US2727423A - Damping means for "electronic" carillons - Google Patents

Description

Dec. 20, 1955 I w. F. MEEKER ETAL 2,727,423

DAMPING MEANS FOR ELECTRONIC" CARILLONS Filed March 26, 1951 2 Sheets-Sheet l AMPLIFIER L l l LOUD SPEAKER g g FIG. I

' INVENTOR.

FRANK H. SLAYMAKER WILLARD F. MEEKER Y %/M ATTORNEY Dec. 20, 1955 w. F. MEEKER ETAL 2,727,423

DAMPING MEANS FOR ELECTRONIC CARILLONS Filed March 26, 1951 2 Sheets-Sheet 2 FIG.2 FIG.3 FIG.4 F|G.5 FIG.7

PERF T FIFT STRIKE TONE FIG. 6

I I :4 II FIG 9 COMPONENTS COMPONENTS FROM PICKUP A FROM PICKUP B PERFECT FIFTH STRIKE TONE A A A Ie\m/8OA b d a T 82/T\|c 82/ 7O 82/? FIG.8 FIG.II FIG..I2 FIG.I3

INVENTOR.

FRANK H. SLAYMAKEF WILLARD F. MEEKER ATTORNEY United States Patent DAMPING MEANS FOR ELECTRONIQ CARILLONS Willard F. Meeker and Frank i-K. Slaymaker, Rochester, N. Y., assignors, by mesne assignments, to General Dynamics Corporation, a corporation of Delaware Application March 26, 1951, Serial No. 217,624

6 Claims. (Cl. 844li4) This invention relates to damping means for electronic carillons and more particularly to means for damping certain partials of the complex tone produced when a vibrant tone member is struck.

Certain objects emit musical tones when struck. Many percussion instruments have been designed to utilize such objects as a source of musical tones which may be selectively controlled. One such instrument is the elec- 'tronic" carillon wherein vibrant tone members are percussed to produce mechanical vibrations which may be translated into electrical currents capable of amplification to a degree suitable for use in a sound reproduction device.

The electronic carillon has been developed to replace the older and more expensive campaniform bell carillon; therefore, it is desirable to use a vibrant member having a tone as nearly like the true bell type carillons as possible. Of course bell shaped objects may be used; however, it is more desirable to use rods, bars, tubes, elongated cylindrical, elliptical or rectangular objects or the like, hereafter collectively identified as bars. When vibrant bar shaped members are used, difficulty has been experienced in obtaining tones having timbre closely resembling those of actual hells. Since the timbre of a tone member is determined by which partials are present in the complex tone produced by percussion, it is necessary to control both the pitch and the volume of each partial in order to reproduce the desired sound. Furthermore, there is a persistency or after ring of tone so that tone control must extend over the decay period if the tonal character is not to depart from that of true campaniform bells during the after ring; thus, it is also necessary to control the rate at which each partial dies away. For example, if high frequency partials decay slowly a live or bright tone is produced; whereas, a quick decay of high frequencies gives the impression of a dead or clunky tone having a great impact at the start.

It is desirable to avoid both the situation where high frequency tones linger too long and the situation where the high frequencies die too quickly. In the first instance the sounds of various notes remain and blend into each other to the extent that a certain muddying of tone results upon the playing of a rapid passage. In the second instance the impression is one of dead clunky tones which are more nearly like that of a plucked violin string than of a bell.

An object of this invention is to provide new and improved percussion musical instruments which produce accurate reproduction of the tones of campaniform carillon bells.

Another object is to provide means for controlling the decay rate of the complex tone produced when a vibrant member is struck.

Still another object of this invention is to povide means for controlling selectively the decay rate of certain partial tones produced by vibrant percussion members.

A further object of this invention is to produce a percussion musical instrument using bar like vibrant mem- "ice hers which have been adapted to simulate the tonal qualities of bell type carillons and to maintain these superior qualities during the after ring or decay period.

This invention accomplishes the above cited objects by controlling selectively'the decay rate of certain high frequency partials. Damping material is attached to tone bars in such a manner as to be effective in only one plane of vibrations of the bars. The cross-sectional dimensions of the bar, the location of the strike and the orientation of the pick-up devices all cooperate to contribute to the final result.

The invention and other objects will become apparent from a study of the attached drawings.

Fig. 1 is a general view of a percussion musical instrument illustrating different embodiments of the invention.

Fig. 2 is a side view of one end of a bar-like vibrant member having one form of damping material attached hereto.

Fig. 3 is an end view of the bar and preferred damping material shown in Fig. 2.

Fig. 4 is also an end view of the bar and a different damping material shown in Fig. 2.

Fig. 5 is a side view of one end of a bar-like vibrant member having a different form of damping material attached thereto.

Fig. 6 is a diagram illustrating the manner in which a vane of damping material may be positioned to affect individual partials.

Fig. 7 is a side view of one end of a bar-like vibrant member having still a diiferent form of damping material attached thereto.

Fig. 8 is a diagrammatic view of a rectangular bar showing the orientation of a striker and two pick up devices.

Fig. 9 represents the various components of the complex tone produced when a tuned campaniform bell is struck.

Fig. 10 shows the manner in which the complex tone produced by the rectangular bar of Fig. 9 is divided as a result of the orientation of the striker and pick up coils.

Figs. 11, 12 and 13 show various ways for selectively controlling the decay rate of the various partial tones of a rectangular bar.

Referring now briefly to Fig. 1 which shows a general view of a percussion type musical instrument sometimes referred to as an electronic carillon and illustrates typical uses to which the various forms of my invention may be put. Here a plurality of bar-like tone members, designated by the numerals 1a to 1e, are suitably mounted to be struck by a device and thereby produce mechanical vibrations which are translated by a pick-up device into electrical currents which may be amplified and reproduced as sound. Each of the bar-like members represents a different way in which damping material may be attached. For example, each of the bars in, 1b and 1c carries a different type of flexible material 60, 40 and 20, respectively, while bars 1d and 1e are plated with suitable deadening material and 80, respectively. The vane-like damping means 20 and 40 is designed to affect all partials in varying degrees if attached to a round bar such as 112 when mounted to be struck as shown, while the damping vanes 20 and 40 and plating 70 and are designed to affect only certain partials when used with rectangular bars such as 10, 1d, and 1e.

Referring to Fig. l in greater detail, tone bars 1a to 1e may be attached to mass element 6 in any suitable manner. For example, bifurcated elements 2 may be provided having two arms 5 defining a slot or opening 8 into which tone bars may be fitted and held securely by an attaching agent such as threaded element 9. The strikers 3 are actuated from any suitable source of power 10 whenever an associated key 11 is closed. The percussion by the striker results in mechanical vibrations in the associated tone bar such as 1a. These vibrations are translated into electrical currents by any suitable sort of a transducer 4 such as a magnetic pick-up coil, for example. These electrical currents are preferably amplified by amplifier 12 and suitably utilized by a reproduction device such as 13 which could be a loud speaker. Bars la and 1b are shown as round in cross sections but any of many suitable cross sectional designs may be used; for example, they may be rectangular bars such as shown and described in our copending patent application Serial Number 199,055, filed December 4, 1950, Patent No. 2,690,091, granted September 28, 1954. If such rectangular bars are used, it is desirable to provide two pick up devices 42 and 4b in order to obtain the full benefit of the rectangular shape. These two devices, 40 and 4b, may be placed with their major axes at right angles to coincide with the center lines of the cross sections of the tone bars.

For illustrative purposes a different damping means is provided for each of the bars 1a through 1e. Each scheme is explained more completely in Figs. 2 through 13. For example, Figs. 2, 3, 4 and 11 illustrate the application of a damping vane 20 to bar 1c of Fig. 1. Fig. 5 is a detailed showing of vane 40 and bar lb. Fig. 7 gives a clear understanding of bar 1a and damping means 60 while bars 1d and 1e are explained in Figs. 12 and 13 respectively.

Fig. 2 shows the lowermost part of bar to which a thin vane of soft, flexible lossy material such as a cellulose or masking tape, for example, has been fastened by any suitable means, as for example, cement, adhesive surfaces or the like. By the term lossy we mean a substance or material having as a characteristic property a high loss of energy due to its internal working or bending responsive to mechanical vibrations such as: rubber, lead, cellulose, certain soft plastics, elastomers and the like, for example. The operation of this vane is explained in Fig. 3. Here bar 10 is assumed to have been struck or plucked so that it vibrates in but a single plane as indicated by the double ended arrow XY. When bar 10 moves in direction X the inertia of vane 20, plus the action of such things as the resistance of the surrounding air, causes the distortion of vane member in a manner indicated by dotted lines and designated by the numeral 22. When bar 10 reaches the limit of its excursion in the X direction, its elasticity causes it to have a return excursion in the opposite or Y direction. This time the vane 21 is distorted so that it bends in the direction shown by dotted lines 21. Thus, it will be obvious I that as the bar vibrates, the damping action of vane 20 controls the decay rate of mechanical motion.

Fig. 4 illustrates a different manner in which a damping vane may be used. In this example, vane is made of a rigid material such as a thin sheet of metal, for example. When bar 1c is struck to move in the direction of double ended arrow XY, there is substantially no bending in vane 32; instead, vane 30 moves between the limits of vibration for bar is in the manner shown by the dotted lines 31 and 32. The resistance of the surrounding air plus the general loss of energy due to the added sound radiating surface of member 30 causes a damping effect on the mechanical excursions of tone bar 10. It is to be recognized that any material is likely to bend it subjected to suflicient bending force; therefore, it is possible that a rigid vane of thin metal such as may be used is subject to bending forces exerted by mechanical vibration of the bar. However, this possible bending will not be effective to damp the bar since the internal mechanical loss of metal due to bending is much lower than the internal loss of a soft, flexible, lossy material such as rubber for example. Normally the flexible vane of Fig. 3 is preferred; however, in some instances it may be desir able to substitute a rigid vane such as 30 for the flexible vane 20 since the properties of a metal vane may be l easily controlled in production and since the damping would remain more constant without changes due to aging, temperature, humidity, air pressure or the like.

Fig. 5 illustrates a different way of applying the same principle. Here a molded damping vane 40 is aflixed to bar lb. When bar 1b vibrates vane 40 acts in the manner of vane 20. Here again any suitable soft, flexible, lossy material may be used, for example rubber or many types of plastics. The dimensions of the vane may be selected to give the desired amount of damping; however, it should be held to as small a size as practicable so as' to minimize the effect on tuning.

One of the most important properties of the vane type damping device is that it is directional; that is, when the bar vibrates in the XY direction, damping is great while there is substantially no damping of vibrations in the plane perpendicular to the XY direction.

Another important property of the damping vane, illustrated in Fig. 6, is that its location on bar 1 may be changed to control selectively the decay rate of the various partial tones. The extent to which any mode is damped depends upon the point at which the vane is affixed along the length of the bar. Since the greatest amplitude of mechanical excursion occurs at the center of a loop, mid-way between two nodes, the greatest damping effect is had at this point. The damping effect tapers off as the vane is moved to coincide more nearly with a node.

When struck, each bar vibrates in a complex pattern. Each complex pattern is composed of a series of simple modes of vibration, illustrated in Fig. 6 as separate patterns 2, 3 and 4 which are produced when the bar is struck at point 3. Each mode of vibrations has a different number of loops and nodes. The nodes of each mode of vibration occur at a different location along the length of the bar; however, each mode of vibration has a node, at the clamped end of the bar and a loop at the free end. lf a damping vane, such as 20 or 40, is placed on the tone bar as graphically represented in Fig. 6 at location 50, each mode of vibration is affected by about the same degree since each mode has a loop at about this point. If, however, the vane is moved to point 51, it coincides with a node of the mode of vibration 3 thereby providing substantially no damping for this mode. In position 51 the mode of vibration 4 is substantially undamped. Thus, it is seen that certain specific modes may be substantially undamped, while other modes will be affected to a greater or lesser degree depending upon how nearly the location of the damping coincides with the center of the loop, or stated another way how far the vane is from the node of a particular mode of vibration.

Fig. 7 is a view of another means for damping. Here a thin walled tube of flexible, lossy material is placed on the end of a tone bar. Any suitable material such as rubber-like or plastic material, for example, may be used. For a given material and wall thickness, the amount of damping depends upon the length of the tubing extending beyond the end of the tone bar.

The schemes of Figs. 2, 5 and 7 afifect the higher frequencies to a greater degree than the lower frequencies. Too much high frequency damping produces a dead tone; however, rapid passages may be played without the muddying in which each note continues to ring during the playing of the ensuing notes.

Therefore, it is desirable to introduce a compromise by which the tones remain lively instead of dead and by which rapid passages may be played without the common muddying efiect. Such a desirable compromise is had by using the damping principle of this invention in connection with rectangular bars such as set forth and explained in our above identified application Serial Number 199,055.

Fig. 8 discloses the manner in which a rectangular bar is preferably used. The arrow 82 indicates the direction in which bar 81 is struck by the striker 3a of Fig. 1. It

has been found that a campaniform bell, when struck, produces a complex tone composed of the series of tones shown in Fig. 9. The hum tone, strike tone, and minor third decay very slowly while the lower perfect fifth is weak and dies quickly. The higher components die more rapidly than the hum or strike tone; however, their decay rates are very different. It also has been found that a bar, when struck as indicated by 82, tends to vibrate in two planes. Each of the planes of vibration follows a certain pattern which may be detected individually by two pick-up devices A and B which are situated at right angles with respect to each other as shown in Fig. 8. This invention is intended to modify the vibration pattern of a rectangular bar as indicated in Fig. so that a pattern more nearly duplicating that of Fig. 9 is produced.

If the ratios of the cross-sectional dimensions are the same as the minor third, that is a ratio of approximately 1.2 to l, the vibrations are such that pick-up A is energized by the complex tone pattern illustrated at the left in Fig. 10 while pick-up B is energized by the complex tone pattern illustrated at the right in Fig. 10. The dotted notes indicated components which are eliminated in a manner described in our above identified application Serial Number 199,055. the outputs of these two pick-up devices may be suitably mixed, amplified and reproduced as a single complex sound which is the sum of the various partial tones detected by pick-ups A and B.

if the decay rate of the two components detected by i pick-up devices A and B are properly controlled, it is possible to have each partial tone decay at a rate which accurately simulates the tones of the campaniforrn bell type carillon. vention, vane it attached to bar 10 in the manner shown in Figs. 1 and 11. This vane 20 is oriented to be efiective in damping the vibrations which excite pickup B; the vibrations exciting pick-up A are virtually free of damping. The damping means shown in Figs. 1 and 5 may be substituted for vane 20.

As was explained above, this type of damping affects the high frequencies much more than the low frequencies. Thus, it is possible to selectively cause the minor third, octave and perfect fifth to die away quickly while permitting the hum tone, the strike tone, and the major third to decay slowly.

Figs. 12 and 13 show other means by which directional damping may be had. A soft, lossy metal having a relatively inefficient vibration transmission characteristic, such as lead or lead-tin alloys, for example, may be used to plate two opposite sides of a rectangular bar 1d, as shown in Fig. 12 at '70. In this example the entire side of the bar is plated to reduce the decay time of vibrations to which pick-up device B is responsive. It has been found that the vibrations energizing pick-up device A are also affected to a certain degree by such plating; however, this effect may be reduced by confining the plating to relative narrow strips 80 as shown in Fig. 13. Moreover, in the direction of the pick-up device B, this strip of plating, till, is as effective as was the full side plating 70 of Fig. 12.

From the above description, it is seen that a device has been provided to control selectively the decay rate of the partial tones resulting from a struck tone bar. The value of such control is very important in a rectangular bar where a separation of certain partials is As is illustrated in Fig. 1,

in accordance with this phase of the inpossible. Without the loss of campaniform bell tonal qualities, we have provided for the rendition of rapid passages of music without muddying the tones and have avoided such common defects as sounds resembling plucked strings and as sounds giving a sensation of great impact at the start of a tone.

Other modifications will become apparent to one skilled in the art. For example, in the case of the device shown in Figs. 12 and 13, plating may be confined to a single side of the bar. Therefore, it is our aim to cover in the attached claims all modifications which fall Within the true spirit of our invention.

What we claim is:

1. In an electronic carillon, a mass element, a plurality of clamp-free tone bars, means for mounting said clamped end of said tone bars on said mass element, a plurality of strikers, one for causing each of said tone bars to vibrate in a complex pattern comprising a plurality of simple modes of vibration, a damping means of soft, lossy material, said damping means being attached to said tone bars for selectively damping said modes of vibrations in varying degrees, said damping means being firmly fixed to said tone bars, whereby said damping is a result of internal working of said lossy material as it moves and bends responsive to said tone bar vibrations, a plurality of electrical pick-ups for converting said vibrations into electrical currents and means for translating said currents into suitable sound waves.

2. The electronic carillon of claim 1 in which said tone bars have a rectangular cross-section with sides in the ratio of 1:1.2, said damping means being oriented to damp vibrations in the plane which is parallel to said side having a width corresponding to the ratio figure 1 and perpendicular to said side having a width corresponding to the ratio figure 1.2.

3. The electronic carillon of claim 1 in which said damping means is vane-like in shape, the broad side of which is disposed perpendicularly to the direction in which said bars vibrate under the influence of said strikers.

4. The electronic carillon of claim 3 and means for attaching said vane-like damping means at different locations along the length of said tone bar, said location being determined by the position of the loops and nodes of certain of said modes of vibrations.

5. The electronic carillon of claim 1 in which each of said tone bars have a rectangular cross-section, and said damping means is disposed along at least a significant part of the length of at least one side of said bar but not along the length of either of the sides adjacent to the side on which said damping means is disposed.

6. The electronic carillon of claim 5 in which said damping means is confined to a strip which is not as Wide as the said side on which said damping means is disposed.

References Cited in the file of this patent UNITED STATES PATENTS 149,585 Hill Apr. 14, 1874 1,140,932 Young May 25, 1915 1,269,511 Roberge June 11, 1918 1,291,550 Kirk Jan. 14, 1919 2,413,062 Miessner Dec. 24, 1946 2,581,963 Langloys Ian. 8, 1952 2,622,467 Kunz Dec. 23, 1952

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