US2613568A - Musical sound generating device - Google Patents

Description

Oct- 14, l952 M. MARTENOT MUSICAL SOUND GENERATING DEVICE 2 SHEETS-SHEET 1 Filed April 5, 1948 Quo :PEA/ri 5 M. MARTENOT MUSICAL SOUND GENERATING DEVICE Oct. 14, 1952 Filed April 5, 1948 2 SHEETS-SHEET 2 NSNN Patented Oct. 14, 1952 UNITED STATES PATENT OFFICE Application April 5, 1948, Serial No. 19,124 In France April 15, 1947 7 claims. (o1. sin-1.06)

Most musical instruments using strings are so designed that a quick damping of the vibration is avoided. This is .particularly true of piano and harp which cannot sustain a long resonance of the emitted sounds.

On the contrary, the sounds emitted by the electric or electronic instruments the output of which is connected to common loud-speakers cannot be sustained longer than the excitation time of the loud-speaker which presents the drawback of a certain dullness of the sounds.

Moreover it is to be observed that the common loud-speakers now available on the market are designed so as to obtain the greatest possible` fidelity by reproducing with a minimum of distortion the sound modulations transmitted to the loud-speakers from the microphone, the radio receiver or the gramaphone with which they are associated. Their vibrating diaphragms are made as aperiodic as possible. However while in ordinary reproduction fidelity is the essential quality, on the contrary in the playing of an electric or electronic musical instrument the point of View is not the same and it seems that here.- tofore nobody has noticed this difference. A certain amount of distortion producing a timbre hitherto unknown may `be then a desirable quality.

Such are the aspects of the technical problem. One object of my invention is to provide a sound generating device which is particularly adapted, on the one hand, to sustain the resonance of sounds longer than the excitation time of the loud-speaker and, on the other hand, to produce a. quality of timbre unknown with the common loud-speakers.

In a first embodiment of my invention, the resonant body in which vibrations are induced by thej modulated electric current is a gong plate. Such a plate which is usually made of ahammer-wrought alloy of copper and tin emits when excited a sound of a very high quality and vibrates, as a matter of fact, simultaneously at most musical frequencies.

Said plate may be operated by an ordinary, magnetic or moving-coil loud-speaker motor connected to one point preferably off-centered of said plate which is partially supported by a frame by means of an ordinary string for example, so that the damping maybe reduced to a minimum.

It is to be understood that the gong plate may be replaced by any other body which is able, like said gong plate, to vibrate in several modes simultaneously. after being excited.

According to another embodiment of my inven- .sets of strings tightened on both sides of a fiat frame and running over a double-nut which receives the impulses of the motor.

The following description with reference to the accompanying drawing given as an illustration which does not limit my invention will provide an understanding of how the object of the invention may be realized. In the drawing:

Fig. 1 is a front view` of one embodiment of my invention. f

Fig. 2 is a section taken along line II-II.

Fig. 3 is a section of an alternative embodiment taken along line III- III of Fig. 4.

Fig. 4 is a front View showing the arrangement of the vibrating strings according to the embodiment shown in Fig. 3 and Fig. 5 is another alternative embodiment.

In the embodiment of Fig. 1 the multi-resonator associated with the loud-speaker is constituted by a gong plate l linked at its upper edge by means of a string 2 to a rigid frame 3 provided With a base 4. On said base is secured a conventional loud-speaker motor 5 of any suitable type, electromagnetic or electrodynamic. The moving member of said motor is integrally connected to a rod B which is rigidly secured on the plate I at one point 'l of said plate. Said rod may, for example, pass through the plate, said plate being provided for this purpose with a hole, and which may be locked on both sides of said plate by means of nuts 8. Point 1 is preferably offcentered with respect to the plate. Motor 5 of the loud-speaker being 4connected to the output of the electric musical instrument, the moving member of said motor vibrates at the frequency of the currents generated by said instrument. Said vibration is transmitted through rod 6 to plate i which is thus excited. The sound generated by the instrument for a given frequency sent to the loud-speaker motor is a complex sound, the fundamental frequency of which is the frequency of the current energizing said motor but which comprises various harmonc frequencies. As the frequency sent to the loud-speaker motor varies, the previous excitation of the plate still goes on during a certain period of time. There is thus obtained very original timbres.

In order to damp at a desired instant the vibration of the plate, there may be provided a felt member 9 mounted, for example, on a support pivoted about a xed. point IIJ and which may be pressed on the plate by the performer by pulling a control rod I I.

In the alternative embodiment shown in Figs. 3 and 4, the multi-resonator comprises vibrating metal, such as steel strings of different natural resonance frequencies. Said strings are tightened in two radial sets ii, i2 on both sides of a rigid frame I3 provided with pegs It and I5 by means of which the tightening of said strings may be adjusted. Frame I3 has the shape of a closed fiat outline which may be a circular outline as shown in Fig. 4 or an oval outline and the strings are tightened between two points of said outline so that in each set they cross one another at a same point A and B respectively, points A and B being preferably symmetrically located relative to the frame. Through said crossing points A and B of the strings passes a rod or a tube IB and the strings are tightened thereover. Frame i3 provided with its strings rests on a base I9 carrying a conventional loudspeaker motor 5 similar to the motor employed in Figure 2. The moving member of said mo'tor is mechanically connected to the rod l5 through a rod 20.

It results from the above description that the vibrations of the moving member of the loudspeaker motor are transmitted to rod I8 and thence to the strings. From a current at sonic frequency exciting the loud-speaker motor, the string resonating to said frequency and the strings resonating to the natural harmonics of said frequency are directly set in vibration. rfhe resultant thereof is a complex sound which is still audible during the decay of the vibration.

As shown in the drawing, the strings may be associated with a diaphragm 2i, made of skin, for example, embedded at its edges in and tightened in frame I3, which may comprise, for eX- ample, two symmetrical parts clamped on both sides of the diaphragm. Near to the frame there may be provided small bridges 22, 23 through which strings il, i2 bears upon diaphragm 2I to which they transmit their vibrations. Said bridges may be independent, one for each string, or several strings may rest simultaneously on one bridge.

Rod I6 passes through a hole 24 of the diaphragm and comprises preferably at this place a part 58a of reduced section so that the hole to be bored may be of a reasonable size.

Alternatively rod i6 may be rigidly secured to the diaphragm so that the vibrations may be transmitted directly to said diaphragm, in which casebridges 22, 23 may be omitted.

In order to ensure ii' desired a quick damping of the strings vibration there may be provided two felted rings 2d, 25 movable coaxially toward the nut on two stationary cylindrical supports 25, 27. Springs 23, 2:2 hold said rings away from the strings and the performer may press them on the strings by actuating fiexible controls 3G, 3i.

According to an alternative.embodiment of the above `device strings may be tightened only on one side of frame i3.

It will be seen that in Figs. 3 and e, crossing points A and B of the strings are off-centered. Thus the same string may respond to two different frequencies with its shorter length for the high-pitched sounds and with its longer length for the lowepitched sounds. Now, instead of having a single string tightened between two points of frame I3 and running at an intermediate point on the rod I6, two string portions of different cross-sections could be secured at one end to the rod I6 and at the other end to the frame.

Another alternative embodiment would consist in tightening the strings but only on one side of a line CD (Fig. 5) which may be a straight line or a broken line and which crosses the rod at A. In this case, the resultant of the string tensions will be supported on the other side of said line by one or more flexible straps 3D.

In each one of the embodiments above described the multi-resonator may be associated with one or more conventional loud-speakers the diaphragme of which would be actuated either by independent motors or by the same motor as the multi-resonator.

For operating the loud-speakers described, loud-speaker motors sufficiently powerful should be used. It seems preferable for this purpose to choose loud-speaker motors of the so-called magnetic type. In such motors the neld may be moreover improved by substituting an electromagnet for the permanent magnet.

It is also to be understood that the embodiments described have been merely given as an illustration and that they could be modinedparticularly by substitution of technical equivalents within thescope of my invention.

What I claim is:

1. An electrical sound generating device particularly intended for electric musical instruments and comprising a vibrating member with front and rear faces, two sets of vibrating strings arranged respectively over said faces, said vibrating member thereby being located `between said sets of strings, a loudspeaker arranged to actuate said strings, and said strings being in vibrations transmitting relationship with said vibrating member to impart vibratory motion to said member.

2. A sound generating device as in claim 1 and a rigid frame having said vibrating member fastened thereto, and said strings being provided with means fastening the same to said frame.

3. A sound generating device as in claim 2 wherein said vibrating member has on at least one of the said faces thereof a bridge upon which at least some of said strings rest at points intermediate the ends of said strings.

4. An electrical sound generating device particularly intended for electric musical instruments and comprising a vibrating member with front and rear faces, two sets of vibrating strings arranged respectively over said faces, said vibrating member thereby being located between said sets of strings, a loudspeaker arranged to actuate said strings, said strings being in vibratious transmitting relationship with said vibrating member to impart vibratory motion to said member, a frame to which said vibrating member is fastened, said strings being attached to said frame, a movable member operatively connected with said loudspeaker, and said strings being connected with said movable member to receive .vibratory motion from said loudspeaker.

5. The assembly of claim 4 and movable means arranged to be pressed on said strings for damping rapidly their vibrations.

6. The assembly of claim 1 and movable means arranged to be pressed on said strings for damping rapidly their vibrations.

7. An electrical sound generatingr device particularly intended for electric musical instruments and comprising a vibrating member with iront and rear faces, two sets of vibrating strings arranged respectively over said faces, said vibrating member thereby being located between said sets of strings, a loudspeaker arranged to actuate said strings, said strings being in vibrations transmitting relationship with said vibrating' member to impart vibratory motion to said member, some of said strings running through a common point, and connecting means fastening said some of said strings at said common point to said loudspeaker so that said strings may derive vibratory motion from said loudspeaker.

MAURICE MARTENOT.

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

UNITED STATES PATENTS Nmnber Name Date 1,216,829 Martin Feb. 20, 191'? 1,893,940 Hammond Jan. 10, 1933 1,899,884 Severy Feb. 28, 1933 1,913,331 Buckingham June 6, 1933 2,230,836 Hammond Feb. 4, 1941 2,270,167 Meissner et al Jan. 13, 1942

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