US3825667A

US3825667A - Alternate high-low and root-fifth selection system for electrical musical instruments

Info

Publication number: US3825667A
Application number: US00332642A
Authority: US
Inventors: R Schrecongost
Original assignee: Hammond Corp
Current assignee: Marmon Co
Priority date: 1973-02-15
Filing date: 1973-02-15
Publication date: 1974-07-23
Anticipated expiration: 1991-07-23
Also published as: AU6385073A; BR7310138D0; JPS552878B2; IT999346B; CA980604A; ZA7425B; JPS49118413A; DE2401353A1; NL7316240A

Abstract

A note selection system for a keyboard type electrical musical instrument which supplies to output leads the note signals corresponding to the highest and lowest notes of a group of notes played, or, in the alternative, the note signals corresponding to the musical root and fifth notes of certain three-note chords whenever only the three notes comprising each of these particular chords are played. The disclosed embodiment responds to playing any of four three-note chords in each of the 12 musical keys to supply the corresponding root and fifth note signals of these chords; if any other three-note chords, or other than three notes are played, the system supplies the highest and lowest note signals of the group of notes played.

Description

schrecongost 4] ALTERNATE HIGH-LOW AND ROOT-FIFTH SELECTION SYSTEM FOR ELECTRICAL MUSICAL INSTRUMENTS [75] Inventor: Ray B. Schrecongost, Park Ridge,

lll.

. [73] Assignee: Hammond Corporation, Deerfield,

Ill.

22 Filed: Feb. 15, 1973 21 Appl. No: 332,642

[52] US. Cl 84/1.0l, 84/DIG. 2, 84/DIG. 22

[51] Int. Cl. ..G10h 1/00 [58] Field of Search 84/1.01, 1.03, 1.17, 1.24,

84/DIG. 2, DIG. 22

[5 6] References Cited UNITED STATES PATENTS Young 84/l.l7

111 3,825,667. 1' July 23, 1974 3,708,604 l/1 973 Hebeisen et al. 84/l.03 3,712,950 1/1973 Freeman 84/l.03

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Stanley J. Witkowski Attorney, Agent, or Firm--Lowell C. Bergstedt s7 ABSTRACT A note selection system for a keyboard type electrical musical instrument which supplies to output leads the note signals corresponding to the highest and lowest notes of a group of notes played, or, in the alternative, the note signals corresponding to the musical root and fifth notes of certain three-note chords whenever only the three notes comprising each of 1 these particular chords are played. The disclosed embodiment responds to playing any of four three-note chords in each of the 12 musical keys to supply the corresponding root and fifth note signals of these chords; if any 3,305,620 2/1967 other three-note chords, or other than three notes are 3,546,355 12/1970 Maynard.... 84/1.03 played, the system supplies the highest and lowest 3,548,066 12/1970 Freeman 84/l.03 note signals of the group of notes played 3,590,129 6/1971 Freeman 84/1.0l 3,665,088 5/l972 Brandet al. 84/1.0l' 10 Claims, 2 Drawing Figures 4 f Til/P55" KEYBOHRD N075 DEIZ'cToR c If? a a" v V q 1 neon amp? T0 Cb'QPpWA/Df' 071/62 GHTES CHORD HA/D" c4755 /f /j 11v /'7F77%q 45 9 0073 07 Z9 0 m Vl' i gmrp/vg MGM/JAIN Low c ewe/Po mam, 3: 2? 55 z o vz 554507 A P0074!!! qorpur 57 REFEIWVCE 64 {)3 Gangs Mfg/{f lls Cum/"s cam/17$ W57? 25 Z Y if 22 Q/A/PUT Q ken/ k T 600 0) 4/ 0077,!- r0 2/ I 59 (ls-x5002 1 v1 ALTERNATE HIGH-LOW AND RooT-EIETII SELECTION-SYSTEM FOR ELECTRICAL MUSICAL INSTRUMENTS BACKGROUND or THE INVENTION Keyboard type electrical musical instruments have incorporated preference circuits to select the note sig nals corresponding to the highest; and lowest notes of a group of notes played, together with frequency dividers, wave-shaping circuits and an automatic rhythm programmer in order to provide automatic bass accompaniment in'predetermined rhythmic patterns. See, for

example, the musical instrument rhythm system disclosed in Tennes and Kern US. Pat. No. 3,567,838, and the high-low note preference systems disclosed in Bode US. Pat. No. 2,874,286, and in my copending patent application filed on 'July 17, 1972, having Ser. No. 272,437, and entitled D.C. KEYED HIGH LOW SE- LECT PREFERENCE SYSTEM FOR POLYPHONIC ELECTRICAL MUSICAL INSTRUMENTS now U.S. Pat. 'No. 3,766,305. A

However, when certain three-note chords of any given key are played such asthe seventh or minor seventh chords, the use of the highest and lowest notes for automatic bass accompanimentfrequently provides a less musically pleasing result than theuse of the musical root and fifth notes of the chord played. For other combinations of notes, use ofbass notes corresponding to the highest and lowest .notes of a group of notes played is, nevertheless, preferred as a simple and efficient method of obtaining automatic bass accompani-' vment. Heretofore, no selection system hasjbeen developed for providing both root and fifth notes of the most commonly played three-note chords or, in the. altemative, the highest and lowest notes of any other played combination of notes.

SUMMARY or THE INvE TIoN .In brief, the present invention provides an improved note selection system for akeybo'ard type electrical musical instrument which 'supplies to output leads the note signals corresponding to the root and fifth notes of selected three-note accompaniment chords, or, in the alternative, the note signals corresponding to the highest and lowest notes of a group of notes played if any other chords, or other than threenotes are played as accompaniment. The present invention comprises: a high-low select preference system (of the order disclosed in the previously mentioned Bode patent or my copending application), high and low note gating means in circuit-with the preference system for connecting the highest and lowest note signals corresponding to a group of notes played to output leads, a series of control means or, more specifically, chord AND gates which provide control voltages in responseto playing certain preselected three-note chords in any given key to root and fifth note gating means for connecting root and fifth note signals of these chords to the output leads, and a three-note detector in a circuit to control each of these two gating means, such that the root and fifth note gating means is operated to provide the root and fifth note signals of a preselected chord in response to control voltages from both a chord'AND gate and the three-note detector whenever only the three notes of any of the preselected chords are played, and the high and low note gating means is operated to provide the. highest and lowest note signals of a group of notes played in response to a control voltage from the three-note detector whenever other than three notes of any of the preselected chords are played.

While the disclosed embodiment of the present invention will be described in conjunction with electronic circuits employing conventional PNP, type transistors,

the present invention is not limited to the use of these components but is particularly suitable for integrated circuit embodiments.

BRIEF DESCRIPTION OF- THE DRAWINGS FIG. 1 is a simplified diagrammatic representation of the preferred embodiment of the present invention; and

' FIG. 2 is a schematic diagram which illustrates in detail the features of the present invention diagrammatically represented in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT signal sources representative of notes of the musical scale. As more fully described hereinafter, a series of leads 11 connect the keys of keyboard 10 to control means or,.more specifically, to 12 chord AND gates,

one for each. of the musical keys, typically illustrated for the C chord at 12. Since all of the chord AND gates function'identically, only the AND gate for the C chord is illustrated and described in detail. The keyboard 10 is also connected to a three-note detector 13 by means of lead 14. The three-note detector 13 is connected to all of the chord AND gates by means of leads 17 connected to a common bus 16.

Each chord AND gate is connected to a corresponding root and fifth gates in amanner similar to that illustrated for the C chord AND gate in FIG. l.- As shown in that figure, the C chord AND gate 12 is connected to the C chord root and fifth gates 18 by means of lead 19. A tone signal source supplies the note signals corresponding to the root and fifth notes of the C chord, namely C and G, to C chord root and fifth gates 18 by means of

leads

21 and 22 respectively. The C chord root and fifth gates 18 are further connected to all of the other chord root and fifth gates by means of

leads

23 and 24, and to root and fifth output circuits 26 by means of

leads

27 and 28.

A high-low select preference system of the order disclosed in the previously mentioned Bode patent or my copending application, illustrated generally at 29, is in circuit with the keyboard 10 by means of leads 30 and is connected to high and low output circuits 31 through

leads

32 and 33. This preference system operates to se lect the note signals corresponding to the highest and lowest notes of a group of notes simultaneously played and connectsthese signals to high and low output circuits 31 by means of

leads

33 and 32 respectively. The

3 three-note detecting means 13 provides control voltages to root and fifth output circuits 26 and high and low output circuits 31 by means of control leads 34' and 36 respectively.

Root and fifth output circuits 26 and high and low output circuits'31 are interconnected by means of leads 37 and 38 such that, when the system operates, either the root or low note will appear on lead 37 and either the fifth or high note will appear on lead 38. Lead 37 is connected to root-low output 39 by means of lead 41, and lead 38 is connected to fifth-high output 42 by means of lead 43. These output terminals can be connected to frequency dividers, desired wave-shaping circuits'and an automatic rhythm programmer in order to provide automatic bass accompanimentto notes played on the keyboard as diclosed, for example, in the previously mentioned Tennes and Kern patent.

The high and low output circuits 31 are controlled by three-note detector 13 by means of a voltage on lead 36 to connect the lowest and highest note signals to leads 37 and 38 respectively. However, when certain three-note chord combinations are played on keyboard 10, the present invention operates to connect the root and fifth note signals of the particular chord played from root and fifth output circuits 26 to leads 37 and 38 respectively in place of the lowest and highest note signals.

The preferred embodiment illustrated in FIGS. 1 and 2 contains 12 chord AND gates which respond to four chords in each musical key. As illustrated in FIG. 1, the C chord AND gate 12 is connected to the keys of said keyboard corresponding to the notes C, D E, G and .A which comprise the four most common chords in the key of C: C major (CEG), C minor (CD #G), C seventh (CEA# and C minor seventh (CD "A Whenever any ofthese three-note combinations are played on-keyboard 10, the C chord AND gate 12 and three-note detector 13 cooperatively operate to connect the root and fifth notes of a C chord, namely C and G, to leads 37 and 38 respectively instead of the highest and lowest note signals of any of these combinations played. In response to playing any of the foregoing'combinations, the C chord AND gate '12 provides a control voltage to C chord root and fifth gates 18..The three-note detector 13, utilizing input voltages from keyboard 10 on lead 14 and the C chord AND gate 12 on lead 16, operates the root and fifth output circuits 26 by means of a control voltage on lead 34 whenever only the three notes of either the C major, C minor, C seventh or C minor seventh chords are played. The C chord root and fifth gates 18 and the root and fifth output circuits 26 are cooperatively operable to provide the root and fifth note signals to leads 37 and 38 respectively only when control voltages are present both on leads l9 and 34 in response to operation of both the C chord AND gate 12 and the threenote detector 13 respectively. If chords other than the C major, C minor, C seventh or C minor seventh are played on keyboard 10, the C chord AND gate 12 will not provide a control voltage on lead 19 to operate C chord root and fifth gates 18. Further, if other than three notes of any'of these chords are played on keyboard 10, three-note detector 13 will not provide a control voltage on line 34 to operate root and fifth output circuits 26. Only when both conditions are satisfied, namely, operation of the C chord gate 12 to provide a control voltage on lead 19 and operation-of three-note detector 13 to provide a control voltage on lead 34 will the root and fifth note signals be connected to leads 37 and 38 in place of the lowest and highest note signals from the high and low output circuits 31. Chord AND gates and chord root and fifth gates corresponding to chords in other keys function in a similar manner.

With additional reference to FIG. 2, the operation of the electronic circuits diagrammatically represented in FIG. 1 will now be described in detail. As shown in FIG. 2, keyboard 10 comprises a series of keys or switches 50, representative of notes of the musical scale, which complete DLC. circuits connecting D.C. bus 51 to tone signal keyers (not illustrated) by means of leads 52 (shown only for one C note), grounded load resistors 53 through isolating diodes 54 (shown only for the B and C notes), and to chord AND gates (typified by C chord AND gate 12) by means of leads 11. It should be recognized that, for purpose of simplification, only those leads 11 from keys 50 corresponding to the C, D E, G and A notes have been illustrated, but the disclosed embodiment contains similar connections (not illustrated) from corresponding keys 50 to other chord AND gates for the major, minor, seventh and minor seventh chords in each of the other eleven keys. Furthermore, only a portion of a typical keyboard, corresponding to the accompaniment section rather than the solo section, is illustrated in FIG. 2, again for simplification. Diodes 54 and resistors 53 together comprise OR gates for octavely related keyswitches so that chords can be played in root position or various inversions.

Each of the leads 11 is connected through resistor 56 to a corresponding transistor in the C chord AND gate 12. Leads 11 from ke-ys 50 corresponding to notes G and A are connected to transistors 57 and 58 respectively. The collectors of each of these transistors are connected to a DC. supply 59, and their emitters are connected together and to the collectors of transistors 61 and 62, which are connected through leads 11 to keys 50 corresponding respectively to notes D and E. The key corresponding to the note C is likewise connected to transistor 63, which has its collector connected to the emitters of transistors 61 and 62. The emitter of transistor 63 is connected to lead 17 through diode 15, to lead 19 through resistor 64 and then to ground through resistor 66. Each chord AND gate, therefore, has three series-connected elements, two of such elements each having another element connected in parallel, to provide four possible combinations of operation of three series-connected elements. All of the transistors in the C chord AND gate 12 are normally biased for cutoff operation. However, simultaneously playing any of the four combinations of keys 50 corresponding to notes C, E and G (C major chord); or C, D and G (C minor chord); or C, E and A (C seventh chord; or C, D and A (C minor seventh) operate the C chord AND gate 12 to provide a control voltage on lead 19 from DC. supply 59 in response to simultaneous conduction of three series-connected transistors biased into saturation from DC. bus 51. The C chord AND gate responds to playing the four indicated chords in the key of C, and the other chord AND gates similarly respond to playing either the major, minor, seventh or minor seventh chords in their respective keys.

A control voltage on line 19 operates to connect the root and fifth notes of a C chord to leads 27 and 28 respectively by operation of the C chord root and fifth gates 18. Lead 19 is connected to transistors 68 and 69 through

diodes

71 and 72 respectively. The emitter of transistor 68 is connected to C note signal input 78 through resistor 79 and to ground through resistor 81.

Similarly, the emitter of transistor 69 is connected to G note signal input 82 through resistor 83, and to ground through resistor 84. Any convenient tone signal sources can be connected to'the 'root and'fifth inputs of the root fifth note signals present on

leads

27 and 28 to leads 37 and 38, and to

respective outputs

39 and 42. Therefore, in order to obtain root and fifth note signals at the

outputs

39 and 42, itis necessary to have control voltages present on both lead 19 (from the C chord AND gate 12) and on lead 34 (from the three-note detector 13). If either of these control voltages is absent, the note signals. corresponding to the lowest and highest notes of a group of notesplayed will be connected toleads 37 and 38, and to

respective outputs

39 and 42.

The high-low select preference system 29 is connected to the emitters. of transistors 93 and 94 by means of leads 32 and33 respectively. Lead'36 from the three-note detector 13 is connected to the bases of transistors 93 and-94 through

resistors

98 and 99. The presence of a control voltage on lead 36 operates to bias normally cutoff transistors 93 and 94 to key the lowest and highest note signals present on

leads

32 and 33 to leads 37 and 38. When three notes are played which operate one of the chord AND gates, the threenote detector 13 will not provide a control voltage on lead 36, but instead will provide a control voltage on lead 34 to operate theroot and fifth output circuits 26 to key the root and fifth note signals of the chord played to the output leads.

It should be noted that, because isolating diodes 54 couple octavely related notes, more than three keys 50 may be played to provide the root and fifth bass notes of a chord as long as the additional notes are octavely related to any of the three notes which operate one of the chord AND gates. However, when notes are played which do not operate one of the chord AND. gates, the system provides bass notes corresponding to the highest and lowest of the actual notes played, within the limits of the high-low preference system 2 One side of the interconnected isolating diodes 54 of keyboard is connected to a diode 101 in series with a resistor'102 (shown only for B and C notes) corresponding to each of the twelve keys. All of the resistors 102 are connected together and to lead 14 at junction 103, which itself is grounded through resistor 104. The voltage inputs necessary to operate the three-note detector 13 are provided by lead 14 from the keyboard 10 and lead 16 connected to each of the chord AND gates through leads 17 and diodes 15.

Lead 14 is connected to the base of transistor 107 of the three-note detector 13 through three seriesconnected diodes 108, and to the base of transistor 111 by means of two series-connected diodes 112 and resistor 113. The collector of transistor 107 is connected to the base of transistor 111 by means of diode 115. The collector of transistor 111 is connected to the base of transistor 116 through resistor 117, and the collector of transistor 116 is in turn connected to the base of transistor 118 through resistor 119. Collectors of

transistors

107, 111 and 116 are connected to DC. input 121 by'rneans of resistors 122. The collector of transistor 118 is connected to DC. input 123 through resistor 124 and to ground through series connected

resistors

126 and 127. The emitter of transistor 118 is directly connected to the collector of transistor 128 to form an AND gate in conjunction with transistor 118. The base of transistor 128 is connected to lead 16 through resistor 129, and its emitter is connected to lead 34 and then to ground through resistor 131. The junction of

resistors

126 and 127 is connected to the base of transistor 132 through diode 133. The collector of transistor 132 is connected to its base through resistor 134 and to DC. input 136. The emitter of transistor 132 is connected to lead 36 and to ground through resistor 137. 1

The values of resistors 102 (10,000 ohms) and 104 (270 ohms) are chosen such that, in conjunction with the resistances of the series combinations of diodes 108 and 112 and 10,000 ohm resistor 113, transistor 111 is biased into a conducting state whenever three or more keys S0 of keyboard 10 are played, and transistor 107 is operatively biased to conduct whenever four or more keys50 are played. Both

transistors

107 and 111 are, however, otherwise nonconducting with the result that transistor 116 is normally conducting because of bias from DC. input 121. Playing only three keys 50 operates to bias transistor 111 into conduction, which operates to turn transistor 116 off by grounding its own bias input. Playing four keys will operate to bias transistor 107 into conduction, which results in turning transistor 111 off by grounding its bias input through inhibiting diode 114. Therefore, transistor 116 will be biased to cutoff only when transistor 111 is conducting in response to playing only three keys 50; if any other number of keys are played, transistor 116 will remain in a conducting state.

It should be noted that whenever transistor 116 is conducting, transistor 118 will be biased into cutoff by grounding its bias input. Only when exactly three keys 50 are played will transistor 111 be conducting, thereby. turning transistor 116 off, resulting in conduction of transistor 118.

Transistors

118 and 128 form an AND gate to provide a control voltage on line 34 from DC. input 123 to root and fifth output circuits 26 whenever both

transistors

118 and 128 are conducting. Transistor 128 will conduct whenever a control voltage is present on lead 16 in response to operation of any chord AND gate. Whenever exactly three keys are played and those three keys correspond to any of the three-note combinations operable to cause a chord AND gate to conduct will the root and fifth output circuits be operated by a control voltage on line 34. In that case, when both

transistors

118 and 128 are conducting, transistor 132 will be biased into cutoff by grounding its bias input, with the result that no control voltage will appear on lead 36 to the high and low output circuits 31. Whenever either or both transistors 118 or .128 are off, transistor 132 will conduct to provide a control voltage to lead 36 from D.C. input 136 because of biasing resistor 134 (470,000 ohms). Transistor 132 will conduct to provide a control voltage on lead 36 to operate the high and low output circuits whenever other than three of the keys 50 are played, or whenever any three-note chords are played which do not operate any of the chord root and fifth gates.

I claim:

1. In an electrical musical instrument:

a plurality of switching elements, each being selectably actuated for keying one of the notes of the musical scale; I

a plurality of chord logic gates, each coupled to a preselected combination ofsaid switching elements and providing an output signal upon actuation of selected subcombinations thereof representing a particular set of chords having at least a common root note;

a plurality of chord tone gating means, each coupled to one of said chord logic gates and being adapted to gate at least one tone signal corresponding to said commonroot note in response to said output signal.

2.Apparatus as claimed in claim 1, wherein each of said chord logic gates is associated with a particular set of chords having both a common root and a common fifth note; and each-of said chord tone gating means comprises two tone signal gates for separately gating two tone signals corresponding to said common root and fifth notes.

3. Apparatus as claimed in claim 2, further compristhree-note detector means comprising: discriminator circuit means coupled to said switching elements for producing a discriminator output signalif and only if switching elements corresponding to three separate notes are actuated, and coincidence circuit means coupled. to saiddiscriminator circuit means and each of said chord logic gates for signalling coincidence of said discriminator output signals and one of said output signals from said chord logic gates; and

.gating circuit means receiving each of said root and fifth tone signals from said chord tone gating means for gating said root and fifth tone signals in response to said coincidence signal.

4. Apparatus as claimed in claim 3, further comprisa tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and lowest notes keyed by said switching elements; and

said gating circuit means further receiving said high and low tone signals for gating the same in absence of said coincidence signal.

5. Apparatus as claimed in claim 2, wherein each of said chord logic gates is coupled to switching elements representing associated root, major third, minor third, fifth, and seventh notes of a particular set of chords and comprises logic gating means for producing an output if switching elements corresponding to one of the following subcombinations of notes are actuated:

a. root, major third, fifth;

b. root, minor third, fifth;

c. root, major third, seventh; and

d. root, minor third, seventh.

6. Apparatus as claimed in claim 5, wherein said logic gating means comprises:

a first transistor having its base electrode coupled to a switching element representing a root note;

a first pair of transistors having emitter and collector electrodes connected in common and base electrodes separately connected to switching elements representing major third and minor third notes; and

a second pair of transistors having emitter and collector electrodes connected in common and base electrodes separately connected to switching elements representing fifth and seventh notes;

said first transistor and said first and second pair of transistors being coupled in series between a source of D.C. bias and ground reference such that coincident operation of said first transistor and at least one transistor in each of said first and second pairs produces an output signal from said chord logic gate.

7. In an electronic musical instrument:

a set of switching elements, each being selectably actuated for keying one of the notes of the musical scale over at least a two-octave range;

a set of logic OR gates, each associated with one of the notes of the musical scale and having inputs coupled to octavely related switching elements associated with said note;

a plurality of chord logic gates, each coupled to a preselected combination of said OR gates and producing an output signal upon actuation of switching elements associated with selected subcombinations of notes representing a particular set of chords having common root'and fifth notes;

a plurality of pairs of chord tone gates, each pair coupled to one of said chord logic gates for gating tone signals corresponding to common root and fifth notes in response to said output signal;

circuit means. coupled to said set of OR gates for de veloping a D.C. voltage corresponding to the number of OR gates actuated and thereby to the number of different notes being keyed by said switching elements;

a three-note detector comprising a discriminator circuit receiving said D.C. voltage and producing a discriminator output signal if and only if three different notes are being keyed and a coincidence circuit coupled to said discriminator circuit and each of said chord logic. gates for producing a control signal upon coincidence of said discriminator output signal and-an output signal from one of said chord logic gates;

a pair of output gatecircuits each receiving in common respective root and fifth note tone signals from said chord tone gates and gating said tone signals to a pair of output leads in response to said control signal.

8. Apparatus as claimed in claim 7, wherein said three-note detector further comprises a control circuit coupled to said coincidence circuit for producing a second control signal in the absence of said first control signal; and further comprising:

a tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and 7 lowest noteskeyed said switching elements; and

" a second pair of output gate circuits each receiving 9. In an electronic musical instrument:

a plurality. of switching elements, each being selectably actuated for keying one of the notes of the musical scale;

a plurality of chord logic gates, each coupled to a preselected combination of said switching elements and providing an output signal upon actuation of selected subcombinations thereof representing a particular set of chords having common root and fifth notes;

a plurality of sets of chord tone gates, each coupled to one of said chord logic gates for gating tone signals corresponding to said common root and fifth notes; I

discriminator circuit means coupled to said switching elements for producing a discriminator output signal if and only if switching elements corresponding to three separate notes are actuated;

coincidence circuit meanscoupled to said discriminator circuit means and each of said chord logic gates for producing a first control signal upon coincidence of said discriminator output signal and one of said output signals from said chord logic gates and a second control signal in the absence of said first control signal;

a tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and lowest notes keyed by said switching elements; and

gating circuit means receiving said root and fifth tone signals and said high and low tone signals and responsive to said first control signal to gate said root and fifth tone signals, respectively, to first and sec- 0nd output leads and responsive: to said second control signal to gate said low and high tone signals, respectively, to said first and second output leads.

10. Apparatus as claimed in claim 9, wherein said gating circuit means comprises first and second pairs of transistor gates; a first transistor in each pair receiving, respectively, said root and low tone signals at emitter electrodes and said first and second control signals at base electrodes, and having commoned collector electrodes connected to said first output lead; a second transistor in each pair receiving, respectively, said fifth and high tone signals at emitter electrodes and said first and second control signals at base electrodes, and having commoned collectors connected to said second output lead.

Claims

1. In an electrical musical instrument: a plurality of switching elements, each being selectably actuated for keying one of the notes of the musical scale; a plurality of chord logic gates, each coupled to a preselected combination of said switching elements and providing an output signal upon actuation of selected subcombinations thereof representing a particular set of chords having at least a common root note; a plurality of chord tone gating means, each coupled to one of said chord logic gates and being adapted to gate at least one tone signal corresponding to said common root note in response to said output signal.

2. Apparatus as claimed in claim 1, wherein each of said chord logic gates is associated with a particular set of chords having both a common root and a common fifth note; and each of said chord tone gating means comprises two tone signal gates for separately gating two tone signals corresponding to said common root and fifth notes.

3. Apparatus as claimed in claim 2, further comprising: three-note detector means comprising: discriminator circuit means coupled to said switching elements for producing a discriminator output signal if and only if switching elements corresponding to three separate notes are actuated, and coincidence circuit means coupled to said discriminator circuit means and each of said chord logic gates for signalling coincidence of said discriminator output signals and one of said output signals from said chord logic gates; and gating circuit means receiving each of said root and fifth tone signals from said chord tone gating means for gating said root and fifth tone signals in response to said coincidence signal.

4. Apparatus as claimed in claim 3, further comprising: a tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and lowest notes keyed by said switching elements; and said gating circuit means further receiving said high and low tone signals for gating the same in absence of said coincidence signal.

5. Apparatus as claimed in claim 2, wherein each of said chord logic gates is coupled to switching elements representing associated root, major third, minor third, fifth, and seventh notes of a particular set of chords and comprises logic gating means for producing an output if switching elements corresponding to one of the following subcombinations of notes are actuated: a. root, major third, fifth; b. root, minor third, fifth; c. root, major third, seventh; and d. root, minor third, seventh.

6. Apparatus as claimed in claim 5, wherein said logic gating means comprises: a first transistor having its base electrode coupled to a switching element representing a root note; a first pair of transistors having emitter and collector electrodes connected in common and base electrodes separately connected to switching elements representing major third and minor third notes; and a second pair of transistors having emitter and collector electrodes connected in common and base electrodes separately connected to switching elements representing fifth and seventh notes; said first transistor and said first and second pair of transistors being coupled in series between a source of D.C. bias and ground reference such that coincident operation of said first transistor and at least one transistor in each of said first and second pairs produces an output signal from said chord logic gate.

7. In an electronic musical instrument: a set of switching elements, each being selectably actuated for keying one of the notes of the musical scale over at least a two-octave range; a set of logic OR gates, each associated with one of the notes of the musical scale and having inputs coupled to octavely related switching elements associated with said note; a plurality of chord logic gates, each coupled to a preselected combination of said OR gates and producing an output signal upon actuation of switching elements associated with selected subcombinations of notes representing a particular set of chords having common root and fifth notes; a plurality of pairs of chord tone gates, each pair coupled to one of said chord logic gates for gating tone signals corresponding to common root and fifth notes in response to said output signal; circuit means coupled to said set of OR gates for developing a D.C. voltage corresponding to the number of OR gates actuated and thereby to the number of different notes being keyed by said switching elements; a three-note detector comprising a discriminator circuit receiving said D.C. voltage and producing a discriminator output signal if and only if three different notes are being keyed and a coincidence circuit coupled to said discriminator circuit and each of said chord logic gates for producing a control signal upon coincidence of said discriminator output signal and an output signal from one of said chord logic gates; a pair of output gate circuits each receiving in common respective root and fifth note tone signals from said chord tone gates and gating said tone signals to a pair of output leads in response to said control signal.

8. Apparatus as claimed in claim 7, wherein said three-note detector further comprises a control cirCuit coupled to said coincidence circuit for producing a second control signal in the absence of said first control signal; and further comprising: a tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and lowest notes keyed by said switching elements; and a second pair of output gate circuits each receiving one of said high and low tone signals and gating said tone signals to said pair of output leads in response to said second control signal.

9. In an electronic musical instrument: a plurality of switching elements, each being selectably actuated for keying one of the notes of the musical scale; a plurality of chord logic gates, each coupled to a preselected combination of said switching elements and providing an output signal upon actuation of selected subcombinations thereof representing a particular set of chords having common root and fifth notes; a plurality of sets of chord tone gates, each coupled to one of said chord logic gates for gating tone signals corresponding to said common root and fifth notes; discriminator circuit means coupled to said switching elements for producing a discriminator output signal if and only if switching elements corresponding to three separate notes are actuated; coincidence circuit means coupled to said discriminator circuit means and each of said chord logic gates for producing a first control signal upon coincidence of said discriminator output signal and one of said output signals from said chord logic gates and a second control signal in the absence of said first control signal; a tone signal preference system coupled to said switching elements for selectively gating high and low tone signals corresponding to the highest and lowest notes keyed by said switching elements; and gating circuit means receiving said root and fifth tone signals and said high and low tone signals and responsive to said first control signal to gate said root and fifth tone signals, respectively, to first and second output leads and responsive to said second control signal to gate said low and high tone signals, respectively, to said first and second output leads.