Note: Descriptions are shown in the official language in which they were submitted.
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A HYBRID STRING MUSICAL INSTRUMENT AND A MEHTOD OF CONSTRUCTING THE SAME
FIELD OF THE INVENTION
The present invention relates generally to musical instruments and
particularly to a hybrid
string instrument combining a modified, ordinary acoustic guitar with a second
string instrument of
a comparable size or smaller, such as a banjo, a ukulele, or a mandolin.
BACKGROUND OF THE INVENTION
The attractive richness of a multi-player, multi-instrument musical
performance is impossible
to replicate in real-time in a solo performance. To add tonal variety to their
performance,
musicians who are proficient on more than one instrument may switch between
instruments for
different pieces or compositional segments, but must do so during sufficiently
long intervals. A
satisfactory solution to the challenge, facing a soloist, of rapidly and
seamlessly switching between
musical instruments has proven elusive.
In the realm of plucked string instruments, to facilitate, at least in effect,
the transitioning
between two or more such instruments, hybrid instruments have been devised,
which may be
categorized broadly into three main types, as follows.
Hybrid string instruments of the first type feature a unitary body and
soundboard commonly
shared between multiple necks. An example of an instrument of this type is
patent US1634730A
(Travaglini; 1927), which teaches the merging of a guitar body and a banjo
body as a unified
instrument. Patent US1828315A (Cavicchioli; 1931) is another example,
featuring a similar
merging of two stringed instruments, with the addition of an adjustable
partition which separates
the common sound chamber into two compartments.
A serious disadvantage of hybrid instruments of this type is that their common
soundboard
restricts how distinctively the merged instruments sound.
Hybrid string instruments of the second type feature a host instrument into
which another,
typically smaller, instrument is fully or partly embedded, or onto which it is
externally affixed, each
instrument retaining its own (possibly modified) body. Patent US1022031A
(Larson; 1912) is an
example of an instrument of this type, featuring an acoustic instrument that
is partly embedded
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into another. Larson employs a unitary soundboard and bridge shared between
two necks and
string sets, but provides distinct bodies and soundholes. Patent US4987815A
(Shockley; 1991) is
another example, featuring an acoustic guitar that is fixedly coupled by its
sided wall to a solid-
bodied electrical guitar, both instruments sharing a unitary soundboard.
Patent US5212329A
(Woodworth; 1993) teaches a means by which a specially contoured electrical
guitar may be
fastened to an acoustic guitar.
Electrical guitars may be made sufficiently small to be conveniently affixed
externally to an
acoustic guitar, where the distinctive tone of each instrument remains largely
intact. An acoustic
instrument of ordinary dimensions, however, must be at least partly embedded
within the host
guitar for the combination to be of a manageable size. When combined in this
manner, if a unitary
soundboard is used, as in the first example above, tonal distinction cannot be
faithfully preserved.
Hybrid string instruments of the third type integrate two acoustic instrument
bodies with a
single, shared neck, and provide some means by which string vibrations can be
directed to the
desired body. Patent US1607449A (Edwards; 1926) is an example of an instrument
of this type,
featuring a banjo mounted pivotally upon a guitar in such a manner that
ordinarily the two
instruments are spaced apart slightly, and bridge vibrations are transmitted
solely to the banjo
head, but by pressing the banjo body against the guitar body, bridge
vibrations are transmitted
directly to the guitar soundboard. Another example is seen in patent 3633452A
(Beasley; 1972),
which features an acoustic guitar whose soundboard is adapted to accommodate
an embedded a
banjo body. Beasley teaches a unique pivotable bridge which may be set to
transmit string
vibrations either to the banjo or directly to the guitar.
Although compact and permitting a rapid transition between instruments, these
devices suffer
from the added complexity introduced by the vibration redirection mechanism,
but more
importantly, from the limitation imposed by using the same string set for both
instruments.
It appears that the challenge of conveniently and seamlessly transitioning
between multiple
string instruments has not hitherto been satisfactorily met. The present
invention addresses this
challenge.
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SUMMARY OF THE INVENTION
It is the first, principal object of the present invention to provide a hybrid
instrument
combining two acoustic string instruments in a manner which allows rapid,
seamless transitioning
between the two instruments.
A second object of the present invention is to provide a hybrid instrument
that fulfills the first
object, in which the distinctive tonal quality of each of the combined
instruments is preserved.
A third object of the present invention is to provide a hybrid instrument that
fulfills the
aforesaid objects, which is of a convenient overall size.
A forth object of the present invention is to provide a method of construction
of a hybrid
instrument that fulfills the aforesaid objects, which may be executed simply
without requiring the
specialized skill and tools of a luthier, and is cost-effective.
These objects are met in the present invention through several features, as
outlined below.
In its principle aspect, the present invention features the integration of an
acoustic guitar with
another, preferably smaller acoustic instrument, so that their respective
necks are proximal and
oriented similarly, and their soundboards substantially coplanar.
A second aspect of the present invention is the coupling of two acoustic
instruments, whose
bodies and soundboards remain distinct.
A third aspect of the present invention is the partial embedment of one
acoustic instrument
within the other, which permits the hybrid instrument to be sized conveniently
for storage,
transportation and playing.
A forth aspect of the present invention is the technique of adaptation and
integration of
existing, ordinary instruments, which provides a hybrid instrument having the
aforesaid features.
These and other objects and features of the present invention are fully
expounded hereinafter
in the description of the preferred embodiment, in which references are made
to accompanying
drawings, described next.
DESCRIPTION OF THE DRAWINGS
Fig. 1 A perspective view of the preferred embodiment of a hybrid instrument
according to the
present invention.
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Fig. 2 A perspective view of the hybrid instrument of Fig. 1.
Fig. 3 A perspective view of the guitar element of the hybrid instrument of
Fig. 1 in isolation.
Fig. 4 A perspective view of the guitar of Fig. 3 with its soundboard and
bridge, fretboard and
strings hidden.
Fig. 5 A perspective view of the banjo element of the hybrid instrument of
Fig. 1 in isolation.
Fig. 6 A perspective view of the guitar element in isolation in an alternative
embodiment of a
hybrid instrument according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the hybrid instrument according to the present
invention is
depicted in Fig. 1 and Fig. 2 denoted generally by the numeral 1. Hybrid
instrument 1 consists of
two main elements: a modified acoustic guitar, denoted 2, and a modified
resonator banjo,
denoted 3.
Referring to Fig. 3 and Fig. 4, guitar 2 is adapted with a shoulder cut-out
within which, in
hybrid instrument 1., a section of the body and resonator of banjo 3 is
embedded. To minimize the
overall size of hybrid instrument 1, the cut-out cavity extends into the body
of the guitar part-way
as deeply as it is possible without appreciably degrading the acoustical
qualities of the guitar. It
has been found that a cut-out cavity which extends as far as, or slightly
beyond the soundhole
perimeter still yields satisfactory results.
The cut-out cavity is defined by arcuate line 2.1, cut through and along
soundboard 2.2,
straight lines 2.3, cut through and perpendicularly to soundboard 2.2 partway
along rib 2.4, and
contoured line 2.5, cut through and along the remaining section of rib 2.4
underlying the cut-out
cavity. Arcuate line 2.1 has a curve radius identical to the outer radius of
the sidewall of the
resonator of banjo 3; cut lines 2.3 extend to such a depth that banjo 3 is
set, in hybrid instrument
1, with its soundboard substantially coplanar with that of the guitar; cut
line 2.5 is contoured
congruently with the curvature of the back of the resonator of banjo 3, so
that the remaining
section of rib 2.4 underlying the cut-out cavity has a height profile which,
in hybrid instrument 1,
allows it to continuously abut the back of the resonator.
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As will be appreciated by the skilled artisan, banjo 3 may be set with its
soundboard offset
from the plane of soundboard 2.2 of guitar 2, if such positioning is believed
to offer superior
playability, structure, or aesthetics, by altering the depth of cut lines 2.3
accordingly.
A concave sidewall segment, denoted 2.6, is fitted and bonded to the edge of
the cut-out
cavity along soundboard 2.2 and, vertically, along rib 2.4. Sidewall segment
2.6 closes the opening
in rib 2.4 created by the cut-out cavity, and provides an attachment surface,
in hybrid instrument
11, onto which the embedded section of the resonator sidewall of banjo 3 is
bonded or bolted.
In the preferred embodiment, sidewall 2.6 is set, prior to installation, with
a permanent
curvature which substantially corresponds in radius to that of the cut-out
cavity. Using a bending
iiron jig is one, well-known technique by which such adaptation may be
achieved. Pre-setting
sidewall 2.6, at least approximately, to the needed bonding curvature
eliminates post-installation
stress, which may, in time, compromise its bonding to guitar 2 and banjo 3.
A plurality of radial apertures, collectively denoted 2.7, is disposed in
sidewall segment 2.6,
which, in hybrid instrument 1, lie in registration with a corresponding set of
apertures in the
resonator of banjo 3 (discussed hereinafter). Registering apertures 2.7 and
3.2 effectively enlarge
the sound box of guitar 2 and banjo 3, in hybrid instrument 1, thus enhancing
their tone.
It will be clear to those skilled in the art that sidewall 2.6 may be
constructed of various types
of solid or laminate wood in a range of thicknesses. It may be of planiform
geometry, provided it
can withstand the flexing necessary for installation.
To compensate for the slight structural weakening of the body of guitar 2
caused by the
shoulder cut-out, an extensible truss member, denoted 2.8, is used to span the
guitar body
longitudinally, and brace head block 2.10 against tail block 2.11. Truss
member 2.8 comprises two
metal tubes, each threaded at one end thereof, and an elongated barrel nut
2.9, by which the two
tubes are adjustably connected. Head block 2.10 and tail block 2.11 are each
adapted with a
shallow circular depression of such diameter that it may tightly receive an
end section of the
respective tube of truss member 2.8. During construction of hybrid instrument
1, truss member
?2.8 is first set with its two tubes screwed approximately halfway into barrel
nut 2.9¨their
threaded ends abutting. One end of truss member 2.8 is then inserted into one
of the aforesaid
block depressions, and the two tubes unscrewed with respect to barrel nut 2.9
to drive the
opposite end into the depression in the opposite block, and bear forcefully
upon it.
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As will be apparent to the skilled technician, solid wood or aluminum rods may
be used
instead of metallic tubes. Alternative, equally effective configurations of
truss member 2.8 are
possible, such as (but not limited to) telescopically engaged tubes, or a
single rod/tube lodged at
one end thereof in one of the aforesaid block depressions, and carrying an
elongated barrel nut at
the other end, where the barrel nut itself is lodged in the opposite block's
depression.
Referring to Fig. 5, banjo 3 is of the type known as a resonator banjo. In
hybrid instrument 1,
as described above, a section of the body and resonator of banjo 3 is embedded
within the
shoulder cut-out of guitar 2. The embedded sidewall section of the resonator,
denoted generally
3.1, is bonded (or bolted) to sidewall segment 2.6 of guitar 2, so that the
necks of the two
instruments are oriented similarly¨their planes of symmetry substantially
parallel. Resonator
section 3.1 is adapted with a plurality of apertures, collectively denoted
3.2, which are disposed
coincidentally with the aforementioned corresponding set of apertures 2.7 in
sidewall segment 2.6
of guitar 2. Apertures 3.2 are sized to maximize acoustic communication
between the bodies of
guitar 2 and banjo 3 without compromising the structural integrity of either
instrument.
The embodiment of the foregoing description provides back support for banjo 3,
which
solidifies its mounting to guitar 2. Keeping the back of guitar 2 intact,
however, limits the overall
height of banjo 3 (body and resonator) to approximately that of guitar 2. In
an alternative
embodiment of hybrid instrument 1, guitar 2', depicted in Fig. 6, is adapted
with a cut-out cavity,
which extends throughout its body¨soundboard through back. This open-back
arrangement
permits a wider choice of banjo types to be used, as well as other string
instruments having an
outer sidewall which is perpendicular to their soundboard (to serve as a
mounting platform), such
as, but not limited to a mandolin or a ukulele. Sidewall 2.6', in this
embodiment, spans the full
body height of guitar 2', and apertures 2.7' are disposed at such height that
when in registration
with the corresponding apertures of the embedded instrument, the soundboards
of the two
instruments are coplanar.
It is to be understood that the forgoing description of the preferred
embodiments of the
present invention and the accompanying drawings are intended to better
elucidate the invention
by way of examples, and not in any way to narrow its purview or the scope of
the appended claims
to the embodiments exemplified.
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