US2323232A - Apparatus for the production of music - Google Patents

Description

June 29, 1943.

B. F. MIESSNER 2,323,232

APPARATUS FOR THE PRODUCTION OF MUSIC Filed May 14, 1940 2 Sheets-Sheet 2 CURRENT 68w SOUR: L 65 86 87 e1 64 614 I 400 7 Ii-ml 94 95 3nnentor Patented June 29, 1943 APPARATUS FOR THE PRODUCTION OF MUSIC Benjamin F. Miessner, Harding Township, Morris County, N. .L, assignor to Miessner Inventions, Inc., Harding Township, Morris County, N. J.,' a corporation of New Jersey Application May 14, 1940, Serial N0. 335,064

16 Claims.

This invention relates to the production of music, and in its principalaspects to that pro! duction involving the translation of sound from sound-representing electric oscillations. Important aspects of the invention involve the production of the sound-representing electric oscillations by translation from the vibrations of tuned vibrators, and more specific aspects involve such translation from the strings of an instrument of the piano type. The invention has been specifically illustrated and described in connection with an instrument of the latter type, but it will be understood that in broader aspects no unnecessary limitation thereto is intended.

It is an object of the invention to provide improved and simplified arrangements for the translation of electric oscillations from the vibrations of tuned vibrators.

It is an object of the invention to provide improved arrangements of the type above described, operating magnetically.

It is an object to provide improved arrangements of the type abovementioned which may be effectively used to modulate high-frequency currents at the vibrational frequencies.

It is an object to provide, in association with arrangements such asabovementioned, appropriate means for controlling the envelopes, or amplitude-time characteristics, of the output tones.

It is an object to provide, in an electronic instrument of the piano type, an improved arrangement of sound-radiating means with respect to the other portions of the instrument.

Other and allied objects will more fully appear from the following description and the appended claims.

In the description of the invention hereinafter set forth, reference is had to the accompanying drawings, of which:

Figure l is a front elevational view of an electronic piano in which my invention has been embodied in one form, most of the front cover member and most of the action being removed for the better illustration of parts therebehind;

Figure 2 is a rear elevational view of the instrument of Figure l;

Figure 3 is a fractional cross-sectional view,

taken along the line 3-3 of Figure 1;

Figure 4 is a fractional cross-sectional view, taken along the line 4-4 of Figure 3, together with a schematic illustration of circuit components;

v Figure 5 is a partial plan view of an electronic instrument of the grand-piano type in which my invention has been embodied in another form, together. with a schematic illustration of certain circuit components; and

Figure 6 is a partial cross-sectional view taken along the line 6-4 of Figure 5, together with a schematic illustration of other circuit components.

An embodiment of my invention has been illustrated in Figures 1, 2, 3 and 4, the latter two figures being enlarged cross-sectional views of restricted portions of the former. Figures 1 and 2 illustrate an instrument of the piano type, which in its general constructionother than that immediately involved in the translation of the string vibrations into electric oscillations may for example be similar to that illustrated and described in Patent No. 2,200,718 to me, to which patent reference may be had for details not in themselves necessary to mention in the following brief description of that general construction.

In Figures 1 and 2 will be seen a vertical, rectangular metallic frame or plate I serving as a basis to which the other components may be directly or indirectly assembled. This plate is conveniently provided around its periphery with the forwardly extending flange 2. The central portions of the plate are apertured; but the plate is reinforced by cross-webs such as 3, some of these being in turn reinforced with forwardly extending flanges such as 4. To the back of the plate may be secured a peripheral framework, comprising for example the wrest-plank 5 across the top, the wooden cross-member 6 across the bottom, and the vertical wooden end members i. To the plate I, through the medium of this framework, may be supported a vibratile system comprising certain bridges (hereinafter described) and a plurality of vibratile ribs 8the tops of the ribs being secured in the wrest-plank 5, the bottoms of the ribs being secured in the cross-member 6, and the ribs being preferably slightly bowed forwardly in their central portions. Forwardly and backwardly extending vertical standards 9 may be secured to'the two ends of the plate I to form a support therefor and, if desired, to form the exposed ends of the only appear in Figure 1, adjacent the, respective vertical end standards 9). The illustration of ribs 2 has been omitted from Figurel in the interest of clarity of showing.

The top portion of the plate I is suitably apertured to permit a plurality of tuning pins II to extend forwardly therethrough from wrest-plank I, wherein they are secured. From these pins to hitch p ns II in lower portions of the plate i extend the several tuned strings of the instrument, of which the upper trebl strings are indicated as It, the lower treble strings as II, and the bass strings as l4--it being understood that each of these groups of strings is only fractionally shown in the interest of simplicity of the draw n sv All the treble strin s have been shown as passing from the tuning pins l2 under a pressure bar If and over a ledge l2 defining the upper extremities of their activ portions; the bass strings II. which may be overstrung (i. e.. disposed slightly in from; of and somewhat transversely to the treble strings), may pass around respective localizin pins Iii in the defin ng ledge II. The bridges over which the strings pass, and which define the lower extremities of the active string portions. are hereinafter described.

For vibrating the strings there may be employed, for example, the impulse or striking excitation usual to the piano, typically by means of the usual piano hammer, damper and pedal action; this has been indicated in Figure 1 as including the keys 20 and pedals 2i and 22, and has been designated generally as A. It may for example be of the "dropped" typedetails of which, over and above the quite fractional showing of Figure 1, have been illustrated and more fully described in the Patent No. 2,200,718 abovementioned. While no particular limitation is intended as to the number of strings per note, I have in Figures 1 and 2 illustrated the use of two strings per note throughout the principal porti of the scale.

The bridges over which the strings pass are shown as 4! and 43 for the treble and bass strings, respectively. These extend transversely of, and are secured to, the ribs 8. The bridge 4i has been illustrated as provided with a portion 42 of reduced thickness extending underneath (i. e., behind) the active string portions (1. e., upwardly), and the bridge 42 with a corresponding extending portion 44. These portions form a con venient, though non-limitative, support for the mechanico-electric translating apparatus shown in this embodiment of my invention.

In carrying out my invention I cause the strings to have magnetic fields which intersect a conductive circuit and which, when the strings are vibrated, oscillatorily infiuence that circuit to create vibration-representing electric oscillations therein. According to an important aspect of the nvention, I arrange the conductive circuit for a plurality of different-frequency strings as a single one, extending transversely of the strings and having portion adjacent thereto to be oscillatorily approached and receded from by the strings during their vibrations.

Such a circuit has been embodied in the construction of Figures 1 through 4 as a single-tum loop for all the treble strings, together with another single-turn loop for all the bass strings. One side of the loop is in close spaced relationship to the strings--typically at a spacing therefrom not greatly in excess of that required to. avoid its being struck by the strings under condit ons of their maximum-amplitude vibrations. It is on this side of the loop that the string vibrations have their significant and intended infiuence. The other, or "return, side of the loop i kept at a much larger distance from the strings, whose vibrations accordingly have negligible effect on it-whlch is desirable, since the latter influence tends to oppose the former within the loop circuit. The loop for all the treble strings has been specifically illustrated as a heavy conductor 50, typically though non-limitatively of rectangular cross-section. The active side Ila of the loop i disposed behind the strings, preferably opposite longitudinal portions thereof which vibrate with the most desirable harmonic development; and since these portions may typically be portions relatively near th bridge extremities of the strings, the loop side a may conveniently be secured to the portion 42 of the bridge abovementioned. This securing has been shown by way of preferred example as carried out through the medium of screws II passing rearwardly through the conductor ill and into the bridge portion 42,

Between the conductor 50 and the bridge portion 42 there may be provided about the screws ll respective expansion springs 52, which urge the conductor forwardly against the heads of the screws 5|; this renders the turning of each screw effective to adjust the precise spacing of the conductor, in the region of that screw, from the strings. Several of th screws Il may be employed at intervals along the conductor 50, and the latter may be made of a relatively soft metal to respond in its several portions to adjustment by the respective screws. Since the degree of influence of the vibrating strings on the loop will be directly affected by the spacing of loop from string, the voicing of the instrument as to relative outputs in different scale portions may be very precisely adjusted by means of the screws ll.

At the extremities of the bridge 4i the conductor I0 may be folded around the end of the bridge portion 42 (as appears for the extreme treble extremity in Figure 4) to form the second or return side lllb of the loop; this may conveniently be secured to the backs of the ribs 8, for example. At a convenient point in the loop side b the loop is provided with a discontinuity, formed between spaced extremities 500 of the otherwise continuous conductor. The loop circuit is closed by connection across these extremities of a very low impedance primary 50a of a transformer l4.

Because of the overstrung arrangement of the bass strings in the particularly illustrated instrument construction, it may be relatively difflcult to extend the one loop 50 into an effective relationship to the bass as well as to the treble strings; accordingly I have preferred to employ for these strings, as indicated in Figures 1 and 2, a separate loop 53 related to them in an analagous manner to that described for loop 50 and the treble strings. While this loop 52 may be connected in any of a variety of ways to merge its output with that from the loop III, I have by way of example indicated in Figure 4 the provision of a separate transformer 81 to the primary I'Ia of which the loop 52 may be connected (as was the loop to the transformer primary Ila). This use of separate transformers may facilitate the minimization of length of leads in the low-impedance loop circuits.

Since the axis of the loop is very approximately parallel with the strings, the magnetic fields which the strings are caused to have are preferably longitudinal of the strings. Such a field is most simply provided for each string by permanently magnetizing it, particularly in the region adjacent the loop. Means and methods for magnetizing the string, being themselves known in the art and forming no necessary permanent part of the instrument, need not be specifically described herein. It will be understood that as any one of the strings is vibrated toward and away from the loop-for example as a result of its being excited by the action Athe influence of its magnetic field on the lcop is osclllatorily varied in accordance with the frequency and wave form of the string portion adjacent the loop, thereby generating in the loop circuit a corresponding alternating voltage representing the string vibration. The voltages so generated by as many strings as may be simultaneously vibrated, superimposed on each-other, are stepped up by the transformers 56 and 51, and appear in their magnified amplitude in the circuit 58 in which the secondaries 36b and 51b of those transformers are both connected.

The circuit 58 forms a load circuit for the utilization of the translated oscillatory voltages. It may comprise a cascade of electrical amplifying and control means and electro-acoustic translating means. In Figure 4 it has been shown as comprising for example amplifier portion 34, tone control 35, amplifier portion'36, volume control 31 (controlled for example by pedal 10), amplifier portion 38, and electro-a'coustic trans lating means 39 and 40. The translating means 39 may be a "low-frequency" sound radiatore. g., a loudspeaker'which, while it may have a response at all audio frequencies, is particularly It may be forwardly directed, and if desired may be baffled by the removable front cover member ll, suitably apertured for this purpose. The relatively smaller high-frequency speaker 40 may be secured to the plate I in any convenient manner, likewise preferably forwardly directed to emit sound through the front cover member i i, which may be further suitably apertured for this loudspeaker. the invention contemplates the disposition of the low-frequency radiator or loudspeaker relatively adjacent the low-note extremity, and the disposition of the high-frequency radiator or loudspeaker relatively adjacent the high-note ex- "t'remity, of the keyboard and instrument, and the speakers have accordingly been so illustrated. I have found this arrangement markedly to enhance the naturalness of pianistic performance by an instrument of this type.

In Figures 5 and 6 I show another embodiment of my invention, wherein the conductive circuit may be in the form of a coil whose axis extends transversely of the strings, peripheral portions of the coil being adjacent the strings A preferred embodiment of to be osclllatorily approached andreceded from I by the strings in their vibrations. Purely by way of example, I have shown this construction embodied in an instrument of the grand-piano type. Thus in these figures there will be seen the rear portion 60 of a metallic plate. or frame, which may further include the front portion Cl and the capo" or cross-bar portion 82 as seen in Figure 6. Underneath the front plate portion 6| appears'the wrest-plank 63; tuning pins 84 may extend downwardly into the wrest plank through oversize holes in the plate portion 0|. From the tuning pins to respective hitch pins 65 in the rear plate portion 60 there may be strung the respective tuned strings 66 of the instrument. These may pass over ledge la on front plate portion ll, under the capo 82, over a bridge 61, and over a ledge 600 on rear plate portion 60.

The strings are caused to engage the bridge; and

while this may be done by respective pairs of bridge pins as in the instrument-of earlier fig-- ures, I have by way of alternative example shown the forward pin of each pair replaced by a grooved screw 63the string resting in the circumferential groove 68a therein, so that adjustment of the screw serves to raise and lower the string (as disclosed in Patent No. 1,915,859 to Miessner et al.). The bridge 61 has been shown as vibratilly supported, for example to the usual vibratile ribs 69. For effecting and controlling the string vibrations I have shown as A, partially schematically, a typical grand-piano action. This may include the pivoted keys HI, hammers II, and action mechanism schematically indicated as I2 interposed therebetween. In the illustration of this embodiment there has been shown, by way of example, the employment tion, the coil being arranged in an appropriate longitudinal configuration; the coil 15 has been illustrated as positioned underneath string portions relatively near the bridge 61. The coil may be mounted sothat its top side is slightly spaced larly arranged to those of the utilization circuit 53 already described, it has for simplicity been shown as comprising the amplifier portion 3|, volume control 82, amplifier portion 83 and loudspeaker in. v

In the various embodiments of my invention there may of course be employed a plurality of the mechanico-electric translating means, or conductive fcircuits, respectively associated with different portions of the strings, with differential phase and/or. amplitude control over their respective, outputs (as disclosed for mechanicoelectric translating devices broadly in Patent No. 1,906,607 to Jacobs). I have illustrated this availability in the instrument of Figures 54) by the showing of a second coil 16 arranged similarly to the coil 15 excepting that it is underneath a more forward portion of each string. To provide the differential control over respective outputs of the two coils, I may connect them across respective potentiometers I1 and 18, the fixed mid-points of the potentiometers being connected together, and their variable contacts being connected to the input of the amplifier portion llthe impedance of this input, and the impedances of the potentiometers, being of course preferably chosen at values appropriate to the impedances of the coils I5 and I8.

With the conductive circuit arrangement illustrated in Figures 56particularly when, as illustrated, the coil axis is obliquely (as distinguished from right-angularly) transverse to the strings-a permanent magnetization of the strings may be employed as in the case of the embodiment of earlier figures. But since the coil axis is mor nearly at right angles to the strings than parallel thereto (and may be quite at right angles to certain strings of the instrument) I prefer that the magnetic fields of the strings extend at right angles to-for example, in planes transverse totheir longitudinal directions. Such a field for a string may be created by the passage of a current longitudinally through the string; and in Figure 6 I have schematically illustrated an arrangement for such current passage.

This arrangement may comprise a current source 05, one ,terminal of which may be electrically connected with the rear plate portion 00 and therethrough to the rear extremities of all the strings. The other terminal of the source ll may be connected to all the tuning pins 00 (i. e., to the front extremities of the strings). For purposes hereinafter apparent it may be desirable that these connections to the front string extremities be individual to the several-strings; and such individual connections may for example be made through individual switches 80. (To preserve the individuality of the front-extremity connect ons, the strings in passing over the ledge 0 la and under the capo 02 may be insulated from those respective elements by thin curved pieces of insulation 6 b and 621) respectively. seen in Figure 6). It will be understood that with the switches 0! closed, currents will be continuously passed through the strings: to limit or to equalize these currents there may if desired be employed, for example in series with the switches 00, respective resistances 81. Th magnetic fields abovementioned will be continuously maintained: the voltages translated from the strings, and the sounds translated therefrom by the electro-acoustic translating means, will have envelopes (or amplitude-time characteristics) correspondingthroughout to those of the string vibrations; and, h an instrument of the disclosed t the tones will accordingly be of initially percussive, pianistic nature.

The creation of magnetic fields by current passage, however, may be employed to permit the variation of the envelopes of the electric oscillations and output tones from those of the string vibrations respectively giving rise thereto. Thus the current passage through each string may be controlled in predetermined relationship to the excitation of that string; and by way of specific example, the current passage may be initiated as or just after the instant of beginning of the string vibration (e. g., of the hammer striking the string), so that the percussive initial peak of the vibration envelope is eliminated from the envelope of the electric oscillations and the output tone.

There have been disclosed in prior patents to me or to me and another (e. g., 1,915,860; 1,915,-

" brational frequencies.

859; 2,071,649) and in a copending application of mine (Serial No. 208,357, filed May 17, 1938, now Patent No. 2,233,058) various variable-resistance arrangements for controlling (by control of sensitizing voltage, oscillation output, or the like) the translation from a string or other vibrator in predetermined relationship to the excitation thereof; and a variable-resistance arrangement basically similar to one of these may for example be employed for the control of the current through the string. By way of example I have shown in Figure 6 a respective variable resistance, designated generally as 95, positioned underneath the front portion of each key I0 for operation thereby. Specifically each variable resistance may comprise a pile of carbon discs 98 retained in a hole 91 in the baseboard 98 of the action A, and resting on a common conductive plate 00 which extends transversely across the bottom of the baseboard and may form a common connection to one side of all the resistances 05. For contact with the top of each pile there may be provided a respective contact button I00, carried for example on the bottom of the front portion of a forwardly extending leaf spring IOI whose rear extremity i secured to the top of the baseboard 98. Extending downwardly from the bottom of each key 10, above the forward extremity of the respective spring IIll, may be an adjustable screw I02.

Each spring I 0| may be biased so that normally there is little or no pressure of the button I00 on the carbon disc pile; accordingly th normal value of each resistance 95 will be very high or infinite. In the downstroke of the key, however, the screw I02 will impinge on the spring and force the button to compress, and lower the resistance of, the carbon disc pile-the structure serving as a downstop for the key. The variable resistances 95 may be connected across the respective switches 86 and resistances 01 abovementioned, becoming effectively substituted therefor when those switche are open. Each screw I02 may be adjusted so that the respective key will have its normal downstroke, and so that the resistance of the respective carbon disc pile will still be high (and the current through the respective string therefore negli ible) at the instant of contact of the respective hammer with the respective stringthe resistance reduction, and consequent rise of current fiow through the string, occurring wholly or principally after that contact.

In its simplest embodiment the current source 05 may of course be a source of direct current. the magnetic fields of the strings accordingly being steady (as distinguished from alternating) fields. The source may alternatively, however, be a high (over-audible) frequency alternating current source. In the latter case the magnetic fields of the strings will b high-frequency alternating fields, and the electric oscillations in the coils I5 and I8 will be high-frequency oscillations modulated at the string vi- In this case the amplifier portion 8| may be operated as a demodulator, so that the oscillations passing to the loudspeaker will be the modulating frequencie and thus will again represent the string vibrational frequencies.

The choice of the type oi source 85 may of course be made independently of whether the current fiow through the string'is to be varied, as by resistance 95, or maintained steady. It may be observed, however, that when the source I! is a direct current source, there may if desired be associated with each variable resistance Ql a filtering or time-delay means, to insure a smoothness and a desired degree of graduality in the rise of the string currents and output tones. Such means have been quite schematically illustrated in Figure 6 as condensers 94 respectively shunted across the variable resistances 8i.

The coils II and I8 may if desired be constructed without magnetic cores, .the cylindrical space therewithin being either open or filled with a generally cylindrical member (such members appearing as 150 and 160 respectively) which in this case may be of insulating material and may act simply as a mandrel for the coil. The members 15c and 16c may, however, constitute magnetic cores for the coils, in which case they may be of appropriate magnetic material in appropriate form. The latter arrangement, in view of an increasing effect on the efllciency of the translation by the coils, is usually to be preferred.

The illustration of the instrument of Figures -6 has been presented in fractional form, since there will be obvious from the earlier embodiment manners in which'the invention will be carried out in a complete instrument. llt will be understood that while I have shown various more specific features of my invention in different groupings in the two embodiments, this has been primarily for purposes of illustration and explanation rather than limitative; many of those features will be seen to be mutually interchangeable. Again, it will be understood that while Iv have chosen instruments of the piano type for the illustration of my invention,- various of its features are obviously applicable to other types of instruments. Finally, it will be understood that in general many modifications of the instruments shown and described will readily suggest themselves to those skilled in the art, and that these will not necessarily constitute departures from the spirit of the invention, or from its scope as expressed in the appended claims.

I claim:

l. In a musical instrument including a load circuit for the utilization of sound-representing side for adjusting the spacing of the same from the vibrators.

4. In a musical instrument including a load circult for the utilization of sound representing oscillations: the combination of a plurality of variously tuned vibrators having magnetic fields tors to be approached and receded from by vibrators and thereby magnetically influenced at the vibrator vibrational frequencies.

5. In a musical instrument including a load circuit for the utilization of sound-representing electric oscillations: the combination of a plurality of variously tuned strings disposed essenoscillations: the combination of a plurality of variously tuned vibrators having magnetic fields and disposed essentially in a plane; and a closed conductive circuit electrically feeding said load circuit, extending transversely of said vibrators with operatively substantially uniform structure continuously throughout that extent and having portions adjacent to said vibrators to be approached and receded from by the vibrators and thereby magnetically influenced at the vibrator vibrational frequencies.

2. In a musical instrument including a load circuit'for the utilization of sound-representing oscillations: the combination of a plurality of variously tuned vibrators having longitudinal magnetic fields and disposed essentially in a plane; and a conductive loop electrically feeding said load circuit, extending transversely of said vibrators with operatively substantially uniform structure continuously throughout that extent and having one side adjacent to said vibrators to be approached and receded from by the vibrators and thereby magnetically influenced at the vibrator vibrational frequencies.

3. The combination according to claim 2, wherein the loop comprises a heavy conductor of relatively soft material, and further including a tially in a plane; means for passing currents longitudinally through said strings, whereby .to create magnetic fields about said strings; and an elongated coil electrically feeding said load circuit, having an axis extending transversely of said strings and having peripheral portions adjacent thereto to be approached and receded from by the strings and thereby magnetically influenced at the string vibrational frequencies.

6. In a musical instrument including a load circuit for the utilization of sound-representing electric oscillations: the combination of a plurality of variously tuned strings disposed essentially in a plane; a plurality of means respectively associated with different-frequency strings for exciting the same; means, operatively associated with each exciting means, for passing current through the excited strings in predetermined time relationship to their excitation; and a closed conductive circuit electrically feeding said load circuit, extending transversely of said strings and having portions adjacent thereto to be approached and receded from by the strings and thereby magnetically influenced at the string vibrational frequencies.

7. In a musical instrument including a load circuit for the demodulation and utilization of electric oscillations modulated at sound-representing frequencies: the combination of a plurality of variously tuned strings disposed essentially in a plane; means for passing high-frequency currents through said strings, whereby to create high-frequency magnetic fields about said strings; and a closed conductive circuit electrically feeding said load circuit, extending transversely of said strings and having portions adjacent thereto to be approached and receded from by the strings, whereby there is induced in said conductive circuit a high-frequency voltage modulated at the string vibrational frequencies.

8. In a musical instrument including a load circuit for the utilization of sound-representing electric oscillations: the combination of aplurality of variously tuned vibrators having magnetic fields and disposed essentially in a plane; and a plurality of closed conductive circuits electrically feeding said load circuit, each conductive circuit extending transversely of said vibrators with operatively substantially uniform structure continuously throughout that extent and having portions adjacent to respective longitudinal regions of said vibrators to be approached and receded from by said vibrator regions and thereby magnetically influenced in accordance with the vibrations of, those vibrator regions.

9 The combination according to claim 8, further including means for varying the relative amplitudes of oscillations fed by the respective conductive circuits to said load circuit.

10. The combination according to claim 8, further including means for varying the relative phases of oscillations fed by the respective conductive circuits to said load circuit.

11. In a musical instrument including a load circuit for the utilimtion of sound-representing electric oscillations: the combination of a tuned string; means for exciting said string; means operatively associated with said exciting means for passing a current longitudinally through said string in predetermined time relationship to its excitation; and a conductive circuit electrically feeding said load circuit, having a portion adjacent to said string to be approached and receded from by said string and thereby magnetically influenced at the string vibrational frequencies.

12. In a musical instrument including a load circuit for the utilization of sound-representing electric oscillations: the combination of a tuned string; means for exciting said string; means operatively associated with said exciting means for passing a current longitudinally through said string in predetermined time relationship to its excitatio and a coil electrically feeding said load circuit, having an axis transverse to said string and a peripheral portion adjacent thereto to be thereby magnetically influenced at the string vibrational frequencies.

13. In a musical instrument including a load circuit for the demodulation and utilization of receded from by the string. whereby there is inassasss duced in said conductive circuit a high-frequency voltage modulated at the string vibrational fre- I quencies.

14. In a musical instrument including a load circuit for the utilization of sound-representing Q for passing a current through said vibrator in predetermined time relationship to its excitation;

and a conductive circuit electrically feeding said load circuit, having a portion adjacent to said vibrator to be approached and receded from by said vibrator and thereby magnetically influenced at the vibrator vibrational frequencies.

15. In a musical instrument including a load circuit for the utilization of sound-representing electric oscillations: the combination of a tuned vibrator; means for exciting said vibrator; means operatively associated with said exciting means for passing a current longitudinally through said vibrator in predetermined time relationship to its excitation; and a coil electrically feeding said load circuit, having an axis transverse to said vibrator and a peripheral portion adjacent thereto to be thereby magnetically influenced at the vibrator vibrational frequencies.

16. In a musical instrument including a load circuit for the demodulation and utilization of electric oscillations modulated at sound-representing frequencies: the combination of a tuned vibrator; means for passing a high-frequency current through said vibrator, whereby to create a high-frequency magnetic field about said vibrator; and a closed conductive circuit electrically feeding said load circuit, having a portion adjacent to the vibrator to be approached and receded from by the vibrator, whereby there is induced in said conductive circuit a high-frequency voltage modulated at the vibrator vibrational frequencies.

BENJAMIN F'. MESSNER.

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