US3267200A

US3267200A - Electronic musical instrument having an attack circuit

Info

Publication number: US3267200A
Application number: US270999A
Authority: US
Inventors: Walter J Anderson; Robert M Grodinsky
Original assignee: Chicago Musical Instrument Co
Current assignee: Chicago Musical Instrument Co
Priority date: 1963-04-05
Filing date: 1963-04-05
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

Aug. 16, 1966 w ANDERSON ET AL 3,267,200

ELECTRONIC MUS ICAL INSTRUMENT HAVING AN ATTACK CIRCUIT Filed April 5. 1963 000/0 5 sYaTEM m Volt/A16 c1200],

Kai/2, d I 30.691 3 AZ Q'fadaw' ATTOR EYS United States Patent 3,267,200 ELECTRONIC MUSICAL INSTRUMENT HAVING AN ATTACK CIRCUIT Walter J. Anderson, Elgin, and Robert M. Grodinsky, Chicago, Ill., assignors to Chicago Musical Instrument Co., Lincolnwood, 111., a corporation of Delaware Filed Apr. 5, 1963, Ser. No. 270,999 Claims. (Cl. 84-126) This invention relates generally to electronic musical instruments, and more specifically to an attack circuit incorporated therein.

Although the principles of the present invention may be included in various musical instruments, a particularly useful application is made in an electronic organ of the type having a number of voicing stops by which the organist may select the timbre of the music to be played. By way of example, organ stops and associated circuits simulate various orchestral instruments. The tones produced by such orchestral instruments are further characterized by the rate at which the tone is produced. By way of example, the various reed instruments require that air be set into motion and the reed to be caused to vibrate before a tone is produced. Similarly, a pipe organ pipe experiences a build-up of air velocity before a useful tone of the desired volume is produced. The same is true for other reed instruments such as the oboe, and the accordion. Collectively, such instruments have tones which, while differing intimbre, are similar in that each is produced with what is here termed as a slow attac On the other hand, other instruments have a sharp or fast attack, examples of which are the' trumpet and other brass instruments, the piano, bells, chimes, and the like. A circuit for controlling the rate of attack of an electronic organic voice has been previously included in the higher priced instruments, such inclusion being one reason for such instrument being initially higher priced. However, the mass organ market is in the lower priced instruments, in which it has not been practical for economic reasons to include such feature. In the past, a controlled attack circuit has been provided by means of a slow charging circuit composed of a large capacitor and a relatively small resistor. By changing the size of such resistor, the rate at which the charge on the capacitor is developed has been varied. However, it has not been both convenient and economical to use a large charging capacitor in combination with various sized resistors. Similarly, it has not been practical to use a small capacitor and large resistance since such large resistance would lower the total voltage applied from the keying circuit, and would further create a robbing situation in response to the depressing of a number of keys when it was desired to produce a chord of tones.

The present invention contemplates the provision of a fast attack-slow attack circuit which employs no large charging capacitor, which does not create a robbing situation when a multiplicity of keys are simultaneously played, and which employs no switch using a large number of contacts for cutting in and out a multiplicity of keying resistors. The present invention is relatively simple in construction, and is economical to provide commercially.

Accordingly, it is an object of the present invention to provide an improved electronic musical instrument.

Another object of the present invention is to provide an electronic musical instrument having an improved attack circuit incorporated therein.

A still further object of the present invention is to provide a novel slow attack circuit for an electronic musical instrument.

Patented August 16, 1966 Yet another object of the present invention is to provide a fast attack-slow attack circuit for an electronic musical instrument.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheet of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

On the drawings:

The single figure is a schematic diagram representative of a portion of an electronic musical instrument provided with an attack circuit in accordance with the principles of the present invention.

As shown on the drawings:

The principles of this invention are particularly useful when embodied in an electronic musical instrument, such as an organ, a representative portion of which is illustrated on the drawing, generally indicated by the numeral .10. The electronic instrument 10 includes a series of generators 11, each of which comprises a signal source for one note. Depending upon the length of the keyboard of the instrument, there may be as few as 36 and as many as 60 such generators. Each generator 11.may comprise an oscillator, a divider stage, or other suitable source, and include an element, here illustrated as being an auxiliary plate 12 which comprises a readout element which, when energized, is electronically coupled to receive a, tone signal, such generators and readout elements being known in the art. Each readout element 12 is coupled by an output isolating resistor 13 'to a signal output bus 14 leading to various voicing circuits 15 which are connected to an audio system 16. Normally the readout elements 12 send no signal from the generators 11, but when a coupling potential is applied thereto, individually, each individual readout element 12 having a coupling potential will conduct a signal from the generator 11, through the output isolating resistor 13 and output bus 14 to the audio system 16.

Such coupling potential is obtained from a source of D.C.-potential 17, one side of which is grounded. The source of D.C.-couplin-g potential is a source of B-lvoltage, 300 volts D.C. being a typical value. The source of potential 17 is grounded at 18, and at its other side is connected through a shuntable load resistor 19 to a keying bus 20. A playing-key operated switch 21 is provided for each signal source, one side or contact 22 thereof being connected to the keying bus 20, and the other side or contact 23 thereof being connected through a load resistor 24 to the readout element 12. By the closing of any one of the key-switches 21, a D.C.-coupling potential is thereby applied to the associated readout element 12 to effect playing of a note having that frequency. In normal playing of the instrument, here referred to as fast attack, the load resistor 19 is shunted by means described below.

In accordance with the principles of the present invention, to provide a slow or delayed attack, a capacitor 25 is connected between one side or contact 23 of each of the keying switches 21, and a pulse bus 26, common to such capacitors 25. A further capacitor 27 is connected between the pulse bus 26 and ground and coacts with each of the capacitors 25 to serve therewith as a voltage divider having a tap or point with an intermediate voltage which is represented by the pulse bus 26. Each time that one of the playing key-operated switches 21 is closed, not only is the readout element 12 energized, but the capacitor means 25, 27 are also charged, such charging causing a surge of potential or pulse to appear on the pulse bus 26.

Pulse bus 26 is connected to one side of a diode 28 which conducts such pulse to an electronic switch 29.

The switch 29 is here illustrated as comprising a triode having a grid 30 to which the pulse bus 26 is connected through the diode 28. The triode further includes a cathode 31 connected to a source of C-lor biasing voltage 32 which is grounded. The triode includes a plate 33 which, with the cathode 31, forms a plate circuit which is connected to the keying bus 20, and hence across the load resistor 19.

A still further capacitor 34 is connected to the pulse bus 26, and more specifically is connected to the grid 30 of the electronic switch 29. A high resistance path to ground is provided from the grid 30, which path includes a resistor 35 which shunts the diode 28, and a resistor 36 which shunts the capacitor 27. By the

high resistance path

35, 36, the charge on the capacitors shown herein will be leaked to ground progressively.

The attack control portion of the circuit is under the selective and operative control of a double-pole singlethrow switch 37 having one section which includes a contactor 38 connected to the pulsing bus 26 and a grounded contactor 39, and a second section having a pair of contactors 40, 41 connected in shunting or short-circuitin-g relation to the load resistor 19.

During normal or fast attack playing of the instrument 10, the selector switch 37 will be in the closed position so that the load resistor 19 is shunted and so that the pulse bus 26 is grounded. During such normal or fast attack playing, any charge received by or pulse conducted by the attack softening capacitors 25 will be conducted directly to ground. Since the capacitors 25 are relatively small, they have only a slight time-related elfect on the output tone. Owing to the rapid onslaught or inrush of the D.C.-coupling potential under this condition, a slight amount of thumping or popping may be experienced at the onset of the production of a tone. Any such thumping is eliminated by the provision of a resistor 42 between the contactor 23 and a point between the resistor 24 and the capacitor 25 of each signal source 11.

When it is desired to employ a voicing stop of the type which should have a slow attack, such as a reed stop, the attack control switch 37 is also manually selectively actuated to the open position, as shown, thereby placing the attack control portion of the circuit in operative standby relation.

During slow attack playing of the instrument 10, a closing of the key-switch 21 also places the coupling potential across the

capacitors

25, 27 so that a pulse or voltage of intermediate value appears on the pulse bus 26 and is conducted unidirectionally by the diode 28 to the grid 30. Since the electronic switchor triode 29 is normally biased to cut-01f, up to this point, no current has been flowing in the plate circuit. However, the presence of the pulse on the grid 30 renders the plate circuit thereof highly conductive, causing a relatively high current to flow in the plate circuit which includes the load resistor 19, thereby creating a substantial voltage drop thereacross, by which the coupling potential on the keying bus 20, from which the pulse was derived, is immediately lowered so that the coupling potential on the readout element 12 likewise is initially temporarily reduced. The pulse on the pulse bus 26 likewise charges the capacitor 34 which tends to maintain the pulse voltage on the grid 30. While the grid voltage cannot leak reversely through the diode 28, the temporarily sustained grid voltage or charge on the capacitor 34 can leak reversely through the high resistance path provided by the

resistors

35, 36 to ground, thereby gradually restoring the electronic switch to a nonconducting relation and simultaneously increasing the D.C.-coupling potential on the keyed readout element 12. Thus the onslaught or attack of tone is regulated to simulate the attack or slow build-up of a slow attack instrument, while at the flick of a single switch, a rapid attack can be provided to simulate the fast onslaught oftone or staccato required of other orchestral voices.

In the fast attack position, the capacitors 25 achieve a slight softening of the attack, but this softening is of electronic switch 29 is not conducting due to its bias voltage, the entire B+ voltage is present on the keying bus 20 to create the pulse when one of the switches 21' is closed. However, such pulse immediately overcomes the cathode bias, causing the switch 29 to conduct heavily and instantaneouslyrso that the coupling voltage likewise takes an instantaneous heavy drop. The switch 29 may thereby be said to operate degeneratively. Any pulse appearing on one of the capacitors 25 as a result of keying, tends to reduce the level of voltage that is causing the pulse, thereby slowing the build-up of the keyed tone.

The capacitor 27 serves to limit the maximum potential of the pulses on the pulse bus 26 so that the pulse cannot be conducted by other capacitors 25 to the readout elements 12 of non-played signal sources 11, which might otherwise occur for an instant. Although the pulse voltage is thereby reduced, it is still sufficiently large tocontrol the electronic switch 29. The load resistor 19 not only serves as a load in the plate circuit of the triode, but.

also tends to slow down the build-up of charge on the capacitors 25.

Typical values employed in the illustrated circuit are as follows:

Resistor 24 1 megohm. Resistor 13 1 megohm. Resistor 42 20,000 ohms. Resistor 36 22 megohms. Resistor 19 300,000 ohms. Resistor 35 5 megohms. Capacitor 25 .01 mfd. Capacitor 27 .01 mfd. Capacitor 34 .02 mfd. (see comment below). Potential 17 300 volts D.C. Potential 32 5 volts D.C. Triode 29 12AX7.

The attack control tube or triode 29 is of the high-mu triode type, and other specific values identified are appropriate to the identified tube.

The time constant of the

resistors

35, 36 and capacitor 34 is adjusted so that the grid 30 of the tube 29 returns to cut-off and restores full firing potential in a period of time which is short compared to the length of time during which a note is held. This produces a slow build-up of the tone or slow attack. Yet the duration of build-up is short enough so that voltage is restored and the process repeated for subsequent notes played in rapid order.

Although various minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within thescope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of our contribution to the art.

What we claim is:

1. An attack circuit for an electronic musical instrument including a series of signal sources having readout elements connected to a common output bus, and a series of key switches operative to apply a coupling potential on the readout elements, said circuit comprising:

(a) a pulse bus having capacitative connections with the readout elements; and

(-b) a triode having a grid connected to said pulse bus,

and a normally non-conducting plate circuit under the control of said grid, said plate circuit being connected across the source of coupling potential.

2. An electronic musical instrument, including in combination:

(a) a series of signal sources having readout elements;

(b) an output bus connected to said readout elements;

(c) a source of D.C.-coupling potential;

(d) a series of key-switches operative when closed to apply the coupling potential to the readout elements to couple the signals to the output bus;

(e) a pulse bus having capacitive means connecting said pulse bus with said readout elements and thus momentarily energized therewith by closing of any of said key-switches; and

(f) a triode having a grid connected to said pulse bus, and a normally non-conducting plate circuit means connected across said source of D.C.-coupling potential, said plate circuit means in response to a pulse on said grid being conductive to momentarily lower the coupling potential.

3. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(-b) a capacitor for each of said switches and connecting said other side thereof to said pulse bus; and

(c) a normally non-conducting electronic switch connected to said pulse bus and being highly conductive in response to any signal on said pulse bus, said switch being connected to said source of potential by such means .as to be operative, when conductive, to impress a load on said source of potential, thereby transiently reducing its effectiveness in effecting coupling of said readout elements.

4. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) capacitative voltage divider means connected to said other side of said switches, and having an electrically common intermediate voltage tap; and

(b) a normally non-conducting electronic switch connected to said voltage tap and being highly conductive in response to any signal on said voltage tap, said switch being connected to said source of potential by such means as to be operative, when conductive, to impress a load on said source of potential, thereby transiently reducing its effectiveness in effecting coupling of said readout elements.

5. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(b) a capacitor for each'of said switches and connecting said other side'thereof to said pulse bus;

(0) a further capacitor connected between said pulse bus and ground;

(d) a triode having a cathode, having a grid connected to said pulse bus, and having a plate connected to said one side of said switches and in circuit with a load to said source of potential; and

(e) means connected to said cathode and normally biasing said cathode to cut-off.

6. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(b) a capacitor for each of said switches and connecting said other side thereof to said pulse bus;

(c) a diode connected to said pulse bus to conduct pulses received therefrom; and

(d) a triode having a grid connected to receive pulses from said diode, and a normally non-conductive plate circuit controlled by any pulse on said grid, said plate circuit being connected to said source of potential and comprising means to load said source of potential to lower its voltage momentarily.

7. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(0) a diode connected to said pulse bus to conduct pulses received therefrom;

(d) a triode having a grid connected to receive pulses from said diode, and a normally non-conductive plate circuit controlled by any pulse on said grid, said plate circuit being connected to said source of potential and comprising means to load said source of potential to lower its voltage momentarily; and

(e) a further capacitor so connected to one side of said diode as to enable it to be charged by any pulse received by said pulse bus, said capacitor being of such size as to lengthen the duration of said pulse on said grid.

8. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-cou-plir1g potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(c) a diode connected to said pulse bus to conduct pulses received therefrom;

(d) a triode having a grid connected to receive pulses from said diode, and a normally non-conductive plate circuit controlled by any pulse on said grid, said plate circuit being connected to said source of potential and comprising means to load said source of potential to lower its voltage momentarily;

(e) a further capacitor connected to said grid for maintaining said pulse on said grid; and

(f) a high resistance leakage path connected to said grid for discharging said further capacitor.

' 9. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected through a load to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(c) a normally non-conducting electronic switch connected to said pulse bus and being highly conductive in response to any signal on said pulse bus, said 7. switch being connected to said load by such means as to be operative, when conductive, to increase the voltage drop across said load, thereby transiently reducing the effectiveness of said source of potential in effecting coupling of said readout elements; and

(d) switch means for selectively simultaneously shunting said load and grounding said pulse bus.

10. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

() a normally non-conducting electronic switch connected to said pulse bus and being highly conductive in response to any signal on said pulse bus, said switch being connected to said source of potential by such means as to be operative, when conductive, to impress a load on said source of potential, thereby transiently reducing its effectiveness in effecting coupling of said readout elements; and

(d) switch means for selectively preventing any pulse on said pulse bus from reaching said electronic switch.

11. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-cou-pling potential, and a series of key-operated switches each having one side connected through a load to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a pulse bus;

(c') a further capacitor connected between said pulse bus and ground;

(d) a diode connected to said pulse bus to conduct pulses received therefrom;

(e) a triode having a cathode, having a grid connected to said. pulse bus, and having a plate connected to said one side of said switches, and in circuit with said load to said source of potential;

(f) means connected to said cathode and normally biasing said cathode to cut-off;

(g) a still further capacitor connected to said grid for maintaining said pulse on said grid;

('11) a high resistance leakage path connected to said grid for discharging said further capacitors; and

(i) switch means for selectively simultaneously shunting said load and grounding said pulse bus.

12. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) means producing a surge of a direct current of momentary duration in response to each activation of each of said key-operated switches; and

(b) means responsive to each such momentary surge and operative to delay build-up of said coupling potential on the associated readout element.

13. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series I of key-operated switches each having one side .connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) an attack control tube normally biased to cut 0E and having a plate circuit means connected across said source of potential and operative to decrease the D.C.-coup1ing potential when conductive; and

(b) a series of capacitors connected between said other sides of said switches and the grid of said tube for applying keyed potential pulses to said grid to thereby render said tube conductive in response to each pulse.

14. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improvement in combination therewith, comprising:

(a) a normally non-conducting attack-control electronic switch forming a part of a load circuit means connected across said source of potential and, said load circuit means being operative to decrease the DC.- coupling potential when said electronic switch is conductive; and

(b) a series of capacitors connected between said other sides of said key-operated switches and a control element of said electronic switch for applying potential pulses thereto under the control of said key-operated switches to thereby render said electronic switch momentarily conductive in response to each pulse.

15. In an electronic musical instrument having a series of signal sources each including an electron-coupled readout element, an output bus connected to said readout elements, a source of D.C.-coupling potential, and a series of key-operated switches each having one side connected to said source of potential, and the other side connected to one of said readout elements respectively, the improve ment in combination therewith, comprising:

(a) a load resistor connected in series between said source of D.C.-coupling potential and said one side of said key-operated switches; and

(b) means, connected across said load resistor, and

operative in response to closing of any of said keyoperated switches, to produce a substantially instantaneous increase in voltage drop thereacross which drop progressively decreases.

References Cited by the Examiner UNITED STATES PATENTS 2,227,068 12/ 1940 Curtis.

2,483,823 10/1949 George 841.26 3,038,365 6/1962 Peterson 841.26

ARTHUR GAUSS, Primary Examiner. I. Q. EDELL, Assistant Examiner.

Claims

1. AN ATTACK CIRCUIT FOR AN ELECTRONIC MUSICAL INSTRUMENT INCLUDING A SERIES OF SIGNAL SOURCES HAVING READOUT ELEMENTS CONNECTED TO A COMMON OUTPUT BUS, AND A SERIES ON KEY SWITCHES OPERATIVE TO APPLY A COUPLING POTENTIAL ON THE READOUT ELEMENTS, SAID CIRCUIT COMPRISING: (A) A PULSE BUS HAVING CAPACITIVE CONNECTIONS WITH THE READOUT ELEMENTS; AND AND A NORMALLY NON-CONDUCTING PLATE CIRCUIT UNDER THE CONTROL OF SAID GRID, SAID PLATE CIRCUIT BEING CONNECTED ACROSS THE SOURCE OF COUPLING POTENTIAL.