US2458178A

US2458178A - Electrical musical instrument with split keyboard

Info

Publication number: US2458178A
Application number: US5573A
Authority: US
Inventors: Langer Nicholas
Original assignee: Central Commercial Co
Current assignee: Central Commercial Co
Priority date: 1948-01-31
Filing date: 1948-01-31
Publication date: 1949-01-04
Anticipated expiration: 1966-01-04

Description

N. LANGER Ag ELECTRCAL MUSICAL INSTRUMENT WITH SPLIT KEYBOARD 2 SheesfShee; l

Jan. 49 1949.

Filed Jan. 51,1948

N. LANGER Jan. 4, 1949.

ELECTRICAL MUSICAL INSTRUMENT WITH SPLIT KEYBOARD 2 Sheecs-Sheet 2- Fled Jan. 5l, .1948

,l llllmllllw" v I INVENTOR.

/V'fa/as [digger HTTRNEY.

Patented Jan. 4, 1949 ELECTRICAL MUSICAL INSTRUMENT WITH SPLIT KEYBARD Nicholas Langer, New York, N. Y., assigner to Central Commercial Company, Chicago, Ill., a corporation of Illinois Application January 31, 1948, Serial No. 5,573

8 Claims. l

This invention relates to electronic musical instruments, and, more particularly, to electronic organs in which a playing manual is split into two portions, each of which is l.assigned to the playing of musical notes of different tone color.

In present electronic organs generally a plurality of playing manuals or keyboards and a pedal keyboard are provided. capable of being actuated by an operator in accordance with the requirements of a musical composition. In general, a separate tone quality or tone color control is provided for each manual and also for the pedal keyboard so that the tone color of the notes produced upon playing each manual and also the pedal keyboard may be individually and independently adjusted. Thus. one or several notes may be played on one of the manuals with the one hand and with a desired tone color or combination of tone colors, other selected notes may be played on the other of the manuals with the other hand with other desired tone colors, and further selected notes may be played on the pedal keyboard Lby the feet with further selected tone colors. In this manner, it is possible to play a complex musical composition in such a way that the several voices forming the composition will be heard with different and desired tone colors thereby producing pleasing musical effects comparable to those obtainable by the musical ensemble composed of several orchestral instruments of different type, such as strings, flutes and reeds.

In smaller and less expensive organs only a single manual keyboard is provided, usually one having a range of ve octaves or 61 notes, together with a pedal keyboard, although the latter maybe omitted in some cases to further reduce the cost of the instrument. In organs of this type, in order to -retain to some extent the ypossibility oi playing voices of different tone color with each hand, an arrangement denoted by the organ term split keyboard is employed. In the "split keyboard arrangement, the keys of the keyboard are separated or divided into two portions at a convenient point, and a separate tone quality or tone color control is provided for each portion. The point of division may vary somewhat with diierent organs but it is always xed and is generally so determined as to provide a greater range, for example 3 octaves (37 notes), or more, for the right hand; which usually plays the leading voice or melody, and to provide a lesser range, for example 2 octaves (24 notes), or less, for the left hand, playing the accompaniment.

(Cl. SLi- 1.17)

While this conventional split keyboard arrangement provided substantial savings in space and equipment and was in general use in small pipe organs and reed organs, its employment was the source of various operating difficulties and disadvantages and imposed serious musical limitations upon the instrument. Thus, the musical range or" which each portion was capable was at best quite limited. When, for example, the upper portion of the keyboard, playing the melody, was assigned to the production of a string or iiute quality and the lower portion of the keyboard, playing the accompaniment, was assigned to the production of a reed quality, it frequently occurred that one or both portions had a range which was insufficient for playing certain musical compositions. Thus, when the frequency range of the accompaniment extended upwards beyond two octaves or that of the melody extended downwards beyond three octaves (that is beyond the point at which the keyboard was split), certain notes of the melody voice would sound with the tone color assigned to the accompaniment, and certain notes of the accompaniment would sound with the tone color assigned to the melof y. Of course, this was extremely disconcerting both to the player well to the musically trained listener. In certain cases some relief was obtained by transposing the composition into a rent key but this was predicated upon transcribing the original composition with great trouble and frequently resulted in a key which was quite dilicult to play. Also, even this rather troublesome expedient frequently failed to produce the c ed results. Although this `problem inseparabiy connected with the operation ci conventional organs ci the split keyboard type was well known to those skilled in the art for many years and considerable thought was devoted to its solution. none, as -l of the suggestions and propos ls made in this direction was completely satisfactory and successful.

I have discovered that problem may be solved in a remarkably .simple manner.

It is an object the present invention to provide an organ of split keyboard 'type which eliminates the disadvantages and inconveniences connected with conventional organs embodying the usual split keyboard feature.

It is another object of the present invention to provide an organ, more particularly an electronic organ, ci the split keyboard type in which the point were the keyboard is divided or split into two portions, assignable to different tone qualities or tone colors, is not fixed but is adjustable and capable of being preset in a manner most suited to the requirements of a particular musical composition.

It is a further object of the invention to provide a single manual electronic organ equipped with means for splitting the keyboard into two sections, independent as regards setting up desired tone qualities, the said means being conveniently arranged and instantaneously actuable by the player to an extent that the point Where the keyboard is "split may be shifted or displaced even while playing a musical composition.

It is also within the contemplation of the present invention to provide an electronic organ of the character described having an instantaneously adjustable keyboard splitting system incorporated therein which is capable of being preset to any desired point within a speci'c range, for example within one octave, of the range of the instrument.

The invention also contemplates a split" keyboard system with adjustable splitting point for electronic organs ofthe single manual type which is extremely simple in character, reliable in operation and which may -be readily installed in existing electronic organs vor incorporated into new electronic organs of advanced design at va low cost.

Other and further objects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings; in which Fig. l illustrates the schematic circuit diagram of a single manual electronic organ embodying the present invention;

Fig. 2 depicts the circuit of a preferred quality control or ilter employed in the organ of the invention, producing a tone color simulative of a string instrument;

Fig. 3 shows the circuit of a similar filter, producing a tone color simulative of a flute;

Fig. 4 is the circuit of another similar filter, producing a tone color simulative of a reed instrument;

Fig. 5 is a side elevational view, somewhat diagrammatic and fragmentary in character of a push button switch of the type that is preferred for the purposes of the invention; and

Fig. 6 is a perspective view, also fragmentary, of a keyboard with quality control tablets or stops and with conveniently arranged push lbuttons for adjusting the point of splitting the keyboard into two independent portions.

Referring now more particularly to Fig. 1 of the drawings, there is shown therein the circuit organization of a single-manual electronic organ embodying the principles of the present invention. Reference characters H-l to I-I-3B denote a plurality of generators of electrical oscillations having frequencies corresponding to those of musical notes within ve octaves of the equally tempered scale, it being understood, however, that a lesser or greater number of octaves may be used. For convenience of illustration only the generators corresponding to the three lowest octaves have been shown and only the generators of the lowest and of the highest frequency in the last two octaves. Also. in each of the three octaves only the generators corresponding to the natural notes (C, D, E, F, G, A and B) have been illustrated although in a practical organ twelve notes including also the so-called Sharps (that is Cit, Dt?, Ftt, G# and A#) are included in each octave, in accordance with `the twelve ,-erators employing notes of the equally tempered scale, now almost universally employed in all keyboard instruments.

The generators or alternating voltage sources may be of any suitable type such as vacuum tube oscillators of the feed-back or of the relaxation type, gas-discharge tube oscillators, electrostatic and electromagnetic generators employing elements movable with respect to each other, genphoto cells and movable waveform scanners, etc. In this connection, reference is made to the following United States patents: Cahill Patent 1,295,691; Langer Patent 1,832,402, Firestone Re. Patent 21,137, and Potter Patent 1,678,872. Among the F1enerators which are particularly suitable for carrying the princi- .ples of the present invention into practice may be further mentioned the cascaded harmonically related multi-vibrators disclosed in the Larsen Patent 2,403,09@ and in the Larsen et al. Patent 2,410,883, and the aperiodic frequency dividing networks of the type disclosed in my co-pending application Serial No. 625,618, led October 27,

rl'he switching arms of key switches S-I to 5 3@ are adapted to cooperate with stationary contacts T-i to "lL-3%. respectively, contact be- Ying made upon depression of the corresponding playing key of the manual. Stationary contacts T-i to lL-36 are respectively connected to youtput terminals 'U-l to YSL-3Q. Oi these, terminals U-i to U-l are connected toa common output bus bar l2, while terminals U-ivi to lll- 36 are connected to another common output bus bar i3.

As to terminals U-fl to T T-4t, which are respectively connected to stationary contacts T--l to 'IL-l5 of keying switches S-l to S-ii, adjoining pairs thereof are electrically Vconnected to each other by means of keyboard splitting switches K-i to K-Q. these switches being normally closed and being capable of selective actuation by depression of push buttons L-l to iff-3, respectively, one of which is coordinated to each splitting switch` for opening the switch coordinated to the actuated push button. Preferably keyboard splitting switches K--i to K-S and their coordinated push buttons klll-l to I -il constitute a mechanically interlocked system of the type now commonly used in push-button tuned radio receivers. As those skilled in the art know and as it will be set forth more fully hereinafter, in a system of the described character only one push button may be actuated at any -time and upon actuation of any one button, any other button which was previously actuated is automatically released.

In Fig. l, with the yexception of K--, all of switches K--l to are closed. As a result, `all terminals from U-l to U-l are electrically connected to the rirst output bus bar i2, whereas all of the remaining terminals U-lS to U-S are electrically connected to the second output bus bar i3. In other words. as illustrated in Fig. l, the keyboard oi the instrument is divided or split between the notes G2 and A2, the output of all generators up to and including generator "H12 being electric^lly associated with output bus bar i2 and the output of all generators beyond and including` H13 being electrically `associated with output bus bar i3.

output signal of musical frequency currents in bus bar ll is divided into three portions which are respectively introduced into iilters IVI-l, M--Z and M-3. These lters modify the waveform of the input signal portions so that upon conversion into musical sounds they are capable oi simulating various musical instruments, for example instruments of the string, flute or reed family. Output signal of modified character may be selectively drawn from filters M-I, lift-2 and M--3 by closing one or more quality control or stop switches Nl, N-2 and N--3. The working contacts of the said switches are connected through individual decoupling resistances R to a main output bus bar I4.

The same description applies also to the output signal of musical frequency currents in bus bar I3. These are likewise divided into three portions which are respectively introduced into iilters Ivi-4, M--5 and M-E. The output signals of modified character or waveform may be selectively withdrawn from filters M-4, M-5 and M-5 by closing one or more quality control or stop switches N-ll, N-E and N-. The working contacts of these switches are likewise connected through individual decoupling resistances R to main output bus bar I4.

The signal in the main output bus bar I4 is introduced into an ampliiier O and after suiiicient ampliiication is converted into sound in a speaker P.

From the foregoing description, the operation of the electronic organ of the invention will be readily understood by those skilled in the art. When it is desired to play a musical composition, the point where the keyboard is desired to be split is preset by depressing one of the push buttons L--l to L-S. This will actuate the corresponding one of switches K-I to K-9, which will interrupt the connection between output bus bars I2 and I3 at a point determined by the selection of the push button. Of course, the selection of the point of splitting the keyboard will be determined by the character or tonal range oi the musical composition which is to be played. In Fig. 1, the point of splitting the keyboard is illustrated to be between the generators or notes G2 and A2. In other Words, all notes below and including G2 are assigned to output bus bar I2 and all notes above and including Aa are assigned to output bus bar I3.

After setting the keyboard splitting point, at least one oi the stop switches N-I, N-2 and N-Zi and at least one of the stop switches N-II, N-ii and N-fi is closed. This will determine the musical duality or tone color imparted to the signal present in the output bus bars I2 and i3, respectively. As illustrated in Fig. 1, stop switches N-S and N-4 are closed. Since stop switch N-S is indicated to be representative of reed duality and stop switch N-4 is indicated to be representative of a string quality, all notes played below G2 will sound with a reedy quality and all notes above G2 will sound with a string quality. Upon operating the playing keyboard and the cooperating switching keys S-I to S-36 in accordance with requirements of a musical composition. musical oscillations from audiofrequency generators H1 to Has will be introduced into output bus bars I2 or I3, respectively, in accordance with the frequency of the notes played being lower or higher' than that of G2 or A2, respect-ively. The output signal in bus bar I2 over ril' r .M -3 and stop switch N-3, and the output signal in bus bar I3 over iilter M-4 and stop switch N-ll will be introduced into the main output bus bar I4 and then into amplifier O. The amplified oscillations of musical frequency are converted into sound ln speaker P. As set 6 forth in the foregoing, all notes played below G2 and generally corresponding to the accompaniment of the musical composition will sound with a reed .quality and al1 notes played above the said note and generally corresponding to the solo or melody portion or the musical composition will sound with a string quality.

Obviously, the point of splitting the keyboard may be changed at any time, even during the time when a musical composition is actually being played. Thus, still assuming that the splitting lpoint has been initially set between Ge and Ai, as this is shown in the example selected for and illustrated in Fig. l, it may happen that during playing a composition, in a certain passage, the accompaniment will go as high as the note C3. In that case, all that is needed is to press button L-S before actually reaching that particular passage, This will instantaneously open switch K-Q and at the same time will close the previously open switch K-G, thus transferring the splitting point by the desired degree. Of course, the said shifting of the keyboard splitting point may be resorted to as freo uently as is necessary during the time a musical composition is executed.

In order to permit repeated shifting of the splitting point with the speed necessary for the execution of this procedure during the actual playing of a musical composition, it is necessary to incorporate certain constructional features into the switching system, First, the actuating mechanism of switches K-I to K-9 has to be light and at the same time positive in action so that it can be actuated easily and rapidly by the operator. Second, mechanical interlocking of the several switches has to be provided so that opening of any one of the switches will automatically close all of the others. Third, the push buttons or other manually operable control elements of the switches are preferably so arranged with respect to the keys of the playing manual that their position directly indicates the point where the keyboard is split upon actuation of each push button. This preferred arrangement or the push buttons will be set forth more fully as the description proceeds.

The character and construction oi the filter networks M-I to M-G will largely depend upon the waveform of the signals, delivered by the generators H1 to Het. Figs. 2 to 4 diagrammatically illustrate iilters of the type that are suitable with generators producing audio-frequency oscillations of sawtooth waveform,

The filter shown in Fig. 2 comprises input and output terminals 2l and 22, respectively, connected by a resistor having a capacitor 24 connected across the same,

Small capacitors

25 and 25 are connected between the ground and terminals 2| and 22, respectively. A iilter of this type, when slecting proper circuit constants, is capable of converting sawtooth wave signals into oscillations of a waveform simulative of the tone color of string instruments.

Fig. 3 shows a low-pass filter comprising input and output terminals 3| and 32, respectively, connected by a choke coil 33. Terminals 3l and 32 are grounded through

capacitors

33 and 34, respectively. A filter of this type, with a choke and capacitors of appropriate value, is suitable for converting sawtooth wave signals into oscillations of a waveform simulative of the flute or diapason qualities of an organ.

Fig. 4 shows a high-pass lter comprising input and output terminals 4I and 42, respectively, conacteurs nected by a capacitor 43; TerminalsM and. 42 are grounded4 through' chokes 44 and'. 45, respectively. A filter of thistype, Withacapacitor and chokes of appropriate value, issuitableffor converting sawtooth wave signals;` into oscillationsiof awaveform simulativeof a reedinstrument. For further details of lters of thetdescribedf'character reference may be. had to my U5. S.v Patenty No. 2,403,664.

Fig. shows somewhat diagrammatically the construction-oa preferred'v form of push button switch which is suitableafor the purposes of' the present invention. For simplicity; offV illustration only 3 of the 9 pushbutton controlledswitches are illustrated.

The switch essentiallycomprisesza pair cfframe plates 5I held' in parallel` spacedrelation. by bracket 52. Push rods 53, 54 and 55 are slideably mounted in frame plates 5| and are biassed out.- wardly by means of4 springs 5S. Each push rod is. provided with a protruding portion 5;?! having an upper inclined edge yand a lower transverse edge. These protruding portionsy are adapted to cooperate with a transverselydisplaceable latching bar'53, pressedto the left by a spring 59.

Push rods 53, 54 and 55v carry movable, contactors 50, 6l and 52, respectively, separated from the body of the rods by insulationt 63. Contactors t0, 51j and 62 are adapted to cooperate with pairs of stationary contacts 64, 65; 66, 51;-and'68,69, g;

respectively. Terminal U-ID' is connected to contact 54; terminal U-II isv connected to contacts 65 and 6B; terminal' U-IZ is connected' to contacts 6l' andl 68y and terminal U--l3 is connected to contact 69. Push rods 53, 54' and 55'are provided with buttons L-4, L-5 and L-6 at their lower end. for convenient manual operation. (See also Fig. 1.)

Normally, in the inoperative condition of the switch, all'of the push rods are initheir outwardly extending position and terminals U-IU; U-I'I, U-I Zand U-lS are all connected` to each other due to the fact that each pair of stationaryV contacts (64, 65; 6E, 61; 68, S9)A is bridged over by the corresponding interposed movable contactor (250, 6l, 62, respectively). However, upon actuation of one of the push rods, for example` 55, con'- tactor 62 will be displaced beyond stationary contacts 68 and 69 andV the circuit will be broken between terminals U-I2 `and U-IS', as this is illustrated in both Figs. 1 and 5. At the lsameitime, latchingr bar 58` will be displaced to the right by the inclined edge of" protuberance 5T against the pressure of spring plate 59. Immediately thereafter'the latching bar will'snap'back" andf`wi11 prevent the push rod to be returned by its spring 56 due to locking engagement of the latching' bar with the transverse portion of protuberance 51'. The push rod will be retained in itsin position until any one of the other pushrods is actuated when the transverse displacement of` latching'bar 58 occasioned by the displacement ofthe push rod being actuated will release the first actuated push rod from its locked position andv permits it to be returned in its original` position by its compressed spring 56. Thus, it:w.i1lbe.n0tedthat upon actuation of any one-of the-pushrods the previously actuated andlock'edI push` rod:A is'V automatically released. Of` course, great variations are possible in the construction of automatically interlocked push button switches offthe' described character and for further' details of! such switch constructions reference maybey had; for example, to Hall et al. Patent No. 2,234,405.

Fig. 6v is a fragmentaryrv perspective view ofthe keyboardportion of; anelectronio organ embodying th'einvention. This'comprises theusual manualv l Ei." of playing keys above which are arranged stop tablets or switchesfN-LN--Zfand N-3 correspondingf tozthe. firstV voice of the'. splitf keyboard, and stop. tabletsA N-4, N--5` and: N-i corresponding toA the second voice or portion ofrthe-split keyboard. Directly underneath the playing keys are arranged thekeyboard splitting switchesoperable byf small'. push buttons Lf-l. to L-Q. It will:benotedtthatthellocation of these push: buttonsI permits them to be conveniently actuated; by the player even While executing a musical composition. It is also to be observed thateach push buttony is placed directlyunderheath thesmallinterspace between two adjoining keys correspondingftov two natural notes of the scale; Thus, the location of each push button directly andi unmistakably indicates the point where the keyboard'will be split uponoperation or'depression of suchfbutton.

In: the event that it is desired to provide also for splitting the keyboard at points between the naturals and the sharps,' the corresponding additional push buttons may bev arranged in a second row, at a level somewhatlower than that of the rst one.

Although the present. invention has been disclosedVK in'. connection with av few preferred embodiments thereof, variations andk modifications maybe resortedf to by: those skilled in the art withoutdeparting from the principles of the presentinvention. I consider allv of these variations and modifications as within the true spirit and scope of the-present. invention, as disclosedf in the foregoingI description andA defined by.y the appended claims.

Whatis claimed is:

l. Aneiectricalzmus-ical instrument comprising in combination a set of audio-frequency generators havingoutfputfrequencies respectively corresponding to successive notes of. the equally ternpcred musical scale, an output terminallfor each of: said generatorsa manually operable switching key interposed` between each of saidgenerators and its` corresponding output. terminal adapted when: actuated torender output signal from said generatorr eective at the corresponding terminal, alfirst output networkpermanently connected' to a first group off said. cutput'terminals, al second output network permanently connected to a second group oi' said output terminals, and switching means for selectivelyr connecting a desired plurality of a third group of terminals to the-oneoutput netwerk and the remainder of said 'thind groupr of terminals to the other output network.

2. Arr electricab musical instrument comprising in combination a. system of' generators for producingy note frequency oscillations corresponding to=notes of a musical scale, an output terminal for each` of said generators, a manually operable switching key interposed .between each of said generators` and its output terminal adapted when actuated, torender outputsignalfrom said generator effective at its terminal, a iii-st output network permanently connected to all output terminals up to a certain predetermined note, a second output networkpermanently connected to all y output terminals above another pre determined note, and a ranges-putting switch interposed between eacli pair or' adjoining terminals in the intermediate range between and including the said predetermined notes, said; switches being normally closed toconnect the terminalsl in the interd mediate range to each other and to the said output networks and being capable of selective actua tion to disconnect the said networks from each other at any desired point in the said intermediate range.

3. An electrical musical instrument comprising in combination a system of generators for producing note frequency oscillations corresponding to notes ci a musical scale, an output terminal for each of said generators, a manually operable switching key interposed between each of said generators and its output terminal adapted when actuated to render output signal from the generator effective at its terminal, a low range output network connected to all output terminals up to a predetermined note, a high range output network connected to all output terminals above another predetermined note, a range-splitting switch interposed between each pair of adjoining terminals in the intermediate range between and including the said predetermined notes, said switches being normally closed to sequentially connect the terminals in the intermediate range to each other and to the said output networks and being capable of selective actuation to disconnect the said networks from each other at any desired point in the said intermediate range, and means responsive to the actuation of any one of said range-splitting switches to render the rest of said switches inoperative.

4. In an electrical musical instrument, the combination which comprises a set of sequentially arranged sources of note frequency oscillations, a primary output bus bar, a switching key interposed between each of said sources and said bus bar adapted when actuated to render signal from said sources selectively effective in said bus bar, a system of splitting switches operable to selectively split said main output bus bar into a pair of secondary bus bars at any one of a plurality of desired points, tone control means individual to said secondary output bus bars for modifying the harmonic structure of the signals present therein, and a common output circuit in which the modified signals derived from both secondary bus bars are rendered collectively effective.

5. In an electrical musical instrument, the combination which comprises a set of sequentially arranged sources of note frequency oscillations, a primary output bus bar, a switching key interposed between each of said sources and said bus bar adapted when actuated to render signal from corresponding sources effective in said bus bar, a system of splitting switches operable to selectively split said main output bus bar into a pair of secondary bus bars at any one of a plurality of points, tone control means individual to said secondary output bus bars for modifying the harmonic structure of the signals present therein, a common output circuit in which the modified signais derived from both secondary bus bars are rendered collectively effective, and an interlocking mechanism for said splitting switches whereby upon opera-tion of any one splitting switch all of the other splitting switches are automatically disabled.

6. In an electrical musical instrument, the combination which comprises a set of sources of complex note frequency oscillations sequentially arranged in the order of increasing frequency, a terminal for each of said sources, a switching key interposed between each of said sources and its terminal, a low-range bus bar permanently connec-ted to all terminals up to a predetermined frequency, a high-range bus bar permanently connected to all terminals beyond another predetermined frequency, an intermediate range bus bar connected to the remaining terminals, a system of splitting switches operable to selectively split intermediate range bus bar into two portions respectively connected to said lowand high-range bus bars, an output circuit, a plurality ol' lter networfs, a stop switch for each of said filter networks to selectively interpose said networks between the low and high range bus bars and the said output circuit.

7. In an electrical musical. instrument, the combination which comprises a set of sources oi note frequency oscillations, a primary output bus bar, a switch interposed between each of said sources and said bus bar adapted when actuated to render signal from corresponding sources effective in said bus har, a playing key for each of said switches collectively constituting a playing manual, a system of splitting switches operable to selectively split said main output bus bar into a pair of secondary bus bars at any one of a plurality of points, tone control means individual to said secondary output bus bars for modifying the harmonic structure of the signals present therein, a common output circuit in which the modiiied signals derived from both secondary bus bars are rendered collectively effective, and manually operable elements for actuating said splitting switches, said elements being so constructed and arranged with respect to the keys of said playing manual as to directly indicate the splitting point that becomes eiective upon operation of any one of said elements.

8. In an electrical musical instrument, the combination which comprises a set of sources of note frequency oscillations, a primary output bus bar, a switch interposed between each of said sources and said bus bar adapted when actuated to render signal from corresponding sources effective in said bus bar, a system of splitting switches operable to selectively split said main output bus bar into a pair oi' secondary bus bars at any one of a plurality of points, tone control means individual to said secondary output bus bars for modifying the harmonic structure of the signals present therein, a common output circuit in which the modified signals derived from both secondary bus bars are rendered collectively effective, an interlocking mechanism for said splitting switches whereby upon operation of any one splitting switch all of the other splitting switches are automatically disabled, and manually operable elements for actuating said splitting switches, said elements being so constructed and arranged with respect to the keys of said playing manual as to directly indicate the splitting point that becomes effective upon operation of any one of said elements.

NICHOLAS LANGER.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Number Name Date 2,045,172 Yungblut June 23, 1936 2,049,616 Lilja Aug. 4, 1936 2,276,390 Hanert Mar. 17, 1942