Improvements in Musical Instruments, specially applicable to their Soundboards.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Musical Instruments, specially applicable to their
Soundboards.
I, Dr. ALFRED SPRINGER, of 387, West Fourth Street, Cincinnati, Ohio,
United States of America, do hereby declare the nature of this invention, and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :--
This invention relates to sound-boards of stringed musical instruments such for
example as pianos, violins, guitars &c.; one of its objects being to produce an
instrument of more sonorous and pleasing tone qualities than those commonly
in use.
In the class of instruments herein specified, the initial tone produced by the vibration
of a string is comparatively weak but is reinforced by the sympathetic vibration in
unison therewith, of a large surface of other material. Such class presents no analogy
to those instruments (such as flutes, horns, bells &c.) in which the sound is produced
either by the intermittent motion of an enclosed column of air or by the vibrations
of a large plate or surface produced by impact of a striker, which instruments do not
require the intervention of a reinforcing sound-board acting sympathetically. In
instruments having a sound-board the quality of "colour" of the ultimate tone
produced, as also its relative amplitude, depend in large measure upon inherent
characteristics of the material composing the sound-board apart from mere structure,
as well as upon constructive features. At present the universal practice is to
construct such sound-boards of wood in which the range of selection is comparatively
limited as most woods are unsuited to the purpose. Attempts have been made to
construct such sound-boards of metal but these efforts so far as I am aware have
heretofore proved failures, and are classed by expert authorities and historians of
the art as '
vagaries" inasmuch as the vibrations produced by the metals heretofore
employed are sharp and interfering, producing a disagreeable tone-quality commonly
known as "metallic."
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The cause of this is defined by writers of acknowledged authority as a general
characteristic of metals, consisting in their peculiar capacity for the maintenance of
comparatively continuous and uniform higher upper partial tones
"which in most
metals are
"inharmonic secondary tones" resulting in a peculiar quality termed
poverty" arising from the comparative strength of these upper partials as related
to the prime tone. Indeed, previous researches and experiments in this direction
have tended to discourage all attempts to employ metals for such constructions, for
the reason that those metals heretofore regarded as of finest and most uniform
consistency produce these higher secondary tones most freely and of greatest
duration.
I have however discovered in aluminium a latent quality which adapts it in a
useful degree to the construction of sounding boards and that it differs from all other
metals so far as I am aware in respect to the absence of comparatively continuous
and uniform higher partial tones which give the tone-colour called "metallic" and
further that it also possesses an elasticity capable of sympathetic vibration uniformly
through a wide range of tone-pitch which renders it in this respect superior to wood
even in the best old violins and other instruments of that class.
A violin which I have constructed of this metal and in a manner hereinafter
described produces a true violin tone characteristic of the best old instruments. The
peculiar tone-colour produced by a violin thus constructed so far resembles that of
wooden instruments that it may be used in the orchestra or in smaller combinations
with good stringed instruments to great advantage without detection of difference
except as a matter of degree in superiority of tone qualities of the same general
character.

page_text: Moreover the tone produced is more powerful more sonorous and of greater
carrying capacity than that of a wooden instrument of the same relative size and
is free from those imperfections in certain portions of the scale which are known
as "wolf-tones."
This invention then consists primarily in a sound-board or sound-body for a
stringed musical instrument composed wholly or in part of aluminium or its alloys,
as it is obvious that such alloys might be employed for structural reasons and
possess the vibrating qualities of the aluminium according to the proportion of
that metal. In fact the commercial aluminium which I have used in the constructions
above referred to contains a certain proportion of other substances such as iron,
silicon &c. imparting certain qualities of hardness and strength without materially
impairing the vibrating quality.
A second feature of this invention relates to the mode of constructing a sound-
board or body for instruments of the class herein designated. So far as attempts
have been made to produce such structures of metal, the analogy of wood constructions
has been followed in fitting together separate pieces and uniting them by rivets or
solder. The general failure to produce satisfactory sound-boards of metal is
attributable not only to the imperfect tone-qualities of the metals employed, but
also to some extent to the above described method of construction, in which the
vibrating quality is impaired by the inherent imperfection of joints. This is for the
reason that the quality and power of such sound-boards--as indeed of all sound-
boards depends somewhat upon the perfection of the union established between the
several parts constituting the board or boards and its or their supports.
This feature of this invention then consists in a sound-board or sound-body formed
complete as a homogeneous structure without contact joints, the joining of separate
parts constituting the sound-board or sound-body of the instrument and the necessary
connections and supports, being effected by welding the parts together at their line of
contact by the employment of the electric current, whereby said parts are united by
fusion forming a homogeneous structure.
This invention is illustrated in the accompanying drawings in which
Fig. 1 is a longitudinal section of a violin constructed according to this
improvement.
Fig. 2 a cross sectional view of the same.
Fig. 3 a plan view of a piano sound-board constructed according to this
improvement and
Fig. 4 a longitudinal section of the same.
In the application of the invention to the construction of violins the instrument A
is constructed in the usual form with its top a, its bottom b, and its sides c of sheet
aluminium cut to proper form and bent and fitted together to form the body of the
instrument when suitably united. The top and bottom of the instrument are formed
of sheet aluminum brought to the proper surface contour by pressure in moulds or
by hammering over a suitable former or in other convenient manner. In this
process the metal is to some extent brought into an improved condition of elastic
tension re-acting favourably upon its vibratory quality. The sides are also cut in
strips from sheet aluminum bent to the desired contour and accurately fitted to
the top and bottom. The union of these parts is effected by the process of electric
welding, the process and the apparatus used therefor being the same as employed
in the arts in other connections and therefore requiring no specific description
here.
By the action of the electric current, the poles of the apparatus being moved
along the line of contact, the contact surfaces are fused together thus bringing the
whole structure into homogeneity.
The neck d together with the finger-board e and perhaps other extraneous parts
may also be formed of metal preferably hollow and united to the body of the
instrument in a similar manner.
In the case of the piano sound-board P a continuous sheet is formed of the metal
and united to its marginal support, preferably a continuous bar P of metal formed

page_text: to the outer contour of the sound-board in a similar manner. The piano sound-
board may be reinforced by a second sheet of metal secured to the under side of the
marginal support as indicated at P' by dotted lines in Figure 4, making a box-
structure corresponding to the violin body.
It will be readily obvious that while the full benefit of the invention is best
realized by employing both the features hereinbefore described yet each feature of
the invention is susceptible of independent use, realizing a certain degree of
advantage. Thus in respect to the employment of aluminum solely for its vibratory
qualities independently of mere structural features, a sounding board of this metal
may be employed and united to supports of wood or of another metal by the ordinary
processes of riveting or soldering. For example I have obtained fairly good
results from an ordinary wooden violin from which the wooden top or sound-board
proper had been removed and replaced by a top of sheet aluminum formed as
described and united to the body of the instrument by rivets or screws.
Also in respect to the separate employment of the second feature of this invention
to wit, the welding of metallic parts together to form a homogeneous structure, a
violin constructed of steel or other elastic metal would be much improved by being
united to its marginal support or supports by fusion as hereinbefore indicated.
I do not therefore confine the claim of invention to the use of both features
designated in combination but claim each feature separately.
As aluminium has been alloyed to some extent with other metals producing
variations of colour texture &c. it is practicable to use such alloys in carrying out
this invention thereby obtaining its benefits in greater or less degree.
It will be readily understood that apart from its improved tone-qualities aluminium
possesses in common with other metals certain advantages over wood in its incom-
bustibility impermeability to moisture and comparative freedom from liability to
injuries such as splitting and warping to which wooden instruments are subject.
This metal however besides its superior tone-qualities is superior to most other
metals in its untarnishability and its lightness (diminished weight) peculiarly
adapting it to the uses herein indicated. Its extraordinary strength and tenacity
are also of value in this connection as the thickness of the sheet employed may be
reduced to such limits as to obtain the utmost amplitude of tone-vibration without
impairing the tone-quality or materially affecting the strength of the instrument as
a mechanical structure.
A special advantage realized in this connection by the electro-welding of the
contact joints, over other processes of uniting metals, is the fact that the heat
required for the fusion of the contact edges is confined to the point of contact and
being due to the electrical resistance at such point instantly ceases when the edges
unite by fusion, whereby the elastic temper of the metal upon which its vibratory
quality in respect to the production of musical tones depends is perfectly preserved
whereas in soldering and particularly in brazing the temper is impaired or
destroyed.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. A sound-board for a musical stringed instrument composed wholly or in part
of aluminium or its alloys substantially as set forth.
2. A sound body for a musical instrument composed of metal homogeneous and
without contact joints substantially as set forth.
3. A metallic sound-board for a musical instrument embodying one or more
vibrating boards united integrally with the marginal or other supports by fusion
in situ substantially as set forth.
4. A sounding body for reinforcing the tone of a string or other tone-producer
consisting of one or more sheet metal plate or plates welded to the marginal or
other supports into a homogeneous structure without extraneous fastenings
substantially as set forth.

page_text: 5. As a new article of manufacture a violin or other stringed instrument or sound-
board for a stringed instrument composed of aluminium either pure or alloyed
secured to its marginal support by welding substantially as set forth.
D
1
101 T
1001
W. P. THOMPSON & BOULT,
Agents for the Applicant.