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40
The Music Trade Review
APRIL 30, 1927
The Technical and Supply Department—(Continued from page 39)
is related to their functions as girders and
not to their duties as transmitters.
Down Bearing
There is another side to this matter of arch
or rrinvn on the sound board. It is highly
necessary that the long and powerful steel
strings should be held very rigidly in place.
Firm but not cramping fastening must be de-
vised. Now, since the bridges must vibrate
with the strings, it is evident that some such
structure as is found in the customary system
of staggered pins between which the wire
passes over the bridge is absolutely necessary.
But such construction again always suffers
from the difficulty of maintaining the strings
firm and unyielding, without at the same time
binding their vibratory capacities. Hence it is
found very useful, in fact absolutely necessary,
to maintain what is called "down bearing,"
whereby the bridge on the sound board is
higher in reference to a given point than the
bearings on the plate at both tuning pin and
hitch pin ends. This "down bearing" can be
carried with advantage to almost any height
so long as the construction will stand it. Down
bearing docs not of itself affect the tension
on the wire, but it does affect the down pres-
sure exerted on the bridge by the wire.
Therefore it is obvious that the higher the
level of the wire at the bridge relatively to
its height at the level of the tuning p.in and
hitch-pin bearings, the greater the down pres-
Mirc on the board, and the more it must be
strengthened accordingly. This strengthening
may be brought about by increasing down bear-
ing, and that in turn by increasing crown.
Of course in any consideration of these facts
the tension level adopted for the scale must
also be taken into account. A high tension
scale will impose a greater quantity of down
pressure upon the board than one of low ten-
sion, and it thus results that crown and bearing
must be adjusted to scale.
Purpose of Crown
The foregoing considerations lead us to the
conclusion that the immediate intention of the
crown on the sound board is to provide
resisting powers and that its effect from the
acoustical standpoint is only secondary. A good
piece of evidence to this effect is found by
testing old pianos, which once had well-
crowned boards but which have now been so
long in use that the crowns have been flattened
out. Here we find a loss of sparkling or of
singing quality, at least in relation to duration
of sound and its physical complexity, but by
no means to so great an extent as might be
expected. Often the tone quality of old pianos
is extraordinarily mellow and lovely, even when
sound boards are badly split and otherwise
physically in an inferior condition. Nearly
always it is found that the crowning or arching
of their boards has in course of time been
completely flattened out.
Again, it is perfectly evident that all the
acoustical considerations which apply to a board
convex on the bridge side would apply also
to one made concave on that side. The
resisting powers would not in the least be
weakened, since an arch resists a stress upon
FAUST SCHOOL
OF TUNING
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Organ and Player Piano
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Tuners and Repairers
Our new illustrated catalogue of Piano and
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2110 Fairmount Ave.
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its apex, no matter how the latter be situated
relatively to a point of orientation.
Thus we may fairly conclude from this line
of reasoning that the sound board of the piano
is crowned primarily because it requires re-
sisting powers which it could not otherwise
possess. And if this be a reasonable conclusion,
then we have to ask ourselves whether we are
entirely on the right track in looking upon the
system of crowning as possessing unique
acoustical value. This is a matter which needs
further investigation.
Steel
Sonic time ago, it may be remembered, I ven-
tured some observations upon the possibility
of a sound board made of steel or of some
other material other than wood. As the rapid
destruction of the nation's forest resources
continues, the question is bound constantly to
assume greater importance. There is no im-
mediate prospect of obtaining tropical woods
equivalent in physical properties to the picoa
alba, which, in its American or its European
form, alone satisfies the acoustic requirements
of piano makers. Thus, when the native sup-
plies have become entirely or almost entirely
exhausted, when at least prices have become
prohibitive while quality has become impossible,
it will be necessary to go to Europe. But
even the European supplies are distinctly
limited in quantity, and prices will be very
high whenever the American demand becomes
pressing, as it necessarily will in due time.
Then questions of substitutes will be burning
questions indeed. Substitutes will not be found
among the woods. They must be sought
among the metals.
Of all possible metals steel probably presents
the most satisfying array of qualities. Its
transmitting properties are very high and it
does not suffer from the defects which the
run of grain imposes upon spruce. Its one
great defect arises, of course, from the very
high rigidity of its physical structure, which
endows it, whether in form of rod, filament or
sheet, with the power of periodic vibration.
A sheet of steel would, of course, have a period
of its own and would reinforce excessively
sounds of periods equal to its own or mul-
tiples thereof. This effect, however, can be
overcome in all probability by building the
sheet in zones separated the one from the other
by circular concentric integral ribs, or by a
construction of similar kind.
ll is evident that here, too, is a field for
investigation which promises most valuable re-
sults.
Historical records show that metal sound
boards in one form or another have been tried
out by many makers. Not only so, but many
other substitutes, such as parchment, have been
tried. The object in every case has been to
eliminate the many difficulties of building a
good wooden board and the many troubles to
which such a board is necessarily subject. The
experiments indeed have always been aban-
doned, but it is extremely probable that this
abandonment has been mainly due to the feeling
that, after all, the results gained were no bet-
ter than those yielded by the ordinary con-
struction, and that, therefore, so long as
the supply of suitable spruce at suitable prices
was assured, there was no cause to make any
radical changes. These favorable conditions,
however, are now ceasing to exist and the
whole situation is changing. Hence these re-
marks.
Correspondence
is solicited and should be addressed to William
Braid White, 5149 Agatite avenue, Chicago, 111.
Opens New Repair Shop
MARION, O., April 25.—Will T. Blue, piano
tuner and technician, has opened a new piano
repair shop at 197 South State street, this city.
Mr. Blue has been identified with the piano
business for many years.
Tuners Carrying Case
LIGHT—COMPACT—SERVICEABLE
Weighs Only 6 Pounds
Outside measurements 15J4 inches long, 7
inches wide, 8 inches high.
No. 150—Covered with seal grain imitation
leather. Each $13.00
No. 200—Covered with genuine black cow-
hide leather. Each $20.00 F.O.B. New York.
When closed the aluminum
trays nest together over the large
compartment, which measures
137/8" x 6" x 4". The two left hand
trays measure 13^" x 2*4" x iy B "
and the two right hand trays 137/£"
x 3^4" x \y%. The partitions in
right hand trays are adjustable or
may be removed. Case is fitted
with a very secure lock and solid
brass, highly nickel-plated hard-
ware.
We have a separate Department to take care of special requirements
of tuners and repairers. Mail orders for action parts, repair materials,
also tuning and regulating tools are given special attention.
Hammacher, Schlemmer & Co.
Piano and Player Hardware, Felts and Tools
-vr.A'.'C'. '
New York Since 1848
4th Ave, at 13th St.