Music Trade Review

Issue: 1932 Vol. 91 N. 4

Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
PIANO FACTORY and
PIANO SERVICING
DR. W M . BRAID WHITE
Technical Editor
,
Some Points on
The Analysis of
Tone Vibrations
DR. WM. BRAID WHITE
I
HAD actually started to write, and was
well on in, a discussion of quite another
kind for this month's contribution, when
a letter arrived from Mr. Roy Elliott, of
Hammond, Ind., who disclosed some questions
of such general interest that I felt I could do
nothing else so useful for THE REVIEW this
month as to answer them forthwith. So here
they are, with my answers:
1. How or by what method are the vibra-
tions of a tuning fork counted, so as to de-
termine an exact number per second?
Answer. There are several possible meth-
ods.
I may begin with one very simple
scheme. Suppose that a very light needle be
attached to one prong of a tuning fork. Now
let the fork be held so that this needle stands
with its point downwards, upon or just above
a table, so that when the fork vibrates the
needle must move transversely back and
forth over this surface. Now let a strip of
smoked paper be caused to move underneath
the path of the needle at a definitely known
and constantly maintained rate of travel. If
now the fork be started vibrating the needle
will trace out a wavy or undulating line on
the smoked paper. If the speed of travel of
the paper be known, then the number of the
wavy lines in any given length will indicate
by a simple calculation the speed of vibration
of the fork. For, if the strip of smoked paper
move at the rate of, say, four feet per second,
then in four feet of the paper's length there
will be recorded the vibrations during one sec-
ond of motion by the fork. If the number of
these waves or undulations so recorded be
+40, in four feet of paper, then the speed of
the fork will be 440 per second. And so on.
Another and more accurate method is to
make the fork part of a magnetic system by
placing one of its prongs between the poles
of a suitable magnet. If now the fork be
vibrated while a direct electric current is
flowing through it, the resulting changes in
the magnetic flux can be registered upon a
string-and-mirror galvanometer. If now the
mirror of the galvanometer be suitably illu-
minated, its motions can be recorded photo-
graphically upon a film moving at a known
and constant speed. The recorded undulations
may then be counted and the fork's speed
rated as before.
Another and better method has been util-
ized with great success and remarkable ac-
curacy by Dr. Dayton Miller, of Cleveland.
In this method use is made of the famous
tuning-fork clock of Koenig, as improved by
Doctor Miller. Here, a clock is furnished
with a pendulum which, in fact, is a tuning
fork vibrating 64 cycles per second and
very accurately rated. By suitable reduction
gearing this fork is caused to control the
clock in the ordinary way just as any pendu-
lum would. There is a special second hand
attached to the tuning fork in such a manner
that it makes one complete revolution around
the face of the clock every second, being con-
trolled by the fork, which runs at 64
complete vibrations or 128 oscillations per
second. The clock is now set running and
of
OF
BUCKSKIN.
T h e MOORE a n d FISHER Manufacturing Co.
Deep River, Conn.
THE
Estate
/HANUFACTORER
WHERE CAN YOU GET
PLAYER ACTION
REPAIRS and SUPPLIES
18
compared carefully with a standard clock.
The rate of the tuning fork is corrected by
sliding weights on it. If the clock is found
to be keeping perfect time then it is known
that the tuning fork pendulum is making
actually 128 oscillations per second, no more
and no less.
Suppose now it be desired to rate a fork
to 440 vibration cycles accurately. Since the
tuning fork pendulum is making 64 cycles
or 128 oscillations normally, we make a cal-
culation and find that the number 7 is the
one that goes into 440 with a quotient near-
est to 64. That quotient is actually 62.85.
By an equally simple calculation we see that
if we are to make the clock fork run its
pendulum at one-seventh of 440, or 62.85
times per second, rather than at 64, it must
be adjusted to lose 1 minute 4.8 seconds in
each hour. The adjustment is made, and
tested for correctness by a standard clock.
The vibration of the fork under test is
then watched through a microscope attached
to the clock fork. A bit of chalk on the end
of the fork prong makes this easy, especially
if it be illuminated brightly. When the two
forks (clock and fork under test) are then
set into vibration together, the clock fork
should be running at just one-seventh the
speed of the other. If this is actually so, then
the interposition of the slow upon the fast
vibration will cause the illuminated bit of
chalk dust to appear to the eye through the
microscope as a figure of the kind first
1049—3rd St.
NORTH BERGEN. N. J.
Tel.: 7—4367
MUSIC
TRADE
REVIEW,
A p r i l , 1932
Music Trade Review -- © mbsi.org, arcade-museum.com -- digitized with support from namm.org
THE MUSIC
TRADE
REVIEW, April, 1932
19
noticed and described by Lissajous and named
4. How do you "set" a temperament. What it was originally the humble servant. As
after him. This figure either stands still
is the best one?
things stand there can be no question what-
steadily or else goes through a cyclic change
Answer. Complete information upon every ever of making any change in the system of
of form, returning to its original shape at aspect of tuning, from the theory of the equal equal temperament. That system is fully de-
regular intervals. If this cycle of change temperament to its practical realization in scribed, both in its theoretical and its prac-
takes place in, say, two seconds, then the fork
practical tuning will be found set forth in full
tical aspect, between the covers of the book
under test is one-half a vibration either sharp but simple detail in my book, "Modern Piano I have mentioned.
or flat. The remaining tests required to bring Tuning and Allied Arts," which may be ob-
When therefore one speaks of one "tem-
the fork to absolute correctness can from this tained from the publisher of this paper, and perament" being better or worse than another,
easily be understood.
concerning which particulars will be found in he can only mean that one tuner succeeds
an advertisement in this issue.
better or worse than another in reducing the
2. What law underlies the fact that a
In this column now I shall merely say a requirements of the equal temperament to
reed, as used in a reed organ, sharps when
word on an aspect of the tuning question practical tuning. I am aware that many
it is scraped at the free end and flats when
it is scraped at its center or near its fixed which may not be thoroughly understood by tuners are not accurately informed as to the
my correspondent and which, in fact, many basis of the equal temperament, and do, in
end?
consequence, fail to translate its principles
Answer. Obviously if we scrape the reed, readers may be glad to have cleared up.
What I wish to make clear is that one must successfully into practice. Nevertheless, this
which is to say, file it down and reduce its
draw a definite distinction between "tempera- is a state of affairs which need not exist and
weight at any point, we alter the physical
conditions under which it vibrates. If it be ment" and the practical method of tuning which only does exist because there has never
made thinner at or near its fulcrum, then the according to it. It cannot too clearly be un- been any recognized authority to which to go
swinging part of its body is thereby made derstood, then, that only one system or prin- in search of the necessary technical training
relatively heavier, and so vibrates more ciple of tuning is allowable in the art and or to which to appeal for ultimate decision
slowly. If we file, that is to say, thin down practice of music. This is the Equal Tem- on disputed points. Each practitioner has
or lighten the reed at or near its free end, perament, which has become the basis of the therefore sought his own direction, with re-
we make the swinging part relatively lighter whole modern art of music and which exerts sults not always particularly happy from
an influence constant and decisive, albeit either a scientific or practical standpoint.
and so increase its speed of movement.
tacit, upon all that concerns the tone art, from
On the other hand, fine tuning appears to
3. How is the tremolo effect produced on the making of musical instruments to the com-
the double-reed harmonica? That is to say, position of symphonies. This system has be- be slowly dying out, at least in the piano-
how are the reeds tuned to obtain this effect? come so thoroughly taken for granted that forte field. The healthier condition of the
Answer. It is well known that when two very few persons, even among musicians, organ industry is helping to keep organ tun-
strings, reeds or other tone producers are seem to be aware that it is a mechanical ing in better technical condition, although
tuned very closely together but not exactly in compromise with the truth, adopted nearly organs are usually more roughly tuned than
unison, the sounding of both at once evokes two centuries ago simply because at the time would be tolerable in the case of pianofortes.
On the other hand, there is no good reason
what are called "beats," that is to say, risings of its adoption the arts of musical instrument
and fallings of the intensity of the combined construction and of musical instrument play- whatever for any failure of skill in piano-
sound, at intervals proportional to the differ- ing were relatively crude and imperfect. The forte tuning, save presumably the economic
ence between the frequencies of the two tones. equal temperament might long ere this have position to which all branches of musical art
This beating supplies the tremolo referred to. been superseded ; yet it has not only survived seem for the moment to have been reduced
and which has served to drive really com-
It is obvious that the speed of such a tremolo but has come to dominate the art of which
petent technicians out of the industry.
may be adjusted as required.
BENCHES
ARE BUILT
on quality Standards
AMCO
To Match any Piano
Prompt Shipments
Write for folder and price list.
COWEN Furniture Company
415 W. Superior Street
How These Dealers Avoided the Sheriff
They concentrated their sales efforts and reduced overhead. One big
savings was effected in delivery and handling costs through the pur-
chase of
Chicago
BADGER BRAND
PLATES
BUCKEYE SILL PIANO TRUCKS
III
III
I I I
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best material and finish and are spe-
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American Piano Plate Co.
Manufacturers BADGER BRAND Grand
and Upright Piano Plates
Racine, Wisconsin
Service
Price
For
Quality
Reliability
Continuous Hinges
Grand Hinges
IN Pedals and Rods
Bearing Bars
Casters, etc., etc.
for sure, easy handling of upright's, baby grands and grands. They
positively eliminate scraping or marring of floors. The center wheel
construction allows balancing and turning without lifting.
Equipped with straps of 2 5 in. 3-ply webbing. Only $39- 4" rubber
tired center wheels with 1 /g" face. (Tires vulcanized to wheels) $5
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Send for literature on our X-70
Refrigerator Trucks and piano
hoists and covers.
SELF-LIFTING
PIANO TRUCK CO.
FINDLAY, OHIO
CHAS. RAMSEY CORP.
KINGSTON, N. Y.

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