US3424850A - Acoustic system - Google Patents

Description

Jan. 28., 1969 J. 5. SOUTHARD ET AL 3,424,850

ACOUSTIC SYSTEM Filed Oct. 20, 1965 ACCOMPANIMENT MANUAL 27 TRIGGER REPEATER SPEED 25 CONTROL 4| 35 W34 V D /l INVENTORS 58' 46 4? 36 JAMES S. SOUTHARD CURT R. WOLFANGER BY M4 2 P ATTORNEYS SK Q v- AMPLIFIER -[K] United States Patent Claims ABSTRACT OF THE DISCLOSURE An electronic percussion device for an electric organ which has a plurality of springs resiliently contacting the diaphragm of the speaker cone. The springs are vibrated by and against the cone when the speaker is driven by generated signals to produce a snare drum effect.

This invention pertains generally to an electronic percussion device, and more particularly to an electronic percussion unit for an electric organ that simulates the sound of a snare drum.

Electric organs have been proposed that include units for making the sounds of various percussion instruments similar to such units contained in pipe organs in theaters and other places. One such unit is described in a copending application Ser. No. 498,889, filed Oct. 20, 1965, and assigned to the assignee of this application.

It is desirable in such percussion units to include the sound of the snare drum. This sound, however, is one of the most difficult of all the percussion instruments to simulate in an electric organ and still use a simple and inexpensive circuit.

It is one object of this invention to provide an electronic percussion device that simulates the sound of a snare drum.

It is another object of this invention to provide an electronic percussion device for use in an electric organ that simulates the sound of a snare drum and is simple and inexpensive to produce.

One feature of this invention is an electronic percussion device having mechanical vibratory means contacting the flexible diaphragm of a speaker cone so that the vibratory means is vibrated to produce a snare effect when the speaker is driven by a generated signal.

Another feature of this invention is a percussion unit for an electric organ having a speaker with a plurality of springs resiliently connected to the basket thereof and lying in contact with the flexible diaphragm thereof. The speaker is driven by a generator actuated by the keys on the accompaniment manual which excite a rate control repeater which periodically pulses the signal generator. A decaying signal from the generator moves the diaphragm of the speaker to produce an acoustical wave simulating a drum beat, and, the springs vibrate to add the snare effect.

In the drawing:

FIG. 1 is a rear elevation of the speaker of this invention with the basket partially removed;

FIG. 2 is a side elevation of the speaker of FIG. 1; and

FIG. 3 is a schematic wiring diagram illustrating one embodiment of this invention.

In practicing one specific embodiment of this invention, a speaker, for use with an electric organ, has a plu rality of springs resiliently connected to the speaker basket and which lie in contact with the flexible diaphragm of the speaker cone. Operation of any one of a plurality of keys on the accompaniment manual of the organ energizes a trigger circuit that excites a repeater circuit which has a regulated repetition rate. The repeater pulses a signal generator which is coupled to an amplifier circuit.

3,424,850 Patented Jan. 28, 1969 ice The generator produces a decaying signal which is amplified and coupled to the speaker. The generated signal flexes the speaker diaphragm to produce acoustic waves representing the beat of a drum. As the diaphragm flexes, the springs in contact with it vibrate and strike the diaphragm to produce acoustic waves representing a snare effect. These waves are mixed with the waves representing the drum beat to simulate the sound of a snare drum.

A better understanding of the percussion unit of this invention may be had by referring to FIGS. 1 through 3 of the drawing. Although the unit is described for use with an electric organ, it should be understood that it would find utility whenever it was desirable to have an electronic percussion unit to produce the sound of a snare drum.

The speaker 10 includes a flexible diaphragm or cone 12 made of a semi-rigid material which is secured to and supported by the speaker frame or basket 14. The diaphragm 12 moves under the influence of a voice coil shown generally at 16 which is secured to the apex of the cone. The voice coil is located within a cylindrical gap of a magnet (not shown) which provides a substantially constant magnetic field across the gap. The magnetic field set up by the audio frequency currents within the voice coil interacts with the constant field of the magnet resulting in physical forces being applied to the voice coil which tend to move the coil and attached diaphragm in a direction parallel to the axis of the cone. Ideally, an electromagnetic speaker as described will produce an acoustic wave in surrounding means which is the exact counterpart of the corresponding electrical signal applied to the voice coil.

Glass filament tape 21 is placed in strips on the exposed walls of the speaker cone or diaphragm 12. A plurality of springs 20 are resiliently connected to the basket 14 by looping each end thereof through the holes 22. When attached in this manner the springs lie in contact with the protective coating of tape 21, on the sides of the cone or diaphragm 12. Therefore, when the audio frequency signal excites the voice coil 16 to move the core 12 to produce acoustical waves representing the frequency of the exciting signal, the movement of the diaphragm 12 causes the spring 20 to vibrate and strike the diaphragm. The acoustical waves produced by the vibrating springs are mixed with the waves from the diaphragm to produce the desired sound. Tension on the springs 20 can be adjusted so that the springs vibrate at the desired frequency.

How this speaker is adapted as a percussion unit in an electric organ is illustrated in FIG. 3. Actuation of one of the keys of the accompaniment manual of the organ energizes the trigger circuit 25. The trigger circuit 25 applies an actuating pulse to the repeater circuit 27 as long as a key is operated. The repeater circuit consists of an astable multivibrator. A variable speed control for controlling the repetition rate is provided for the repeater circuit 27 and can be adjusted by the organist to the repetition rate desired. Therefore, when a note is played on the accompaniment manual, the voltage pulse will cause the repeater 27 to operate continuously to provide repeating pulses until the actuating pulse is terminated.

A switch or stop 30 and resistor 31 couple the pulses from the repeater 27 to the signal generator 32. The signal generator produces a burst of tone having a frequency on the order of 166 cycles per second. A decaying burst is produced each time the pulse is applied thereto.

The signal generator 32 is a phase shift oscillator and includes transistor 34 having a three mesh ladder line connecting the collector 35 thereof to the base 36. The line includes resistors 40, 41 and 42 and capacitors 45, 46 and 47. The pulse from the repeater 27 is differentiated by capacitor 50 and resistor 52, with the positive pulse being applied through diode 54 across capacitor 46 in the second mesh of the phase shift network. The negative differentiated pulse is blocked by the diode 54. 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 resistor 58 which is bridged across capacitor 46 and controls the Q of the feedback circuit. Thermistor 60 provides thermal stability for the oscillator.

The burst of tone from the signal generator 32 is coupled to the amplifier 62 and speaker 10. The acoustic Waves developed by the speaker 10 representing the tone burst from the signal generator 32 are mixed with the acoustic waves caused by the springs being vibrated against the diaphragm by the movement of the diaphragm 12, as heretofore described, to simulate the sound of a snare drum.

What has been described is an electronic percussion unit especially adaptable for use in a simple and inexpensive circuit for an electric organ that includes a unique speaker for simulating the sound of a snare drum.

We claim:

1. An electronic percussion device including in combination, speaker means including a movable diaphragm and a rigid support therefor, mechanical vibratory means connected to said support and positioned in direct contact with said diaphragm, signal generator means coupled to said speaker means and responsive to the application of a pulse thereto for producing a signal to move said diaphragm to produce an acoustic Wave representing said signal, said moving diaphragm striking said vibratory means to generate an acoustic Wave at a frequency other than the frequency of said signal.

2. An electronic percussion device including in combination, speaker means including a movable diaphragm and a rigid support therefor, mechanical vibratory means connected to said support and positioned in direct contact with said diaphragm, signal generator means coupled to said speaker means and being responsive to the application of a pulse thereto for producing a signal to move said diaphragm to produce an acoustic wave simulating a drum beat, said moving diaphragm striking said vibratory means to vibrate the same against said diaphragm thereby producing an acoustic wave simulating the sound of a snare drum.

3. An electronic percussion device, including in combination, speaker means including a flexible diaphragm and a rigid support therefor, spring means resiliently connected to said support and lying in contact with said diaphragm, signal generator means, repeater means coupled to said generator means and including repetition rate control means, and amplifier means coupling said generator means to said speaker means, said repeater means operating to produce pulses at a rate determined by said rate control means, said repeater means being connected to said signal generator means so that said pulses from said repeater means excite said signal generator means for producing a signal to move said diaphragm thereby producing an acoustic wave representing said signal, said diaphragm moving against said spring means and vibrating the same against said diaphragm thereby producing an acoustic wave at a frequency other than the frequency of said generated signal thereby simultating the sound of a snare drum.

4. A percussion device for an electric organ including in combination, speaker means including a flexible diaphragm and a rigid support therefor, spring means resiliently connected to said support and lying in contact with said diaphragm, signal generator means, repeater means including repetition rate control means coupled to said generator control means, amplifier means coupling said generator means to said speaker means, said repeater means operating to produce pulses at a rate determined by said rate control means, said repeater means being connected to said signal generator means so that said pulses from said repeater means excite said signal generator means for producing a signal to move said diaphragm thereby producing an acoustic Wave representing said signal, said diaphragm moving against said spring means in contact therewith to vibrate the same against said diaphragm thereby producing an acoustic Wave at a frequency other than the frequency of said signal to simulate the sound of a snare drum.

5. A percussion device for an electric organ including in combination, a speaker including a diaphragm and a basket for supporting the same, a plurality of springs resiliently mounted to said basket and each lying in contact with said diaphragm, a signal generator, an accompaniment manual and a trigger circuit responsive thereto for providing an actuating pulse, a repeater having a speed control, said repeater being coupled to said signal generator and being responsive to said actuating pulse from said trigger to repeatedly pulse said signal generator at a repetition rate established by said speed control, and an amplifier coupling said signal generator to said speaker, said signal generator producing a decaying signal in response to said pulses to move said diaphragm to produce an acoustic wave representing said signal, said movement of said diaphragm causing said plurality of springs in contact therewith to vibrate against said diaphragm thereby generating an acoustic wave at a frequency other than the frequency of said decaying signal to produce the sound of a snare drum.

References Cited UNITED STATES PATENTS 2,768,235 10/ 1956 Knoblaugh. 2,853,145 9/1958 Martin. 3,039,347 6/1962 Krauss et a1. 84l.01 3,149,692 9/ 1964 Rehde.

ARTHUR GAUSS, Primary Examiner. B. P. DAVIS, Assistant Examiner.

US. Cl. X.R.

Images