US2365566A - Duophonic electrical musical instrument - Google Patents

Description

Dec. 19, 1944. N. LANGER DUOPHONIC ELECTRICAL MUSICAL INSTRUMENT Filed May 8, 1942 2 Sheets-Sheet l a ,N. M T T H.

Dec. 19,1944. NQLANGER 2,365,566

DVUOPHONIC ELECTRICAL MUSICAL INSTRUMENT Filed May 8, 1942 2 Sheets-Sheet 2 INVENTOR. N/Cf/OL HS LHIVG'E/P HTTORNEY Patented Dec. 19, 1944 DUOPHONI c 'nmc'rnrcar. MUSICAL ms'raumm'r Nicholas Lang-er, New York, N. Y., assignor to Central Commercial Company, Chicago, 111., a corporationof Illinois Application May 8, 1942, Serial No. $42,225

7 Claims. (Cl. 84-132) The present invention relates to electrical musical instruments, and, more particularly, to an electrical musical instrument of the type in which space discharge tubes, suchas thermionic ployed to denote instruments of the prior art in which one, or more, oscillation producing space discharge devices are employed in such circuit combinations as to produce only a singleimusical note at a time upon depression of any single playing key. It is acknowledged that instruments of the monophonic type have obvious musical limitations, in that they cannot produce harmonies or chords and can only carry a single voice or melody. As those skilled in the art know, with the exception of the piano, the harp, and the organ, practically all of the conventional musical instruments are of a generally monophonic character, although greatly restricted and largely transient polyphonic eiiects may be produced by most string instruments. Therefore, a substantial field of musical literature is available for interpretation by means of monophonic instruments, particularly if these instruments are accompanied byother instruments of the conventional or electrical type.

With the development of the art of electrical musical instruments, it has been found increasingly desirable to provide an electrical musical instrument which is capable of producing two musical notes at the same time. An instrument of this type would have considerably less musical limitations than the instruments of the menophonic type and in addition to interpreting a great portion of existing musical literature, various pleasing and novel eil'ects could be obtained thereby. For convenience, in the following, the term duophonic will be employed to denote an instrumentof this type, capable of producing two musical notes at the same time from the same or common-keyboard. p

The simplest and most obvious way of obtaindescribed character ing a duophonic electrical instrument would be to combine a pair of monophonic instruments in a single case, each of said instruments having its own oscillation producing space discharge devices, sound producing means, and manually operative-elements, such as keyboards, for controlling the pitch of the notes produced. Considerable practical difliculties are, however, encountered in carrying'this concept into practice. First of all, the duplication of all parts doubles the cost and the space requirements strument. Another and even more serious disadvantage is that two playing manuals have to be provided, both of which have to be simultaneously operated by the player. This greatly increases the dimculty of playing as frequently the fingers of the same hand had to be playing on diiferent manuals or keyboards, this obviously requiring such manual deiterity and training which, while available to is highly skilled organist, is beyond the skill of the average music lover.

I have discovered that the outstanding problem may be solved in a remarkably simple manner with resultant musical advantages that have never before been attained.

It is an object of the present invention to provide an electrical musical instrument which avoids the foregoing difllculties and inconveniences, and which makes it possible to produce duophonic music by, means of an extremely simple playing technique.

It is another object of the present invention to provide a duophonic electrical musical instrument in which a pair of monophonic'electrical musical instruments arecombined with a slngle playing manual or keyboard in such a manner that any two musical notes within the range of the two monophonic instruments may be produced simultaneously.

A further and important object of the present invention resides in the provision of an organization of parts, including an electrical network and a common key-board, wherein upon simultaneous actuation of any two playing keys-one part of said electrical network automatically functions to produce audible sound of the pitch of the note associated with one of such keys, during similar production by another'part of said network of audible sound of the pitch of the note associated with another key, thereby causing a simultaneous audible production of tones corresponding to the musical frequencies oi notes associated with diflerent playing keys of said common keyboard, substantially in the same manner as when two keys are simultaneously actuated in any well known instrument of the heretofore I mentioned polyphonic type.

The invention also contemplates a 'duophonic musical instrument which is extremely simple in construction and easy to manufacture and to operate and which may be readily manufactured and sold on a practical and commercial scale at a price which i only slightly higher than that of a monophonic musical instrument.

Other and further objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which Fig. 1 illustrates a circuit diagram of a preferred embodiment of the present invention in which gaseous discharge tubes, such as, for example, glow-discharge tubes, neon tubes, and the like, are employed for producing electrical oscillations of musical frequencies; and

Fig. 2 depicts a similar circuit in which space discharge tubes of the thermionic type are employed for producing the electrical oscillation within the audible range which are ultimately converted into musical sounds.

Broadly stated, according to the principles of my invention, I provide a duophonic electrical musical instrument in which a pair of monophonic oscillators are incorporated. Each of these oscillators comprises at least one space discharge device electrically associated with electrical elementssuch as resistances, capacities. inductances of suitable value and with switching means for selectively connecting such elements of difierent value to the space discharge device. Generally speaking, the type of electrical elements employed and the method of their connection with the'switching means varies with the type of oscillator which is employed. Thus, in gaseous discharge tube oscillators it is preferred to employ resistances and capacitors of appropriate value to tune the oscillator to the desired pitch, while in thermionic tube oscillanotes, that is: notes not corresponding to any note of the tempered scale, produced. For example, when a chain of serially-connected resistors is used, the note actually produced will conform to the higher one of the two coordinated to the actuated pair of keys, while when a chain of serially-connected capacitors is used. the note actually produced upon actuation of 'two keys or switching elements will'conform t 1 the lower one of the two coordinated to the actuated pair of keys.

tors resistances and capacitors or inductances and capacitors of predetermined values may be employed to selectively tune the instrument to any note within the musical range of the instrument. It has been found desirable to maintain one of the said elements fined, while the other one is adjustable in steps by means of the switching elements. For example, in the case of glow-discharge tube oscillators, a wide range of musical frequencies may be produced by connecting a capacity of determined value to the tube and by connecting resistances of dlfierent values to such capacity. The same result may be obtained by connecting a resistance of deflnite value to the tube and connecting the same in circuit with capacitors of different value. Inthe first case the "keyed element is the resistance in the other the capacity and to control the pitch of the oscillations produced, generally as many keyed elements are provided as there are musical intervals within the range of the instrument. It has been found that best results are obtained when the keyed element is provided in the form of a chain of elements connected in series 01' which one or more are rendered effective by actuation of a suitable switching key. The advantage of this arrangement is that when it happens thatmore than one switching element is actuated at the same time. only the switching element which is the lowest, (or highest) in theseries becomes effective, connecting the chain up to that point with the O In the following the expressions high-responsive" and low-responsive" will be appliedto the combination of a space discharge device with a network of tuning elements variable in steps by means of key-controlled switching elements when upon simultaneous actuation oi any two keys, the higher or the lower of the two will respectively determine the frequency of the resulting oscillation.

In order to provide a duophonic electrical musical instrument, in accordance with the principles of the present invention, a fhigh-responsive and a "low-responsive monophonic oscillator with associated switching elements are coordinated to a common playing manual in such a manner that each key of the playing manual has two switching elements coordinated thereto, electrically associated with the respective monophonic oscillators. I have found that when in an instrument of the described character any two keys are depressed simultaneously. the two switching elements corresponding to the "highresponsive" oscillator will cause said oscillator to oscillate at the higher frequency of the two, while the two switching elements corresponding to the low-responsive oscillator will cause the said oscillator to oscillate at the lower frequency of the two. In other words, upon depression of any two keys, two frequencies will be produced, one oscillator automatically being assigned to the higher one of the two and the other being automatically assignedto the lower one of the two, as it will be explained more fully as the description proceeds. It will be readily understood by those skilled in the art that certain elements of the two monophonic oscillators may be in common in order to save space and mate because any change in the voltage of the current supply will substantially uniformly influence both monophonic oscillators.

The invention will now be explained more fullytothoseskilledintheart,referencebeing had to the accompanying drawings. in which certain preferred embodiments of my invention are illustrated.

now more particularly to Fig. 1 of the drawings. the simplified circuit of a duophonic electrical musical instrument employing two-electrode gaseous discharge tubes is shown. Reference character O-i generally denotes a monophonic gaseous discharge tube oscillator comprising a tube G-l having two electrodes, connected in series with a condenser C and a source of direct current voltage B-i, through the primaryv winding of an output transformer T. A serially connected chain of resistances R-I, R-2 R-E is connected at one end to the common point of tube G-I and condenser C and has normally open, key-actuated switches or key contacts S-l, 3-2 S-S between the other ends of the respective resistances and a common bus bar D-l connected to the other plate of condenser C. Each switch is operatively connected with a key of the playing manual, switch S-l being connected with key K-I, switch 8-2 with key K4, and so forth. It will be noted that upon depression of each key, a predetermined number of the serially connected resistances is connected across condenser C. Thus, upon depression of K-i, switch S-l is closed and resistance R-I will be connected across C, upon depression of K-2 both serially connected resistances R-i and R-2 will be connected across condenser C, etc. As those skilled in the art know, in a circuit of the described character electrical oscillations will be produced, the frequency of said oscillations being determined by the capacity and the resistance in the circuit, provided that the other factors having bearing on the frequency such as the break-down and extinction voltages of the tube and the voltage of current source B are maintained constant. By appropriate selection of C and of resistances R-l, R4, etc., it is possible to produce frequencies corresponding to suecessive notes of the tempered scale. Preferably, resistances Rr-i; R4 R-i are adjustable in order to facilitate tuning of the instrument to its proper pitch. It is also advantageous to provide capacitor C in the form of a variable condenser to adjust the general pitch of the device, experience having shown that varying the capacity of C has the effect of varying the frequency of the oscillations produced upon depression of any key by substantially the same amount without aphave been shown, obviously any desired number of such tuning elements may be employed in accordancewith the extent of the desired musical range. Thus, in practical. instruments it has been found desirable to use 31, or more, playing keys and associated resistances, covering the range of three octaves, or more.

Although oscillator 0-! with its associated network of switches and resistances constitutes a monophonic electrical musical instrument and consequently at any time only one key has to be depressed, in playing an instrument of this type with the conventional playing technique familiar to players of keyboard instruments it is unavoid able that at times more than one key is depressed at the same time. This seems to be particularly the case in playing -legato passages when in order to obtain a closely knitted sequence or flow of successive notes, the next key is depressed already before completely releasing the last. To determine the effect of this occurrence. let us assume that first key K-l is depressed and then key K4 is depressed, before releasing K-l. The depression of K-i will close switch S-l and will connect resistance R-l across condenser C.

-This will tune oscillator 04 to its highest frequency in view of the fact that the lowest value of resistance will be connected into the circuit. Assuming that now key K4 will be likewise depressed, this will close switch S4 but will not change the amount of resistance connected across C, because resistances R-2 and R4 between switches S-l and 8-3 are short-circuited by the corresponding portion of bus bar D-i. In other words, in oscillator 0-! when more than one switching key is depressed at the same time, the oscillator will be tuned to the highest of the frequencies corresponding to the depressed keys. In the terminology introduced in the foregoing, this may be expressed by stating that oscillator 04 is a high-responsive monophonic oscillator.

The oscillations produced by oscillator O-i may be taken off through a transformer T and may sistance R and with the source of direct current B through the primary winding of transformer T, thesource of current and the output transformer being in common with oscillator 04. A chain of serially connected condensers 0-5.

C4 0-4 is connected at one end to the common point of resistance R and tube G-2. Switching keys or key contacts S-iil, S-9 8-6 are connected between each common point between successive condensers and common bus bar D-I whereby any desired number of serially connected condensers may be connected across resistance R in accordance with the switch operated. Thus, it will be noted thatwhen key contact S-lli is actuated, condenser 0-5 will be connected across resistance R which will cause oscillations of musiof two condensers connected in series is lower corresponds to the frequencies of successive notes I of the tempered scale. To facilitate such tuning of the oscillator, condensers 0-! to C-5 and also resistance R, may be made adjustable. By

A adjustingcondensers C-l to C-J. the proper tuning of the oscillator may be readily accomplished and each note may be readily brought into the proper and desired pitch of the tempered scale I while by adjusting R, the general pitch of the ous notes. Of course, in a commercial instrument a relatively large number of condensers and key contacts is used, such as, for instance 31, corresponding to the range of three octaves.

It is worth noting that in an oscillator of the described character in which a chain of serially connected condensers is employed, upon actuation of more than one key contact at the same time, always the frequency corresponding to the lowest actuated key contact will be produced. This will be readily understood from contemplation of the circuit of oscillator -2 in Fig. 1. Assuming that key contact S-Hl is closed, condenser 0-! alone will be connected across resistance R, tuning the oscillator to the lowest frequency of its range. When new key contact 3-! is likewise closed, serially connected condensers C4, C4 and 0-5 will be all connected across resistance R through bus bar D-2. However, the portion of the chain between contacts 8-8 and 5-", that is condensers C-3 and (3-4, will be short-circuited through the said contacts and the said bus bar and will have no effect on the frequency of the oscillations produced, such frequency being determined only by the capacity of 0-5. In other words, in case more than one key contact is closed at the same time, the frequency of the'oscillations produced is determined by the key contact corresponding to the lowest frequency between the key contacts actuated, or reverting to the special terminology introduced in the foregoing, an oscillator, such as 0-2, employing a condenser chain in series connection is a low-responsive monophonic oscillator.

The oscillations produced by means of'oscillator 0-2 are-withdrawn through transformer T which is in common with oscillator O-l. These oscillations,together with the oscillations produced by means of oscillator O-l are amplified by amplifler A-l and are converted into musical sounds by means of translating device or loudspeaker L-l.

In the circuit constituting Fig. 1 of the drawing, a. high-responsive," serially-connected resistance-tuned monophonic oscillator O-l is combined with a low-responsive" serially-connected condenser-tuned monophonic oscillator 04, both oscillators being supplied from a current source in-common and fceding their.output into a com- 7 mon amplifier and device. As it will I be likewise readily observed in Pig. 1, key contacts 8-! to 8-! cause production of oscillations having step by step decreasing frequencies of the tempered scale, same as closure of contacts 8-! to S-l I, associated with oscillator 0-2. In view of the fact that the longer the chain of resistances R-l to 3-5, the higher the resultant resistance is, and.'on the other hand, the longer the chain of serially-connected condensers, the lower the resultant capacity is, oscillators 0-! and 0-2 and their respective key contacts are coordinated in reversed relative sequence. Thus, key contact 84 is directly W upon key contact 8-. key contact 8-! is-directly su rposed upon key contact 8-1, etc. In other words, key contacts of oscillators 04 and 0-! are superposed upon each other in such an arrangement that contactscorresponding to the same frequencies are superposed upon each other and may be actuated by the depressionof the same key of the playing manual. This is indicated by means of'the dotted lines connecting key contacts S-l and 8-0, 8-2 and 8-1 which may be closed simultaneously by depression of keys K 4 and K4, respectively. This mechanical connection may be readily secomplished by mounting corresponding key contact sets directly underneath of the same key of the playing manual, as those skilled in the art will'understand without any detailed explanation.

From the foregoing description, the operation of my duophonic electrical musical instrument will be readily understood. When any two keys of the playing manual, or keyboard, are simultaneously depressed, two pairs of key contacts will be simultaneously closed, two of these contacts being in the circuit of 04 and two of these contacts in the circuit of 0-2. In view of the fact that oscillatorO-l with its chain of serially connected resistances is a high-responsive" monophonic oscillator and oscillator 0-2 with its chain of serially connected condensers is a low-responsive" monophonic oscillator, oscillator O-l will be tuned to the frequency corresponding to the higher one of the depressed keys, while oscillator 0-2 will be tuned to the frequency corresponding to the lower one of the depressed keys. Thus, upon depression of any two keys of the playing manual, the higher one of the two will be automatically assigned to oscillator 04 and the lower one will be automatically assigned to oscillator 0-2. The two oscillations simultaneously produced may be amplified by amplifier A-l, which is inductively coupled with both osciloscillators.

lators, and may be rendered audible by means of translating device L-i which is likewise in common for both oscillators. Of course, it is quite possible to provide separate outpu'qmeans, ampliners and translating means for both oscillators but in most cases this is not necessary, nor desirable.

While generally the same musical range is assigned to both oscillators so that upon depression or any single playing key both oscillators are tuned to the same note of the tempered scale, in'

some cases further musically valuable results may be obtained by so adjusting the general pitch of the two oscillators that there is a definite and constant interval therebetween. This interval may be that'of an octave, of a fifth, a third, etc. and may be readily obtained by proper adJust- ,ment of condenser C in oscillator O-l and or re- 'sistnnceRinoscillator 0-2. In this case the de- Dression of any single key of the p aying manual will cause the production of two notes which are separated from each other by the constant interval separating the general pitchof the two oscillators, while upon deprusion of'any two keys of the playing manual two notes will be heard which will be separated from each other by the interval between the two playing keys Plus or minus the diflerence between the Whenstsnytimemorethantwokeyssre 3 simultaneously depressed in m duophonic electricsLonlythehlshestsndthelowestwillbesffcctive in determining the pitch of the two simultaneously heard notes while the intermediate kuswillhavenoeifectonthehmingofthelnstrument.

Pig. 2 illustrates a modifledembodiment of the principles of the present invention into a duo- Dhonic electrical musical instrument in which thermionic tubes are employed for producing the electrical oscillations of musical frequency. ,The ch'cuitdcpictedlnl'lg willbefolmdtobemwh similartothstshowninl'lg.1inthatahigh-' responsive" and s "low-responsive monophonic electrical musical instrument is combined into a single instrument with a common playin manusl or keyboard. The high-responsive monogeneral pitch of the two are converted into musical sounds by means of translating means L4 and L4, respectively. The general pitch of oscillators -3 and'O-4 may be adjusted by means of variable condenser C-l l and variable resistance R-II, respectively. In the simplest case the general pitch of both oscillators may be the same, or, if desired, any appropriate musical interval may be provided between their general pitch, such as that of an octave, fif h. third, etc. The volume of the two oscillators m y be adjusted individually by means of volume control potentiometers P-2 and P-l, respectively,

' which may be combined in a single, collectively addusted unit, if desired.

Although the present invention has been described in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the present invention. Thus, various refinements may be applied to the monophonic oscillators to produce wave forms of modified shape and thereby simulate the tone quality of different instruments or to obtain tone color or timbres of novel and musically useful type, toincorporate tremolo, percussion and the like eifects. While the monophonic oscillators disclosedcomprise only a single space discharge device, the invention is also'applicable to oscillators of the type in which a plurality of space discharge devices tuned to harmonically related frequencies is employed to produce asingle musical note of the tempered scale at a time.

Instead of a chain of series-connected resistances, a tapped inductance may be employed with equal, or similar, results, particularly in the circuit disclosed in Fig. 2. I consider all of these variations and modifications as within the true spirit and scope of the present invention, as disclosed in t e foregoing description and defined by the appended claims.

I claim:

l. A duophonic electrical musical instrument comprising in combination a pair of electronic oscillators tunable in steps to frequencies within a musical range; each of said oscillators including a space discharge device, a'series of tuning elements, and a plurality of switches for selectively connecting portions of said series into oscillation-producing relation with said space discharge device; said tuning elements and their associated switches being so connected in circuit that upon actuation of more than one switch at a time the oscillators are tuned to frequency s respectively corresponding to the highest and to the lowest of the actuated switches; a playing frequencies corresponding to successive notes of the tempered scale within a desired range; each of said oscillators including a space discharge device, a series of tuning elements, and a pinrality of switches for selectively connecting portions of said series into oscillation-producing relation with said space discharge device; said 2,ses,sss

ated switches; a playing manual for operating said switches in pairs appertaining to different oscillators; sound producing means responsive to the output of said oscillators; and individual means for adjusting the general pitch and the amplitude of the-oscillations produced by each oscillator.

3. An electronic musical instrument of the twin melody type which comprises in combination a pair of relaxation oscillators tunable in steps to frequencies corresponding to notes of a musical scale; each of said oscillators including a glowdlscharge tube having only two electrodes, a tapped tuning element, and a plurality of switches for selectively connecting taps of said element into oscillation-producing relation with said tube; the tapped tuning elements and their associated switches being so connected in circuit that upon simultaneous actuation of a plurality of switches the oscillators are tuned to a frequency respectively corresponding to the highest and to the lowest of the actuated switches; a playing manual for operating said switches in pairs appertaining to different oscillators; and sound producing means responsive to the output of said oscillators.

4. An electronic musical instrument of the twin melody type which comprises in combination a pair of relaxation oscillators tunable in steps to frequencies corresponding to notes of a musical scale; one of said oscillators including a glowdischarge tube, a tapped resistance element, and a plurality of switches for selectively connecting taps of said resistance element in oscillationproducing relation with said tube: the other of said oscillators including a glow-discharge tube, a tapped capacitor element, and a second plurality of switches for selectively connecting taps of said capacitor element in oscillation-producing relation with said last-named tube; the taps of said resistance and of said capacitor element and their associated switches being so connected in circuit that upon simultaneous actuation oi a plurality of switches the oscillators are tuned to a frequency respectively corresponding to the highest and to the lowest of the actuated switchs; a playing manual in common for both oscillators for operating said switches in pairs appertaining to diiferent oscillators; and sound producing means responsive to the output of said oscillators.

5. An electronic musical instrument of the twin melody type which comprises in combination a pair of relaxation oscillators; one of said oscillators including a two-electrode glow-discharge tube, a plurality of serially connected resistances. and a plurality of switches for selectively connecting a determined number of said resistances in oscillation-producing relation with said tube;

the other of said oscillators including a two-elem in: manual in common for both oscillators for tuning elements and their associated switches i being so connected in circuit that upon actuation of a plurality of switches at a time the oscillators are tuned to a frequency respectively corresponding to the highest and to the lowest of the actuoperating said switches in pairs appertaining to different oscillators; and sound producing means responsive to the output of said oscillators.

6. An electronic musical instrument of the twin melody type which comprises in combination a pair or oscillators: each of said oscillators beins independently tunable in steps to frequencies corresponding to successive notes of the tempered 7 scale and including a space discharge device havaccuse ing at least a cathode, a grid and an anode, a series of tuning elements, and a plurality of switches for connecting a determined number of said tuning elements in oscillation-producing relation with said space discharge device; said tuning elements and their associated switches being so connected in circuit that upon actuation ot a plurality of switches at a time the oscillators are tuned to a frequency respectively corresponding to the highest and to the lowest oi. the actuated switches; a playing manual for operating said switches in pairs appertaining to difierent oscillators; and sound producing means responsive to the output of said oscillators.

7. An electrical musical instrument comprising in combination a pair of oscillators individually tunable in steps to frequencies corresponding to successive notes of the tempered scale and of the type in which audio-frequency oscillations are respectively corresponding to the highest one and to the lowest one of the actuated switches; a playing manual for operating said switches in pairs appertaining to different oscillators; and sound producing means responsive to the output of said oscillators.

NICHOLAS LANGER.

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