US3429976A

US3429976A - Electrical woodwind musical instrument having electronically produced sounds for accompaniment

Info

Publication number: US3429976A
Application number: US549397A
Authority: US
Inventors: Daniel J Tomcik
Original assignee: Electro Voice Inc
Current assignee: Bosch Security Systems Inc
Priority date: 1966-05-11
Filing date: 1966-05-11
Publication date: 1969-02-25
Anticipated expiration: 1986-02-25

Description

D'. J. rcbMclKv Feb. 25, 1969 ELECTRICAL WOODWIND MUSICAL INSTRUMENT HAVING ELECTRONICALLY PRODUCED SOUNDS FOR ACCOMPANIMENT Sheet of 5 Filed May 11, 1966 Inventor' DANIEL. J. ToMczlK D. J. TOMCIK Feb. 25, 1969 3,429,976 ELECTRICAL wooDwIND MUSICAL INSTRUMENT HAVING ELECTRONICALLY PRODUCED SOUNDS FOR ACCOMPANIMENT Filed May 11, 1966 n I l f I l 1 Inventor* .DANIEL J. ToMceK a Ku;

pl-f-lforneg Feb. 25, 1969 D. J. -roMclK 3,429,976

ELECTRICAL WOODWIND MUSICAL INSTRUMENT HAVING ELECTRONICALLY PRODUCED SOUNDS FOR ACCOMPANIMENT Filed May 11, 196e v sheet 5 J IrLvf-:r-:jcor` DANIEL J. TOMCIK @ma Kuki..

.fl-Horne@ United States Patent O 3,429,976 ELECTRICAL WOODWIND MUSICAL INSTRU- MENT HAVING ELECTRONICALLY PRO- DUCED SOUNDS FOR ACCOMPANIMENT Daniel J. Tomcik, Buchanan, Mich., assignor, by mesne assignments, to Electro-Voice Incorporated, Buchanan, Mich., a corporation of Delaware Filed May 11, 1966, Ser. No. 549,397 U.S. Cl. 84-1.12 19 Claims Int. Cl. Gd 5/00; G10h, 1/02, 3/00 ABSTRACT OF THE DISCLOSURE A monophonic wind type instrument is disclosed employing a piezoelectric pickup communicating with the air column of the instrument. The piezoelectric pickup is utilized to generate electrical signals which are amplitied, filtered as to tone, and reproduced by a loudspeaker. The electrical signals are also shaped and utilized to drive a pulse generator to produce multiples and submultiples of the frequency of the tone produced by the woodwind instrument. The output of the divider is tone ltered to produce a voice independent of the wind instr-ument. A gate circuit is provided lbetween the trigger circuit an-d divider to delay in actuation of the divider following initial production of a tone by the instrument in order to avoid spurious mechanically excited electrical outputs.

The present invention relates generally to musical instruments, and particularly to instruments which are provided with electrical amplification.

The use of electrical amplification for musical instruments is of course conventional, and special pickups have been designed for use with ditferent instruments to avoid picking up the sounds generated lby other instruments, such as the microphone of Rudd, Patent No. 2,574,591, which is disposed in the mute of a horn, the pickup of Barron, Patent No. 2,984,140, which is directly mounted on a woodwind and coupled to the interior of the instrument, and the pickup of Abreo, Patent No. 3,144,801, which employs a pickup directly mounted on the tubular portion oit a clarinet immediately adjacent to the mouthpiece and which communicates with the interior of the tu-bular portion by means of a passage. All such devices, however, simply reproduce the sound generated by the instrument with greater amplitude. It has also been known, however, that voicing filters may be employed to shape the electrical waves generated by a pickup on a musical instrument, as disclosed by Miessner in Patent No. 2,138,500l

It is, in general, an object of the present invention to provide an electrical musical instrument for reproducing tones generated by a conventional musical instrument of improved construction. In accordance with the present invention, the inventor has provided an electrical musical instrument in which tones generated by a mechanical musical instrument may be played simultaneously with and in musical composition with tones having voice properties independent of the instrument `from which the tones are generated. Further, in accordance with the present invention, a conventional musical instrument, such as a woodwind, is utilized to generate controlling signals which are utilized for the generation of tones independent of the tone of the generating instrument.

Prior to the present invention, acousto-electrical pickups have 'been mounted upon conventional instruments, such as the woodwin-d instruments, and the electrical output of such a pickup has been utilized to produce an electrical signal which in turn may be converted into sound. The acousto-electrical pickups are responsive to acoustical vibrations, but they are also responsive to vibrations from other sources. For this reason, the keying of the instrument, or nervous movements by the performer, will result in an electrical output from the pickup, and hence an acoustical output from the electrical musical instrument. It is an object o'f the present invention to provide an electrical musical instrument which employs a conventional mechanical musical instrument and an acousto-electrical pickup and which possesses reduced probability of an acoustical output from spurious mechanical vibrations.

It is also an object of the present invention to provide an electrical musical instrument which utilizes a monophonic mechanical musical instrument to generate the basic tones, and produces an acoustical output enriched by one or more subharmonics of the tones generated and chords therefrom.

Further objects and advantages of the present invention will be apparent to those skilled in the art from a further consideration of this specicaiton, particularly when viewed in the light of the drawings, in which:

FIGURE 1 is a sectional View of the mouthpiece of a saxophone incorporating an acousto-electrical transducer in accordance with the teachings of the present invention;

FIGURE 2 is a block circuit diagram of an electrical musical instrument according to the teachings of the present invention employing the pickup illustrated in FIG- URE l;

FIGURE 3 is a schematic electrical circuit diagram of the electrical circuits illustrated in FIGURE 2, the power amplifier and pickup 4bein-g omitted from FIGURE 3; and

FIGURE 4 is a schematic electrical circuit `diagram of the electrical circuits of another embodiment of the present invention, FIGURE 4 omitting the pickup and power amplier and constituting the same functional elements set forth in FIGURE 3.

FIGURE 1 illustrates the mouthpiece of a woodwind instrument, and in the particular instrument, the mouthpiece is that of a saxophone, although other types of mechanical instruments may be utilized. As illustrated, the mouthpiece itself is designated 10, and the mout-hpiece has an outwardly extending tubular portion 12 which is disposed within a recess 14 in a stem 16 of the saxophone. The tubular portion 12 is provided with a layer of cork 18, or some other soft material to dorm an acoustic seal, on the exterior surface thereof. The mouthpiece 10 has a central channel 20 which extends from an opening 22 and communicates with a channel 24 in the stem 16. A vibratal reed 26 is mounted on the mouthpiece removably by a circular adjustable ring 28, in the conventional manner.

As is conventional with saxophones, clarinets, and other instruments, the vibratal reed 26 is set into vibration by the action of a performer blowing on the reed. As a result of the vibratal motion of the reed, a column of air within the

channels

20 and 24 is placed in oscillation, and it is the oscillation of this column of air which is heard when the instrument is played.

In accordance with the present invention, an opening 30 is provided in the stem 16 of the saxophone, and a pickup 32 is mounted on the stem 16 at the opening 30. The pickup 32 has a housing 34 of electrically conducting material, such as aluminum or copper, land in the particular construction, the housing 34 has a cylindrical external wall 36. The housing 34 is provided with an internal cavity 38 which is formed by a cylindrical Wall 40 coaxial with the wall 36. The cavity 38 is provided with a circular shoulder 42 disposed normal to the axis of the

cylindrical walls

36 and 40, thus forming a portion 44 of restricted diameter. The portion 44 of restricted diameter also forms a at circular shoulder 46 disposed normal to the axis of the

walls

36 and 40 and spaced from the shoulder 42, and a bore 48 extends through the housing 34 on the axis of the

walls

36 and 40 into the restricted portion 44 of the recess 38. The wall 36 also has a cylindrical recessed portion 50 confronting the bore 48, and the opening 30 in the stem 16 of the saxophone is sealed about the recessed portion 50 of the outer wall of the housing 34.

A circular piezoelectric generating element 52 is mounted on the shoulder 42 within the housing 34. The generating element 52 comprises two

piezoelectric discs

54 and 56, and the two discs S4 and 56 are mechanically mounted together and electrically interconnected by a layer 58 of electrically conducting material, such as silver. In addition, a layer of electrically conducting material designated 60 is disposed on the surface of the disc 54 remote from the layer 58, and a layer 62 of electrically conducting material is disposed on the surface of the disc 56 remote from the layer 58. The layers 60 and 62 form electrodes for the generating element 52. Further, the disc 54 and the disc 56 are electrically polarized in opposite directions relative to the electrically conducting layer 58, so that electrical signals are generated on the electrodes 60 and 62 of opposite sign as a result of bending of the generating element 52.

The electrode 60 is disposed in abutment with the shoulder 42 of the electrically conducting housing 34, and the electrode 60 is secured on the shoulder 42, as by electrically conducting cement. The electrode 62 is electrically insulated from the housing 34 by providing a gap between the electrode 62 and the wall 40 of the housing 34. In like manner the electrode 58 is electrically insulated from the housing 34 by providing a gap between the electrode 58 and the wall 40 of the housing 34.

The pickup 32 also has an electrically conducting cover disc 64 which is mounted on the housing 34 and electrically connected thereto, the disc 64 closing the cavity 38. One terminal 66 is mounted on the cover disc 64 and electrically connected thereto, the terminal 66 being connected through the housing 34 to the electrode 60 of the generating element 52. A second terminal 68 is also mounted on the cover disc 64, but the electrode 68 is electrically insulated from the cover disc 64 by a grommet 70 of insulating material, such as rubber or Bakelite. The terminal 68 is electrically connected by a wire 72 to the electrode 62 of the generating ele- Iment 52.

Because of the fact the the reed 26 is placed in vibration by the breath of the performer, considerable moisture enters the channel 20 and passes through the channel 24. In order to prevent this moisture from entering the cavity 38, a thin nonporous layer 74, such as a Mylar film, is cemented on the shoulder 46 of the housing. The moisture barrier in FIGURE 1 also includes a second layer 74A of the same material applied directly on the electrode 60 of the generating element 52, and the layer 74A can be used as a second defense against moisture, as here shown, or `as a substitute for the layer 74. The layer 74 must pass variations in air pressure to the cavity 38 so that these variations in air pressure will be effective to bend the generating element 52, thus producing an electrical output.

FIGURE 2 illustrates the pickup 32 connected to the input of an amplifier 76. The output of the amplifier 76 is electrically connected to a 'plurality of tone filters, three being illustrated in FIGURE 2 and designated 78, 80, and `82. The output of each tone filter is connected through a

switch

84, 86, or 88, to the input of a further amplifier 90, and the output of the amplifier 90 is connected to a power amplifier 92, and hence to a loudspeaker 94 for converting the electrical signals into acoustical energy.

Since the pickup 32 generates electrical signals which may be converted into sound to produce substantially the same tones as generated in the mouthpiece of thel 4 f musical instrument, these may simply be conducted through the amplifiers to the loudspeaker 94 to produce an amplified tone of the character of the musical instrument, and a stop switch 96 has been provided for this purpose. However, if the switch 96 is open, and one or more of the .stop switches 84, 86, or 88 is closed, the tone filter associated with the stop switch will modify the frequency distribution of the electrical signal generated by the pickup 32, and produce an electrical signal at the input of the -amplifier which when converted into sound by the loudspeaker 94 will differ from the tone generated in the mouthpiece 10. In this manner, the sound of the musical instrument may be tailored to the performers wishes. Further, a tremolo generator 98 is electrically connected to the amplifier 90 to vary the gain of the amplifier 90 at a tremolo rate, such as 3 or 4 cycles per second. In this manner, additional tremolo may be added to the tone generated by the musical instrument to produce an effect desired by the performer.

The electrical signal appearing in the output of the amplifier 76 is also conducted through a wave shaper 147 to the input of an amplifier 100. The output of the amplifier 100 is converted into pulses by the trigger circuit 102, and the pulses from tlhe trigger circuit 102 are utilized by a frequency divider 104 to produce electrical signals one octave below the tone generated in the mouthpiece 10 of the instrument. The output of the frequency divider 104 is connected to the input of the amplifier 90, and mixed with whatever signal is passing through the stop switches 84, 86, 88 or 96. In this manner, the output of the loudspeaker is enriched both in tone and in subharmonic content. Also the output of the wave Shaper 147 is coupled to the input of a chord generator 300 which will be described hereinafter.

FIGURE 3 illustrates the electrical circuits utilized in one embodiment of the present invention from the input of the amplifier 76 to the output of the amplifier 90. It will be recognized that the loudspeaker 94 and power amplifier 92 are of conventional design, and need not be further illustrated. The output of the pickup 32 is electrically connected from the terminals 66 and 68 to an input jack 106 for the amplifier 76. The amplifier 76 em* ploys a terminating resistor 107 connected across the input jack 106 and a capacitor 108 to couple the electrical signal from the jack 106 to the base 110 of a transistor 112. The transistor 112 has a collector 114 electrically connected to the positive terminal of a power source 116 through a resistor 118 and a capacitor 119 is connected in parallel with the resistor 18. Also, the base of the transistor 112 is biased by a resistor 120 connected to the junction of a voltage divider consi-sting of resistors 122 and 124 connected between the collector 114 and the negative terminal of the power source 116. The transistor 112 also has an emitter 126 connected to the negative terminal of the power source 116 through a resistor 128, and a capacitor is connected between the emitter 126 and the junction of the voltage divider consisting of resistors 122 and 124.

The output of the amplifier 76 is in the form of the input to the amplifier 76 and is conducted through a capacitor 132 to the tone filters 78, 80, and 82. The tone filters comprise combinations of resistors and capacitors, as indicated in the figure, but could equally well use other components to produce the desired frequency characteristics, and hence will not be further described.

The amplifier 90 has a volume control 134 with one terminal connected to a terminal of each of the stop switches 84, 86 and 88. The other terminal of the volume control 134 is connected to the common ground or negative terminal of the power supply 116, and the tap of the volume control 134 is connected through a capacitor 136 and resistor 137 to the base 138 of a transistor 140. The transistor 140 is connected in a circuit similar to the amplifier 76, except for component sizes, and hence will not be further described. The transistor 140 has a collector 142 forming the output terminal of the amplifier 90, and the collector 142 is connected through a capacitor 144 to an output jack 146. The output jack in turn is connected to the power amplifier 92, as illustrated in FIGURE 2.

The circuit thus far described is capable of amplifying the electrical signals produced by the pickup 32 and modifying these signals in tonal qualities. FIGURE 3 also illustrates the circuit-s yfor generating subharmonics.

A portion of the audio signal appearing in the output of the amplifier 76 is fed through a wave shaping circuit 147 to input of an amplifier 100. TheM output is taken from the emitter 126 of Iamplifier 76 through a direct current blocking capacitor 148 which is connected to a signal averaging circuit and direct current clamp circuit which together constitute the wave shaping circuit 147. Because of the fact that complex waves are generated by a musical instrument, such as a saxophone, a wave shaping .circuit is desirable to produce an electrical signal which crosses the zero axis only with the frequency of the fundamental wave. This averaging function is provided by a filter which employs

capacitors

149 and 150 connected in series with capacitor 148, a first adjustable choke 151 connected in parallel with capacitor 149 and a second adjustable choke 152 connected in parallel with capacitor 150. In addition, the filter has 'by-

pass capacitors

153i, 155 and 157 connected to the terminals of the

chokes

151 and 152 and to the common ground, respectively. The filter is selected to have a cut-off frequency above the highest fundamental frequency of the instrument, and in the particular example the cutoff frequency is 1400 cycles per second. The clamp consists of a resistor 159 connected in parallel with capacitor 153 (the output of the filter circuit) and a diode 160 connected to bias the base 154 of the transistor 156 of the lamplifier 100, as well as clamp unsymmetrical input wave forms to this bias potential.

The input to the amplifier 100 is formed by the base 154 of transistor 156. The transistor 156 has an emitter 158 connected to the common ground or negative terminal of the power source 116. The transistor 156 also has a collector 162 connected through a resistor 164 to the positive terminal of the power source 116. The base 154 is provided with a lbias potential through the circuit consisting of a resistor 166 electrically connected between the collector 162 and base 154, the diode 160, and resistor 159 connected to the negative terminal of the power source. The base 154 is clamped to its positive bias potential, since the signal appears in series with resistor 159 and decreases the flow of current through the bias circuit, thereby increasing the positive potential on the base 154 to provide the input signal for the amplifier 100.

The output of the amplifier 100 is conducted through a capacitor 170 to the input of the pulse generating circuit 102 which is in the for-m of a Schmitt trigger circuit. Since the Schmitt trigger will produce square waves in its output and is not dependent upon the wave form of the input, the form of the output of the amplifier 100 may be sinusoidal or a complex wave form. The Schmitt trigger employs two

transistors

172, and 174, and the transistors have emitters 176 and 178, respectively, connected to a common bias resistor 180 which is connected to the common ground terminal.

The transistor 172 has a base 182 connected to the capacitor 170, and the base 182 is also connected to the common ground terminal through a diode 184 and a resistor 186, and to the positive terminal of the power source 116 through a resistor 188. The diode 184 is connected to conduct negative signals to ground Iand is back biased through resistor 188. Hence, negative peaks impressed on the base 182 are limited to a fixed value which may be selected by the value of resistor 186. Further, the base 182 and emitter 76 of transistor 172 provide a similar diode function, and with the series resistor 180 limit positive peaks `on the base 182. AS a result, the potential of the input signal to the Schmitt trigger is limited to a value within a narrow range, regardless of the output of the amplifier 100, thus eliminating faulty triggering of the Schmitt trigger as a result of excessive positive or negative peaks on the input signal. The transistor 172 has |a collector 190 connected to the positive terminal of the power source 116 through a resistor 192. The collector 190 of transistor 172 is coupled to the base 194 of the transistor 174 through a resistor 196, and the base 194 is connected to the common ground terminal through a resistor 198. The transistor 174 has a collector 200 electrically connected to the positive terminal of the power source 116 through a resistor 202, and the output of the Schmitt trigger 102 is taken from the collector 200.

The square wave output of the Schmitt trigger is differentiated by a capacitor 204 and resistor 206 connected between the collector 200 and the common ground terminal. A diode 208 connected between the junction of the capacitor 204 and resistor 206 and the common ground terminal cuts off the positive portion of the differentiated wave from the capacitor 204 and resistor 206 and serves as a clamp to produce negative pulses for the divider 104. The divider 104 employs two

transistors

210 and 212. These transistors are connected in a bistable multivibrator circuit which is driven with the negative differentiated pulses connected to the input of the multivibrator 104. The

transistors

210 and 212 have emitters 214 -and 216, respectively, connected to the negative terminal of the power source through the gate circuit described hereinafter, and the

transistors

210 and 212 have collectors 218 and 220, respectively, connected to the positive terminal of the power source 116 through

resistors

222 and 224, respectively. The transistor 210 has Aa base 226- connected to the junction of capacitor 204 and resistor 206 through a capacitor 228, and the transistor 212 has a base 230 connected to the junction of capacitor 204 'and resistor 206 through a capacitor 232. The

bases

226 and 230 are connected t-o the common ground through resistors 234 and 236, respectively. Further, the base 226 of transistor 210 is coupled to the collector 220 of transistor 212 through a resistor 238 and a capacitor 240 connected in parallel, and the base 230 of transistor 212 is connected to the collector 218 of transistor 210 through a resistor 242 and `a capacitor 244 connected in parallel. The multivibrator thus formed is connected to cycle at a frequency one half of its input, thereby producing an electrical signal one octave below the signal generated by the pickup 32.

The output of the divider 104 is taken from the collector 218 of transistor 210 and is connected to a tone filter 246. The tone filter comprises serially connected

resistors

248 and 250, and capacitors 252 land 254 connected between the common ground terminal and opposite ends of resistor 250. Further, a volume control 256 is connected in parallel with capacitor 254, and the tap of the volume control 256 is connected through a resistor 257 to the volume control 134 at the input of the amplifier 90.

The pickup 32 generates a monophonic electrical wave which is amplified by the amplifier 76 and the amplifier to produce a suitable input signal for the Schmitt trigger 102. The output of the Schmitt trigger 102 is a square wave, which is differentiated, and the negative pulses are utilized to control the frequency of the multivibrator of the divider 104. In this manner, the output of the divider 104 has .a frequency one half that of the electrical signal generated by the pickup 32, and the output of the multivibrator 104 is essentially square wave in form. As a result, the output of the multivibrator 104 iS independent of the wave form generated by the pickup 32, and is rich in harmonics. The tone filter 246 tailors the -frequency characteristics of the output of the divider 104 to produce a suitable electrical wave for further amplification and conversion into sound. The volume control 256 permits the output of the multivibrator 104 to be manually adjusted by the performer to emphasize or deemphasize the subharmonic of the instrument he is playing.

The pickup 32 responds to vibrations applied to the generating element 52, whether they are` the result of oscillations generated in the channel 20 of the mouthpiece 10 of the instrument or the result of spurious mechanical movements, such as movement of the instrument by the performer, or accidental bumping of the instrument. Because of the fact that spurious mechanical movements may result in an electrical output, the divider 104 is provided with a gate circuit 258 to introduce a time delay in the subharmonic system.

The gate 258 employs ya transistor 260 with a collector 262 electrically connected to the

emitters

214 and 216 of the

transistors

210 and 212 of the multivibrator 104. The transistor 260 has an emitter 264 connected to the ground terminal, and in this manner the emitter to collector circuit of the transistor 260 is in series with the ground return of the

transistors

210 and 212 `of the multivibrator 104. The base 266 of the transistor is connected to a source f positive direct current potential which builds up with time on the application of a sustained note in the mouthpiece `of the instrument. The transistor 260 will not conduct between the emitter and collector until the magnitude of this direct current potential reaches a threshold value, thereby providing a time delay between the beginning of an output from the pickup 32 and operation of the frequency divider 104. The direct current potential is developed across a capacitor 268 which is connected to the base 266 through a resistor 270. The output of the Schmitt trigger 102 is conducted through a capacitor 272 to a rectifying diode 274, and the positive portions` of the rectified Wave are conducted to the capacitor 268 through .a resistor 276. A resistor 278 is connected in parallel with the capacitor 268 to adjust the magnitude of the potential across the resistor 268 to the threshold value of the transistor 260 and to provide a suitable time constant for capacitor 268 to charge and discharge.

The introduction of a time delay between the output from the pickup 32 and operation of the divider 104 prevents the divider from actuating on a spurious sig nal, since it will only respond after the lapse of a pel riod of time to an input signal.

In the particular construction described in FIGURES 1 through 3, the pickup 32 has a -diameter of approxiI mately 7A; inch, and is greatly exaggerated in FIGURE l for purposes of clarity. The diameter of the bore 48 is approximately 1A inch, `and the layer 74 is a Mylar film. The transistors used throughout the circuits set forth in FIGURE 3 are Fairchild SE 4002/2N 3565 silicon transistors. The diode 274 is a 1N34 diode, and the capacitor 268 has a capacity of 10 microfarads.

Resistors

270 and 276 are each 33,000 ohms, and resistor 278 has a resistance of 22,000 ohms. Capacitor 272 has a capacity of 0.33 microfarad, and the power source 116 develops approximately volts direct current. The delay achieved by the gate 258 between initiation of a sustained tone in the mouthpiece 10 and triggering of the divider 104 is only a fraction of a second, but is effective to eliminate faulty triggering of the multivibrator which constitutes the divider 104 unless sustained mechanical impulses actu- -ate the pickup 32.

FIGURE 4 illustrates schematically another embodiment of the present invention, and FIGURE 4 corresponds to the elements set forth schematically in FIGURE 3 lfor the first embodiment of the invention. Many of the elements set forth in FIGURE 4 are identical to those set forth in FIGURE 3, and bear the same reference numerals.

It will be noted that the output from the pickup 32 is connected to the terminal 106 of the amplifier 76, and the output of the amplifier 76 is coupled to a plurality of tone filters 78, 80, and 82, as in the previous embodiment. Also, the output of the tone filters is coupled through a volume control 134 to an amplifier 90, and the output of the amplifier is coupled through a capacitor 144 to an output ja-ck 146. Also, the output of the amplifier 76 is coupled through an amplifier to a Schmitt trigger 102, the output of the Schmitt trigger is coupled to the input of a frequency divider 104 through an integrating circuit, as in the previous embodiment. In this embodiment, however, the gate circuit 258 is not utilized to key the emitter return, and the

emitters

214 and 216 of the

transistors

210 and 212 are directly connected to the common ground or negative terminal of the power source 116.

The embodiment of FIGURE 4 also employs the gate circluit 258 connected to the output of the Schmitt trigger 102, but the gating action of the gate 258 is utilized to interrupt the flow of audio signals from the capacitor 144 of the amplifier 90 to the jack 146, thus interrupting the entire electro-acoustical output of the electrical musical instrument.

The collector 262 of transistor 260 is connected to a coil 280 of a relay 282, the other terminal of the coil 280 being connected to the positive terminal of the power source 116. The relay 282 has a pair of

contacts

284 and 286 which are connected in a series circuit with a direct current power source 288 and a lamp 290. The lamp 290 is focused on -a photocell 292, or the lamp 290 and photocell 292 may be constructed as a single unit, such as the Raytheon Raysistor. A resistor 294 is connected between the junction of the photocell 292 and the capacitor 144 and the common ground, and a resistor 296 is connected between the junction of the photocell 292 and the jack 146 and the common ground.

The photocell 292 has a high resistance unless illuminated, and in its darkened condition, the resistance of the photocell greatly exceeds the resistance 296 so that any signal appearing in the output of the amplifier 90 appears predominantly across the resistor 292 and is isolated from the jack 146. This will be true of substantially all spurious signals, since the gate circuit 258 provides a time delay before actuation of the relay 282 and illumination of the lamp 290. When the lamp 290 is illuminated, the resistance of the photocell 292 falls, and the output of the amplifier `90 appears across resistor 296 and the jack 146. Hence, a sustained signal from the pickup 32 results in an output at the jack 146, but a signal which does not persist longer than the delay time of the gate 258 is prevented from producing an output.

FIGURE 4 also illustrates the tremolo generator 98 electrically connected between the direct current source 288 and the lamp 290. The tremolo generator will vary the intensity of the lamp 290 at a tremolo rate, namely 4 to 6 cycles per second, and hence modulate the output appearing on the jack 146 at a tremolo rate, since it will vary the impedance of the photocell 292 at the tremolo rate. This tremolo system may be used in lieu of varying the gain of the amplifier 90.

FIGURE 2 also illustrates a chord generator which utilizes the fundamental frequency of the instrument and two additional frequencies to produce a chord. The two additional tones are generated from the fundamental of the musical instrument by means of frequency multipliers and dividers.

The output of the Schmitt trigger 102 is used to drive a. first frequency multiplier 302 and a second frequency multiplier 304. The output of the first frequency multiplier 302 drives a first frequency divider 306, and the output of the second frequency multiplier -drives a second frequency divider 308. The

frequency dividers

306 and 308 have ground returns including the gate 258, so they also are controlled in the manner of the divider 104. In each case, the frequency `divider divides by a different factor than the multiplication factor of its driving multiplier, so that the output of the divider differs by a fixed ratio from the fundamental frequency of the musical instrument. Further, the outputs of the two dividers are different. In a preferred construction, the first frequency multiplier has a multiplication factor of three, and the rst frequency divider has a division factor of two, hence producing a note one-half higher in frequency than the fundamental. If the fundamental frequency is middle C for example, the output of the first divider will be G above middle C. Also in the preferred construction, the second frequency multiplier 304 has a multiplication factor of five and the second frequency divider 308 has a division factor of four. If the fundamental frequency is middle C, the output of the second divider 308 will be E above middle C. In the same manner as the frequency divider 104 previously described, the

dividers

306 and 308 include wave shaping circuits to voice the outputs, since the waveshape at the outputs of the

dividers

306 and 308 are independent of the instrument. Also, a stop switch 310 is provided in the connection between the outputs of the

dividers

306 and 308 and the input to the amplifier 90 to permit the performer to control the chord generator. A volume control also may be provided in the manner of the divider 104.

In some auditoriums, it is desirable to provide additional reverberation to that achieved by the auditorium. For this purpose, a reverberation unit 312 is provided and connected to the amplifier 90. Since well known reverberation units are suitable for the reverberation unit 312, it will not be further described.

Those skilled in the art will readily devise many modifications of the structures herein set forth. For example, the present invention may be utilized with other types of instruments than Woodwinds, as here illustrated, including horns and even stringed instruments. Many embodiments which are intended to be within the scope of the present invention will be recognized by those skilled in the art from the teaching set forth herein. It is therefore intended that the scope of the present invention be not limited by the foregoing specification, but rather only by the appended claims.

The invention claimed is:

1. A musical instrument and electrical amplifier assembly comprising a mechanoacoustical instrument having a passage containing a column of air adapted to carry sound waves when the instrument is played, means for impressing sound waves on the column of air, an electroacoustical pickup mounted on the instrument having a sound wave receiving port in acoustical communication with the passage of the mechanoacoustical instrument and adapted to generate an electrical wave responsive to sound waves entering the port thereof, an electroacoustical transducer, coupling means electrically connected between the electroacoustical transducer and the electroacoustical pickup including a gate circuit having a control input, said gate requiring a signal above a threshold value on the control input thereof to permit conduction of signals from the pickup to the electroacoustical transducer, and a time delay circuit electrically connected between the pickup and the control input of the gate to permit actuation of the gate responsive to a signal from the pickup after the lapse of a period of time.

2. A musical instrument and electrical amplifier assembly comprising the combination of claim 1 wherein the pickup comprises a housing mounted on the mechanoacoustical instmment having a cavity therein and a port communicating between the exterior of the housing and the cavity, said port communicating with the passage of the mechanoacoustical instrument, a piezoelectric generating element disposed within the cavity confronting the port, and a non-porous lm extending across the port forming a vapor seal between the cavity and the passage of the instrument, said film being vibratal for audio frequencies and the cavity within the housing of the pickup containing a gaseous medium.

3. An electrical musical instrument and amplifier assembly comprising the combination of claim 2 wherein the housing is provided with an interior shoulder disposed on a fiat plane and confronting the cavity, and the piezoelectric generating element comprises a pair of fiat piezoelectric discs extending across the cavity and sealed on the shoulder of the housing, said discs being mounted together and electrically polarized in opposite directions relative to each other, and said generating element having electrodes disposed on the surface of each disc remote from the other disc.

y4. A musical instrument and electrical amplifier assembly comprising the combination of claim 1 in combination with a frequency divider having an input electrically coupled to the acoustoelectrical pickup and an output electrically coupled to the electroacoustical transducer.

5. A musical instrument and electrical amplifier assembly comprising -the combination of claim 4 in combination with a first tone filter having an input electrically connected to the pickup and an output, a second electroacoustical transducer electrically coupled to the output of the tone filter, and a second tone filter electrically connected between the frequency divider and the first electroacoustical transducer.

6. A musical instrument and electrical amplifier comprising the combination of claim 4 in combination with a frequency multiplier connected in cascade with the frequency divider, the frequency multiplier having a different factor for multiplication than the factor of the divider for division, thereby forming a tone generating circuit.

7. A musical instrument and electrical amplifier comprising the combination of claim 6 in combination with a second tone generating circuit including a second frequency multiplier and a second frequency divider connected in cascade with the second frequency multiplier, said second frequency multiplier having a different factor for multiplication than the factor for division of the second divider, and the output of the second tone generator being different than the output of the first tone generator.

8. A musical instrument and electrical amplifier assembly comprising the combination of claim 1 wherein the coupling means electrically connected between the electroacoustical transducer and the pickup comprises a pulse generator having an output electrically coupled to the electroacoustical transducer and an input, and a wave shaping circuit electrically connected between the input of the pulse generator and the pickup, said wave shaper including a filter having a cut-off frequency above the fundamental frequency of the mechanoacoustical instrument and below the frequency of a harmonic of the mechanoacoustical instrument.

9. A musical instrument and electrical amplifier assembly comprising a monophonic mechanoacoustical instrument having a frame with a passage containing a column of air adapted to carry sound waves when the instrument is played, said frame having an aperture extending from the passage to the exterior of the frame, a pickup mounted on the frame having a housing with a cavity therein and a port extending from the cavity and communicating with the passage of the instrument, an acoustoelectrical transducer disposed within the cavity for generating electrical potentials responsive to pressure variations of the air in the cavity of the pickup, a first electrical amplifier having an input electrically connected to the acoustoelectrical transducer and an output, a plurality of tone circuits each having an input electrically connected to the output of the first amplifier and an output, a second arnplifier having an input and an output, a separate stop switch electrically connected between the output of each tone circuit and the input of the second amplifier, a loudspeaker electrically connected to the output of the second amplifier, a pulse generator having an input circuit electrically coupled to the output of the first amplifier and an output, a voice control circuit having an input electrically connected to the output of the pulse generator and an output, and electroacoustical means electrically coupled to the output of the voice control circuit.

10. A musical instrument comprising the combination of claim 9 wherein the input of the second amplifier includes a first volume control and the output of the voicing control circuit includes a second volume control.

11. A musical instrument comprising the combination of claim 9 in combination with electrical gating means having an input and an output electrically coupled to the pulse generator to render the pulse generator inoperative in the absence of excitation on the gating means, and a time delay circuit electrically connected between the pickup and the input of the gating means.

12. A musical instrument comprising the combination of claim 9 wherein the voice control circuit is coupled electrically to the loudspeaker in combination with an electrical gating circuit electrically connected between the loudspeaker and the output of the Voice control circuit and the second amplifier including a control input, said gating circuit forming a stop for audio signals in the absence of a signal on the control input of the gate circuit, and a time delay circuit electrically connected between the pickup and the control input of the gating circuit.

13. A musical instrument comprising the combination of claim 9 wherein the pickup includes a nonporous flexible film disposed across the aperture forming a vapor seal between the cavity of the pickup and the channel of the instrument.

14. A musical instrument comprising the combination of claim 9 in combination with a filter having a cut-off frequency above the highest fundamental frequency of the mechanoacoustical instrument and below a harmonic of the mechanoacoustical instrument, said filter being electrically connected between the pickup and the input of the pulse generator.

15. A musical instrument comprising the combination of claim 14 in combination with a clamp circuit electrically connected between the filter and the input of the pulse generator.

16. A musical instrument and electroacoustical assembly comprising a mechanoacoustical instrument having a passage containing a column of air adapted to carry sound waves when the instrument is played, means for impressing sound waves on the column of air, an electroacoustical pickup mounted on the instrument having a sound passage receiving port in acoustical communication with the passage of the mechanoacoustical instrument and adapted to generate an electrical wave responsive to sound waves entering the port thereof, an electroacoustical transducer, a variable frequency pulse generator having an input electrically connected to the pickup and an output, the :frequency of the pulse generator being controlled by the electrical wave and the waveform of the pulse generator being independent of the electrical wave, and a voice control circuit electrically connected between the output of the pulse generator and the electroacoustical transducer.

17. A musical instrument and electroacoustical assembly comprising the combination of claim 16 in combination with a wave shaper electrically connected between the pulse generator and the pickup, said wave Shaper limiting the shape of electrical waves to those crossing the zero axis only once in each cycle.

1S. A musical instrument and electroacoustical assembly comprising the combination of claim 16 wherein the pulse generator has an output with a frequency equal to a multiple or sub-multiple of the frequency of the input thereto.

19. A musical instrument and electrical amplifier assembly comprising a mechanoacoustical instrument having a sound wave carrying member when the instrument is played, means for impressing sound waves on said sound wave carrying member, an electroacoustical pickup mounted on the instrument having a sound wave responsive generating element in acoustical communication with the sound wave carrying member of the mechanoacoustical instrument and adapted to generate an electrical wave responsive to sound waves impressed on the generating element, an electroacoustical transducer, coupling means electrically connected between the electro acoustical transducer and the electroacoustical pickup including a gate circuit having a control input, said gate requiring a signal above a threshold value on the control input thereof to permit conduction of signals from the pickup to the electroacoustical transducer, and a time delay circuit electrically connected between the pickup and the control input of the gate to permit actuation of the gate responsive to a signal from the pickup after the lapse of a period of time.

References Cited UNITED STATES PATENTS 2,138,500 ll/l938 Miessner 84-1.l2 2,494,390 1/1950 Johnson 84-382 X 2,984,140 5/1961 Barron 841.04 3,144,801 8/1964 Abreo 84-380 3,154,996 1l/1964 Krilanovich 84-380 X JOHN S. HEYMAN, Primary Examiner.

U.S. Cl. X.R. 84-l.22, 385, 1.04, 1.13, 1.26