US2500821A - Electrical musical instrument - Google Patents

Description

ELECTRICAL MUSICAL INSTRUMENT i# l V SQIL-'t' IIIITLIM', i

March 14, 1950 J. M. HANERT ELECTRICAL MUSICAL INSTRUMENT 3 Sheeizs-Sheet 2 Filed Feb. 16, 1948 MAMMA J. M. HANERT ELECTRICAL MUSICAL INSTRUMENT 3 Sheets-Sheet 5 w ANS March 14, 1950 Filed Feb. 16, 1948 Patented Mar. 14, 1950 ELECTRICAL MUSICAIIINSTRUMENT John M. Hanert, Park Ridge, Ill., assignor to Hammond Instrument Company, Chicago, Ill., a corporation of Delaware Application February 16, 1948; Serial No. 8,680

(Cl. SLi- 1.24)

7 Claims.

My invention relates generally to electrical musicaly instruments and more particularly to improved key-operated control circuits for such instruments.

In electrical musical instruments played in non-reverberative rooms, it is desirable that the tones producedv have a gradual decay after the release of the key, thereby to produce the equivaient of the reverberation eiect. Since it is the depression of the key which necessarily determines the pitch of the tone to be sounded, the release of the key leaves indeterminate the pitch of the decay portion of the tone unless there is `incorporated some mechanism or circuit in the instrument which is capable of remembering the last key depressed until another key is depressed. While this may be accomplished mechanically by the usefof various types of latch and bail mechanisms, such mechanisms usually require the use of a large number of parts which must be made with precision .and are thus costly, are subject to wear, and may become noisy in operation.

Itis thus a primary object of my invention to provide improved means for controlling an electrical musical instrument to secure the reverberationeil'ect by causing the tones produced to decay gradually after the release of the key which was depressed to cause the .tone to sound.

A further object is to provide van improved key controlled circuit for an electrical musical instrument which has means for causing a tone` to'be sounded `for a predetermined time after the re lease of the key.

A furtherv Objectis to provide an improved electrical vmusical instrument in which yrelays are employed in the key circuits and in which each of the relays is provided with a holding circuit and is adapted to control the pitch of the tone produced.

Other objects'will appear from the following description, reference being Vhad to the accompanying drawingin which:

Figure l is aschematic'wiring diagram ofan exemplary form of -the invention;

Figures 2, 3 and 4 are similar diagrams of modified forms of theinvention.

For purposes-of illustration the invention'will be described as incorporated in an instrument of the melody type, that is, one which is capable of playing but a singlevnote at one time andyis provided with a generating system for producing the notes of the pedal register of an organ, yor for use as a piano accompanimentinstrumentzof the ltype showninmyprior Patent No. 2,357,191.

The instrument comprises a plurality of pedals CO to. Cl for the co-ntrol of tones having fundamental frequencies of 32,703 to 65,406 C. P.S. All thekeys except Cl are arranged upon depression ,to close.y a switch A and open a switch B, the key CI operating to close a switch A only. Each of the switches A (except the switch A for key CO) is adapted upon closure to complete a circuit through a winding of a relay l0, which, upon being energizedcloses a switch C and opens a switchD.

:Energization of the relays is accomplished through Aa circuit'including a source of `potential indicated as a terminal +24 v. connected to a conductor IZ'through a relay Winding Ill. Upon closure of a switch A (except for key CO) a circuit is completed toa relay I0 which has one grounded terminal. Upon energizationof the relay l0 its switch Cv closes to complete a holding circuit which connects the ungrounded terminal of the winding of relaywl through this switch C and theV seriesofswitches B associated with all keys of` lower pitch, the circuit being thus completed to the +24 v. terminal.

It-will be apparent from the circuit diagram that .as a resultof the completion of the relay holding circuits through the switches B oi lower keys, that depression of any key lower than that previously depressed will open the holding circuit of. the .previously depressed key, whereas depression cfa keyhigher ,than the previously depressed key willnotunlock the holding circuit established by the previously depressed key.

VThe switches D are connected in series, the highestkey Cl having its switch D connected to ground. The junctions intermediate the switches D are connected to a conductor I6 through parallelucapacitors CI8. Thus, depending upon which of the relays ID is energized none, or any other numben-or all of the capacitors CIS will be connected in parallel between the conductor 1G and ground andA will thus be in parallel with a capacitor C29 which forms part of a parallel resonant mesh including a variable tuning inductance L22, thelatterzbeing coupled to a feedback inductance L24. The `conductor .i6 -is connected through a grid leak resistor R26 and a capacitor C28 with the'grid of pentode 32, the cathode and suppresser grid of vwhich are connected to ground through the inductance L24. Operating potentials are supplied to the screen grid and plate of the pentode '32 from a suitable source of potential indicatedas a terminal +B through a Voltage dropping resisto-r R36 and a load resistor R38 respectively. The-screen grid is connected to ground through a filtering capacitor C39. The pentode 32 with its associated circuits thus comprises an oscillator, the frequency of operation of which is determined by the number of capacitors CI8 which are connected in parallel with its capacitor C20. rIhe oscillator is initially tuned by adjustment of variable inductance L22.

The output of the oscillator pentode 32 is coupled to suitable tone controls through a blocking capacitor C42. The tone controls may comprise any suitable types of selectively coupled resonant circuits having different frequency response characteristics and controllable by selectively operable switches, such as shown, for example, in my prior Patent No. 2,276,390. The signal, as modied by the tone controls, is impressed upon the control grid of a phase splitting trode 44 having its cathode connected to ground through series resistors R46 and R41. The junction of these two resistors is connected to the control grid through a grid resistor R48. Plate voltage is supplied through a load resistor R50 connected to a suitable source of potential indicated as +B, and the plate is coupled to the control grid ci a control pentode 52 through a blocking capacitor C54.

In a similar manner the junction between the resistors R46 and R41 is connected to the control grid of a control tube 53 through a blocking capacitor C55. The suppressor grids of the pentodes 52 and 53 are connected to their cathodes while the screen grids are connected together and have a suitable operating potential im pressed thereon through voltage dividing resistors R60, RSI and variable volume control resistor R62 connected between a +B terminal and ground. The cathodes of these pentodes are connected to ground and are connected to a junction point 64 through a decay capacitor C66, which may have a capacitor C68 connected in parallel therewith upon closure of a manually operable switch 10. The terminal 64 is connected to the control grids of pentodes 52 and 53 through grid resistors R12 and R13 respectively, and a negative cut-off bias is normally supplied to the grids through R'i4 which is connected between the terminal 64 and a suitable cut-oif biasing potential source indicated as a terminal v. The terminal 64 is connected through a resistor R16 and conductor 18 to one pole of aswitch forming part of relay I4, the other pole of the swtich 80 being connected to ground.

In View of the fact that the key CO does not have a relay I0 associated therewith, its switch A is adapted to connect a suitable compensating load resistor R82 between conductor I2 and ground when the switch is closed, the resistance of R82 being comparable to that of the winding of a relay I0.

The relays I 0 and I 4 preferably have anti-spark resistors (not shown) connected in parallel therewith to prevent excessive sparking at the contacts of switches A.

The pentodes 52 and 53 are supplied with plate voltage from a terminal +B through load resistors R84 and R85 and the output of these pentodes is coupled to the input of a push-pull amplier 86 through blocking condensers C88 and C89 respectively. A speaker 90 is coupled to the output of the power ampliner 86.

From the foregoing it will appear that when any one of the keys CO# to CI is depressed the closure of switch A will result in the energization of its associated relay I0 and the opening of the switch B will cut off the supply of energizing current to all relays I0 associated with keys higher in the musical scale. The closure of the switch A will also result in energization of relay I4 with the resultant closure of switch 80, thereby connecting terminal 64 to ground through resistor R16. The resistors R14 and R16 thus form a voltage divider, determining the potential on the terminal 64. The potential on this terminal will thereioer rise gradually as the capacitor C66 is discharged, and the gain of the pentodes 52 and 53 will therefore increase gradually from below cutoff to a substantial value suicient to transmit the signal at maximum amplitude. The rate of attack will of course depend upon the relative values of R16, R14 and C66 (also C58 if switch 10 is closed) and the tone will thus be produced by the speaker 90 at gradually increasing intensity, the maximum value of which may be controlled by the volume control variable resistor R62.

Upon energization of the relay I0 associated with the depressed key its switch C closes and switch D opens. Closing of the switch C establishes the holding circuit previously described, while the opening of the switch D determines the number of capacitor CIB which are in parallel with the capacitor C20 in the tuning circuit of the oscillator pentode 32. The values of the capacitors CI8 are so chosen so that the oscillator will oscillate at a frequency corresponding to the pitch of the depressed key.

Upon release of the depressed key the relay I4 is deenergized, opening the switch 80 and permitting the potential of terminal 64 to drift gradually to its cut-off bias potential of -60 volts, the rate at which this is accomplished depending mainly upon the relative values of R14 and C66 (and C68 if switch 10 is closed). The relay I0 associated with the depressed key will however be maintained in energized condition until another key is subsequently depressed. If the second key depressed is of higher pitch than the rst depressed key the relay associated with the first depressed key will remain energized.

i Thus, for example, if the keys CO-tto Cl were depressed in succession, all of the relays I0 would eventually be locked in an energized state.

By virtue oi` the fact that this is a possibility it is necessary that the source of current for the operation of these relays be adequate to permit this to take place. On the other hand, if the keys are successively depressed commencing with the key CI and ending with the key CO, the depression of each key will open the holding ciri cuit for the relay of the prior depressed key and thus the load on the +24 v. current source will be limited to that required for the energization of but one of the relays at any one time. In playing a musical composition it will be seldom that more than three or four of the relays I0 will be simultaneously energized.

The switches D are intended to be representative of any switch in any musical instrument which controls the selection of the pitch to be sounded. For example, the switches D, instead of being opened upon the energization of their associated relays, might be arranged to be closed thereby, and the switches might then be arranged to eiTect the selective energization of solenoid-operated valves controlling the wind supply to organ pipes. They might also be used to connect electrical generators (e. g. of the type shown in Hammond Patent 1,956,350) to a suitable output circuit, or to control the energize.- tion of other types of electrical tone signal genassassin 5 oratore. Iny utilizing .the .-keyacontrolcircuits@ of;A the invention withf the. fpipe organ :and othervin. struments it may not be necessary to providefthe.. relay I4.. Instead the conductor IZwmight be. connected directly tothe operating. potential source +24 v.

The invention ishof greatest utility when,v eme ployedinconnection with the bass register. tonesy oan-instrument since the-reverberation effect is not as essential.inftheproduction 01E-.treble register tones.` In the .basse register a longdecay of` the tones will produce the effect .of along reverberation time. The duration of the decaytime may be.suited to the, enclosure in which thev instrument is to bey played by vproper selec7 ionofzthe valuesof C66,l C68'and`R114.,

In the `circuit shown in fFig.' 1 the highest of. aplurality of simultaneously depressed keys de termines the frequency to which the oscillator istuned.v Insorne instances it may be preferred to have the lowest of several simultaneously de-., pressed keys determine the frequency generated.V The .latterresult maybe accomplished by they circuit shown in Fig. 2;

In Fig. 2, each of the keys CO to CI, upon depressiom. closes a switch. IDI; and in addition eachof the. keys CO# to yCI opens a switch |02. Closure of aswitchIUI. associated with keys C0 to. BO connects` a conductor |03 toground througha relay winding |il4,associatedwith the. depressed key, whileclosure of switch |0| asso.- ciated. with key CI connects conductor |03v to.. grou-nd` through a compensating` resistor RISE; The-conductor. |03 zis connected' to .a suitable source of. current, indicated as -a +24 v. terminal, 'through a relay: winding |08;`

Each of the relays |04 isadapted, upon energization, to close a switch Ii! `to. complete a holding circuit. It will be noted that the holdingcircuit forl each of the relays |04: includes in series the switches |02 for all of the higher pitch keys, andnvill therefore be brokenr upon clefv pression of any higher key'.,

Each of relays |04, upon energization, also closes-a switch ||2, eiective to tunetheoscillator-to the pitch corresponding to the lowest ofA severalv simultaneously depressed keys. Each ofr the switches I I2 has one pole connected to ground and theother pole 'connected to oneof a series of.; junction points between a series oflcapacitors CII-L The last capacitorV CI I4 ofthe series is connected to ground lso thatthe series is effectively; in parallelwith capacitor C2 0f and variable; inductanceLZZ. These capacitors, together with the inductance L22 form the resonant tuning cir-Y cuit of an oscillator similar to that described with` reference to Fig. 1. The `same reference characters have therefore been applied,v to the corresponding parts of the two oscillators.

The oscillator of Fig. 2 has its output coupled to anl output system. I I5v similar topthatshown ingreater detail in Fig. l, and the signals from this output systemv are translated into sound by a speaker H8. The relay |08 operatesa switch iin-(corresponding to switch l8|) of Fig. 1).to control the attack and decay of the tone signals transmitted*by-thel output system I6.

The instrument shown-'in Fig.` 2 operates `in substantially the sa-me manner as that showny in Fig. 1 except that in the apparatus oi Fig,` 2 the. lowestV of several simultaneously depressed keys or pedalsdeterrnines they pitch of the tone produced. If a numberof notes are, played commencing atthe high end of thescale; `the relay lassociated Awith thepvvhigher key` will remain in locked conditionvafter. such keyis released,pbut;

on-the otherhand,if:.a series ofkeys areplayed.-

commencing at the lower end of the scale, each-` higher key upon itszdepression will open the circuitsupplying energizing current for all there-- lays |04. associated with the lower keys..

The modified viormsof the invention shown; in theFigs. 3 and 4have manyl'parts identical.

fwhen'moved to dotted line position makeconi nection with one ofi the outputterminals oi a tone frequency vgenerator |32; whichr may; bef of the phonic wheel type, as shown inv thepatentgto Laurens Hammond No. 1,956,350.. The-generator;

|32may also bean' electronic oscillator, a vibra,u

tory reed `with electric'pickup, or of anyv'othersuitable type, preferably generating a. `complex wave. The switch |310; for the vnote C| isfcone nected to anV amplifier |34whicl'1-v may. includev tone, attack, decay; andy volume controls, the

output of the amplierbeing fed to `a speaker |3,6;

From the foregoing, it -Wll be clear that the highest of a plurality of depressed keys. will,

through operation loi' its associated .switch |30,

connect its` generator4 |32 .totl the amplifier and also open the circu-itbetween the ampliiier |34 and all ofthe generators |32 associated with.

any of the keysand will cause the ampliiier toy transmit the` signal with vthe' desired attack, and upon release of thekeys, the switch 80 will open and the gain of the-amplifier will decrease at a. predetermined rate to` provide the desired decay.

It will be noted however, that the highest energized relay I0 will remain locked so that its associated generator will continue to supply thetone signal to the amplifier throughout this decayv period.

In theembodiment oi the invention shown in 55. Fig. 4, the relay operated-switches Dare con-V nected to control thev supply of energizing cur-r rent to the plates of vacuum tube oscillators;

The relay operated switch 80, when closed, con-- nects a source of plate current indicated as B+ 60 to a conductorr |40 which is connected to one through a grid bias resistor R|54 anda bypass.,

capacitor CISG., the other terminal of the in ductance L|52 being connectedv to ground. A. 7 5' capacitor C|58 is connected in parallelwiththa the, same reference; characters have therefore The switches |30 are. connected in serieswwhen in full line position, and..

The switches |3,.

d' inductance Ll52, and the cathode of the triode |48 is connected to a tap |60 on the inductance L|52.

The output of the oscillator |44 is transmitted to an amplifier |62 through a blocking capacitor C|64 and a resistor Rl 66. The amplifier |62 may include the usual tone quality and volume con* trols and has its output connected to a speaker |65. The switch 8!) is provided with a dashpot |66 which permits the switch 80 to close rapidly but delays the opening of the switch after its relay winding I4 has been deenergized, for an interval in the order oi 1.5 seconds.

From the foregoing it will appear that when ever one of the keys is depressed, its associated relay 4D will be energized and the switch C of this energized relay will close to establish a holding circuit. Also the switch D of the energized relay ||l will be moved from iull to dotted line position and thereby supply plate current to the associated oscillator and cause the latter to commence oscillating. The capacitors (H50, together with their associated resistors R|42 and RMS, operate as filters to reduce transients which may be caused by the closure of the switches D. It will be understood that there is an oscillator, such as |44, associated with each of the playing keys and that the outputs of these oscillators are connected in parallel to the amplifier |62. These oscillators are intended to be representative of any musical tone generator, electrical or mechanical, the operation of which may be controlled by the completion of a circuit supplying electrical energy thereto. For example, electromagnetically operated valves controlling the sup ply of wind to organ pipes may be substituted for the oscillators.

In playing any of the instruments disclosed the player may, without any attention upon his part, merely by depressing the pedals or keys in a staccato manner, cause the tones to persist through the desired decay period and thus produce a desirable reverberation elect. If the keys are depressed in a legato manner, the tones will have the usual intensity envelopes i sustained organ tones. Since, in the forms of the invention shown in Figs. l, 2, and 3, the amplifier is cut off when no keys are depressed, the depression of a key or pedal does not, as a result oi the closure of its switch D, i3d, or |I2, produce any undesirable transients in the signal supplied to the speaker, and thus key clicks or thumps are not present in the tone produced.

While I have shown and described particular embodiments of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereoi", without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument having electrical musical tone signal generating means, a plurality of playing keys; a relay associated with each of said keys; a circuit for each of the keys including a switch operated by the key, the winding of its associated relay and a source of energy in series; a holding circuit for each of said relays, each holding circuit including in series a switch operated by the relay, a source of energy, and switches opened respectively by operation of keys for notes lower in the musical scale; switches operable by the relays respectively to determine the pitch of the tone signal provided by the generating means; and an output system including an amplifier and electroacoustic translating means, said amplier having means to control its gain in response to depression of any of said keys thereby to cause the sounding of a tone with gradual attack.

2. In an electrical musical instrument havingY an output system including an amplifier electroacoustic translating means, an electrical musical tone signal generating means capable of providing signals of the frequencies of the notes of the musical scale, and a plurality of playing keys; the combination of a switch A associated with each key and closed upon depression thereof, a switch B. associated with each key and opened upon depression thereof; a relay associated with each of the keys; a source of electrical energy; an energizing circuit for each relay including in series the Switch A, the relay winding, and the sou;cc; a pair of switches C and D respectively closed and opened upon energization oi the relay; a holding circuit for each relay including in series the relay winding, the source, and all of the switches B associated with keys of lower pitch; means responlsive to the operation of switch D to cause the generating means to supply to the output system a signal oi frequency corresponding to the pitch oi" the depressed key; and means associated with the ampliiier and controlled in common by all of the keys to render said amplifier ineffective to transmit signals when none of the keys is depressed and to cause the amplier to transmit the signal with gradual attack upon depression of any key and with gradual decay upon release of the key.

3. In an electrical musical instrument of the melody type having an amplifier including a terminal, the potential of which determines its gain, an electroacoustic translating means coupled to the amplifier output, and a tunable oscillator coupled to the input of the amplifier; the combination of a keyboard comprising a plurality of playing keys, a pair ol` Switches A and B associated respectively with each of said keys, switches A being closed and switches B beine opened upon depression of the associated key; a key relay associated with each key, each key relay including switches C and D, switch C being closed when the relay is energized; a control relay operating a switch 80 when energized; a mesh including switch 8S and connected to the said terminal of the amplier to cause the potential on the terminal to change in a direction to cause gradual increase in the gain of the amplifier when the switch is closed and to cause the potential on the terminal to change gradually in the opposite direction when the lswitch is opened; a circuit including in series a sour-ce of energy, the winding of the control reay, and said switches A in parallel; means controlled by the switches D to tune the oscillator to the various musical tone frequencies; and a holding circuit ior each of the key relays, each of the holding circuits including all the switches B associated with keys nearer one end of the keyboard than the key with which the particular relay is associated.

4. In an electrical musical instrument having electrical tone signal generating means; a keyboard comprising a plurality of playing keys; a relay associated with each key; a circuit for each of the keys including in series a switch operated by the key, the winding of its associated relay, and a source of energy; a holding circuit for each of the relays, each holding circuit including in series a source of energy, a switch closed by the relay, and switches opened respectively by the depression of keys nearer one end of the keyboard than the key with which the relay is associated; switches operated respectively by the relays, the switch of the relay associated with the key farthest from `said end of the keyboard being effective to determine the pitch of the tone signal provided by the generating means; and an output system for `amplifying the tone signals provided by the generating means and translating the amplied signals into sound.

5. The combination set forth in :claim 4 in which there is provided an additional relay energized upon the operation of any of the keys, and in which this relay controls the intensity envelope of the tones produced by the translating means.

6. In a musical instrument having musical tone producing means; a keyboard comprising a plurality of playing keys; a relay associated with each key; a circuit for each of the keys including, in series, a switch operated by the key, the winding of its associated relay, and a source of energy; a holding circuit for each of the relays, each holding circuit including in series a source of -energy, a switch closed by the relay, and switches opened respectively by the depression of keys nearer one end of the keyboard than the key with which the relay is associated; and additional switches operated respectively by the relays, and means controlled by the additional switches to cause the tone producing means to produce a tone of a pitch corresponding to that of the key by which it is controlled and when a plurality of keys are operated at the same time to produce a tone of the pitch corresponding to that one of the operated keys which is farthest from said end of the keyboard.

7. The combination set forth in claim 6`in which there is provided an additional relay energized upon the operation of any of the keys, and in which this relay controls the intensity envelope of the tones emitted by the tone producing means.

J OHN M. HANERT.

No references cited.

Images