US1183244A - Expression control for electrical musical instruments. - Google Patents

Description

M. L. SEVERY & G. B. SINCLAIR.

EXPRESSION CONTROL FOR ELECTRICAL MUSICAL INSTRUMENTS.

APPLICATION FILED JUNE 26, 1907- 1,183,244;

2 SHEETSSHEET 1- Figrl In'venfiW f, fifdvin L. Severy, George S indair;

' Patented May16, 1916.

flftarng M. L. SEVERY & G. B. SINCLAIR. EXPRESSION CONTROL FOR ELECTRICAL MUSICAL INSTRUMENTS. APPLICATION FILED JUNE 26.1907. 1,183,244. Patented- May16, 1916.

2 SHEETS-SHEET 2.

flfl' 63 I Im/m LETJ,

2 W fiwz I LTeIviI LL. Severy,

UNITED sTATEs PATENT OFFICE.

MELVIN L. SEVERY, OF ARLINGTON HEIGHTS, AND GEORGE B. SIN CLAIR, OF MELDFORID,

' MASSACHUSETTS, ASSIGNORS TO CHORALGELO COMPANY, OF BOSTON, MASSACHU- SETTS, A CORPORATION OF MAINE.

EXPRESSION CONTROL FOR ELECTRICAL MUSICAL INSTRUMENTS.

Specification of Letters Patent.

Application filed June 26, 1907. Serial No. 380,987.

To all whom it may concern Be it known that we, MELVIN L. SEVERY, of Arlington Heights, county of Middlesex, and Commonwealth of Massachusetts, and GEORGE B. SINCLAIR, of Medford, county of Middlesex, and said Commonwealth, both citizens of the United States, have made cer tain new and useful Improvements in EX- pression Control for Electrical Musical Intruments, of which the following is a specification.

This invention pertains to that class of musical. instruments wherein magnetically attractive sonorous bodies are vibrated by means of electromagnets having properly timed electric pulsations delivered thereto;

and the object of our invention is the construction of means for controlling the volume and loudness of the music produced by the instrument. We set forth in this case a type of our invention in which the sonorous bodies are metallic strings of the kind usually employed in musical instruments.

One of the essential features of our invention comprises a permanent individual loudness control operating to voice the individual tones of the musical gamut, and consisting of specially wound electromagnets for the actuation of the strings, so adapted that the attractive energy of each magnet is proportioned to the peculiar conditions of its associated string or strings, to the end that the instrument shall be correctly voiced. I

Another feature of our invention consists in changing at will the voltage of the current which energizes the electromagnets, and thereby varying the amplitude of vibration of their associated strings.

In certain co-pending applications we have shown, described and claimed features which are illustrated and described in the tions we have broadly claimed the art of producing musical tones, which art is involvedbut is not claimed in the fpresent application. All matters set forth-an'd claimed in co-pending: applications filed in our names, or in the names of either of us, and not specifically claimed herein, are expressly saved and reserved for one or another :of such applications. Among these may be generator 40.

noted our joint applications Serial No.

Patented May 16, 1916- 273,199, filed August 7, 1905; Serial No. 377,571, filed June 6, 1907; Serial No. 379,714, filed June 19, .1907; Serial No.

537,257, filed January 10, 1910; Serial No. 740,201, filed January 4, 1913; Serial No. 753,013, filed March 8, 1913; and Serial No. 7 54,47 5, filed March 15, 191-3.

Referring to the drawings forming part of this specification, Figure 1 is a perspective digrammatic view of a musical instrument embodying our invention. Fig. 2 is a detail plan view of the magnet rail and its adjusting devices. Fig. 3 is a diagram illustrative of the pedal operated octave coupler, and of certain types of variable resistances used in connection with the instrument.

The sonorous bodies, which are shown in the drawings as magnetically attractive strlngs 1, are vibrated by means of electromagnets 10, to which properly timed electric pulsations are delivered upon the depression of the keys 3. The means for producing the properly timed pulsations consists of a source of electric current, and make-andbreak devices comprising uniformly rotated toothed disks 12 and brushes l3 contacting therewith.

The circuit between the generator 40 shown in Fig. 1, and the electromagnets 10 comprises the wire 16, brush 14, shaft 11, disks 12, brushes 13, and wires 39; the return from said electromagnets 10 embracing the wires 26, contacts 25, brushes 24 of such keys as are depressed, Wire 59, (where the keys depressed are treble ones), brush 96, contact 97 (where the octave coupler bar 90 is in the position shown in Fig. 1)' wire 100,

brush 53, contact 51, wire 62, resistance 60, wire 61 to the proper armature brush of the The return circuit for the bass electromagnets will embrace wires 26, contacts 25, brushes 24, wire 58, brush 55, contact 50, wire 52, contact 51, wire 62, resistance 60, and wire 61 back to said armaturebrush. If, now, a key 3 is slightly depressed, its brush 24 will be put into touch with a contact 25,-and the current .will traverse the resistances 28,28 and the short connecting wires 29, 29 to the wire 26, and thence to the electromagnet associated with the same. This gives a greater resistance to the current than is received when said brush is raised into touch with the contact 25 and hence only one resistance 28* is traversed; while the elevation of the brush to the contact 25 short circuits all such resistances, and gives the full strength of actuating current to the electromagnet associated therewith. If desired, additional contacts and resistances may be employed, and thus give a still finer degree of differences. This gives the player a control approximating as closely as may be desired to that of the ordinary piano, as far as delicacy of touch is concerned.

Our first-mentioned loudness-control is produced by winding the electromagnets 10 in accordance with our discovery that the resistance of such windings should be inversely proportional to the frequency of the vibrations. The theory underlying this is that the 7 more rapidly a string vibrates,reaching for the upper notes about two thousand per second-, the more the self-induction of the windings and the magnetic lag of the iron core of such electromagnet will interfere with the fiow of the current, and conse quently the less strongly the magnet will be actuated. In other words, the amount of current which will flow through an electromagnetwhen the current is continuous, will be far greater than the amount which will flow when the current is rapidly interrupted; the strength ofthe magnets attraction being found to diminish asthe rapidity of interruption is increased. Hence to producetheoretical uniformity in magnetic attraction on the part of all the electromagnets of the gamut, such electromagnets should be wound with wire of diminished resistance as the scale is ascended. In some cases we find it sufiiciently satisfactory to use the same size of windings for several electromagnets; the heaviest sizes of wire being for the upper treble magnets, the finest being for the low bass, and the intermediate magnets having windings of medium sized wires; although we show in the drawings only three such groups of windings, it is evident that any desired number may be used. Further, owing to the amplitude of the bass strings vibrations and their consequent liability of striking their electromagnets, such electromagnets must be adapted for a strength of attraction which will permit them to be located at a greater dis tance from the strings; one suificient to avoid the danger of such striking while at the same time properly actuating the strings. By thus constructing the electromagnets associated with the different strings so that the attractive force of each magnet shall be proportioned to the peculiar conditions of its string, we make an important advance in the proper voicing of the instrument.

Another method of voicing the strings consists in so proportioning the distance of the electromagnets 10 from their respective strings that all the latter shall be actuated with equal sonorous effect. Economy would naturally suggest locating the magnets as near as possible to their strings, but other conditions determine how near they can be placed. The upper treble strings being of limited vibrational excursion, can have their electromagnets located close thereto without danger of contact. At the same time, because of their slight mass and high tension, their magnets must be very close thereto in order to properly actuate them. On the other hand, the low bass strings, because of their large mass and inertia, need to have their electromagnets located as near to them as is consistent with the danger of contact above referred to; but of course not so near as are the upper strings to their magnets. Moreover, the upper strings act so slightly upon the sounding board of the instrument that they must be more energetically vi,- brated than are the others; thus still more needing closeness of proximity between them and their magnets; while the low bass strings by their superior mass or weight, and a consequently more vigorous vibration of the sounding board, do not require to be as close to their magnets as do the upper strings. The intermediate strings,

sion than the highest strings, and their consequent easier actuation, taken in connection with the increased effective current-action owing to their less rapid current-interruption, need to have their electromagnets located farther away from them in order to maintain substantial equality in sonorous effect with the strings both above and below them. This feature of our invention is illustrated'by Fig. 2 which shows the electromagnets at the right hand end of the magnet rail to be located much closer ,to their strings 1 than are the electromagnets at the extreme left hand, or bass end; while the electromagnets in the vicinity of the point 71 on said rail, are farther away from their strings 1 than are the bass magnets. Said point of maximum distance we find to be about one third up from said bass end.

. While the electromagnets may be permanently fixed in their positions relative to their strings, we prefer to have them capable of movement at will toward and from the latter in order to provide the player with another means for varying the loudness of music produced. This can only be done, however, by some means which will move the intermediate magnets more than the others, and the most practical way in which this can be accomplishedns by jointing the magnet rail at the point 71,"and also hinging the ends of the same'at 75 and 76, and adapting the rail to be angularly moved by devices under the control of the player. This is most important, for, were the magnet-rail to be moved through a series of positions each parallel with the other, a movement sufficient to affect an upper treble string would give no, appreciable alteration to others; and a movement away from the strings sufficient to reduce slightly the strength of vibration of the intermediate strings, would be enough to render the upper treble strings or even the low bass strings practically mute. Moreover, other natural laws come in play which must be considered in adjusting the magnet-rail. In the first place the upper treble strings are so fine and so close to their electromagnets that they do not appreciably come under the law of inverse squares, but mainly under that of the magnetic shell, the strength of attraction varying almost directly as the distance. Consequently, the upper electromagnets can be given a greater range of adjustment than would be the case under the law of inverse squares; but the electromagnets being normally very close to their strings, such adjustment must be slight.

The intermediate electromagnets, owing to the greater mass of the strings and their distancefrom them, act mainly under the usual law of inverse squares; and the bass electromagnets being slightly nearer their strings than are the intermediate ones, but not so close as the upper electromagnets, act under a different combination or permutation of the two laws. It is therefore an evidently difficult task to shift the magnetrail at will, and still accurately preserve the relative sonorous effects upon all the strings of the scale. To this end, several details are essential; that the pivotal point 75 of the treble end of the magnet-rail" be not too far from the upper-most string; that the pivotal point 76 be preferably much nearer the lowest string than the highest string, and that the juncture 71 be adjusted toward and from the strings by a pedal, knee-swell or other device adapted to move said juncture so that equal increments or decrements of the pedal will produce equal increments or decrements of sonorous effect. We have discovered that whenever a direct current is broken it becomes practically like an alternating current, and it offers an immensely greater lmpedance as the breaks become fasing current. On account of the many factors already referred to it is necessary, in order to produce these results, that equal movements of the pedal shall produce unequal and shifting degrees of motion of the rail. To accomplish the last requirement, the knee-swell 78 is provided With a cam or suitably plotted Wedge 77 engaging a rod 74 connected with the lever 72 pivotally supported at 73 and having its short arm joined to said juncture; such wedge or cam being so proportioned that a uniform movement imparted to the pedal 78 will cause a similarly uniform variation in the sound produced.

Another method of expression control, that of changing at will the Voltage of the magnet-energizing current, is accomplished by suitably altering the strength of excitercurrent, delivered to the field windings of i the generator 40. To do this we preferably but not necessarily have the exciter current entirely outside the armature circuit, and introduce into the same a resistance cut in and out by a suitable pedal. The important feature is to provide any means of increasing and diminishing current in the field of the generator, whether external or not. The generator field windings 41 are joined by a wire 42 to one pole of the current source 43, and by a wire 48 to the brush 46 movable byapedal 47 along a resistance 45 which is joined by a wire 44 to the opposite. pole of said current-source. When said pedal is in its elevated position, its brush is in contact with the lower end of said resistance, and so introduces a maximum resistance into the circuit and allows a mimimum current to pass to the field magnets. This causes a current of lowest voltage to be generated by the generator 40, and thereby supplies to the electromagnets 10 a minimum intensity of energy. As said pedal 47 is depressed, successive increments of resistance are cut out, with a corresponding increase in excitercurrent, in voltage of current generated, an

in strength of sound evolved.

Another method of control, that by which I we preserve a proper sonorous balance be tween the various parts of the instrument, is needed in order to overcome the tendency which we have discovered of the bass notes being overbalanced by the treble notes when increased current is delivered to their actuating magnets 10. The means by which we correct this consists of a rheostat 60 adapted to be switched into the energizing circuits to the bass and treble strings by means of a suitable|pedal=56, with a'constantly larger amount of-resistance in the treble circuit than in the bass circuit." 111 doing this, the pedal 56. is operatively'connected with a swmging arm 57 carryingbrushes 53, 54, 55 in touch with the two sets of contacts 51, 50. Each of the contacts 51 arm 57 said brush 53 will sweep over more of the contacts 51 for the same angular movement of said arm, than does the brush 55 over its contacts, with the result that after the arm 57 has been moved to any degree the brush 53 will be in touch with the contact 51 connected with a greater resistance 60 than will be the brush 55. Such dissimilarity in currents we find to be suflicient to equalize the two section's of the instrum'ent, and render them equal in expression however much such expression is varied in the instrument as a whole.

In our method which pertains to means for preventing the abruptness of transition from one number to another number of strings simultaneously sounded, our purpose is to out less resistance into the treble circuit when the octave coupler is operated, than when it is not used; the bass circuit being unchanged. For we have discovered that although the tones produced by a few simultaneously energized the brush 54 being shorter than the brush 55, more resistancewill be switched into the treble circuit than the bass circuit, in the same way as is done by the two brushes 53 and 55. But it will be noted that less resistance is cut into the treble circuit by the brush 54, than is put into the same circuit by the brush 53 when the coupler bar 90 is in its normal elevated position. Hence whenever the coupler bar 90 is depressed a lesser resistance will be cut into the treble circuit than when it is not depressed, through the above. described arrangement; and the coupled magnets will be caused toreceive sufficient additional current to make up for the loss of energy due to',subdivision among the several magnets. When the coupler bar is thus depressed the circuit will include wire 61, topmost wire 62, contact 51, wire 52, contact 50, brush 54,

wire 99, contact 98, brush 96, wire 59 to the brushes 24.

v electromagnets will not be materially weaker than the tone produced by a single electromagnet which Another method of varying the loudness of the instrument is illustrated in Fig. 3, and consists in the introduction of a resistance into the circuit of each electromagnet 10 of the entire gamut, and the provision of a pedal 83 adapted for cutting in and out suitably proportional degrees of all such resistances simultaneously. As shown, the resistances 80 are each connected by a wire 39 to the electromagnets 10, While brushes 81 are joined by wires 84 to the appropriate make-and-break brushes l3. Said brushes 81 are carried by a bar 82 which is moved by said pedal 83, so that when said bar rises through the depression of said pedal all the brushes 81 are made to cutout the proper amounts of resistance and increase the strength of the currents delivered to the electromagnets; thereby increasing and properly modulating the music produced. This is what we term our individual pedal rheostat, and it serves to enable the loudness to be varied in sensibly equal amount for each string, independently of whether one or several strings are simultaneously sounded. A further expression control is also illustrated in Fig. 3, and is one wherein a pedal 87 cuts in or out at will a resistance to the common part of the circuits of all the electromagnets. The resistance 85 shown here is connected at one extremity to the key brushes 24-by means of a wire 88, while said pedal is provided with a brush 86 and is itself connected by a wire 89 to the current source 15. By depressing said pedal, said brush is elevated and made to cut out successive increments of. resistance, and thereby to increase the strength of the sound produced. Still another method of expression is obtained by the introduction of a resistance 95 into each of the coupling wires 94 of certain of the coupler brushes 93. Through this arrangement the coupled magnets 10 on the side of the resistance opposite that on which the keys are depressed will be less strongly energized than the mag nets upon the same side as the depressed keys; and either the lower strings can be made to predominate over the upper strings,

or the upper over the lower, by playing upon the keys associated with the strings desired to thus predominate.

Another exceedingly important element of our musical instrument is that by means of which the electric pulsations delivered to the electromagnets 10 shall be timed with absolute accuracy. The slightest degree less than this renders the instrument a failure as a musical instrument. A variation of one ten-thousandth of a second in the rotation of the make-and-break disks 12, cannot be allowed. Accordingly, a governing device for said disks which can control the same with an accuracy heretofore undreamed of, is not simply desirable, but is absolutely essential. After years of experimentation, we produced such a governor and applied the same to our electrical musical instruments, with the result of converting them into an unqualified success, where all others were failures. Such a governor is indicated at 111 in Fig. 1 of the drawings forming part of this specification, as controlling and timing the rotation of the disks 12.

Although we have described our invention as applied to electromagnetically actuated strings, we do not restrict ourselves thereto, as other types of sonorous bodies with the respective bodies for effecting their may be employed.

What we claim as our invention and for which we desire Letters Patent is as follows, to wit v 1. An electric musical instrument having sonorous bodies of different pitch, electromagnets for their actuation, a source of current, currentpulsating means, and circuits including said source, electromagnets and pulsating means, the circuits associated with sonorous bodies of lower relative pitch be ing given materially greater resistance than the circuits associated with bodies of higher pitch.

2. An electric musical instrument havin sonorous bodies of different pitch, electromagnets for their actuation, a source of current, current-pulsatingmeans, and circuits including said source, electromagnets and pulsating means, the electromagnets associated with sonorous bodies'of higher rela tive pitch being given less resistance than the electromagnets associated with bodies of lower pitch.

3. An electrical musical instrument comprising, in combination, sonorous bodies ,of different pitch; electromagnets associated vibration; and means for supplying the coils of the respective magnets with pulsations of electric energy differing in frequency for the different magnets, the windings of different magnets offering predce termined resistance difiering in degree to compensate for varying impedance ofiered by said'windings incident to varying frequency of pulsation of current therein.

4. A musical instrument comprising magnetically attractive sonorous bodies, electromagnets to which said bodies respectively bear the relation of armatures, and means, including circuits and a source of electrical power, for delivering properly-timed elec-. tric pulsations to said electromagnets; said electromagnets being located at differing distances from their sonorous bodies, and including in their circuits resistances which vary inversely proportional to the frequency of said pulsations. 5. A musical instrument comprising tuned sonorous bodies, electrO-magnets for their sonorous bodies, electro-magnets for their actuation, means for delivering properlytimed electric pulsations .to said electromagnets, a source of power, and circuits in cluding said source and electromagnets; said circuits having different ohmic resistances, said resistances increasing from the treble magnets to the bass magnets.

7. A musical instrument comprising tuned sonorous bodies, electro-magnets for their actuation, and means for delivering properly timed electric pulsations to said electromagnets; the electromagnets actuating upper sonorous bodies being wound with heavier wire than the electromagnets of the sonorous bodies lower in thescale.

8. A musical instrument comprising tuned sonorous bodies, electromagnets for their actuation, and means for delivering properly timed electric pulsations to Said electromagnets; said electromagnets being dissonorous bodies, to a wire of relatively high resistance, for the lowest sonorous bodies.

9. A musical instrument comprismg magnetically attractive sonorous strlngs, electromagnets to which said strings bear the relation of armatures, and means for delivering properly timed electric pulsations to said electromagnets; the electromagnets actuating the upper sonorous strings being wound to have a low resistance and being located closer to their strings than the electro-' magnets, farther down the scale.

10. An electrical musical instrument comprising a sonorous body, an electromagnet for its actuation, a rotary pulsation-pro ducing means, a source of current therefor, and means under the control of the operator for varying the amplitude of vibration of. said body by gradually varying the voltage of the current generated by said source.

11. An electrical musical instrument comprising, in combination, sonorous bodies and electromagnets for effecting their vibration; a rotary pulsator; a motor for driving said pulsator; a source of electric energy in circuit with the pulsator and electromagnets through branch circuits; means operative at will for varying the voltage of the source of ing atwill the resistance of the branch circuits containing the electromagnets.

12. A musical instrument comprising, in

combination a sonorous body; an electromagnet for its actuation; a rotary makeand-break devlce; a source of electnc cur rent; means for conveying current from' of the generator.

14. A musical instrument comprising, in combination, sonorous bodies; electric means for their actuation; a generator supplying current to said means; a rotary circuit breaker for producing pulsations in said current; an exciter delivering current to the field windings of said generator; and a pedal-controlled rheostat for varying the strength of current delivered by said exciter to said field.

15. A musicalinstrument comprising, in combination, a series of sonorous bodies; a source of electric energy a series of electromagnets directly attracting 'and thus efiecting vibration of said bodies, one magnet for each such body;.branch circuits each including a magnet of the series means for simultaneously introducing a separate resistance into the circuit of each magnet; and means for completing the several magnet circuits independently.

16. A musical instrument having strings difiering in size and length, electromagnets, and means for delivering electric pulsations thereto for the actuation of said strings, the electromagnets actuating the large and long strings being Wound with many windings of relatively fine wire, and the electromagnets actuating the finer and shorter strings being wound with relatively heavy wire.

17. A musical instrument having strings difi ering in size and length; a magnet rail, and magnets carried thereby for the actuation of said strings, the magnets for the fine and shorter strings being wound with heavier wire than is used for the windings of the other magnets.

18. A musical instrument having strings differing in size and length, a magnet rail, electromagnets carried by said rail, and

means for delivering properly timed electric pulsations thereto, the magnets associated with the fine and short strings and also with the long and heavy strings being located nearer to their strings than the magnets associated with the intermediate strings.

In testimony that we claim the foregoing invention, We have hereunto set out hands this 20th day of June, 1907.

MELVIN L. SEVERY. GEORGE B. SINCLAIR. Witnesses:

A. B. UPHAM,

CHARLES GARRISON.

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