot
do that.

Dr. Clarence Hickman realized that hammer velocity is the secret
to measuring piano dynamics.  Hammer velocity is the result of key
movement, whether the key is fully depressed on not.  The Hickman
article describing the spark chronograph, talks of the necessity of
measuring the hammer velocity.  That article is in the MMD Archives.

The fact that no one has yet to duplicate a reliable version of the
Welte machine strongly suggests that while it might have functioned as
a note recorder, and crudely generalized key velocity, it was totally
inadequate to measure dynamics in an accurate manner.  The data
collection point is in the wrong place.

Bob Taylor