Music Trade Review

Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
MARCH 25,
1922
9
THE MUSIC TRADE REVIEW
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The Measurement of Hammer-velocity Offers the Player Engineer a Wide
Field for Active Experimentation and the Resultant Discoveries Will Do
Much to Evolve Some New Principles of Pneumatic Construction and Design
Two fields for experimentation and research
lie before the pneumatic engineer, neither of
which has as yet been treated with merited re-
spect. It is not at all likely that the mechan-
isms for tone production in the piano will be
subjected to any special modification through
the interposition or influence of the pneumatic
player mechanism, and it is quite certain that
the especial mechanical advantage of that method
—the dynamic value of the variable hammer-
blow—will always be preserved. It therefore be-
comes at once obvious that the pneumatic mech-
anism ought to be developed with especial refer-
ence to this feature and with the purpose of tak-
ing the utmost advantage of its peculiarities.
Already much excellent work has been done
in respect of obtaining variations of air-pres-
sures in the pneumatics, whereby the velocity of
motion of the same in action may correspond-
ingly be varied, either at the will of the human
operator or by automatically controlled pressure-
regulating devices. But there are two incidental
fields which are not yet developed to any extent,
and which deserve a great deal of attention. One
of these relates to the weights to be moved dur-
ing the action of operating the hammers. The
other relates to measurement of hammer-velocity
and the determination of power consumption in
obtaining such velocities.
Measuring Velocities
Every engineer who has examined the piano
action can see at once that the strength of the
hammer-blow, which is variable in (theoretically)
an unlimited number of degrees, is a function of
the velocity of travel of the hammer between the
position of rest and the string. Nor is any argu-
ment needed to convince an engineer that the
only possible way of discovering how exactly to
command these velocities through appropriately
controlled pneumatic mechanisms is to begin by
measuring the velocities themselves. First we
must know what speeds produce certain results,
and then only can we determine the precise de-
sign of the mechanism to be employed in pro-
ducing them.
The player mechanism as now designed is, of
course, the product of empirical experiment. It
performs its functions very well, but it should
perform them even better. At present, when the
human performer is at the pedals, controlling the
air-pressure from moment to moment, according
to the musical needs of the composition he is
interpreting, no great exactness of design is im-
perative. The performer acts in one way upon
the piano and exerts a control quite as powerful
as that exercised more directly by the manual
pianist. But when we consider the automatic-
expression player mechanisms and observe how
necessary it is to eliminate all chance for error
and to take advantage of every mechanical or
physical fact that may assist in making the auto-
matic control more perfect we see how the be-
havior of the piano action under all conditions of
motion ought to form the subject of a special re-
search for the purposes and on the behalf of the
player mechanism.
The Two Principles
The problem involved in measuring the
velocity of a hammer's motion is not very diffi-
cult in principle. It may be considered in two
possible ways. On the one hand, the time inter-
val between the termination of the period of rest
and the contact with the string may be deter-
mined electrically, by means of the regular
chronoscopic system. On the other hand, advan-
tage may be taken of the rebound of the hammer
to test the velocity index by measuring the
amplitude of the rebound. It is obvious thai
much can be said for each of these principles.
The electric measuring system has the advan-
tage that it disturbs least of all the mechanism oi
touch and that therefore the pianist is less likely
to register erroneously or interpret imperfectly
through exposure to unaccustomed and defective
instrumental conditions. But it is a question
whether any form of measurement involving the
calculation of time intervals is as convenient as
one based upon mechanical motion. Of course,
if a series of time-interval registrations arc taken
during the performance of a piece of music the
resulting figures can be platted on a graph which
will show clearly the course of the interpretation
as concerns dynamics. In this way a valuable
check may be obtained upon the action of the ex-
pression mechanism of the player.
(Continued on page 10)
Simple, Accessible Design
Good Workmanship and Materials
Automatic centralizing and
tracking device
Double-acting motor
3-piece valve
Metal tubing, cloth covered
Hardwood construction
"Built to play"
SPECIFY "Pratt R e a d "
OVER 48,000 ALREADY IN USE
The Pratt Read Player Action Co.
Main Office and Factory, Deep River, Conn.
Foreign Office, 21, Mincing Lane, London.