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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electrical string-instrument.
2. Description of the Prior Art
In recent years, the so-called electrical guitar has widely been used as an
electrical string-instrument. The electrical guitar has six strings and a
support member having a major surface which includes a string receiving
surface and on which the strings are stretched in substantially the same
plane in parallel relation to one another and in opposing relation to the
string receiving surface. On the string receiving surface of the support
member, a plurality of frets which extend substantially at right angles to
the strings, are sequentially provided in the direction of extension of
the strings. Further, in the area other than the string receiving surface
in the area opposite to the strings, there are provided electromechanical
transducer means for converting mechanical vibrations of the strings into
corresponding electrical signals.
When playing the guitar, the player plucks a desired one or more of the
strings while pressing them against the string receiving surface with his
fingers or leaving the strings in the so-called open-string state. A sound
signal which is obtained from the electromechanical transducer means when
picking the guitar without pressing the string against the string
receiving surface, is called an open-string sound signal. In the case of
pressing the string against the string receiving surface with a finger,
the sound signal derived from the electromechanical transducer means has a
higher frequency than the abovesaid open-string sound signal. The reason
is that the string is urged against the fret nearest the pressed position
on the side of the electromechanical transducer means with respect to the
position where the string is pressed. In the case of picking an ordinary
electrical guitar, the string plucked by the finger performs a damped
oscillation. Accordingly, the amplitude of the sound signal derived from
the electromechanical transducer means is attenuated with the lapse of
time. Therefore, the ordinary electrical guitar provides a sound signal
having a damped effect but cannot produce a sound signal having a sustain
effect.
Heretofore, attempts have been made to obtain the sound signal having the
sustain effect with the electrical guitar. However, no satisfactory
electrical guitar has been obtained for the reasons that the electrical
guitar becomes bulky, and that the sound signal obtained from the
electromechanical transducer means is unstable.
In the ordinary electrical guitar, the string, when twanged, performs a
damped oscillation as described above, so that a sound signal having the
damping effect can be obtained. In the state in which a sound signal
having the damping effect is being produced by plucking a certain string,
if a sound signal also having the damping effect is obtained from another
string, these two sound signals respectively having the damping effect are
combined with each other to provide a composite signal.
Accordingly, in the conventional electrical guitar, in the abovesaid case,
the former sound signal is always provided. Consequently it is impossible
with the prior art electrical guitar to obtain a sequential monophonic
signal which has the damping effect and in which the two sound signals
respectively having the damping effect are sequentially arranged.
Of course, in the conventional electrical guitar, in the case where a sound
signal having the sustain effect is produced from one string while a sound
signal having the sustain effect is being obtained from another string, it
is impossible to obtain a sequential monophonic signal which has the
sustain effect and in which the two sound signals are sequentially
arranged.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a novel electrical
string-instrument such as an electrical guitar which is simple in
construction as a whole but capable of stably producing a sequential
monophonic signal having the sustain effect.
Another object of this invention is to provide a novel electrical
string-instrument such as a guitar which is simple in construction as a
whole but capable of stably producing a sequential monophonic signal
having the damping effect.
Other objects, features and advantages of this invention will become more
fully apparent from the following description taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view schematically illustrating an embodiment of this
invention as being applied to an electrical guitar;
FIG. 2 is a cross-sectional view schematically showing an example of an
electromechanical transducer for use in the electrical guitar depicted in
FIG. 1;
FIG. 3 is a cross-sectional view schematically showing an example of
magnetic field generating means for use in the electrical guitar shown in
FIG. 1;
FIG. 4 is a schematic diagram illustrating an example of the electrical
construction of the electrical string-instrument shown in FIG. 1; and
FIG. 5 is a schematic cross-sectional view illustrating an example of a
common electromechanical transducer for use in the electrical guitar
depicted in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, reference numeral 1 indicates generally an example of an
electrical guitar of this invention which is the electrical
string-instrument proper for use in the electrical string-instrument. The
electrical guitar has six conductive and magnetic strings A.sub.1,
A.sub.2, . . . A.sub.6 and a nonconductive support member 4 which has a
major surface 3 including a string receiving surface 2 and on which the
strings A.sub.1 to A.sub.6 are stretched in substantially the same plane
in parallel relation to one another and in opposing relation to the string
receiving surface 2.
On the string receiving surface 2 of the support member 4, a plurality of
conductive frets B.sub.1, B.sub.2, . . . , which extend substantially at
right angles to the direction of extension of the strings A.sub.1 to
A.sub.6, are sequentially disposed in the direction of extension of the
strings A.sub.1 to A.sub.6. That part of the support member 4 which has
the string receiving surface 2 is referred to as a neck portion 5. The
part which includes an area 6 of the major surface 3 of the support member
4 except the string receiving surface 2 in the area opposite to the
strings A.sub.1 to A.sub.6, is called a body 7. The neck portion 5 extends
upwardly from the body 7. At the lower side of the area 6 of the body 7,
there are disposed fixing means 8, to which the strings A.sub.1 to A.sub.6
are fixed at one end. The other ends of the strings A.sub.1 to A.sub.6 are
respectively retained at individual fixing means F.sub.1, F.sub.2, . . .
F.sub.6 which are provided on the upper end portion of the neck portion 6
and each have a screw 9 for adjusting the tension of each string. A little
above the fixing means 8 on the area 6 of the body 7, a fret 11 is
provided for bridging the strings A.sub.1 to A.sub.6. Disposed alightly
below the fixing means F.sub.1 to F.sub.6 on the neck portion 5 is a fret
10 for similarly bridging the strings A.sub.1 to A.sub.6. The strings
A.sub.1 to A.sub.6 are held by the frets 11 and 10, by which they are
stretched to extend on the support member 4 in substantially the same
plane in parallel relation to each other and in opposing relation to the
string receiving surface 2.
At lower positions in the area 6 of the body 7, electromechanical
transducer means C.sub.1, C.sub.2, . . . C.sub.6 for converting mechanical
vibrations of the strings A.sub.1, A.sub.2, . . . A.sub.6 into
corresponding electrical signals E.sub.1, E.sub.2, . . . E.sub.6 are
sequentially disposed in the direction of array of the strings A.sub.1 to
A.sub.6 in opposing relation thereto. An example of each of the
electromechanical transducer means C.sub.1 to C.sub.6 is such a magnetic
head type one as shown in FIG. 2 which comprises a bar or plate-like
magnet 22, a magnetic core 22 coupled at one end with one end of the
magnet 21, another magnetic core 23 coupled at one end with the other end
of the magnet 21 and having the other end disposed opposite to the other
end of the magnetic core 22 to form an air gap g, and a coil 24 composed
of two parts respectively wound on the cores 22 and 23. The
electromechanical transducer means C.sub.i (i = 1, 2, . . . 6) is disposed
opposite to the string A.sub.i so that the widthwise direction of the air
gap g may be substantially perpendicular to the direction of extension of
the string A.sub.i. Accordingly, when the string A.sub.i is vibrated by
being touched at the portion opposing the surface of the area 6, a
vibration voltage, which corresponds to the components of vibration in the
direction perpendicular to the surface of the area 6, is obtained as an
electrical sound signal E.sub.i across the coil 24 of the magnetic head
type means C.sub.i.
At the upper position in the area 6 of the body 7, there is disposed
magnetic field generating means 31 which sets up a constant magnetic field
to cover the strings A.sub.1 to A.sub.6. An example of the magnetic field
generating means 31 is such, for example, as depicted in FIG. 3, which
comprises two bar or plate-shaped magnets 32 and 33 disposed on both sides
of an area corresponding to the area of array of the strings A.sub.1 to
A.sub.6 in their widthwise direction, and a magnetic core 34 extending
between one end of the magnet 32 and one end of the magnet 33. In this
case, the one end of the magnet 32 coupled with the core 34 forms the
magnetic north pole and the other end the magnetic south pole. Further,
the one end of the magnet 33 coupled with the core 34 forms the magnetic
south pole and the other end the magnetic north pole. Accordingly, at the
upper position in the area 6 of the body 7, there is generated a magnetic
field 35 emanating from the magnetic north pole of the magnet 33 to the
magnetic south pole of the magnet 32 in a direction perpendicular to the
direction of extension of the strings A.sub.1 to A.sub.6 to cross them.
Therefore, if a current flows in the string A.sub.i, the string A.sub.i is
moved by the Flemings law in the direction perpendicular to the area 6 in
accordance with the direction of the current flowing in the string
A.sub.i, as indicated by the arrows 36 and 37.
The body 7 has disposed therein an electrical circuit 41 indicated by the
broken-line block in FIG. 1. In the electrical circuit 41, as shown in
FIG. 4, the electrical sound signals E.sub.1, E.sub.2, . . . E.sub.6
respectively derived from the coils 24 of the electromechanical transducer
means C.sub.1, C.sub.2, . . . C.sub.6 are amplified by preamplifiers
G.sub.1, G.sub.2, . . . G.sub.6, and then supplied to threshold circuits
J.sub.1, J.sub.2, . . . J.sub.6 through ganged switches H.sub.1, H.sub.2,
. . . H.sub.6, respectively, by which signals, shaped into rectangular
waveforms which are "1" or "0" in the binary representation depending upon
whether the electrical sound signals E.sub.1, E.sub.2, . . . E.sub.6 are
above or below predetermined levels, respectively, are obtained as
feedback signals M.sub.1, M.sub.2, . . . M.sub.6. Then, the signals
M.sub.1, M.sub.2, . . . M.sub.6 thus obtained are amplified by driving
amplifiers K.sub.1, K.sub.2, . . . K.sub.6, respectively. An actuator 38
for the ganged switches H.sub.1 to H.sub.6 is provided on the major
surface 3 in the area on the body 7.
The outputs of the driving amplifiers K.sub.1, K.sub.2, . . . K.sub.6 of
the electrical circuit 41 are respectively connected at one end to the
ends of the strings A.sub.1, A.sub.2, . . . A.sub.6 on the side of the
fixing means 9, and grounded at the other end. Also, the abovesaid
conductive frets B.sub.1, B.sub.2, . . . are grounded. Accordingly, when
the string A.sub.i is plucked by one finger at the position opposite to
the area 6 while being urged by another finger against the string
receiving surface 2 and engaged with the fret B.sub.j (j = 1, 2, . . .), a
feedback current I.sub.i based on the amplified feedback signal M.sub.i
derived from the driving amplifier K.sub.i flows in the string A.sub.i as
long as the string A.sub.i is pressed against the string receiving surface
2 and engaged with the fret B.sub.j. Consequently, if the polarity of the
feedback signal M.sub.i is selected such that the string A.sub.i may be
moved by the Fleming's law in the same direction as the direction of
vibration of the string A.sub.i when plucked, when the string A.sub.i has
once been twanged by a finger while being urged against the string
receiving surface 2 and engaged with the fret B.sub.j, the string A.sub.i
continues to vibrate as long as it is pressed against the string receiving
surface 2 and engaged with the fret B.sub.j. Accordingly, the sound signal
E.sub.i from the electromechanical transducer C.sub.i or preamplifier
G.sub.i is obtained as a sound signal corresponding to the continuous
vibration of the string A.sub.i. Such a signal is called a sound signal
having the sustain effect. Further, when released from the abovesaid
pressed state, the string A.sub.i immediately starts to perform a damped
vibration. As a result of this, the sound signal E.sub.i from the
electromechanical transducer C.sub.i or preamplifier G.sub.i is obtained
as a damped sound signal. The sound signals E.sub.1 to E.sub.6 derived
from the preamplifiers G.sub.1 to G.sub.6 are led out as one kind of
output from the electrical circuit 41 to the outside through a multi-jack
43 disposed on the side 42 of the body 7. Further, the sound signals
M.sub.1 to M.sub.6 having rectangular waveforms, derived from the
threshold circuits J.sub.1 to J.sub.6, are similarly led out as another
kind of output from the electrical circuit 41 to the outside through a
multi-jack 44 disposed on the side 42 of the body 7.
Further, the electrical circuit 41 is designed so that the amplified
electrical sound signals E.sub.1 to E.sub.6 from the preamplifiers G.sub.1
to G.sub.6 are mixed by the mixing circuit 45 to derive therefrom a signal
EO into which the electrical signals E.sub.1 to E.sub.6 are combined. The
electrical signal EO thus obtained from the mixing circuit 45 is led out
as another kind of output from the electrical circuit 41 to the outside
through a jack 46 provided on the side 42 of the body 7. Accordingly, if
the electrical guitar of this invention is played in the state in which
the abovesaid switches H.sub.1 to H.sub.6 are held in the off state by the
aforementioned actuator 38, the feedback signals M.sub.1 to M.sub.6 are
not derived from the threshold circuits J.sub.1 to J.sub.6, so that the
currents I.sub.1 to I.sub.6 do not flow in the strings A.sub.1 to A.sub.6.
As a result of this, the electrical sound signals E.sub.1 to E.sub.6 from
the electromechanical transducer means C.sub.1 to C.sub.6 are not the
sound signals corresponding to the abovesaid continuous vibration of the
string, so that the signal EO led out to the outside through the jack 46
is obtained as a sound signal of the same mode as a sound signal obtained
with an ordinary electrical guitar. However, when the electrical guitar of
this invention is played with all or some of the strings A.sub.1 to
A.sub.6 urged by fingers against the string receiving surface 2 in the
state in which the switches H.sub.1 to H.sub.6 are held in the on state by
the actuator 38,, electrical sound signals derived from all or some of the
electromechanical transducer means C.sub.1 to C.sub.6 corresponding to the
strings pressed against the string receiving surface 2 in this case are
obtained as sound signals corresponding to the aforesaid continuous
vibration, so that the signal EO led out to the outside through the jack
46 is a sound signal having the sustain effect. Further, the electrical
circuit 41 has a mixer 47 which is adapted such that the signals M.sub.1
to M.sub.6 of the rectangular waveform, derived from the threshold
circuits J.sub.1 to J.sub.6 are mixed together to provide a composite
signal MO. The signal MO thus obtained from the mixer 47 is led out as
another kind of output from the electrical circuit 41 to the outside
through a jack 48. Accordingly, when the guitar is played in the state
that the switches H.sub.1 to H.sub.6 are closed by the operation of the
actuator 38, the sound signal MO of rectantular waveform having the
sustain effect is led out to the outside.
Though not shown in FIG. 1, there are provided separately of the electrical
guitar proper 1 timing signal generators Q.sub.1, Q.sub.2, . . . Q.sub.6
which are respectively supplied with the sound signals E.sub.1, E.sub.2, .
. . Ee.sub.6 from the preamplifiers G.sub.1, G.sub.2, . . . E.sub.6 to
provide timing signals T.sub.1, T.sub.2, . . . T.sub.6, as illustrated in
FIG. 4. The sound signal E.sub.i, which is derived from the preamplifier
G.sub.i when the string A.sub.i is plucked, with the switches H.sub.1 to
H.sub.6 of the abovesaid electrical circuit 41 held in the off state, is
generally obtained as a vibratory wave which performs a damped vibration
from the moment of plucking the string A.sub.i. However, when the string
A.sub.i is twanged with the switches held in the off state, the sound
signal E.sub.i derived from the preamplifier G.sub.i is obtained as a
vibratory wave whose level is higher than that of the time of plucking the
string A.sub.i and remains constant. The timing signal generator circuit
Q.sub.i is comprised of an envelope detector 71 for detecting the envelope
of the sound signal E.sub.i composed of such a vibratory wave and an
amplifier 72 for amplifying with saturation the envelope detecting output
from the envelope detector 71 to obtain a rectangular wave. Accordingly,
the timing signal T.sub.i is obtained as a rectangular wave derived from
such an amplifier 72. The leading edge of such a timing signal T.sub.i is
indicative of the moment when the string A.sub.i has been plucked.
Further, there are provided separately of the electrical guitar proper 1
gate signal generators W.sub.1, W.sub.2, . . . W.sub.6 which are
respectively supplied with the timing signals T.sub.1 to T.sub.6 to
provide gate signals S.sub.1, S.sub.2, . . . S.sub.6, as shown in FIG. 4.
The gate signal generator W.sub.i is composed of a flip-flop 73 having a
set terminal S which is set by the leading edge of the timing signal
T.sub.i, and an OR circuit 74 whose output end is connected to a reset
terminal r of the flip-flop 73. The OR circuit 74 of the gate signal
generator W.sub.1 is supplied with the timing signals T.sub.2 to T.sub.6
except T.sub.1 ; the OR circuit 74 of the circuit W.sub.2 is supplied with
the signals T.sub.1 and T.sub.3 to T.sub.6 except T.sub.2 ; the OR circuit
74 of the circuit W.sub.2 is supplied with the signals T.sub.1, T.sub.2,
and T.sub.4 to T.sub. 6 except T.sub.3 ; the OR circuit 74 of the circuit
W.sub.4 is supplied with the signals T.sub.1 to T.sub.3, T.sub.5 and
T.sub.6 ; the OR circuit 74 of the circuit W.sub.5 is supplied with the
signals T.sub.1 to T.sub.4 and T.sub.6 ; and the OR circuit 74 of the
circuit W.sub.6 is supplied with the signals T.sub.1 to T.sub.5.
Accordingly, if the timing signal, for instance, T.sub.2 is obtained after
the timing signal T.sub.1 is produced, a rectangular output, which
presents a value "1" in the binary representation from the moment of the
leading edge of the signal T.sub.1 to the moment of the leading edge of
the signal T.sub.3, is obtained as the gate signal S.sub.1. Generally,
when one (hereinafter identified by T.sub.p) of the timing signals T.sub.1
to T.sub.6 except T.sub.i is provided after the timing signal T.sub.i, a
rectangular output which presents the value "1" in the binary
representation from the moment of the leading edge of the signal T.sub.i
to the moment of the leading edge of the abovesaid one timing signal
T.sub.p is derived as the gate signal S.sub.i from the flip-flop 73 of the
circuit W.sub.i.
Moreover, there are provided separately of the electrical guitar proper 1
gate circuits X.sub.1, X.sub.2, . . . X.sub.6 which are respectively
supplied with the sound signals E.sub.1, E.sub.2, . . . E.sub.6 from the
preamplifiers G.sub.1, G.sub.2, . . . G.sub.6 of the abovesaid electrical
circuit 41. On the other hand, outputs Y.sub.1, Y.sub.2, . . . Y.sub.6
from the gate circuits X.sub.1, X.sub.2, . . . X.sub.6 that the sound
signals E.sub.1, E.sub.2, . . . E.sub.6 are gated, are supplied to a mixer
75, from which is derived at its output terminals 76 a composite signal Z
that the outputs Y.sub.1 to Y.sub.6 are combined with one another. In this
case, the gate circuit X.sub.i is adapted to gate the signal E.sub.i with
the gate signal S.sub.i derived from the gate signal generator W.sub.i.
Accordingly, for example, if the string A.sub.3 is plucked after the string
A.sub.1, the electrical sound signal E.sub.1 is obtained from the
preamplifier G.sub.1 and then the sound signal E.sub.3 is derived from the
preamplifier G.sub.3. When such sound signals E.sub.1 and E.sub.3 have
once been obtained, the timing signal T.sub.1 is derived from the timing
signal generator Q.sub.1 and then the timing signal T.sub.3 is derived
from the timing signal generator Q.sub.3. Further, the gate signal S.sub.1
is obtained from the gate signal generator W.sub.1 and then the gate
signal S.sub.3 is derived from the gate signal generator W.sub.3.
Consequently, the output Y.sub.1 that the signal E.sub.1 is gated by the
gate signal S.sub.1 is derived from the gate circuit X.sub.1 and then the
output Y.sub.3 that the signal E.sub.3 is gated by the gate signal S.sub.3
is derived from the gate circuit X.sub.3. As a result of this, the output
Z which is derived at the output terminal 76 of the mixer 75 is obtained
as a sequential monophonic signal in which the output Y.sub.1 resulting
from gating of the signal E.sub.1 with the gate signal S.sub.1 and the
output Y.sub.3 resulting from gating of the signal E.sub.3 with the gate
signal S.sub.3. Further, after the string A.sub.i is plucked, if one of
the strings A.sub.1 to A.sub.6 except the string A.sub.i (hereinafter
identified by A.sub.p) is twanged, the output Z derived at the output
terminal 76 is obtained in the form of such a sequential monophonic signal
that the output Y.sub.i produced by gating the signal E.sub.i with the
gate signal S.sub.i and the output Y.sub.p produced by gating the signal
E.sub.p with the gate signal Y.sub.p are sequentially arranged, the signal
E.sub.p being derived from the preamplifier G.sub.p corresponding to the
string A.sub.p and the gate signal Y.sub.p being obtained from the gate
signal generator X.sub.p similarly corresponding to the string A.sub.p.
When the switches H.sub.1 to H.sub.6 of the abovesaid electrical circuit 41
are in the on state, the sound signal E.sub.i from the preamplifier
G.sub.i has the sustain effect as described above, so that the output z,
obtained as such a monophonic signal, is produced as a sequential
monophonic signal having the sustain effect. Further, when the switches
H.sub.1 to H.sub.6 of the electrical circuit 41 are in the off state, the
sound signal E.sub.i from the preamplifier G.sub.i has the damping effect
as described above, so that the output Z derived from the sequential
monophonic signal is obtained as a sequential monophonic signal having the
damping effect.
The foregoing description has been given of the case where the sequential
monophonic signal having the sustain effect and the sequential monophonic
signal having the damping effect are both such signals based on the sound
signals E.sub.1 to E.sub.6 obtained from the preamplifiers G.sub.1 to
G.sub.6 of the electrical circuit 41. However, it is also possible that
the rectangular, sequential monophonic signal having the sustain effect is
obtained based on the rectangular sound signals M.sub.1 to M.sub.6 derived
from the threshold circuits J.sub.1 to J.sub.6 of the electrical circuit
41. In this case, as illustrated in FIG. 4, gate circuits X.sub.1 ',
X.sub.2 ', . . . X.sub.6 ' which are respectively supplied with the
signals M.sub.1 to M.sub.6 respectively derived from the threshold
circuits J.sub.1 to J.sub.2, are provided separately of the electrical
guitar proper 1, and these gate circuits are respectively controlled by
the gate signals S.sub.1, S.sub.2, . . . S.sub.6 derived from the gate
signal generators W.sub.1, W.sub.2, . . . W.sub.6. Further, outputs
Y.sub.1 ', Y.sub.2 ', . . . Y.sub.6 ', produced by gating the signals
M.sub.1, M.sub.2, . . . M.sub.6 from the gate circuits X.sub.1 ', X.sub.2
', . . . X.sub.6 ' with the gate signals S.sub.1, S.sub.2, . . . S.sub.6,
are supplied to a mixer 75'. It will be evident that in such a case, there
is derived at the output terminal 76' of the mixer 75' an output Z' which
is composed of a sequential monophonic signal having the sustain effect
based on the sound signals M.sub.1 and M.sub.6, though not described in
detail.
Further, it is also possible to perform the following operation:- The
output Z' derived from the mixer 75', composed of the sequential
monophonic signal having the sustain effect, is supplied to a
voltage-controlled type filter 77 whose frequency characteristic is
modulated by a voltage control, and the output therefrom is supplied to a
voltage-controlled type amplifier 78 whose amplification degree is
similarly modulated by a voltage control. On the other hand, the timing
signals T.sub.1 to T.sub.6 from the aforesaid timing signal generators
Q.sub.1 to Q.sub.6 are applied to trigger pulse generators Q.sub.1 ' to
Q.sub.6 ' to provide trigger pulses T.sub.1 ' to T.sub.6 ' at the moments
of the leading edges of the respective timing signals. The trigger pulses
T.sub.1 ' to T.sub.6 ' thus obtained are respectively applied to envelope
voltage generators W.sub.1 ' to W.sub.6 ' to produce envelope voltages
S.sub.1 ' to S.sub.6 ' of desired waveforms from the moments of generation
of the trigger pulses T.sub.1 ' to T.sub.6 '. These envelope voltages
S.sub.1 ' to S.sub.6 ' are combined by a mixer 79, the composite output
from which is supplied as a control voltage to the aforementioned
voltage-controlled type filter 77 and voltage-controlled type amplifier
78, thereby to derive at the output terminal 80 of the voltage-controlled
type amplifier 78 an output of the mode that the frequency characteristic
and amplitude of the output Z' have been modulated by the composite output
of the envelope voltages S.sub.1 ' to S.sub.6 '.
Also, the following operation is possible. The output Z' from the mixer
75', composed of the sequential monophonic signal having the sustain
effect, is supplied to a known fundamental wave extractor 81, the output
from which is supplied to a cascade-connected circuit of a filter 77' and
an amplifier 78' respectively similar to the voltage-controlled type
filter 77 and the voltage-controlled type amplifier 78 described above.
The abovesaid filter 77' and amplifier 78' are controlled by the composite
output of the envelope voltages S.sub.1 ' to S.sub.6 ', derived from a
mixer 79, whereby to provide at an output terminal 80' of the amplifier
78' an output of the mode that the frequency characteristic and amplitude
of the fundamental wave component of the output Z' are modulated by the
composite output of the envelope voltages S.sub.1 ' to S.sub.6 '.
Also, it is possible to effect the following operation:- The output Z' from
the mixer 75' is supplied to a fundamental wave extractor 81', the outut
from which is, in turn, applied to a frequency-voltage converter 82. Then,
the output from the converter 82 is supplied to a voltage variable type
oscillator 83 and its oscillation output is applied to a cascadeconnected
circuit of a filter 77" and an amplifier 78" which are similar to the
abovesaid voltage-controlled filter 77 and amplifier 78. The filter 77"
and the amplifier 78" are controlled by the composite output of the
envelope voltages S.sub.1 ' to S.sub.6 ' which is derived from the mixer
79, thereby to obtain from the oscillator 83 a fundamental wave output of
a desired frequency corresponding to the fundamental wave component of the
output Z', or a composite output composed of the abovesaid fundamental
wave output and its harmonic wave component. Thus, there is derived from
the output terminal 80" of the amplifier 78" an output of the mode that
the frequency characteristic and amplitude of the output from the
oscillator 83 is modulated by the composite output of the envelope
voltages S.sub.1 ' to S.sub.6 '.
The foregoing description has been given of the case where only the
electromechanical transducer means C.sub.1, C.sub.2, . . . C.sub.6 are
disposed on the area 6 of the electrical guitar proper 1 in opposing
relation to the strings A.sub.1, A.sub.2, . . . A.sub.6, respectively.
However, it is possible to dispose opposite to the strings A.sub.1 to
A.sub.6 at the center of the area 6 electromechanical transducer means C'
which converts mechanical vibrations of the strings A.sub.1 to A.sub.6
into a composite signal E' of electrical signals corresponding to the
vibrations and which is common to the strings A.sub.1 to A.sub.6, as shown
in FIG. 1. The electromechanical transducer means C' is, for instance,
such a multigap magnetic head type one as shown in FIG. 5, which is
composed of a bar or plate-like magnet 51, a magnetic core 52 coupled at
one end with one end of the magnet 51, a magnetic core 52 coupled at one
end with the other end of the magnet 51 and having the other end disposed
opposite to the other end of the magnetic core 52, mangetic core elements
P.sub.1, P.sub.2, . . . P.sub.5 disposed between the other ends of the
magnetic cores 52 and 53 to form air gaps g.sub.1, g.sub.2, . . . g.sub.6,
and a coil 54 composed of two parts respectively wound on the magnetic
cores 52 and 53. The electromechanical transducer means C' is disposed
opposite to the strings A.sub.1, A.sub.2, . . . A.sub.6 so that the
widthwise directions of the gaps g.sub.1, g.sub.2, . . . g.sub.6 may be
substantially perpendicular to the direction of extension of the strings
A.sub.1, A.sub.2, . . . A.sub.6. Accordingly, when the string A.sub.i is
plucked to vibrate, a vibration voltage which corresponds to the
components of vibration in the direction perpendicular to the surface of
the area 6 is obtained as the electrical sound signal E' across the coil
54 of the magnetic head type means C'. Further, when some or all of the
strings A.sub.1 to A.sub.6 are simultaneously twanged to vibrate, a
voltage that vibration voltages corresponding to the components of the
vibrations in the direction perpendicular to the surface of the area 6 are
superimposed one on another is obtained as the electrical sound signal E'.
The sound signal E' thus derived from the electromechanical transducer
means C' is led out to the outside through a jack 55 mounted on the side
42 of the body 7, as is more apparent from FIGS. 1 and 4.
In the foregoing, magnetic head type transducers are used as the
electromechanical transducer means, but may also be electrostatic head
type. In such a case, the strings need not be magnetic. Moreover, the
foregoing has described the embodiments of the present invention as
applied to the electrical guitar but it should be understood that the
invention is also applicable to electrical string-instruments similar to
the electrical guitar.
It will be apparent that many modifications and variations may be effected
without departing from the scope of novel concepts of this invention.
* * * * *
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