US3433880A - Percussion system - Google Patents

Description

Marh 18, 196.9 J. s. sou'rHARn PERCUSSION SYSTEM Sheet of 5 Filed Oct. 20, 1965 /nvenfnr JAMES S SOUTHA RD BY @wrm ATTYS.

March 18, 1969 J. s. souTHARD PERCUSSION SYSTEM Sheet Filed OCT.. 20, 1965 United States Patent O Claims ABSTRACT OF THE DISCLOSURE Percussion system for electric organ having generators for producing sounds of drums, blocks and other percussion instruments and noise source for producing signals keyed to provide brush and cymbal sounds. The generators and keyers are actuated by multivibrators controlled by accompaniment and pedal keyboards. Repeat action `and production of alternate tones can be selectively provided'.

This invention relates generally to percussion units for electric organs, and more particularly to a system actuated by the keys of a keyboard and/or a pedal board of an organ and which selectively produces the sounds of a plurality of different percussion instruments.

Pipe organs as used in theaters and in other places have included provisions for making sounds of percussion instruments, such as drums, blocks, castinets, brush and cymbal. Electric organs have been provided having characteristics similar to that of theater organs, and it is desired to provide the percussion sounds by simple and inexpensive circuits. It is further desired that the sounds be the same or very similar to the sounds produced by the percussion instruments themselves. This requires that the sounds for the different percussion instruments have quite different characteristics. It is also desired that the system be arranged so that the organist can use the sounds as desired without developing new and difficult techniques.

An object of this invention is to provide an improved percussion system for use with an electric organ, and which is actuated by the keys of the organ and provides the sounds of various different percussion instruments.

A further object of the invention is to provide an electric percussion system which can be actuated selectively by the accompaniment manual and by the pedal board of an organ to provide one or more of a plurality of different percussion instrument sounds.

Still another object of the invention is to provide a percussion system for an electric organ which is actuated by the pedal board and which provides percussive sounds when a pedal is operated and/ or when a pedal is released.

A still further object of the invention is to provide an improved percussion system wherein percussive sounds can be repeated and/or alternately sounded.

A feature of the invention is the .provision of a percussion system having a plurality of tone generators ywhich produce bursts of tone in response to pulses applied thereto, and having multivibrators selectively operated by keys of a manual of the organ and/or a pedal board for providing the actuating pulses.

Another feature of the invention is the provision of a percussive generating system including a noise generator and keyer for providing a burst of signals from the noise generator. The action of the keyer can be controlled by multivibrators actuated by keys of an organ which also actuate other generators for producing percussive sounds, and may be further controlled by a shimmer generator to produce desired brush sounds.

A further feature of the invention is the provision of a percussion actuating system for operation by the accompaniment manual of an organ which provides an actuating pulse in response to operation of a key below middle 3,433,880y Patented Mar. 18, 1969 ICC C and a further actuating pulse in response to operation of a key above middle C. An alternator can be used to apply the actuating pulses to two generators in turn to provide two percussive sounds alternately.

A still further feature of the invention is the provision of a percussion system including a switch device operated by keys of the pedal board of an organ and which closes a first contact when a key is operated and a second contact when a key is released, with the contacts being selectively connected to produce actuating pulses to cause per cussive sounds.

The invention is illustrated in the drawings wherein:

FIG. 1 illustrates in block diagram an electric organ with the percussion system of the invention coupled thereto;

FIG. 2 is a circuit diagram of the percussion system of FIG. 1; and

FIG. 3 is a block diagram of a more complex percussion system.

In practicing the invention there is provided a percussion system for an electric organ for producing various percussive sounds as the organ is played. A plurality of -generators produce the sounds of drums, blocks and other percussion instruments. A noise source produces signals which are keyed to provide brush and cymbal sounds. The percussion sound tone generators and the keyer are actuated by multivibrators controlled respectively by the lkeys of the accompaniment keyboard and the pedal board. The multivibrator for the accompaniment keyboard is actuated by the individual keys and may be actuated by operation of a key below middle `C and again by operation of a key above middle C. A repeater may be provided or repeatedly actuating the generators, and the accompaniment multivibrator 4may be connected to an alternator for initiating two tones in turn, such as the wood block and the temple block sounds. The pedal multivibrator can be actuated from a pedal tone keyer or from separate contacts provided on the pedals. A double throw switching device can be used to actuate a first pedal multivibrator when a pedal is depressed and to actuate a second pedal multivibrator when the pedal is released, as may be desired for brush and cymbal sounds.

In FIG. l there is shown a block diagram of an organ having a percussion or rhythm section in accordance with the invention. The organ illustrated includes a solo keyboard or manual 10, an accompaniment keyboard or manual 11, and a pedal board 12. A plurality of tone generators 13 apply tones to a keying circuit 14 controlled by the keys on the solo keyboard 10, and to a keying circuit 15 controlled by the keys on the accompaniment keyboard 11. The signals passed by the keying circuit 14 are applied to a voicing circuit 16, with string and reed type tone signals being applied through the string preamplifier 17 and the string post amplifier 1S to the string power amplifier 19. The flute tone signals from the voicing circuit 16 are applied through the `flute preamplier 21 and the ute post amplifier 22 to the ute power amplifier 23. Signals applied through keying circuit 15 by control of the accompaniment keyboard 11 are applied to voicing circuit 20, and to the string preamplifier 17 and the ute preamplifier 21 in the same manner as the signals from the voicing circuit 16 for the signals from the solo keyboard.

A separate tone generator 25 applies tone signals to a keying circuit 26 controlled by the keys or pedals on the pedal board 12. The pedal tone signals are applied through voicing circuit 27 and pedal amplifier 28, and then through resistor 29 to the string power amplifier 19', and through resistor 30 to the flute power amplifier 23. The organ system which has been described has been used for a period of years.

The percussion or rhythm section for the organ makes use of an additional Contact which is provided on the keys on the accompaniment keyboard 11. These contacts are numbered 40 for the keys below middle C and 41 for the keys above middle C. The contacts 40 are arranged to engage a `fixed contact 42, and the contacts 41 engage a fixed contact 43. The contact 42 is connected to the junction between resistor 44 and capacitor 45, which provides a positive potential to the contact 42. The contact 43 is similarly connected between resistor 46 and capacitor 47 which provides a positive potential thereto. The movable contacts 4t) and 41 are all connected through the single conductor 48 to the accompaniment multivibrator 50 for actuating the same.

The accompaniment multivibrator 50 applies a pulse of fixed amplitude and duration in response to actuation of any key of the accompaniment keyboard. The accompaniment multivibrator 50 is connected through separately actuated switches 51 and 52 to the wood block generator 53 and the brush-cymbal keyer 54 respectively. Each time an actuating7 pulse is applied to the wood block generator 53, a decaying burst of tone having a frequency of the order of 590 cycles per second is produced thereby. This is represented by the waveforms a to the right of' the wood block generator 53.

A noise generator 55 provides noise having a gaussian distribution around 20 kilocycles which is applied to the brush-cymbal keyer 54. When the switch 52 is closed, a pulse from the multivibrator t) actuates the keyer `54 to pass a decaying burst of noise as shown by the wave b to the right of the keyer 54. The keyer 54 is connected to switch contact 56 which is grounded by switch arm 57 for short sustain of the brush-cymbal burst. When the contact 57 is ungrounded, long sustain is provided.

The outputs of the wood block generator 53 and of the keyer 54 are applied to amplifier `60 which has variable gain to control the level of the signal. The output of amplifier 60- is applied to the string post amplifier 18 of the organ audio system by resistors 61 and 62. This signal is also applied to the string power amplifier 19 through resistors 61 and 63. The output of the string post amplifier 1S is applied to the string power amplifier 19. This provides control of the level by the string post amplifier 18 as well as by the amplifier 60. The level of the signals is further controlled by switch 64. When this switch is closed, the signal at the output of amplifier 6i) is divided by the action of resistor 61 and the series circuit including resistor 65 and capacitor 66. When the switch contact 57 is in the long sustain position and engages contact 68, capacitor 67 is connected in parallel with resistor 65 and capacitor 66 to further divide down the signal, particularly at the higher frequencies.

The percussion system is also actuated by the pedal manual of the organ. Pedal keyer 26 is actuated when any pedal is operated. rThe keyer 26 is coupled to `monostable multivibrator 70, which is generally similar to the multivibrator '50. This provides a pulse of a predetermined amplitude and duration each time a pedal key is operated. The multivibrator 70 is connected to separately operated switches 71 and 72. Switch 71 connects the multivibrator 70 to the keyer 54 so that this keyer applies brush-cymbal percussive bursts as has been described in connection with the operation of keys on the accompaniment manual. Switch 72 applies a pulse from the multivibrator 70 to the bass drum generator 74 which produces a burst of tone having a frequency of the order of 66 cycles per second. A decaying burst is produced each time a pulse is applied thereto as presented by the curve c at the right of the generator 74. The output of the bass drum generator 74 is also applied to the amplifier 60 together with the outputs of the wood block generator 53 and the brush-cymbal keyer 54.

FIG. 2 shows the circuit diagram of the percussion system of FIG. 1. The keys of the accompaniment manual of the organ have contacts 40 and 41 individually operated by the keys as described in connection with FIG. l.

4 Operation of any one of the contacts 40 will charge the capacitor 75 by connecting the same in parallel with capacitor 45 which is charged through resistor 44 from the +6 volt terminal. The voltage across capacitor 75 is applied to the differentiating circuit including capacitor 76 and resistor 77 and positive differentiated pulses will be applied through diode 78 to the base of transistor 79 of the accompaniment multistable multivibrator 50. Only one pulse is provided each time a contact 40 is closed until all contacts 4t) are released. However, resistor 82 discharges capacitor 75 so that closing of a contact 41 connects the capacitor 75 in parallel with capacitor 47 which is charged through resistor 46 from the +6 volt supply. This will provide a new voltage pulse across capacitor 75 which is applied to the differentiating circuit 76, 77 to provide a pulse through diode 78 to again trigger the multivibrator 50.

The multivibrator 50 is of known construction and includes transistors 79 and 80. Transistor 79 conducts in response to the trigger pulse to cut off transistor 80 so that a voltage pulse appears at the collector of transistor 80 which is applied through conductor 81 to the switches 51 and 52 previously described.

The wood block oscillator 53 is of the phase shift type including transistor having a three mesh ladder line connecting the collector thereof to the base. This includes resistors 86, 87 and 88, and capacitors 89, 90 and 91. The pulse applied through switch 51 is differentiated by capacitor 92 and resistor 93, with the positive pulse being applied through diode 94 and resistor 95 to the second mesh of the phase shift network (across capacitor The series resistor 95 acts to soften the attack of the oscillator. The negative differentiated pulse is blocked by the diode 94. The frequency of the oscillator depends upon the constants of the ladder line which forms the feedback circuit, and the decay depends upon the setting of the resistor 96 which is bridged across capacitor 90, and which controls the Q of the feedback circuit. The thermistor 97 serves to temperature compensate the Q for temperature changes.

The output from the oscillator is derived from the collector of transistor 85 and applied through resistor 98, capacitor 99, the parallel limiting diodes 100 and 101 and output leveling resistor 102 to the output bus 103. The diodes 100 and 101 act to eliminate noise. A series resonant circuit including inductor 164 and capacitor 105 acts to reshape the clipped waveform from the noise elimination diodes to provide the desired waveform.

The pedal multivibrator 70 is generally similar to the accompaniment multivibrator 50. As shown in FIG. 1 this is operated from a keying circuit rather than from switch contacts operated by the pedals. Terminal iS connected to the pedal keying circuit, and a voltage thereon is applied to the differentiating circuit including capacitor 111 and resistor 112. The positive differentiated pulse is applied through diode 113 to the transistor 115 of the multivibrator. This acts to cut off normally conductive transistor 116 to produce a pulse at its collector which appears on conductor 117. Transistors and 116 operate in the same manner as transistors 79 and 80- of monostable multivibrator 50.

Switch 72 actuates the bass drum generator 74 as described in connect-ion with FIG. l. This switch applies the pulse on conductor 117 to a differentiating circuit including capacitor 119 andvresistor 120. The positive differentiated pulse is applied through diode 121 to the phase shift oscillator.

The bass drum oscillator itself includes transistor 124 having its collector connected through a ladder line to its base. The ladder line includes resistors 125, 126 and 127 and capacitors 128, 129 and 130. The frequency of the oscillator, which is previously stated is of the order of 66 cycles per second, is controlled by the constants of the ladder line. Variable resistor 132 controls the decay of the oscillations by control of the Q of the feedback circuit. The output of transistor 124 is applied from the collector thereof through level control resistor 133 to the output bus 103.

The noise source for producing brush-cymbal sounds is formed by diode 135, inductor 136 and capacitor 137. The `diode is back biased from the 25 volt supply through resistor 138 and produces shot noise, recombination noise and l/ f noise, which is developed across the inductor 136. This noise is applied to the amplifiers including transistors 140 and 141, with the level being controlled by variable resistor 142 which couples signals from transistor 141 to transistor 144. The amplified noise signal is applied to the emitter of transistor 144 which functions as the gate of the keyer. The keyer is rendered operative when a pulse is applied to the base electrode of transistor 144 from emitter follower transistor 145. When the keyer is actuated from the accompaniment manual by the connection through switch 52, the pulse from the monostable multivibrator 50 is applied through resistor 150, diode 151 and resistor 152 to the coupling circuit including capacitor 153 and resistor 154. The positive pulse is applied across diode 155 and capacitor 157, which functions as an integrating circuit to stretch the pulse. The pulse is then applied in parallel to resistor 156 and the emitter follower 145. When switch contact 158 connects resistor 159 in parallel with resistor 156, the pulse stretcher capacitor discharges more rapidly to provide a short sustain of the brush-cymbal sound. When the switch 158 is open, `the resistance of the discharge path is greater and a longer sustain is provided. The emitter follower transistor 145, when conducting, applies pulses through resistor 160 to the base of the gate transistor 144 so that the noise is passed thereby to the series resonant circuit including capacitor 161 and coil 162. The output across the coil 162 is applied through resistor 163 to the output bus 103.

When switch 71 is closed so that a pulse is applied to the noise keyer from the pedal monostable multivibrator, the pulse is applied through diode 165 and resistor 152 to the coupling circuit including capacitor 153 and resistor 154. This path does not include resistor 150 or a similar resistor so that a longer duration pulse is provided to produce a lon-ger brush-cymbal sound when initiated by the pedal monostable multivibrator. This 'pulse is stretched by capacitor 157 and then applied to the emitter follower transistor 145. Switch 158 further controls the sustain, as previously described.

The output from bus 103 is applied to an amplifier including transistors and 171. Resistor 172 controls the feedback between the stages and is adjustable t0 provide control of the amplifier gain.

In FIG. 3 there is shown a more complex percussion system which includes the features of the system of FIGS. 1 and 2 as previously described, and additional features. The accompaniment multivibrator 50, which may operate the saine as the multivibrator 50 in the systems of FIGS. l and 2, is actuated from the accompaniment keyboard through a circuit which diiiers somewhat from the circuit shown in FIGS. 1 and 2. The contact 175 common to all of the keys is connected through resistor 176 to a positive potential which is bypassed by capacitor 177. Contacts 178 are associated with the keys of the accompaniment keyboard below middle C, and contacts 179 are associated with the keys above middle C. When any of the contacts 178 engages the contact 175, the potential from contact is applied -through diode 180 and resistor 181 to charge capacitor 182. Resistor 183 is provided to discharge the capacitor 182 and provide the desired time constant. The pulse developed by the charging of capacitor 182 is applied through capacitor 184 to the accompaniment multivibrator 50, and the D.C. component is applied through diode 185 to a repeater circuit 186i.

When a key above middle C is operated, one of the contacts 179 will provide a potential from contact .175 through diode 188 and resistor 189 to charge capacitor 190. Resistor 191 provides the desired time constant. The pulse across capacitor is applied through capacitor 192 to the accompaniment multivibrator 50, and the D.C. component is applied throu-gh ydiode 193 to the repeater 186. The accompaniment multivibrator 50 and the repeater 186 will, therefore, each be actuated when la keyer on the accompaniment manual is operated. After one key is operated, operation of a second key will not cause a further pulse across capacitor 190 unless it is on the opposite side of the middle C break. A switch 195 is provided to connect the two sections so that a second pulse cannot be produced until all keys of the manual are released and a key is then operated.

The accompaniment multivibrator 50 operates as previously described to produce an actuating pulse for the percussion generators. Accompaniment multivibrator 50 is connected through switch 200 to wood block generator .201, which may be the same as wood block generator 53 in FIG. l. The accompaniment multivibrator is connected through switch 202 to brush keyer 203. The brush keyer selectively applies signals from the noise generator 204, and the noise generator and brush keyer can be identical to the noise generator 55 and brush keyer 54 in FIG. 1. The multivibrator 50 is also connected through switch 205 to the tom-'tom generator 206. The tom-tom generator may be generally similar to the wood block generator and the bass drum generator, and has a frequency of the order of 173 cycles per second.

The accompaniment multivibrator 50 is connected through switch 208 to the alternator 209. The alternator may be a flip-Hop circuit, which responds to applied pulses to alternately apply pulses to output conductors 210 and 211. Output conductor 210 is connected to wood block generator 201 and output conductor 211 is connected to temple block generator 212. The temple block generator may be of the same construction as the wood block generator but has a higher frequency which may be of the order of 75() cycles per second. Accordingly, when switch 208` is closed, repeated operation of keys of the accompaniment manual to produce repeating pulses from the accompaniment multivibrator 50 will cause alternator 209 to alternately actuate the wood block generator 201 and the temple block generator 212. Therefore, the tones produced by these generators will be alternately applied to the amplifier 214.

The repeater 186 is connected by switch 215 to snare drum generator 216 and by switch 220 to clave-castinet generator 221. The repeater 186 can be an astable multivibrator having a frequency of the order of 0 to 2() cycles per second. A variable control is provided for the repeatelnwhich can be adjusted by the organist to the desired repetition speed. Accordingly, when a note is played on the accompaniment manual, the D.C. voltage pulse will cause the repeater to operate continuously until the pulse is terminated. It is noted that the pulses are not applied to the repeater through a capacitor so that they are not differentiated to produce a single trigger pulse, as are the pulses applied to the accompaniment multivibrator 50i.

The snare drum generator may be similar to the wood block `generator 53 and bass drum generator 74 shown in FIG. 2, and has a frequency of the order of 166 cycles per second. The output of the snare drum generator is applied through an amplier 217 to aA speaker 218. The speaker 218 can be specially designed to reproduce the sound of a snare drum.

The clave-castinet generator can be similar to the generator previously described but has a relatively high frequency of the order of 2500 cycles per second. This will be operated repeatedly by the repeater 186 as long as the actuating pulse is applied thereto.

The pedal multivibrator 70 is actuated by operation of the pedals through switch contacts 225 connected thereto. These contacts engage the fixed contact 226 which is at ground potential. Operation of any pedal causes actuation of relay 227 so that the sealed reed contact 228 thereof engages down contact 229. This applies a positive pulse to the pedal multivibrator 70 to actuate the same each time a pedal is operated. When the pedal is released, the reed contact 228 returns into engagement with the upper contact 230. This applies a pulse to the pedal up multivibrator 231 to actuate the same.

The pedal down multivibrator 7 0 is connected through switch 232 to the base drum generator 233. Bass drum generator 233 `can be identical to the bass drum generator 74 shown in FIG. 2, and is actuated by the multivibrator 70 in exactly the same manner. The pedal multi-vibrator 70 is connected through switch 235 to the brush-cymbal keyer 236. The brush-cymbal keyer is connected to the noise generator 204 and operates in the manner previously described in connection with FIG. 2. The pedal multivibrator 70 is -connected through switch 238 to the temple block generator 212, and through switch 241i to the tonitom generator 206, which have previously been described. Accordingly, actuation of the pedal multivibrator causes operation of the bass drum generator, the brush-cymbal keyer, the temple block generator and the tom-tom generator, when the switches 232, 235, 238 and 240 are closed. The switches are provided as stops for the organist to control so that any one or m-ore can be operated at any time.

The pedal up multivibrator 231 is connected through switch 241 to the brush-cymbal keyer 206. Accordingly, the brush-cymbal keyer can be operated when a pedal has been operated and is released. When both switches 235 and 241 are both closed, the keyer 236 will be operated when a pedal is operated and again when it is released. Operation of either of these switches `will cause the keyer to operate at one or the other of the times.

The brush-cymbal keyer is also connected to switch 242 which selectively grounds a terminal of the brush-cymbal keyer to provide short sustain of the burst of noise signal provided by the keyer. This switch is equivalent to the switch 158 in FIG. 2 which controls the sustain of the keyer 54. In the system of FIG. 3, a separate keyer is provided for the accompaniment brush sound and for the pedal brush-cymbal sound. This makes it unnecessary to change the operation of the keyer when actuated by the accompaniment and pedal multivibrators. The brush-cymbal keyer 236 is also controlled by shimmer generator 244. This is a generator which provides a frequency of the order of 14 cycles per second, which modulates the amplitude of the noise signals passed by the keyer, to provide a shimmer effect.

The outputs of the wood block generator 201, the brush keyer 203, the tom-tom generator 206, the temple block generator 212 and the brush-cymbal keyer 236 are all fed to amplifier 214. The output of amplifier 214 is applied to the string channel post amplifier 245 and to the string power amplifier 246. The output of the string channel post amplifier 245 is also applied to the power amplifier 246. This is generally the same connection shown in FIG. 1, but in that system all of the percussion sounds are applied to the string channel. The `string power amplifier 245 dri-ves one or more loudspeakers indicated as 247 and 248. The output of the `clave-castinet amplifier 221 and o-f the bass drum generator 233 are applied to amplifier 250. Amplifiers 214 and 250 may have a common gain control, as indicated by the arrow 249. The output of amplifier 250 is applied to the fiute channel of the organ, being applied to the flute channel post amplifier 251 and to the -power amplifier 252. The flute channel post amplifier 251 output is also applied to the power amplifier 252. This permits control of the output both by the amplifier 250 and by the flute channel post amplifier 251. The output of the power amplifier 252 is applied to loudspeakers 254 and 255. One of these speakers may be a speaker including a rotating member to provide a tremolo effect, as is commonly used in the finte channel of au organ.

The percussion system which has been described maybe provided in various different forms, as illustrated by the simple form shown in FIG. 1, and the more complex form shown in FIG. 3. In each case, generators providing the sounds of percussive instruments are selectively actuated by multivibrators controlled by the accompaniment manual and the pedal board of an organ. Various difierent generators for simulating various instruments can be provided as may be desired in a particular application. The accompaniment manual can control the generators through a repeater to provide the repeated -sounds of a snare drum and clave-castinet. An alternator can be used to give alternate sounds of different types, such as alternate Wood block and temple block sounds. The generators when controlled by the pedals can operate when a pedal is depressed and/ or when a pedal is released. This provides a wide latitude in arrangements which can be made.

I claim:

1. A percussion system for an electronic organ having keys `for producing notes of a musical scale and sound reproducing means, said system including in combination, trigger means for providing a trigger pulse in response to operation of a key, alternator means having first and second terminals and responsive to successive trigger pulses to alternatively provide actuating pulses at said first and second terminals, first and second generators coupled to the sound reproducing means for applying thereto signals of different frequencies, each of said tone generators being responsive to the application of an actuating pulse thereto to produce a signal pulse, and means connecting said first and second terminals to said first and second generators respectively so that signals are alternatively applied therefrom to the sound reproducing means by operation of the organ keys.

2. A percussion system for an electronic organ having keys on a manual for producing notes of a musical scale which extend above and below a reference note, and sound reproducing means, said system including in combination, trigger means lfor providing an actuating pulse, -means coupled to said trigger means and responsive to operation of the keys to actuate said trigger means, with operation of a key for a note below the reference note causing actuation of said trigger means and operation of a key for a note above the reference note causing a further actuation of said trigger means, a plurality of generator means coupled to the sound reproducing means for applying thereto signals of different `frequencies, each of said generator means being responsive to the application of an actuating pulse thereto to produce a signal pulse, and switching means selectively connecting said trigger means to said generators so that signal pulses are selectively applied to the sound reproducing means by operation of the keys.

3. A percussion system for an electronic organ having keys on a manual for producing notes of a musical scale which extend above and below a reference note, tand sound reproducing means, said system including in combination, trigger means for providing an actuating pulse, actuating means coupled to said trigger means and responsive to operation of the keys to Iactuate said trigger means by operation of a key for a note below the reference note and again by operation of a key for a note above the reference note, a plurality of generator means coupled to the sound reproducing means for applying thereto signals of different frequencies, each of said generator means being responsive to the application of an actuating pulse thereto to produce a signal pulse, a noise generator, keyer means coupled to said noise generator for selectively applying noise signals therefrom to the sound reproducing Imeans, and switching means selectively connecting said trigger means to said generator means and to said keyer means, so that signal pulses are selectively applied to the sound reproducing means by operation of the keys.

4. A percussion system for an electronic organ having keys provided by at least one manual and a pedal board, and sound reproducing means, said system including in combination, iirst trigger means for providing an actuating pulse in response to operation of a key of the manual, second trigger means for providing an -actuating pulse in response to operation of a pedal key, third trigger means for providing an actuating pulse in response to release of an actuated pedal key, a plurality of generators coupled to the sound reproducing means for applying thereto signals of different frequencies, each of said generators being responsive to the application of an actuating pulse thereto to produce a signal pulse, and switching means selectively connecting said first, second and third trigger means to said generators so that signal pulses are selectively applied to the sound reproducing means by operation of the keys of the manual and pedal board.

5. A percussion system for an electronic organ having keys provided by at least one manual and a pedal board, and sound reproducing means, said system including in combination, first trigger means for providing an actuating pulse in response to operation of a key of the manual, said rst trigger means including means providing repeated actuating pulses, second trigger means for providing an actuating pulse in response to operation of a pedal key and in response to release of an operated key, a plurality of generators coupled to the sound reproducing means Ifor applying thereto signals of different frequencies, each of said tone generators being responsive to the application of an actuating pulse thereto to produce a signal pulse, generator means producing 10 random noise signals, keyer means coupled to said generator means for selectively applying said random noise signals to the sound reproducing means, said keyer means being responsive to the application of an actuating pulse to provide a burst of random noise signals having predetermined attack and decay characteristics, alternator means connected to a pair of said tone generators for applying actuating pulses thereto in turn in response to successive actuating pulses applied to said alternator means, and switching means selectively connecting said rst and second trigger means to said generators, said keyer means and said alternator means, so that signals are selectively applied to the sound reproducing means by operation of the keys of the manual and pedal board.

References Cited UNITED STATES PATENTS 3,309,454 3/1967 Cutler et al 84--1.l7 3,327,047 6/ 1967 Slaats 84--1.24 3,358,069 12/ 1967 Hearne 84-1.03

JOHN S. HEYMAN, Primary Examiner.

B. P. DAVIS, Assistant Examiner.

U.S. Cl. X.R. 84-1.03, 1.24

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