Apparatus for automatic production of music

2,541,051 Feb. 13, 1951 J. M. HANERT APPARATUS FOR AUTOMATIC PRODUCTION OF MUSIC

11 Sheets-Sheet 3 Filed Nov. 1, 1945

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2,541,051 Feb. 13, 1951 J. M. HANERT APPARATUS FOR AUTOMATIC PRODUCTION OF Music

Filed Nov. 1, 1945 ll Sheets-Sheet 4

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‘J. M. HANERT 2,541,051

APPARATUS FOR AUTOMATIC PRODUCTION OF MUSIC

Filed Nov. 1, 1945

Feb. 13, 1951

11 Sheets-Sheet 5

2,541,051 J.‘ M. HANERT

APPARATUS FOR AUTOMATIC PRODUCTION OF MUSIC Feb. 13, 1951


[?ve/22%,; John M Heme/‘t

2,541,051 J. M. HANERT

APPARATUS FOR AUTOMATIC PRODUCTION OF‘ MUSIC

Feb. 13, 1951


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2,541,051

11 Sheets-Sheet 9

J. M. HAN ERT

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Feb. 13, 1951 APPARATUS FOR AUTOMATIC PRODUCTION OF MUSIC

Filed Nov. 1, 1945

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APPARATUS FOR AUTOMATIC PRODUCTION OF‘ MUSIC

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Feb. 13, 1951

Filed Nov. 1, 1945

Patented Feb. 13, 1951 2,541,051

UNITED STATES PATENT OFFICE 2,541,051

APPARATUS FOR AUTOMATIC PRODUCTION OF MUSIC, .

John ‘M. Hancrt, Park Ridge, 111., assig-nor 1:0 Hammondlnstrument. Company, Chicago, 111., a. corporation-of Delaware

Application November 1, 1945“, Serial No. 626,150

(01. 841-405.): 28‘ Claims. "I:

My‘lnvention relates generally to apparatus for the automatic production of music.

In‘ general the object of the invention is to pro vide apparatus by’ which musical scores may be translated into musical renditions suitable for production‘ as sound or as a signal‘ for recording purposes, without the employment of musicians in anyway vwhatsoever. In other words, the in" vention contemplates that'a composeror-arrang er may, using‘ the apparatus of- the invention, score the musical composition, whereupon the music‘ will be producedautomatically by the ap paratus with all the variations usually present in orchestral renditions of music, such variations being‘ in pitch and tone quality, in volume, in accent of individual’ notes, in tempo, and in tone intensity envelopes. While some features of the invention are ap

plicable to the control of conventional mechan ical- and electrical musical instruments, the in vention is herein illustrated‘v as applied to the control of ‘electronic musical instruments and apparatus‘

It is thus among the objects of the invention to provide:

1'. An apparatus whereby a suitable record marked upon paper or the like and representing all of theycharacter-ist‘cs oi'tone quality, of tone intensity envelope, accent, tempo and the like may be automatically translated into electrical signals representative of an orchestral‘ rendition of a musical composition;

2‘. An improved means for producing a record of the musical score;

3. An improved means for controlling the out- ;. put of a plurality of electrical musical instru ments;

4. Improved means for detecting and translat ing a. musical score marked on paper into signals utilizable for the control of musical‘ instruments;

.5. An improved'apparatusin which one record may be used to control the pitch, accent and‘ the‘ like whereas another marked recordis selectively operated by the ?rst marked record to secure pre determined changes in the instrumentation, vi_ 1 bratov and volume;

6. An improved apparatus for securing a mul tiplicity of predetermined, changes in tone qual ity, tone intensity envelope, accent, tempo, vi brato and likev by means of a single mark on " the main controlling record‘;

7.. An improved record of paper or similar ma terial composedof a. plurality of cards‘ overlap ping in a shingle-like manner soas to form a long record-in which shrinkage of the paper or

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2 other’ material‘ does not vhave any appreciable effect;

8. A series of overlapping tables for supporting the record whereby leveling of the tables is fa cil'itated;

9. An improved notation card‘ ‘having im printed thereon a set of timing or rhythm mark ings and. a set of note "position markings extend“ ingv perpendicular ‘to. the timing or rhythm mark lugs;

10. An improved scanner mechanism operat ing in timed sequence for sensing the musical no tations marked upon the. record cards;

11., An improved scanning, mechanism. which does not injure, obliterate or otherwise render. ineffective the scored musical markings. even though used repeatedly;

12. An improved electrical transducer for con verting the scannedmarkings intov corresponding changes in electrical current flowing through an electronic load circuit;

1'3. An improved alternating current generat ing system producing musical tone frequencies with means for transmitting, collecting, and con trolling the intensity envelope characteristics of the tones by a direct current determined by a scanning mechanism;

1%. An improvedlorchestral, registration and control table having means for moving’ it in response to score markings;

15. An instrumentality of the above mentioned, type in which the overall expression in the out put. is controlled by markings on a record; and

1.6.. An improved record scanning mechanism in which the speed of scanning is controlled by markings on the record being scanned. Other objects. will appear from the following,

description, reference being .had to the accom panying drawings in which: Figure l is .a schematic diagram showing the

relationship of the-various components of, the complete apparatus‘; Figures 2, 3, 4 and 5 are schematic diagrams

of various forms of scanning circuits and associ ated ‘elements;

Figure 16- is aschematic diagram of the circuit employed to operate the solenoidoi the instru mentation sequence table under the control of markings ‘on vtl-lerecord ;

Figures '7 and 8 ‘are schematic diagrams of the circuits and associated elements of two modi?ed tor-ms of scanning apparatus; Figure 9‘ is a plan view’ of, thetime sequence

or record supportingstable;

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Figure 10 is a side elevational view of said table;

Figure 11 is an enlarged fragmentary sectional view taken on the line l |-—! I of Fig. 9 and show ing one of the record card locating pins; Figure 12 is a plan view of the instrumentation

sequence table; Figure 13 is an end elevational view taken on

the line l3—l3 of Fig. 12; Figure 14 is a plan view of one of the record

cards showing exemplary control markings there on;

Figure 15 is a schematic wiring diagram show ing the circuits for producing accents and for causing changes in overall volume of the out put; .

Figure 16 is a schematic circuit diagram of the coupler system and the means for controlling the transmission of tone signals to the output sys tem;

Figure 17 is a schematic wiring diagram show ing the means for producing Xylophone-like tone envelopes; Figure 18 is a schematic diagram showing the

circuits and associated elements for producing sustained tones;

Figure 19 is a schematic diagram illustrating the means for controlling the production of per cussive effects such as drums and the like; Figure 20 is a schematic diagram showing the

circuits and associated elements for controlling tone quality;

Figure 21 is a schematic diagram showing the means for causing acceleration and deceleration of the scanning apparatus relative to the record; and

Figure 22 is a schematic diagram showing a modi?cation of the means for sensing card nota tions.

General description

It is customary practice in the production of orchestral music for the composer to write the original score, possibly with only infrequent nota tions as to the instrumentation to be employed, and in some instances without any instrumenta tion. This score is then used as a guide by the arranger (who may also be the composer) and the scores for the various instruments of the orchestra are written, usually a separate score for each instrument of the orchestra by which the composition is to be rendered. In music to be arranged for an orchestra of a large number of pieces this is a tedious process, while it never theless requires a high degree of artistry and skill. Thereafter the “arrangements” of the musical

compositions are utilized by the members of the orchestra for rehearsal and ?nal rendition of the composition. The composer ultimately usually has but slight control over the instrumentation employed by the orchestra and it is only after these tedious and time consuming steps have been taken and the orchestra ultimately renders the composition that the composer can actually audi tion his composition played in the manner the public may be expected to hear it.

Especially in the making of phonographic or similar sound recordings frequent rehearsals are necessary in order to assure that the recording made will accord with reasonable ?delity with the ideas of the composer and orchestra conductor as to how the composition should be interpreted and rendered. In actual practice it is seldom that a recording represents the closeness to perfection which is anticipated by the composer and con ductor, since in each rendition by an orchestra

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4 a fault or imperfection in technique by one or more of the musicians is likely to manifest it self. In endeavoring to correct the faults of a previous rendition, the conductor is likely to find that other faults have insinuated themselves. The difficulties inherent in the orchestral pro

duction of a composition may be compared to those which would confront an artist who found it necessary in painting a picture to destroy the complete or partially complete picture he was painting every time he became dissatis?ed with any slight detail of the picture. The painter is not subject to such stringent regulation but instead merely repaints such minor portion of the whole picture which does not represent the subject being painted sufficiently accurately to meet his artistic approval. In endeavoring to make a musical phonographic recording, the ar tist conductor does not have this opportunity to erase and correct slight blemishes in details but instead must rehearse the orchestra repeatedly until the complete composition can be rendered in reasonable compliance with his artistic con cept of how the rendition should sound. In the method and apparatus of this inven

tion the composer, arranger, or conductor has at his command means for controlling the quality of each note, its intensity, intensity envelope, the degree of accent, duration, and tempo without necessarily affecting any other note or tone of the composition. He thus has under his con trol, within the limitations imposed by the ap paratus as a whole, facilities for producing, un der his sole control, any of a substantially in

r ?nite variety of renditions of a composition. In actual practice it has been found that it is

not ordinarily practical to provide too many sep arate instrumentalities for producing the tone frequencies and controlling their various char acteristics such as quality, tone intensity enve lopes and the like, since in the music ultimately produced, even the most trained musician cannot detect minor changes in these qualities of the music. Since most auditory as well as other per ceptions are governed by the Weber-Fechner law that the stimulus must increase in geometrical steps to cause noticeable differences in sensation, the number of steps of gradation in volume, de gree of vibrato, change in intensity envelope, and changes in tone quality, need not be very great. The apparatus includes means for supporting

marked notation or record cards, comprising a long sectional table having rails along its longi tudinal edges for a motor driven scanning car riage. The record notation cards have suitable perforations cooperating with locating pins pro jecting upwardly from the table, the cards being laid on the table in overlapping shingle fashion. The cards may be of any suitable size, one prac tical size being approximately 11" x 12". The cards suitable markings indicating the measures of the music to be scored thereon, each measure being divided into quarter tones, 8th tone‘ intervals as well as making provision for triplets aggregating a quarter tone. In aggregate length there are sui?cient cards (39) to score a compo sition of at least 96 measures. For convenience there are three cards side by side to accommodate the usual number of required varieties in orches tral control. In addition, there are provided two instrumentation control cards which are located on a separate instrumentation table and coop crate with a separate scanning apparatus. In scoring a composition to be produced the

composed or arranger may suitably mark cards in

'5. aznackz'and: by'rmaztltine the-cards todndicaterthei order-.1 in. which; thev, are . to; he; placed. upon: thee tables,._they5 may; be~.initially scored, by; the .com: - poser." or: arranger; at". his; home;v or; desk. The: scoring?mayhege?ec-tediira; variety or ways; asqby markings-the cardszwith; asuitable graphitepencil _ to; make an. electrical conducting: mark,_ or; by‘ using; a; conducting ; ink such. as a? quick; drying aquadegarsolution... rifhe useof a pencil. has been found; most; practical. because: of‘ ther-ease- with which correcticnscan be made-by erasures. The scanning;apparatuscomprises; a pair. of

contact brushes; for-each line of each'ayof-the no; tation» cards; thesezcontac-ts-ibeing in the: grid; cir cllitsgof .vacuum; tubes having relaysin their-out" nut? circuits-.~. selected tone, generatorsto theoutputsystem and to. » determine: the . tone duality; tone intensity- en velopesz. and? the like; One.‘ of, thQl‘OWSeOf; mark. ingscn the record" cards: may beutilized to con-7 trolthe operation oi- the. instrumentation se quence-scanner; this-preferably; being weightor springioperated.andreleased .to'imove single step through-a suitable: electrcmagnetically operated, eseapement mechanism. Thus whenever-a major change of instrumentation is desired amarlrwill: lie-placed uponv the notation cards-to cause ad vancingg ofa theinstrumentation sequence-scanner onerstepi Thevlatter scanner is. similar toithat oi“ the notation, scanner but= the?relays operated‘un den its control .e?ect moreor less-overall changes in -.instrumentation. and vibrato‘ and. the’ like.

Accent andoverall outputvolume may be con trolledzfrom theinotation cards. The output is supplied to a; monitoring‘speaker; and to a phono graphic or similar recorder tenths-production of‘ a mastery recordfrom which the usual commercial pressings or other reproductionsqmayhe made.

Layout- of apparatus The. overalllayout of the apparatus. best.

be understoodhy the referenceto Fig. l in which" thecarrangement is diagrammatically illustrated. The timesequence table 35.; hears the notation cards. which control the operation of-thetime see quence scanner 32. This scanner operates throughrelays andsolenoids tocon-trol'the opera tion. of the. instrumentation sequence table 34, withitsscanner .36, as .wellas to control .the open ation of directcurrent control systems I; II, III andlV illustrated asbloclrs Al, 42, ‘lit-and 44. Furthermore, relays. controlled by thescanner

32 control accent systems I to IV illustrated inv Fig.1 as ‘clocks El, 52. 53and, respectively. In addition-,..the scanner 32. controls the operation of an overall expression control 56.’ The instrumentationsequence scanner controls.

the.vibrato.introducing. means 65, 62,‘ 63v and Eli respectively for the tone»generating;systemsl. to IV shown as blocks ‘H tol?. In addition, an in strumentation frequency scanner controls the operation of tone quality systems I to IV shown as. blocks Site 84 andv volume systems I to IV‘ shown as blocks 9% to 941 respectively in Fig. 1. Eachoi-the-tone generating systemsli toils/sup plies~ musical time signals to. the-direct current. controlsystems .415 toldd,.lrespectively; and‘the sig~ nals-zfrom: the latter-are. supplied tothetone dual-. itysystems?l-to respectively; . Assmodificdby" the tone qualitysystems, thesignalissunplied‘to the accent systems 51 to 54-, and-theoutput there of; is.‘ amplitude. controlled lav-the: volume system,

The“ c_utput_s_—_ of; the latter.v volume: eyes. terns-are. supplied-to; the expressionjcontrol. appaz» ratusi?zand the signelfromthe latterapparatus:

9-], to 94.

The‘ relays operate=_to-_ connect the»

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3; isasupplieeh thmughr. an. oupuirsystem 9.5.. toa res; cordec 9.51 orimonitoring speaker; 91 , or. both, def» pendingsuponz ‘the: positions, or.‘ manually operated: switchesrt?zand?t’.

Scanningapparatus;~v

The notation» cardswhich are‘pl'aced upon the‘ timesecuence table was Well as the instrumen tation determining‘cards mounted? on the instru

' mentatio'n sequencetablo are preferablyof' the» general‘ formindicatedi‘inFig 14'. The card I00» shown in Fig. 14 is prov-idediwith-a: locating aper tnre- i il‘ l 'Fand" an. alignment aperture‘ iii? to main-

instrumentation sequence table. The details of themai'kingsrappearing on the cards tilt‘ of Fig; l‘éf‘wil‘li be described hereinafter ‘out’ it will‘ be noted'that the card isprovidedwith a plurality‘oi' markingstsuch: as that; these markings-beingv of ' graphite, aquad'ag or si ‘ ‘or conductingmater-iali which maybereadily an lied to the cards. The scanningxapparatus shown inFig. 2 com-~

prises a1 pair-of contact brushes 166, which may I hev inwthe form of thin wires of Phosphorbronze

‘ or similar: resilientconductingv'material, and: are’

arrangedito brush along the surfaces of thecards Hill: as the scanning apparatus moves along the» time sequence table. (or as the instrumentation sequence table. moves past its scanner). Upon" passinga conducting mark 5%‘ on. a card: asso— ciated'with a pairof the contact brushes [96; a» circuit‘. from the positive terminal of a source of plate current [06 to the control grid’ Hii?-of at» pent‘od‘e H2‘ is completed, this circuit including a- suitable series grid. resistor R! M‘. When the contacts’ 596? are. not in’ engagement with a con-l ducting mark, the pentode I I2 is'negativelyhiased" substantially to or beyond cutoff by,v connection of’ thegrid' l lilto the negative terminal oiv'abias. battery ‘Hit; the connection-‘to the grid 1 it’ being through the resistor R514 and. a resistorRH?, the latterwhaving acapaoitor Clfl'liin shunt there‘ with; The cathode and suppressor grid offthe pentode “'2' are illustrated. asv connected to ground‘, this being the potential of the-negative termiinal ofthe'voltage source I08 and the posi»v tivev terminal? of' the biasing voltage source I I6. The-screen grid'of this pentocle is connected to the=positive terminal of‘ the plate voltage source» H38.

A1 direct current control circuit‘impedance i1‘ lustrate'd- as a- resistance R! i8 is connected‘ be tween thev plate of the pentodev H2 and the

. positive terminal oi’the source Hi3, while a con ' trol‘lmeans 4 L44, which may or may not include a relay (as will appear from thedescription of Figs. 6 and 3), is connected across the plate load‘ resistorRllc ofthe pentode H2‘. This means controls thetransmission of tonesignals from a tone generating-system ‘i'! to ‘id-‘to a transmission means i255‘, which-may he considered as compris ing elements contained in blockaE-i-Bd; 5I—54, Sit-At, 56’. 95“; Q5 and 91.

I ltfwilrb’e apparent froma consideration of the: circuitlshown- in Fig. 2 that-when ‘contactbetween-v

brushes iil? is completed by engagement‘ of conducting'marlc {M1 on one of, the record nota~

tion cardsv Hit‘, the gridv iii) will rapidly shift positive withvv respect to the cathode: of thepen-l tocl'eI llZFcausing a sudden ?ow of plate current; Theiresulting dropin voltage across the imped ance‘ RI 2%? provides a1 substantial signal impulse“ through. the conductor H91 ‘which connects-theM

. plate ' oft pentode-r Iii-2'“ with the: control means‘

tain it in proper position on the time sequencelor

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4I-—44. As a result, the wires I I9 may be long and those for the various pentodes II2 (of which there are in the illustrated embodiment I68 in the time sequence scanner and I I2 in the instru mentation frequency scanner) may be joined in a cable without danger of interference by induc tive or capacitative coupling between the indi vidual wires or of resistive leakage. The plate current drawn by the tube H2 is relatively con stant and independent of the actual impedance at the pencil marks, being, in all cases, limited by the series grid resistor Ri I4 to that value that just corresponds to the initial ?ow of grid cur rent.

In some instances it may be desirable to couple the contact brushes I06 directly to the control means, as illustrated _in Fig. 3. In this ?gure the signal from a source such as 1I-14 is impressed directly across the input circuit of a non-linear control pentode I22, the character of the input signal being capable of being modi?ed to some extent by closing a switch I24 to connect a ca pacitor (H25 in parallel. with a capacitor CI26 and with a grid resistor RI28. The contact brushes I06 control the potential of the cathode from a value beyond cuto? to a suitable operat ing potential by connecting the cathode to a suitable negative potential source, shown as a terminal —-135 v., through an appropriate tonal envelope attack and decay network comprising capacitors CI30 and CI3I and resistors RI32 and RI33. Suitable operating potentials are applied to the remaining electrodes of the pentode I22, the plate potential being applied through load resistor RIM. The signal. appearing across the load resistor RIM is impressed upon the trans mission means I20. In operation, completion of a circuit across the

contact brushes I06 results in increasing the cathode to screen potential on the pentode I 22, thereby to cause plate current how at a rate de termined by the mesh CI30, CI3I, RI32, Rl33, and upon breaking the circuit between the brushes I06 the cathode potential will increase at a rate, determined principally by the values of CI30 and RI33, to a value where screen and plate current cease to ?ow. CI3I will ordinarily be small rela tive to CI35] and is provided mainly to prevent undesirably rapid transients. Thus the signal originated in the generator 1I-14 will appear in the transmission means I20 with an intensity envelope determined by the mesh RI32, RI33, CI30 and. Ciel. RI32 is of value in the order of 2 megohms, thus making the resistance of the pencil mark small in comparison. The cathode voltage (as well as signal amplitude) is substan tially independent of the resistance of the pencil mark. The pentode I22 will act as a non-linear class C ampli?er so that only the most positive portions Of the signal wave impressed upon the grid will produce a signal in plate circuit. The result will be that the output signal appearing in the transmission means I20 will vary somewhat in tone quality with amplitude, as is more fully described in the patent to Laurens Hammond, No._2,l26,1l64. A further modi?ed form of scanning means is

shown in 41. In this embodiment of the in vention the notation card is made or“ conducting material such as a metal sheet or a composite metal foil and paper sheet “in. The sheet is connected at all times to the negative terminal of the biasing battery I I6. To make notations upon the conducting card I40, short strips I 42 of ad

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8. hesive cellulose tape, or the like, are placed upon the sheet I46 at such points at which it is de sired to have a tone signal controlling relay op erate. The control grid I44 of a pentode I46 is connected to a single brush !48 through grid re sistor RI50. Thus the grid I44 is normally main— tained at the negative biasing potential. When ever the brush contacts one of the insulating strips I42, this circuit to the negative bias po tential is broken and a positive potential is im pressed upon the grid I44 through a resistor RI 52 which in this circuit is in series with RI50. RI52 will normally be of su?iciently high value rela tive to RI50 that the pentode I46 will be cut oiT or substantially cut off whenever the brush I48 makes contact with the conducting notation card I40. When the brush passes over an in sulating strip I42 the grid swings positive and plate current flows through winding I54 of a re lay I56, the switch contacts of which may form part of the direct current control system 4I-44. Undesirable chattering at the relay I54, due to small insulation particles or dust on the conduct ing notation card, is prevented by the inclusion of a small condenser CI51 connected from grid to cathode. As a further example of the manner in which

the notation cards may be marked and the mark ings translated into a direct current, there is shown in Fig. 5 a capacity pickup system. In this system notation cards, such as the card I00, are placed upon a conducting surface provided by a metal plate I60, the markings I04 on the card being likewise made by aquadag or graphite. One terminal of a source I62 of radio frequency is connected to the metal plate I60 while the other terminal is connected to the cathode I64 of a detector pentode I66. A single brush I68, adapted to wipe past the marks I04 and to make contact therewith, is connected to the control grid of pentode I66 through a grid resistor RI'I0. This control grid is normally connected to a suit able negative potential source through a resistor RI‘III and a resistor RI12 in series therewith, the cutoir potential being su?icient to maintain the pentode I66 cut off despite the presence of low amplitude RF signals picked up by the brush I 68 due to stray capacity effects. The output cir cuit of the pentode comprises a relay winding I14 having an RF bypass capacitor CI16 in par allel therewith. A switch I18, closed upon en ergization of the relay winding I14, may be in a direct current control circuit. From the foregoing it will appear that the ap

paratus shown in Fig. 5 is adapted to close the relay switch I18 whenever the brush I68 is capaci tatively coupled to the radio frequency source I62 due to its contact with one of the conducting marks I04, but that normally the pentode I66 is biased beyond cutoff, so that the relay I14 is de energized and switch I18 open.

Escapement operating circuit for instrumenta tion sequence table

The circuit shown in Fig. 6 is particularly adapted for the operation of the escapement mechanism of the instrumentation sequence table, to be described hereinafter. This circuit includes a pair of brushes I66 adapted to make contact with the markings I04 on notation cards I00 in the manner described with reference to Fig. 2 and thus change the grid bias on pentode I'80 from cutoff to a conducting value, thereby energizing winding I02 of a relay having a switch I84. The lower contact I85 of the switch I84‘

is connected‘ to ground through a relatively. large capacitor C186 and. is connected to’ an operating potential'source indicated asv +300 v. through a relatively, high. value resistor RIBS. The other contact of the switch. IE4 is connected‘ to one ter minalof a solenoid winding let,- the other termi nal of the solenoidbeing connected to, ground. When the brushes make contact with‘ a

mark N34,,the relay 582 is energized to close the switch 184. It will be apparent. thatthe capacie tor C186 is at all timesconnected across a suite able operating potential source‘. through the re‘ sistor R188. Therefore, when the switch i813‘ closes, the capacitor Cl83 will discharge rapidly through the solenoid winding list} andv cause the latter to operate its-plunger. This‘ solenoid- must be, relatively powerful for reasons which Will-ape pear hereinafter and, if it were not for theruseof the energy storing capacitor (H86; the‘ solenoid would impose an undueload upon‘ any conven tional vacuum tube power supply system: By providing this capacitor, however, thedrainfup'on the power supply extends over an appreciable time interval‘ and thus the amperage of thecu'r renttdrawn is very. low, but the energy- supplied over. such a long period ofitime is: instantly avail able for energiz'ation or thissolenoidwinding E90; assuring quick and powerful action-of this sole noid'.

If‘desired, the scanning of the notation'cards andthe instrumentation--sequencecards may be accomplished by photoelectric means, as shown in Figs. rland 8. In Fig; 7 the card lil?a bearing contrasting

lightintensity markings iilll- is illuminated by a’ neon tube i94- provided with a suitable con denser lens system let‘. The neon tube‘ is'ener gized by an alternating current- source i96~ of suitable frequency, such for example: as 200» to 50010. .p. s. Aphototube i98i having-a lens 'sys~ tem I991 directed at the ‘portion’ of‘the’card il luminated by the neon‘ tube {94; is» connected across the input of a detector p‘ento‘d'e 2%; Either of: the lens systems‘ I96 and I99,» espe cially the latter, preferably» includes a suitable mask sothat each of the: phototubes I98 willire spond only to'markings on- a particular‘ row‘ of‘ the card: I 00a‘, as the latter moves past the‘ photo' tube, for example, init'ne direction indicated by the arrow. Operating potential for the photo tube I98 is supplied from a suitable source through a resistor RZQZ and thesignal, there from is impressed upon the controli gridot a: pentode-2ii5,through a capacitor C264 and gridv resistor R296. A potential suf?cient to bias the. pentode Zililbeyond cutoff isimpressed upomthe grid of this .pentode through azea inseries. withv RZiiii. The output circuit. of the pentOdeYZOt-rin cludes a relay winding 210 in parallel with a high frequency by-pass condenser C212. From the foregoing description of the appa

ratus shown in Fig. '7, it will appear that when ever. the phototube I98 scans a dark mark on. the notation card iota, the intensity of the sig nal produced thereby will decrease’ suiiiciently; that the pentode 2% will be biased beyond cut~ ofLthereby interrupting- the plate; current and; deenergizing the winding 2m of the relay, per-r mitting its sWitchZM-to close. When,- however, the?dark- mark has passed the ?eldof‘ View. of; the phototube £98,- a. signal corresponding to. the frequency of the source I93. willxbeimpressedl across the input iiltlandf will ‘result .in .plate. our-v rent- ?ow throughthe relay winding?iiil: to open‘:

It , will be‘, understood . that: the its. switch; 21 4.

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10 Switch 214;‘will be‘ in adirect' current control‘ cir-' cuit and control the: transmission- of a signal from the tone: generating system to the output system» or the instrument. To assure less inter; ference from'out‘si‘de- light sources, the portion of the notation‘ card 1256a being scanned is prefer ably shielded bya= light shield 2-16; Instead of‘ utilizing the‘ photoelectric scanning

system tov operate relays in the direct current control ineansythe signal produced by the ‘phototubes in scanning markings-email be‘us'edldirectly to control the transmission of‘ the» signal‘ from the tone generating" system to the output sys; tem, as :show'n'i'n Fig. 8': l'nathis ?gure- the means for illumination or the card» and the- photoelec tric pickup is substantially identical with that described with reference to Fig. '7; but the card are preferably iso'f ‘non-re?ecting‘ black- andi has white notation markings; thereon. The signal from the phototube I-QEoi‘iFig; 8 isimpressedupoii the grid‘ of a pentode 222 through» a- blocking condenser C224. Suitable cutoff and* light thresholdv bias is - impressed'- upon tl-i'ej grid of the pentode 222»? through a: resistor R2I~2Bi Thus- as the amplitude of the output of the phot'otube 198' increases, the alternating component of the plate current of \ pentode 222lwilli correspondingly increase invalue. The output or: the pentode 222' is‘ coupled vthrough a. capacitor C228‘ with a mesh comprising a- recti?er cuode23cin-para1ie1 with a capacitor C232 andresistor- R234‘; This mesh is connected to the cathode 2i36’~of| arnoh=linear signal; control? pentode 2538 through a' resistor R249; The musical tone signal."ge'r‘ieratedE by a: source 2132: is . impressed‘ across- the“ input Dru-1e pentode 238, one terminal of the generator'being connectedto the gridzaaz-cr the pentode-through a‘ decoupli'nlgres-is'tor R266. Anraudioafre'quency by-pass capacitor GMBdsconnectedIin the/oath’ ode circuit while the remaining: electrodes of this pentode are connectediin the usual manner to suitable sources. of operating. potential. It‘ willbe seenzt-hatthe outputof the p'entod‘e» 2221' is recti?edandi?lteredx andimpressed upon the cathode 236, to, cause the‘pentode 2381to‘c0'n duct plate. current under: the controror the sig nal.impulsesuprovidedby, the generator 242. The: rate atv which the: cathode . 2:36.15" drivennegative by the alternating: signalzprodu'ced in the output of: pentode. 2.22isac0ntr0‘l1'ed by the valuesoi the ?ltering and delaying. capacitor ‘ C232". and r’e'sis» tor R234; .ancl. tozsomei extent by. the values of" RNBIan‘dIGHB'. By-selecting these resistors and; capacitors, . of - appropriate values; the‘; amplitude of: the signal output. or the i pentodew 238"- mayr be made to‘ occurv with any. desired predetermined’. tone intensity envelope uponthe'scanning of! a notation. mark on .the card'i228.

Notatiorn'and instrumentationsequence cards ~

The notation and sequence instrumentation cards are identically printed as“ illustrated in Fig.- 14.. As previously stated, the-carols are ap= proximately ll" x 12" ‘and vhave imprintedtheree 011355 columns numbere’djii‘?'il- to 3'66’ in-Fig. 14‘. Each column- is arranged ‘to ‘be scanned‘by a‘pa'lr'

There are three‘rows'r-1 of brushes W6 (Fig. 2). of‘ notation" cards‘ placed‘ side» by 7' side’ and two! instrumentation card'sv placedIside-by side; The cards are‘preferably made of a-duil ?nish

material which will readily‘ take pencil marks‘ and are of several ply thickness so they'm‘ay? be» durable and-ieasily'handled‘: The paper may be‘ specially treated to render it less ‘subject to’ shrinkageldueto changes-in humidity; and; is

2,541,051 11

preferably tested to make sure that no parts thereof are electrically conductive. In 14 the card is illustrated as having ex~

emplary markings I04 thereon, the markings being indicated by cross-hatching. It will be noted that the columns 30! to 366 are arranged in rough simulation of a piano keyboard in that the Cit and D# columns are "X’d” while the F#,- IG# and Aii columns have parallel line. shading. This facilitates marking all the cards by the arranger or composer. In order to avoid the necessity that the composer or arranger completely ?ll in the block markings I04, he may merely draw a line parallel to‘ and within the column and an assistant may thereafter ?ll in a complete marking represented by the cross hatching in Fig. 14. As illustrative of the character and scope of the

instrumentation available, the character of the operations controlled by the various columns of the notation and instrumentation cards which have been found practical, will be set forth. Of the ?rst notation card, columns 30! to 34!

will be used to determine which of the notes C2 (‘130.81 c. p. s.) to E5 (1318.51 0. p. s.) of gener~ ating system I are to be sounded. Columns 342 to 353 of the ?rst card will be used to determine which of the notes F0 (43.654 0. p. s.) to E! (82.407 0. p. s.) of the bass generating system II shall be sounded. Column 354 will be marked when any note of generating system I is required to be weakly accented. Columns 355 and 356 will be marked to cause strong accents on tones of generating system I, and medium accents on the tones produced by the generating system II, re spectively. Of thesecond notation card, columns 30! to

34! will be marked to determine which of the notes C2 (130.81 0. p. s.) to E5 (1318.51 c. p. s.) of the generator system III shall be sounded. Columns 342 and 343 will respectively cause weak and strong accents of the tones of generator sys tem III. Columns 344 to 356 will respectively con trol notes G2 (196.0 0. p. s.) to G3 (392.0 c. p. s.) of the accompaniment generator IV. Columns 30! to 34! of the third notation card "

will be used respectively to control notes C2 (130.81 0. p. s.) to E5 (1318.51 0. p. s.) of a generating system V. Column 342 is used to control medium accents on the notes of accompaniment genera tor IV, while columns 343 and 344 are utilized re spectively to control weak and strong accents on generating systems V. Columns 345 and 346 of the third card are used respectively to cause rapid and slow deceleration of the motor driving car riage to produce decelerando eifects. Similarly, columns 341 and 34B are used to produce slow and rapid accelerando effects. Marks in columns 349 to 35! are utilized to produce various degrees of decrescendo effects, while marks in columns 352 and 354 are utilized to ‘provide various degrees of crescendo effects. Marks in column 355 produce drum effects. A mark in column 356 will produce an orchestration shift, that is, a change in the instrumentation sequence table so as to effect any desired change in the overall instrumentation em ployed. The ?rst instrumentation card utilizes a mark

in columns 30! to 304 to control the output vol ume of generating system I. are used to determine the register of generating system I. Columns 309 to 3!3 are utilized to se lect the tone quality of generating system I. Column 3!4 is used to mute the tones of gen erating system I, while column 3l5 is used to,

Columns 305 to 308 -

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1 cent table.

12 determine whether the tones of generating sys; tem I shall have vibrato. Columns 3!‘! to 325 control the percussion branch of generating sys tem I, columns 3!‘! to 320 determining the de gree of volume, while columns 32! to 325 select any one of ?ve tone qualities for the percussion branch of generating system I. Columns 328 to 33! are used to select any one

of four degrees of volume for bass generating system II, columns 332 to 334 selecting any one of three registers for this generating system, and columns 335 to 339 selecting the tone quality of the bass generating system I. Columns 342 to 354 control the operation of generating system III, the ?rst four columns determining the volume, the next three the register, the next ?ve the tone quality and column 354 controlling the vibrato. On the second instrumentation card, marks in

columns 30! to M0 control the output of the ac companiment generator IV, the ?rst four col umns controlling four different degrees of vol ume, the next ?ve columns ?ve different tone qualities, and the tenth column the vibrato. Col umns 3I3 to 323 are for the control of generating system V, the ?rst four columns of this group controlling different degrees of volume, the next ?ve different tone qualities, while the last two respectively control the mute and the vibrato. Marks in columns 325 to 333 control the output of the percussion branch of generating system V, the ?rst four controlling different degrees of vol ume, while the remainder control different tone qualities. Columns 336 to 346 control the drum section, the ?rst four columns determining dif ferent degrees of volume, the next five different tone qualities, and the last two determining dif ferent tone intensity envelopes. In the center of each card there are numbers

0 to 9 imprinted in alignment with transverse lines 360. The distance between these lines will normally represent the time interval of a quar ter note, thus four times this distance between the lines 360 will represent a measure in 4/4 time. Intermediate the lines 360 there are dash lines 362 dividing the quarter tone interval into eighth tone intervals. There are also light lines 364 dividing each quarter tone interval into three equal parts for the scoring of triplets.

The notation card table

As shown in Figs. 9, l0 and 11, the notation card table is built up in sections, the ?rst section 366 being constructed in the manner of a con ventional table with four legs 36". The remain ing table sections 368 are provided with only two legs, both at one end of the table section, the other end of the table resting upon brackets 310 projecting from the adjacent legs of the adja

Suitable shims 312 are provided so as to make the tables 368 level with one another. A pair of tracks 314, preferably of inverted T-' section, are secured to the tables by suitable brackets 376 and successive sections thereof are‘ bolted together by suitable ?sh plates 318. By virtue of this arrangement, the tables may quick ly and easily be assembled with the tracks smooth and level. The locating pins for positioning the notation

cards upon the tables are preferably of the con struction shown in Fig. 11. From this ?gure it will be seen that each of the pins is mounted in the table top 31'! projecting through an enlarged hole 380 formed in the top. Each pin 382 has a reduced diameter rounded end portion 384 for

‘engagement in the.- perforations. of. the‘ cardS,. and has. a washer 385rwelded thereto. The lower end of; the. pin. is. threaded for a clamping nut. 3.88 which bears against; awashei: 389‘, aqsuitable lock washerc'sil'being. utilized‘. The washers 3-86 and 389 are‘. of .suihciently great diameter that. upon loosening. the nut 388., the pin 7.3.82. may be moved in. any direction within the. limits of the hole 384;. thereby facilitating accurate. location of the ends 384 of the pins. in the‘ table? with. the tolerances‘ customary in woodworking: practice and‘ after the rails 314 have been secured to the tables and all‘ of the tables are assembled‘, the ends 334: or the: pins may be accurately located with. reference. to: the pins in: adjacent tables so that. their. spacing may they accurate to a high degree of precision.

The scanning carriage

The'scanning carriage, designated generally by the reference» character v2W2, is mounted upon V grooved or ?anged wheels 393 resting on the tracks 314- and is driven by a motor 394- through a suitable speed reducing gearing which is en closed in the motor housing. Suitably mounted on the carriage are 168' pairs of brushes Hl5~ which project downwardly a-t'an angle so as. to resil iently contact the three cards placed side by side upon‘the surface of the‘ table. > Most of the‘ ele ments of the circuit shown in Fig. 2, such as the pentodes H2 and circuit elements EH4, RH5- and RI l8 and Cl H, are alsocarried by the- carriage. The conductors iii-‘91 from the ?fty-six pen-todes H2, as well as conductors supplying’ operating ‘potential for these pen-todes are‘ bound in a ?ex ible cable 396 leading" to‘ the other components of the apparatus.

The instrumentation sequence table

The instrumentation sequence table is shown in Figs. 12 and 13 as comprising a base‘4'0ll hav ing a pair of V-grooved rails 4E2 mounted there on for the reception of ball‘. bearings 40.4’. A movable table 406 has corresponding grooved rails 408 which rest upon the balls. 454,, thus providing an anti-friction support for longitudnial move ment of the table 496- relati-ve to the ‘base 400. Suitable locating and aligning pins “382-, ‘384’ are provided for properly positioning a pair of cards I00‘ (Fig.14) upon the table‘ 496. Along the center of the’ table are’ two‘rows of

staggered upwardly projecting pins M0 for co operation with’ an escapement pawl 412‘ which is suitably pivoted on a cross frame‘ 414 and op erated by a solenoid I98‘. The table 406 is drawn rearwardly by a long tension spring 4i8‘ which has its end respectively anchored‘ to the base 400 and a pin 420 projecting downwardly from the table 406. The cross frame 414 is guided for vertical movement in a. pair of grooved posts 422 projecting upwardly from the base 400‘. The cross frame carries two banks of contact brushes I06, there being 56 pairs of contact brushes H16 in each bank. These contact brushes cooperate with the markings on the cardsv l?il to complete circuits and cause energization of relays in a manner such as disclosed in Figs. 2, 4 or 5. Thus when there is a conducting mark in col

umn 356 of the third notation card, the contact brushes I06 making contact therewith will ren der the tube I83 (Fig. 6) conducting, energiz ing the plate circuit relay I82, I84 and permitting the charge stored in they capacitor (N861 to ener gize the solenoid. I90‘. Whenever the solenoid 1-90

The holes380. may be drilled .

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25

50

35

40

60

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75

- through» resistors R443, R449 and R450.

14' is energized, the escapement. pawl 41-2“ is shifted back; and. forth so as to permit the. spring, 41.18 to. draw the. table 438 one step toward the rear (upward of Fig. 12) thereby to bring the next set of instrumentation controlling marks into en gagement with the banks of contact brushes N16. The. completion of the circuits, such as those in Figs. 2, 4 or 5,..associated with suchof these brushes as contact marks on the card, results in energization of relays which, as: indicated in Fig. 1, cause changes in the character of the output signals of the various generating systems. The system as a whole is preferably rendered

more ?exible in use by providing means whereby the connections of the conductors us (Fig. 2) maybe selectively coupled to any of the various control means. In this way‘ there may be as many tone generatingsystems as desired and only those selected for the rendition of a particular composition may be coupled to the instrumen tation sequence scanner.

Expression control and volume system

The expression control indicated by the block 56 in Fig. 1' and the volume control systems rep resented‘ by the blocks 9i to 9:2 of Fig". l are pref erably of the nature shown in Fig. 15. In the latter ?gure the output systems of seven

generators are diagrammatically illustrated, these output systems corresponding to the outputs of the'tone quality systems 8i to 34 of Fig. 1', each being illustrated as being coupled by a trans former having a secondary winding 436) to the input of a preampli?er tricde 432 through meshes comprising resistors R433 to R438 in series and shunt resistors R439 and R440. Each of the re sistances R433 to R43‘! is shunted by a switch 44'! operated by a relay 449a, these relays being operated‘ by the scanning brushes use when they contact appropriate markings on the notation cards of the time sequence scanning system.‘ The resistors R433 and R435 are of properly

graded values so that upon energization of the relays’ associated with resistors R433 and R434 di?erent degrees of accent willv be produced by changing the impedance of the mesh, which in cludes these resistors, for the particular generat ing system upon which the accented note is de sired. Likewise the resistors R435, R436 and R431 are preferably of such values that upon suc cessive operation of the relays £45m associated therewith the volume may be increased and de creased logarithmically. The shunt resistors R440 of the various outputs of the generating systems are connected in series between ground and the decoupling resistor R4558 so as to mix the signals of the various generating systems.

' The amplitude of the combined signal of all the generating systems has its amplitude controlled by decrescendo relays 44th, F542 and 4-43 and crescendo relays 444, 445 and 4%. The relays 441* to 443- upon energization are adapted to connect the control grid of the preamplifier tri» ode 432 to a grounded conductor 423? respectively

These resistors are of graded values so that upon suc cessively energizing the relays 443, 442 and 44lb the amplitude of the combined signal appearing on the grid 432 will be decreased in logarithmic steps. On the other hand, the energization of the relays 444, 445- and 4516 will result in open ing circuits through resistors R455, R452 and R453 so as. successively and in a logarithmic man ner increase the effective resistance between the grid. of triode. 4,32. and the grounded conductor

2,541,051 15

441. In this manner overall crescendo and de crescendo eifects may readily be obtained by ap propriate markings in the six columns or the no~ tation card. The output of the preampli?er triode 432 is

coupled to a power ampli?er 454 (forming part of the output system 95-Fig. 1) and supplied to the monitoring speaker 91, or the recorder 96, or both.

Octave coupler system

As shown in Fig. it, suitable controls are pref erably provided in the apparatus for effecting octave coupling so that by the provision of a single mark upon the notation card the output signals of a number of octavely related generators of a particular system may be simultaneously coupled to the output of the apparatus as a whole. in Fig. 16 there are ?ve pairs of scanning contact brushes 106 which are representative of the brushes cooperable with two or three octaves of markings for a particular generating system. Each pair of brushes operates through a pentode such as H2 (Fig. 1) to control a relay, these re lays bearing the reference characters 468, 46!, 462, 463 and 464 respectively. These relays, upon energization, are adapted to connect a source of suitable operating potential, indicated as +210 v., to bus conductors 416, 41!, 412, 413 and 414 re spectively. A plurality of octave coupler control relays 415, 416, 411 and 418 (Fig. 16) are adapted to be energized by appropriate markings upon the instrumentation sequence cards, and respec tively control the addition of the second octave, the octave, the unison, and the sub—octave. Each of the relays 415 to 418 has a plurality of switches 419, one associated with each of the bus con ductors 416 to 414, so as to connect the latter through a high value decoupling resistor R488 to the input or" one of the plurality of suitably biased recti?er pentodes tit-2. Connections be tween the resistors and the recti?er tubes 482 are such that when the relay 411’ s energized and a relay such as 4th is energized, only the note represented by the marking which has resulted by the energization of relay 466 will be sounded, whereas if in addition the relay 416 is energized, the note and its octave will be sounded, since in this case the bus file will be connected through two decoupling resistors R489 to different recti fier pentodes 482 as will hereinafter appear. This will result in sounding of the note and its octave. Each of the rectifier pentodes 462 has a relay

484 in its output circuit, this relay being adapted upon energization to connect a suitable potential shown as —l35 v. to the cathode of a control pentode 480 through a circuit identical with that shown in 3 and operating in the same manner to cause the transmission of a signal from a tone generator 1 [~14 to its output system repre sented by a signal collector conductor 488. Since in Fig. 16 only a representative portion

of a complete octave coupler system is disclosed, the generators 'i‘iM‘Hi will generate octavely re lated frequencies such as those of the notes Ci to C6, While the relays 4613 to ‘2655 Will be respec tively associated with ‘the contact brushes 106 of the card columns representing octavely re— lated notes C2 to C6. The resistors R463 are of high value relative

to the input impedances of the pentodes 42. Thus when two or more of the relays 415 to 418 are energized at the same time, no spurious circuits can be completed because the resistors R488, being of high value (with respect to the grid-to -cathode

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25

50

16 resistance when the grid is drawing current) pre vent substantial current ?ow in a reverse direc tion. For example, if the relays 411 and 418 were energized and the note controlling relay 460 on ergized the ?rst and second pentodes 482 (from the top) would have an operating potential im pressed upon their grids, suihcient to cause grid current ?ow and thus to reduce their input re sistances from in?nity to a value low in compari son with R486. Thus, this enormous drop in in put impedance prohibits a substantial current .to flow from the grid conductor of the second pen tode 482 through its associated resistor R480 to the conductor 41!. It will be apparent that if there were any appreciable flow through said last named resistor R486 to the conductor 4“, cur rent might also ?ow to the grid of the third pen tode and energize the latter. However, as each of the pentodes 482 is rendered conducting and at very low input impedance by impressing the high grid voltage (+216 v.) on its grid circuit through R486, there is su?icient grid-to-cathode current flow in the pentode so that the actual potential of the grid is very low and, therefore, there can not be a su?icient potential buildup upon grids of other pentodes 42 through the previously de scribed spurious paths to cause the latter to con duct current. In Fig. 16 it is assumed that the generator sys

tem is of limited gamut, extending through the note C5 but not extending to the note C1. As a compromise result, the switches connected to bus conductor 414 and associated with the relays 415, 416 and 411 and the resistors R480 connected thereto are in parallel and connected to control he generator for the note C6. The generating system employed with the oc

tave coupler control system of Fig. 16 is pref erably of the type shown in the patents to L. Hammond Nos. 2,126,464 and,2,126,682. It will be noted that the method of signal amplitude control which includes the pentode 486 of Fig. 16 is similar in principle to that disclosed in said Patent No. 2,126,464.

Xylophone tone signal generating system

It is nearly a practical necessity for the artistic rendition of orchestral music that percussive tones be employed to provide contrast to the sus tained tones and, therefore, means for producing percussive tones of the Xylophone type, as shown in Fig. 17, is provided. In Fig. 17 contact brushes I 06 are adapted, through the pentode l I 2, to con trol the operation of a relay 490, which upon en ergization connects a negative potential source, indicated as —135 v., through a mesh, compris~ ing resistors R491, R492, R493 and R494, to a terminal 495 of the tone quality system 84. The resistor R492 has a capacitor C496 in parallel therewith and the junction between the resistors R493 and R494 isconnected to ground through a resonant mesh comprising an inductance L491 and a capacitor C498. A control pentode 499, which corresponds to one of the pentodes 486 (Fig. 16) is adapted to control the output of a suitable signal generator 11-14, the output of the pentode 499 being suitably coupled to a tone qual ity system 8l—94. The terminal 495 rep~ resents a common terminal for a plurality of the meshes R45“ to R494, C496, C498 and L491 as sociated with other relays similar to relay 490. The frequency generated by the particular tone

generator 1|——14 associated with the pentode 489 is preferably the same as'that at which the mesh L491, C498 is resonant. Upon energization of

417 "the-relay-MB thetransient-produced upon; closure ‘:0! ‘its 1 switch 7 is ‘transmitted ‘to the ‘terminal "495 through“ the intervening’ mesh, but only suchifre vquencies as correspond ‘rather closely to 'fre quencies of the generator ‘II-M will be trans- 1mitted to the outputsystem. The resonant mesh L491,’ C498 *does not have a su-?iciently @high’ Q to“ exclude lrequencies'di?eringby'as muchzas a semitone or - morefrom ' the output and‘ therefore this signal ‘ is - heard as a percussive - musical-‘tone of recognizable -but=not'-~‘a-s~ olearly-"de?ne'dY-in ~pitch as the usual sustained type of tone. lUpon ‘closure of the switch of relay 14153 ‘the

negative ‘135 v. potentialis impressed uponthe cathodeof the pentede 49-9, throughit'he resistor R49! and additional attack resistor iRS'iiEl, ata rate determined inpart loyv capacitor C591; there "byirendering the-pentode v499 conductive-"of't-he ‘signal supplied'by the generator I'll-74. “After 'deenergization \ of the =re'lay i450; cathode current isgstill supplied to<theepentode>r499 from theca vipacitor 0501, so that the 1tone willdecay ‘at a :gr-adualirate determined by the ‘relative values-or‘ ‘R550 and C595. 'Thus upon energization-of'the .1 relay ‘A9 0 a: signal :constitu-ting l both » a- percussiw~ tone and a‘sustained ‘tone ('the’latter beingpro ‘duced‘bythe-generator'i'lkel? of rapid attack and slightly r-slower vdecay, will be produced in :the :outputi-system. ' This tone -.~willl be respective :lynf fthexylophoneeand brassltypes and-will iuseful inimany orchestral renditions.

Generator system jjQTi'fIMTQZLSSiU? ‘piano-like tones

~In"Fig. l8»th'ere"is"illustrated acircuit suitable for the control of the ‘tone envelope of a.gen~ J ierator system iprcducing sustain-ed ‘tones, under 'the- co-ntrol'of "conducting 'markings ‘on a'notation card. ‘In this ‘circuit contact "brushes ’ I do, ‘upon passing 'over "a conducting ‘mark on ‘the card.

change the grid f-‘bias of a'pentode 582 from ‘negative-value beyond "cutoitto a “positive value

in a manner similar to that previously described with reference ‘to ‘Fig. 13. ;In :Fig. 18, however, the ‘pentode 5B2 operates as an impedance ‘changer 'sojthat thevalue oif‘the resistance‘iin posed ‘by ‘the markingjon'th‘e card across the 'brush'es‘lll? is not‘o‘f controlling character. ‘This ‘is"b‘ec,ause"th'e ‘perito‘de ‘5'62 decouples the card 'mark‘ and "cable ' impedances ‘from the. remainder

‘of ‘the ‘circuit‘whi'ch‘is ‘of high impedance -would be susceptible ‘to spurious leakage, etc.

‘The anode 'of‘thefperitode "502 is supplied from "a :suitable source 'ofiplatevoltajge‘through are sistor'R5?4 in parallel with a capacitor 105%. ‘The anode of the .pentode 202 is also connected to ‘the cathode "5118 of a control .pentoide ‘5E0 ‘through a ‘resistance 'R5l2. The .pentode 15h‘! vhas a sharp peak wave impressed thereon ,by a generator 'H-“l4 and the output of the pentode ‘is suitablycouple'd 'toa signal collector conduc~ .tor .51‘4 throug'ha capacitor ‘C515 and a decou plingresistor R5l8. The anodes of a,_,p1uraiity ofjpentodes Slil‘may'beconnected to thecollector conductor ‘5 M ‘through the ‘same, capacitor C5 i ii and resistor R518. When the contact brushes I96 pass over a

control marking onfa notation card, the ,pen‘tode ‘502' is rendered conducting so that .the potential of "its plate drops at a rate determined by ‘the tube characteristicsand the values of'CEBG, and "R584. This drop in plate‘potential'is re?ected on the cathode?'UB of the...pentoder5llland therefore renders thejlatter conductive. o‘fvthe signal ‘im spressed ‘upon itsinput circuit. 'It will-"he noted ‘that ‘the plate of pentode "502 is normally at a‘

20

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55

5319 ‘and 553?! ‘thereof through --'a time- constant capacitor -' G532 and resistor R534. v~-Pla~te potential "is provided

‘is jpotential or? volts vabove that’ ofthefcathode’tilti ‘dueto the provision “of ‘a‘ba‘ttery? Hi. ‘This latter 'potentialnormally completely cuts'off plate. ‘cur "rent ‘in tube 5 i=0. ‘

The circuit of Fig. 18 is of advantage'oversome of the previously described control ‘circuits in that no electromagnetic relay‘ is required. -

Apparatus "for producing-drum signals ‘

An important elementof orchestral music,~.par ticularly that .of popular nature, is imparted .by the percussion beat -of @drums. .I have therefore provided :a means for electronically producing electrical signals corresponding to the beats-Inf drums. Such .an vapparatus? is .shown in Fig. (19 as comprising the random .frequency generator 520. This generator may be any suitable source of random noise -such,- for examplewa signal picked up from the phonograph record of the noise of waves --breaking L 'ongla ‘beach, ~ but: is-preferably an electronic generator utilizing‘ the ‘noise ~‘due Yito :thermal ‘ agitation as 1 the signal : source.

ierator of this type is disclosedin the icopending ~ application of ‘- applicant and - David Hancock,‘~fSe—

.rial1No. ‘£47,770, ?led v‘June12O, 5-1942, rwhi'chihas unaturediinto PatentiNumber 2-,4'32 ,~l52 ,1‘ datediDe ~cemher-l-9, .1947. ~ > ‘

The output‘ of i the‘ random ‘frequency generator 526 vis connectedto'the-‘primary of a transformer

Ipr-ising Iresi-stor-s R524, R525 in series and a vshunt mes-h?comprising R526 and G521. *Aflo'ad ‘resistor R528 vvis -' connected in parallel with-"the primary ‘W-indingof ‘a transformer: 522. ' These'c "ondary- of the ‘transformer 522 has a centerf'tap -- connected to - a 'suitable biasing ~.~.potential-~‘souree indicated as~a 7 terminal "4:7 iv.‘- and has its termi nzils-connec-ted‘to the grids'of apair ofv'push-pull pentodes‘ES-ll, i531. ‘Thei‘screens of the Ipento‘des

‘ ‘are » connected ‘to ‘the cathodes

"from a source ‘indicated ‘as ‘a. +300 v. terminal through load-‘resistors R536 ‘and R531 as/well‘as through the center Ltap primary "of "an output transformer ‘The-‘screen grids of the pen ‘to'des Y153!) and 53 I are ~1nor-mally v'maintain‘ei'l "at ‘ground "or cathode ~~potential 'loy virtue of ith'e'ir ‘connection to the cathodes'of‘these-tubes-by-‘the resistor-R534. When theicontactibrushes to'ii'ifor

‘ the “control of this-‘percussion ' generating “system pass ;over a mark on-thenotationcard a relay i546 is energized to'connect the ‘screens-grids 10f ‘the.pentOdes-"S‘BQJESI to a suitable source-0'1c rop ‘erating potential shown-as ‘a +100 1v. terminal, ‘this .connection being effectedithrough a-nattack resistor "IRMB. Two -.or ‘more rlcapacitors ‘ C543,

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ground. upon closurelofl switches 545, 5616-‘ respec tively. ‘Wheniboth switches ‘555 and 5419319 open, ‘the scre‘enlgridsof ‘the pentodes 153i), *53l-‘will1‘be rapidly-raised to operating potential v‘when "the relay 5% is "energizedgandthus producefalper cussion tone with a very sharp attack. ‘Wnen=~'5it is desired to lessen the sharpness of this attack and to prolongthe'decay period-orthe percussion ,drum tone, either switch.545, or switch r5461, or ‘both, will ‘be closed, (thereby _ slowing up the ,j rate at which the substantially 100 voltpotentialmay berlouilt .up on the screen grids and prolonging the period during .Whichanoperating potential will remain on thescreenogrids and thus prolong ingaperiod-of decay of the tone. i'i‘he secondary of 1 the output ‘transformer T538 is suitably cou 'pled to one of'tone quality systems '8’! to 8'4,‘ and

Documents

Apparatus for automatic production of music