U.S. patent number 3,813,473 [Application Number 05/301,372] was granted by the patent office on 1974-05-28 for electric guitar system.
This patent grant is currently assigned to 254803 Investments Limited. Invention is credited to Paul Francis Terymenko.
United States Patent |
3,813,473 |
Terymenko |
May 28, 1974 |
ELECTRIC GUITAR SYSTEM
Abstract
An electric guitar having a plurality of strings and including
circuitry for adjustably attenuating the input signals from the
strings not played, circuitry for adjustably varying the attack of
the output signals representing notes and chords, gain control
circuitry utilizing a photoconductor, and a mechanically coupled
feedback path for applying output signals back to the strings to
sustain vibrations.
Inventors: |
Terymenko; Paul Francis
(Oshawa, Ontario, CA) |
Assignee: |
254803 Investments Limited
(Toronto, Ontario, CA)
|
Family
ID: |
23163067 |
Appl.
No.: |
05/301,372 |
Filed: |
October 27, 1972 |
Current U.S.
Class: |
84/742; 84/702;
984/374; 84/711; 984/367 |
Current CPC
Class: |
G10H
3/186 (20130101); G10H 3/24 (20130101) |
Current International
Class: |
G10H
3/24 (20060101); G10H 3/18 (20060101); G10H
3/00 (20060101); G10h 003/00 () |
Field of
Search: |
;84/1.04,1.05,1.11,1.12,1.15,1.16,1.19,1.24,DIG.10,1.26,1.14,1.21 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Weldon; U.
Attorney, Agent or Firm: Davis, Hoxie, Faithfull &
Hapgood
Claims
I claim:
1. An electronic plural-stringed musical instrument having:
means associated with each of the strings independently for
producing an electrical signal derived from the vibration of that
string, and
means for selecting only the electrical signal having an amplitude
above a threshold level and for attenuating electrical signals
derived from the remaining strings.
2. The instrument of claim 1 wherein the means for selecting
includes
means for producing control signals for effecting the attenuation
of the signals derived from each of the remaining strings.
3. The instrument of claim 2 wherein the degree of attenuation is
adjustable.
4. An electronic musical instrument having:
a plurality of strings passing over a supporting bridge,
means associated with each of the strings independently for
producing an electrical signal derived from the vibration of that
string,
means for selecting only the electrical signal having an amplitude
above a threshold level and for attenuating electrical signals
derived from the remaining srings, voicing means for processing the
said selected electrical signal, a mixing device coupled to the
voicing means for receiving the said processed selected electrical
signal, and
means connected to the said mixing device for producing a vibratory
motion related to the selected signal and applying the motion
directly to the bridge only to sustain the vibration of the string
originating the selected signal.
5. The instrument of claim 4 wherein the motion producing means
includes an electromagnetic coil and core assembly and a
substantially rigid connection between the assembly and the
bridge.
6. An electronic plural-stringed musical instrument having:
pick-up means associated with each of the strings independently for
producing an electrical signal derived from the vibration of the
string,
independent amplifier means associated with each of the pick-up
means for amplifying the signal from that pick-up means,
means for selecting only an amplified electrical signal from one of
the amplifier means having an amplitude above a threshold level and
for producing from said amplified signal control signals for
effecting the attenuation of the signals derived from each of the
remaining strings.
7. The instrument of claim 6 wherein the means for selecting
includes diode means having a threshold voltage at the threshold
level.
Description
The present invention is a musical instrument comprising a guitar
body having several novel features and associated electronic
circuitry.
Current electric guitars, and the devices for modification of their
output signals commonly known as "fuzz" boxes, have several
inherent limitations in performance because of certain aspects of
their design. While these limitations do not affect the utility of
such guitars and devices for many musical purposes, they do prevent
the achievement of desirable musical effects.
For example, with current electric guitars it is difficult to
produce a sustained note, that is, a note which will not "die
down", except by utilizing an extremely high sound volume level.
Therefore, a musician must play the guitar very loudly if he
desires to use the sustained-note effect. Furthermore, because the
sustained-note effect in current electric guitars is dependent on
the total acoustical environment of the guitar, it is difficult to
predict which notes will sustain themselves in a given setting.
This means that a travelling performer has no assurance that a note
which will sustain itself in one concert setting will also do so in
another.
Current electric guitars severely limit the ability of the
performer to play melodies or chords without accompanying
interference from the strings not played. Sympathetic vibrations
among the strings cause signals to be generated at strings other
than those being played, and these spurious signals are amplified
and (when the guitar is used in conjunction with a tone
modification device) modified along with the desired sounds,
producing interfering output signals and, in the latter case,
inter-modulation distortion. In fact, it is difficult just to keep
conventional guitars silent, especially when they are used in
conjunction with tone modification devices.
A third limitation of current electric guitars derives from the
fact that the action of a guitar pick on the string makes the
guitar in a sense a percussive instrument. This limitation is
accentuated by the use of "fuzz" boxes and the like. Flowing
melodies are difficult to execute, and the louder the instrument is
played, the more prominent is the initial click of sound produced
by the plucking of the string.
The present invention overcomes each of these limitations of
current electric guitars and thereby allows a performer greater
opportunity for display of his ability. A sustained-note effect,
reproducible in any acoustical environment independent of the
performer's volume level, is achieved according to the invention by
utilizing a mechanically-coupled feedback path within the guitar of
which the string is the frequency-determining factor. The
undesirable effects of sympathetic vibration are eliminated by
providing performer-controlled, automatic selector circuitry to
eliminate unwanted signals from the strings not played. The
percussive feature presently inherent in electric guitars is
controlled by other performer-controlled, automatic circuitry which
gives the melody or chord a bowed rather than struck sound.
These and other features of the invention will be more apparent
from the illustrative embodiment described and illustrated in the
accompanying drawings, in which:
FIG. 1 is a block diagram of the guitar system of the present
invention, as applied to a six-string guitar;
FIG. 2 is a circuit diagram of the Automatic Input Selector
stage;
FIG. 3 is a circuit diagram of the Voice Module stage;
FIG. 4 is a circuit diagram of the Mixer stage, also showing the
Preset and Stepping Voice Selectors and, in schematic form, the
Expression Pedal;
FIG. 5 is a circuit diagram of the AGC and Percussion Regulator
stages, also showing, in schematic form, the Volume Pedal;
FIG. 6 is a circuit diagram of the electrical portion of the
Sustain Vibration system;
FIG. 7 is a cut-away side view of a guitar body containing the
mechanical portion of the Sustain Vibration system; and
FIG. 8 is a top view of the guitar body shown in FIG. 6.
Referring first to FIG. 1, this Figure at its left side shows
signal inputs from individual pick-ups mounted beneath each of the
six guitar strings A, B, C, D, E and F, which, in the present
invention may be made of any ferromagnetic material. The signal
from a given string will be hereinafter referred to as, e.g.,
signal A, signal B, etc. Signal A enters the Automatic Input
Selector circuitry associated with string A and, if no "ATTENUATE"
or blocking signal also enters that Automatic Input Selector
circuit, signal A in amplified form is applied to the input of the
Voice Module circuitry associated with string A. In the Voice
Module, the signal from string A is processed to produce, in this
illustrative embodiment, six "voices" or electronically modified
and amplified versions of the original signal. These voices are
identified herein by one of the subscripts u-z following the letter
of the string from which the signal is derived, as for example, Au,
Av, Aw, Ax, Ay, and Az. At the Mixer all of the like voices from
the several strings are combined into a single voice, e.g., Au, Bu,
Cu, Du, Eu, and Fu are combined into a single voice hereinafter
referred to as voice U. Similarly, all the individual v voices are
combined to produce voice V, etc.
Referring now in detail to FIG. 2, the circuitry of which it should
be understood is repeated for each string, signal A from the
magnetic pick-up mounted in the guitar body beneath string A is
applied to the base of transistor Q1 across the parallel
arrangement of potentiometer R1, used to balance the amplitudes of
the incoming signals from the various strings, and C1, which shunts
any radio frequency noise to ground, and through coupling capacitor
C2. Signal A is also applied to the base of transistor Q3 through
coupling capacitor C3.
The function of the Automatic Input Selector (AIS) circuitry shown
in FIG. 2 is to provide the performer with the means to attenuate
or completely block all signals from the strings not being played
at a given time, thereby eliminating unwanted sounds from the
melody being played.
Transistor Q1 amplifies the signal, which then passes through
capacitor C4 to diode D1. Potentiometer R2 is adjusted to allow
only a short burst of negative-going signal to pass diode D1, which
in this illustrative embodiment may have a threshold voltage of
about 0.3 volts. The spike of signal passed through diode D1 passes
through coupling capacitor C5 to transistor Q2, which is biased
into saturation when no signal is applied. The application of the
pulse to the base of Q2 results in a strong positive-going burst of
signal at the collector. This pulse is applied across diodes
D100-04 to the "ATTENUATE" inputs of the AIS circuitry of the other
strings, not shown. For example, if the AIS circuitry for string A
is being discussed, then diodes D100-04 would be connected to the
"ATTENUATE" circuitry associated with strings B, C, D, E and F.
Direct coupled transistors Q3 and Q4 and their associated resistors
comprise a flat response circuit capable of amplifying or
attenuating the signal applied at the base of Q3 depending on the
bias conditions. The bias conditions in turn are dependent on the
state of transistor Q8, connected between the positive source and
the collectors of Q3 and Q4. The AIS control is exerted at this
point, by causing Q8 to vary between cut-off (in which case the
supply voltage to Q3 and Q4 is low and the output at the collector
of Q4 is attenuated) and saturation (in which case the supply
voltage to Q3 and Q4 is relatively high and the Q3-Q4 combination
functions as an amplifier).
The AIS circuitry attenuates a signal in the following way. If
string B only is struck, in the manner described above a positive
signal pulse appears at the "ATTENUATE" input of the AIS circuitry
of string A and is applied to the base of transistor Q5, through
potentiometer R3, which functions as a sensitivity adjustment.
Transistors Q5 and Q6 are arranged in flip-flop fashion, so that
the "ATTENUATE" pulse just described puts Q5 into saturation and Q6
into cut-off. Had string A been plucked, Q6 would have been put
into saturation by the application of the positive burst to the
base of Q6 through diode D2. With Q6 in cut-off, its high collector
voltage is applied to the base of transistor Q7 across
photoconductor PH1, a variable resistor located in the AIS pedal,
operation of which is controlled by the performer.
The AIS Pedal, and other performer-controlled pedals discussed
below, all include a neon bulb and one or more photoconductors.
Depression of the pedal by the performer varies the exposure of the
photoconductor to the neon bulb NE1 and hence the characteristics
of the circuit of which it is an element. In the present case, if
PH1 is at its lowest resistance value (pedal fully depressed), the
voltage applied to the base Q7 puts that transistor into
saturation. This in turn lowers the collector voltage of Q7, which
lowers the base voltage of transistor Q8, biasing Q8 out of
saturation and sharply reducing the supply voltage to transistors
Q3 and Q4. In this way, the application of an "ATTENUATE" signal to
the AIS circuitry of a given string, given the depression by the
performer of the AIS Pedal, causes the output from transistor Q4 to
be attenuated.
The performer can vary the application of this function by
depressing the AIS Pedal to less than its full extent, thereby
leaving photoconductor PH1 with a substantial resistance value. If
the pedal is not depressed at all, the resistance of PH1 may be
made sufficiently high so that no attenuation occurs, in spite of
the presence of a signal at the "ATTENUATE" input. The choice is
left to the performer.
Depending on the presence or absence of an "ATTENUATE" signal and
the extent to which the Pedal is depressed, a signal of a
predetermined strength appears at the collector of Q4. This signal
is the input to the Voice Module illustrated in FIG. 3.
The function of the Voice Module of string A, the circuitry of
which is repeated for each other string of the guitar, is to
process electronically the amplified signal from the collector of
transistor Q4, modifying or amplifying that signal to produce, in
this embodiment, six voices from signal A.
Through the parallel combination of capacitor C7 and capacitor
C8-resistor R4, signal A is applied to the base of transistor Q9.
Capacitor C7 has a small value which serves to boost the high
frequency response of the circuit to compensate for any losses and
to provide clear high notes. The output of Q9, denominated voice
Az, is the natural sound of guitar string A.
Through capacitor C9 signal A is applied to the base of transistor
Q10, which amplifies it and applies it both to the primary of
transformer T1, and, through capacitor C10, across the parallel
combination of reversed diodes D4 and D5. The parallel arrangement
of diodes D4 and D5 acts as a limiter in reverse, blocking the
middle strength values of the signal and passing the positive and
negative peaks intact. The output from the parallel arrangement of
diodes D4 and D5, signal A with the middle values removed, becomes
voice Av.
Through C8 signal A is also applied to the base of Q11. The
collector of Q11 is shunted to ground through a large capacitor C11
leaving a residual sawtooth signal which is coupled to the bases of
transistors Q12 and Q13. The amplified sawtooth signal at the
collector of Q12 becomes voice Aw and is also applied, together
with the input to Q12, through capacitor C12 to the secondary of T1
where it mixes with the other current in the secondary to produce
voice Au. The collector of Q13 is coupled through capacitor C13 to
the limiter composed of diodes D6 and D7. The resulting signal, a
near square wave, is the basis for the other three voices.
Through trimmer resistor R5, transistor Q14 receives a portion of
the signal from the limiter composed of D6 and D7 and projects an
amplified image of the signal 180.degree. out of phase with the
original (because of the nature of a common-emitter transistor
amplifier) into the junction of diodes D8 and D9 through D9. The
same signal with the original phase comes to that junction directly
from the limiter through D8. Diodes D8 and D9 act as a full wave
rectifier, and the signal at their junction is raised one octave.
The symmetry of the new signal appearing at the junction of D8 and
D9 is controlled by potentiometer R5. This new signal is applied to
the base of transistor Q15 through the parallel combination of
capacitor C14 and resistor R6, which boosts the high frequency
components of the signal. The output of Q15 at its collector is
voice Ay and also comprises one possible input to transistor
Q16.
Transistor Q16 obtains its input from the collector of either Q14
or Q15, depending on the setting of manual switch S1. That is, its
input is either the square wave signal from the collector of Q14 or
the signal from the collector of Q15, with a very strong second
harmonic. Switches similar to S1 are provided in each Voice Module;
they allow the performer to choose between two "X" voices for each
string independently of the "X" voices chosen for the other
strings. The output at the collector of Q16 is voice Ax.
It should be understood that all of the preceding circuitry is
repeated for each string, so that, in the present six-string
illustrative embodiment, the circuitry shown in FIGS. 2 and 3 is
repeated six times. The circuits that follow, on the other hand,
are constructed only once.
As is illustrated in FIG. 4, the Mixer comprises six separate
amplifier circuits, one for each set of similar voices from the six
strings. For clarity, only two are illustrated: the circuit
carrying the summation of all the u voices, designated U, and the
circuit carrying the summation of all the w voices, designated W.
It should be understood that the remaining circuits are identical
in design to that for these voices.
The u signals Au, Bu, Cu, Du, Eu, and Fu are all combined and
applied through capacitor C16 to the base of transistor Q18.
Variable resistors R8 and R9, together with capacitors C17 and C18,
control the frequency response of the circuit and hence the tone of
the U voice. The amplified output of Q18, voice U, is applied to
both the Preset Voice Selector and the Stepping Voice selector. The
other Mixer circuits operate similarly. The amplified sawtooth
voice W is also used as an input signal to the Percussion
Regulator, discussed below. One of the Mixer output signals may
also be chosen to drive the Sustain Vibration Amplifier, also
discussed below.
The Preset Voice Selector is simply a switch wired to select as its
output any one of the six incoming voices, or various combinations
of those voices. In the illustrative embodiment, the switch is
wired to select any one of U, V, W, X, Y, Z, UY, UZ, VW, VX, WX or
WY. These particular outputs are entirely a matter of choice; the
ear of the performer being the ultimate decision-maker. Any other
outputs could be selected. The output is made available as one
input to the Expression Pedal, discussed below.
The Stepping Voice Selector is a stepping relay whose action is
controlled by a microswitch actuated by a backward swing of the
Expression Pedal. In this illustrative embodiment, the Stepping
Voice Selector repeats its cycle every six steps and applies one of
the input voices U, V, W, X, Y or Z as a second input to the
Expression Pedal.
Footswitch S2 makes available the natural sound of the guitar,
voice Z, as a third input to the Expression Pedal, replacing the
second input from the Stepping Voice Selector.
The Expression Pedal carries neon bulb NE2 and is designed so that,
when the pedal is depressed, NE2 first illuminates only PH3, and
then only PH2. The output from the pedal therefore varies from the
Stepping Voice Selector signal to the Preset Voice Selector signal
as the amount of pedal depression is increased.
The output signal from the Expression Pedal is further processed by
the Automatic Gain Control (AGC) circuit and the Percussion
Regulator circuit (both shown in FIG. 5) before becoming the
ultimate output signal. The signal is applied to the base of
transistor Q20 through potentiometer R11 and capacitor C20.
Potentiometer R11 should be adjusted to keep the maximum incoming
signal below a level which would cause distortion in the second
stage transistor, Q21. Through conventional amplifier circuitry the
signal becomes available at the collector Q21 for the Volume Pedal
and the ultimate output.
Photoconductor PH4 is connected between the collectors of Q20 and
Q21, and the bias values to those transistors are adjusted so that
their collector voltages are equal and no D.C. current flows
through PH4. Since the signal at the collector of Q21 is
180.degree. out of phase with the signal at the collector of Q20,
because of the nature of a common-emitter transistor amplifier, if
PH4 has relatively low resistance value, the output from Q21 will
be attenuated because of negative feedback from the collector of
Q21, through PH4, to the base of Q21. On the other hand, if PH4 has
a relatively high resistance value, little negative feedback will
occur and the output from Q21 will not be attenuated.
The resistance level of PH4 is controlled by neon bulb NE3, located
in the collector circuit of pnp-type transistor Q22. A portion of
the output signal at the collector of Q21 is applied to the base of
transistor Q23 through potentiometer R12, the manually-set AGC
level control. Transistor Q23 amplifies the signal and passes it to
the rectifier circuit composed of diode D11 and capacitor C21. The
signal here is converted to a negative D.C. value indicative of the
amplitude of the output signal at the collector of Q23. This
negative voltage is then applied to the base of transistor Q22. The
negative bias causes Q22 to conduct, sending current through NE3,
thereby reducing the resistance of PH4 and, ultimately, attenuating
the signal to the Volume Pedal in an amount dependent on the
effective resistance value of R12. Therefore, the signal level at
the Volume Pedal is regulated by the value of R12.
Potentiometer R12 controls the ratio of the volume of single notes
to the volume of chords. Potentiometer R12 should be adjusted so
that single notes do not cause NE3 to light and thus do not cause
any attenuation of the output signal but that chords, having a much
higher RMS value than single notes, make NE3 glow sufficiently to
attenuate the output signal to the strength of the single note
output signal.
The Percussion Regulator (FIG. 5) takes as its input the sawtooth
voice W from the Mixer. Its function is to remove the sharp "click"
heard when the guitar pick strikes the strings, thereby making
melodies sound bowed rather than struck. It operates by causing
each note to be eased into audibility, reaching its full volume
about one/half second after the note has been struck.
When the Percussion Regulator is not in operation (i.e., if switch
S3 is in its open position), very little current flows through NE3
because of the relatively high resistance in series with NE3.
Therefore, in this condition the resistance value of PH4 is
relatively high and no attenuation occurs. Closing S3, however,
puts Q24 into saturation because of the relatively low resistance
path thereby established between B- and its base, and this makes
NE3 glow brightly. The glow of NE3 attenuates the output at the
Volume Pedal by about 90 percent in the manner described above.
When any string is plucked, the W voice derived from that string in
the Mixer is applied to the base of transistor Q25 and amplified by
Q25 and Q26. The interstage coupling capacitor C22 is made
relatively small to accentuate the high frequency components of the
signal. This is done in order to compensate voice W for its
relative weakness in high frequency components which results from
the manner in which voice W was generated, i.e., the presence of
capacitor C11 between the collector and the base of transistor
Q11.
The output signal from Q26 is rectified by diode D12 into a
positive D.C. signal proportional to the strength of the W signal
applied. Capacitor C23, of relatively large value, smoothes this
signal. This positive signal serves to lower the degree of negative
bias at the base of pnp-type transistor Q24, tending to turn this
transistor off and thereby dim NE3. Photoconductor PH4 is a
comparatively low speed photoconductor, for example a NSL-457,
whose frequency response drops off sharply below about 60 Hz, and
because of its slow recovery rate and the time delay in the circuit
controlling NE3 caused by capacitor C23, the output signal at the
collector of Q21 rises gradually in strength from a low level
determined by the maximum attenuation available by the action of
PH4 to its normal unattenuated level, with the initial percussive
attack eliminated from the note. The maximum attenuation is that
produced by the lowest attainable resistance value of PH4.
Potentiometer R13, at the input to the Percussion Regulator,
controls the audible duration of the note and the overall
sensitivity of the system.
Capacitor C22, by boosting the deficient high frequency component
of voice W, ensures that the Percussion Regulator will operate in
the same manner for high and low notes. If the high frequency
components were not boosted, voice W for a low note would be a
stronger signal than voice W for a high note, and this would cause
a low note to rise into audibility more rapidly, last longer, and
decay from audibility more rapidly than high note. This would be an
undesirable musical characteristic.
The Volume Pedal (FIG. 5) is a neon-photoconductor combination as
described above which allows the performer to vary the volume of
the output signal.
The circuitry just described possesses an additional advantage. One
conventional tone modification device in wide use, known as a
"wah-wah" pedal, comprises a passive electrical circuit in series
with the output signal of the guitar and including as one element
thereof a variable resistance element under the control of the
performer. Depending on the instantaneous setting of the
resistance, a matter determined by the performer, this device
primarily passes only low or high frequencies. In operation,
performers attempt to synchronize their depression of the pedal
with the playing of the notes, to give each note a similar
frequency profile, but this is quite difficult to accomplish.
The present system provides means for obtaining the "wah-wah"
effect automatically without relying on the performer's skill. Neon
bulb NE3 is illuminated each time a note is struck, and this causes
the resistance of photoconductor PH4 to drop each time in the
manner described above. If a photoconductor similar to PH4 were
placed in series with the output signal and exposed to NE3, the
"wah-wah" effect could be achieved automatically.
If the performer desires, a note played on this guitar can be
sustained for any desired length of time, at any volume level, in
any acoustic environment. This is accomplished, as indicated
generally in FIG. 1, by amplifying and shaping one of the "voices"
from the string being played and converting the processed signal
into a mechanical vibration conveyed back to the string. In the
illustrative embodiment shown, the input signal for the Sustain
Vibration system is chosen to be the X signal from the Mixer, but
another voice could be used if desired.
The Sustain Vibration circuit, shown in detail in FIG. 6, includes
a two stage transistor preamplifier of standard design, a limiter
made up of diodes D15 and D16, the Sustain Pedal, transformer T2,
switch S5, and a power amplifier of standard design feeding the
Sustain Vibrator coil. When the Sustain Pedal is depressed, neon
bulb NE5 illuminates photoconductor PH6, lowering its resistance
and allowing the amplified signal from transistors Q27 and Q28 to
pass to the rest of the system. The limiter ensures that,
irrespective of the strength of the signal from the Mixer, the
signal applied downstream will have a preset strength. This allows
the Sustain Vibration system to maintain the same output volume
level whether chords or single notes are being played.
When the Sustain function is activated, the amplified signal from
the power amplifier is converted into a mechanical vibration
conveyed back to the guitar string by apparatus shown in FIGS. 7
and 8. The apparatus, shown in relation to guitar body 50, includes
a permanent magnet 51 mounted in the guitar and a coil 52 in
movable relationship to the magnet and rigidly attached to the
underside of extension 53 of guitar bridge 54. FIG. 7 shows this
relationship between the coil and extension schematically. The
coil, which conveniently may be several turns of copper wire on a
form, receives its signal from the power amplifier. It is free to
move with respect to the magnet as much as the flexibility of the
extension will allow. Bridge 54, including its extension 53, is
commonly made of steel and is securely held in place by supporting
posts 55. Strings 56 extend from tailpiece 57, across the bridge
54, over pickups 58, and on to the neck of the guitar.
In operation the presence of a signal in coil 52 causes it to
vibrate vertically with respect to magnet 51, rigidly mounted in
body 50. These vibrations are transmitted to that part of the
bridge in contact with the strings by its extension 53, thereby
completing a feedback path of which the guitar string is the
frequency determining factor. Operation of this system is totally
independent of the output volume level of the guitar and the
acoustics of the concert setting.
The coil-magnet combination can be mounted anywhere on the guitar
provided only that it is not in the inductive range of the pickups.
Furthermore, the coil could transmit its vibrational energy to the
strings through a connection other than the bridge extension here
disclosed. The system should be designed so that there is no
dominant resonant frequency in the coil-string coupling within the
frequency range of the strings. In addition, correct phase
alignment between the signal at the coil and the signal at the
pick-ups should be maintained. Correct alignment is obtained by use
of switch S5 and transformer T2. The center tap of the
transformer's secondary winding is common and the two extremes are
both available, by activation of S5, as alternate sources for the
coil driving signal.
With the sustain vibration system in operation, the performer can
play with his left hand only, the minute response found naturally
in each string, when fed back to the bridge by the mechanical
feedback system here disclosed, being sufficient to sustain the
note. This can be done without affecting the quality or volume of
the ultimate guitar output.
The following are the values of the circuit components used in the
illustrative embodiment of my invention previously discussed:
A. Components discussed
R1 470 ohms (Phillips EO97AC series Trimmer Potentiometer) R2 10K
ohms (Phillips EO97AC Potentiometer) R3 1K ohms (Phillips EO97AC
Potentiometer) R4 120K ohms R5 470K ohms (Phillips EO97AC
Potentiometer) R6 24K ohms
R8 500K ohms R9 500 K ohms
R11 47K ohms (Phillips EO97AC Potentiometer) R12 500K ohms R13 100K
ohms (Phillips EO97AC Potentiometer) D1 IN270 D100-04 IN270 All
other diodes IN4001
c1 300 mf 30v C2A,B 6.4 mf 30v C2C,D 10 mf 30v C2E,F 25 mf 30v C3
25 mf 30v C4A,B,C 0.22 mf 70v C4D,E,F 0.33 mf 70v C5A,B 0.1 mf 70v
C5C,D,E 0.22 mf 70v C4F 0.33 mf 70v
C7A,B 680 pf 70v C7C 0.001 mf 70v C7D 0.0015 mf 70v C7E 0.002 mf
70v C7F 0.005 mf 70v C8A,B 0.03 mf 70v C8C,D 0.05 mf 70v C8E,F
0.068 mf 70v C9A,B 0.01 mf 70v C9C 0.02 mf 70v C9D 0.02 mf 70v C9E
0.033 mf 70v C9F 0.05 mf 70v C10A 0.05 mf 70v C10B,C,D 0.1 mf 70v
C10E 0.133 mf 70v C10F 0.168 mf 70v C11A,B 25 mf 70v C11C,D,E 50 mf
70v C11F 100 mf 70v C12A 0.01 mf 70v C12B 0.015 mf 70v C12C,D 0.02
mf 70v C12E 0.03 mf 70v C12F 0.033 mf 70v C13A,B 0.05 mf 70v C13C
0.168 mf 70v C13D 0.2 mf 70v C13E 0.22 mf 70v C13F 0.1 mf 70v
C14A,B,C 0.02 mf 30v C14D 0.25 mf 30v C14E,F 0.03 mf 30v
C16 6.4 mf 25 v C17 0.005 mf 70v C18 0.01 mf 70v
C20 6.4 mf 25 v C21 16 mf 25 v C22 0.1 mf 70v C23 2.5 mf 25 v
Q1 2N3415 Q2 2N3415 Q3 2N3415 Q4 2N3415 Q5 2N2711 Q6 2N2711 Q7
2N2430 Q8 2N2430 Q9 2N3415 Q10 2N3415 Q11 2N3415 Q12 2N3415 Q13
2N3415 Q14 2N3415 Q15 2N3415 Q16 2N3415 Q18 2N3415 Q20 2N3415 Q21
2N3415 Q22 2N4412 Q23 Q24 2N3415 Q25 2N3415 Q27 2N3415 Q28
2N3415
b. components not specifically discussed
70 100K ohms 71 3K ohms 72 33K ohms 73A,B no resistor 73C,D,E,F 22K
ohms 74 2.2M ohms 75 39K ohms 76 510 ohms 77 100 K ohms 78 13K ohms
79 82K ohms 80 75K ohms 81 100K ohms 82 18K ohms 83 120 ohms 84
120K ohms 85 0.1 mf 70v 86 20 mf 25v 87 3 mf 25v 89 610 ohms 90
0.02 mf 30 v 91 30K ohms 92 68K ohms 93 8.2K ohms 94 3.6K ohms 95
36K ohms 96 11K ohms 97 680K ohms 98 15K ohms 99 4.3K ohms 100 100
ohms (Phillips EO97AC Potentiometer)
110 120K ohms 111 5.6K ohms 112 68K ohms 113 470K ohms 114 51K ohms
115 20K ohms 116 9.1K ohms 117 56K ohms 118A,B,C, 1.6 mf 70v
118D,E, 2.5 mf 70v 118F 6.4 mf 70v 119 100K ohms 120 3.3K ohms 121
62K ohms 122 100K ohms 123 6.8K ohms 124 110K ohms 125A,B,C, 1.6 mf
70v 125D,E 2.5 mf 70v 125F 6.4 mf 70v 126 15K ohms 127 2K ohms 128
130K ohms 129 130K ohms 130 360K ohms 131A,B, 0.02 mf 70v 131C 0.03
mf 70v 131D 0.04mf 70v 131E 0.05 mf 70v 131F 0.07 mf 70v 132 4.7K
ohms 133 100K ohms 134 68K ohms 135 1.3M ohms 136 82K ohms 137 100K
ohms 138 3K ohms 139 43K ohms 140 270K ohms 141 47K ohms 142A,B,
1.2M ohms 142C,D 910K ohms 142E,F 1M ohms 143 1K ohms 144 91K ohms
145 75K ohms
150 2K ohms 151 160K ohms 152 16K ohms 153 12K ohms 154 6.4mf 25v
155 20K ohms 156 6.4 mf 25v 157 62K ohms 158 47K ohms
160 14K ohms 161 3.9K ohms 162 56K ohms 163 470 ohms 164 0.33 mf
70v 165 56K ohms 166 3.9K ohms 167 470 ohms 168 6.4 mf 25v 169 62K
ohms 170 3K ohms 171 1K ohms 172 100 mf 64v 173 36K ohms 174 36K
ohms 175 6.4 mf 25v 176 56K ohms 177 3K ohms 178 39K ohm 179 56K
ohms 180 3K ohms 181 33K ohms 182 6.4 mf 25v 183 7.5K ohms 184 62K
ohms 185 560 ohms 186 5.6K ohms 187 7.5K ohms 188 300K ohms 189 10M
ohms 190 560 ohms 191 100K ohms (Phillips EO97AC Potentiometer) 192
91K ohms 193 100K ohms 194 110K ohms 195 39K ohms 196 43K ohms 197
8.2K ohms 198 6.4 mf 25v 199 33K ohms 200 56K ohms 201 2.7K ohms
202 0.22 mf 70v
210 43K ohms 211 56K ohms 212 3K ohms 213 33K ohms 214 0.22 mf 70v
215 470K ohms (Phillips EO97AC Potentiometer) 216 56K ohms 217 3K
ohms 218 33K ohms 219 6.4 mf 25v 220 62K ohms 221 10K ohms 222 6.4
mf 25v 223 1600 mf 64v
Miscellaneous
R8/r9 is an ohmite dual potentiometer No. CCU-5041.
All neons are AIA.
All photoconductors are Phillips B8-731-05 except PH4, which is an
NSL-457.
The transformers T1 and T2 are both Armaco At-46.
* * * * *