Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
JUNE 24,
1922
9
THE MUSIC TRADE REVIEW
The Arrangement of the Pneumatic Stack in Player Grands Has Given the
Designers of Player-Pianos Several Rather Complicated Problems to Solve—
The Merits of the Super-keybed Position Over the Under-keybed Position
The interest which is being generally expressed
in trade circles in connection with the reproduc-
ing piano leads inevitably to consideration of the
technical methods of fitting the pneumatic action
to the grand, since so many of the latter are now
being used for player purposes. There appears
now to be some general agreement among de-
signers to place the stack below the keybed and
to hide it from sight as best they may by the
rather clumsy expedient of a moulding run
around the bottom of the case.
It needs little experience to perceive that there
are grave objections to this so generally adopted
method. Since, however, these objections appear
to be very little understood or appreciated some
statement of them now will undoubtedly be
useful.
Under-keybed Objections
The under-keybed position of the pneumatic
stack requires the keybed to be cut with a groove
of at least one inch in width from end to end.
The keybed is thus weakened and rendered less
able to resist warping or twisting.
The stroke of the pneumatic is given against
the underside of the keys under the capstan
screw positions. The whole weight of each key
must therefore be lifted, although there is no
compensating advantage whatever. Furthermore,
of course, this means that the keys must always
move up and down when the player is at work.
The stroke of the pneumatics upon the keys
involves a great deal of friction, which detracts
from the repeating power, the delicacy and the
responsiveness of the pneumatic action.
The weight of the stack suspended from the
keybed tends to warp the latter. If an attempt
is made to suspend this weight from the legs of
the piano, as is done in some cases, the immediate
objection is indeed removed, but the task of tak-
ing down the pneumatic stack is rendered much
more difficult.
Furthermore, if and when a double-valve action
is desired the problem of housing this in the sub-
keybed position is very difficult, in view of the
space requirements.
The sub-keybed position is also unsightly, as
was said above, and its only strength lies in the
fact that it demands no elaborate change in the
super-keybed arrangements. Yet, as a matter
of fact, grand pianos which are to have player
actions in them are to-day mostly designed with
extra-long keys, so that the spool-box may be
placed above the keys. This being the case the
task of providing the room needed for the stack
as well is not very much greater, while there
are compensating advantages of much impor-
tance.
Super-keybed Advantages
The advantages of the super-keybed position
had better first be considered, and we can then
talk about the difficulties or disadvantages, if any.
The modern pneumatic stack, built on the. sin-
gle-valve system, takes up much less room than
the older models did, and can be accommodated
in behind the fallboard of the grand piano above
the keys by the addition of about two inches in
the length of the keys, provided that the shape
of the fallboard is changed somewhat.
Now if a pneumatic stack is made in this way
the first great advantage is that the weight of
the keys is eliminated. The pneumatics co-act
directly with the piano action, and in the latter
one change only need be made. This change,
indeed, is important, but it has already been by
several inventors anticipated. Several patents
in the U. S. A. and abroad have been taken out
for inventions designed to care for it. The
change in question relates, of course, to the rais-
ing of the dampers, which arc normally oper-
ated by the backs of the keys. When the keys arc
not being utilized the dampers must be raised
by an additional lever on the piano action.
A second great advantage of the super-keybed
position lies in the connection between stack and
tracker-bar. If the two are in contact with each
other the whole difficulty of piping between the
tracker-bar and the stack is rendered extremely
simple and becomes no difficulty at all. On the
other hand, when the stack is below and the
tracker-bar above, the task of pneumatically con-
necting them is extremely difficult. In one case
we know of, the tubes are gathered together in
two groups, one for each half of the action, and
are then led into a hardwood perforated block
behind each keyblock.
This block fits on
(Continued on page 10)
a
> n o i : i ">
Players Built of Hardwood
are naturally tighter, more durable, and
less susceptible to climatic and atmos-
pheric conditions than those made of
gum or poplar.
,. :i .„ t
Pratt Read Player Actions,
built of clear, seasoned maple and
birch, stand up and stay sold, year in
and year out.
The Pratt Read Player Action Co.
Main Office and Factory, Deep River, Conn.
Foreign Office, 21, Mincing Lane, London.