US2672781A - Vibratory reed electronic musical instrument - Google Patents

Description

March 23, 1954 Filed Oct. 15, 1951 B. F. MIESSNER 2,672,781 VIBRATORY REED ELECTRONIC MUSICAL INSTRUMENT 3 Sheets-Sheet l LLI CD D d E 1 11 111 111 Y 111 1111 11111 IX PARTIAL N03 RELAT|VE 1 2 3 4 5 6 7 8 9 FREQUENCY' 4 A FIG? AMPLITUDE ACTUAL OUND IDEALIVZED SOUND BOARD nua uwm /0 20301050 /00 300 .500 I000 amo w c FREQUENCY IN CYCLES PER SECOND OF THE VIBRATORS (STRINGS) INVENTOR ATTOR EY March 23, 1954 B, WESSNER 2,672,781

VIBRATORY REED ELECTRONIC MUSICAL INSTRUMENT Filed Oct. 15, 1951 I 5 Sheets-Sheet 2 Z8, m, 2.2 m, m, 26, /a

5 FIG. 6

SPEAKER TRANSLATOR AMPLIFIER J Jj L,

INVENTOR BENJAMIN E MIESSNER ATTO March 23, 1954 F; MESSNER 2,672,781

VIBRATORY REED ELECTRONIC MUSICAL INSTRUMENT Filed Oct. 15, 1951 3 Sheets-Sheet 3 64 FIG. /0

INVENTOR BENJAMIN F. MI ESSN ER ATTO NEY Patented Mar. 23, .1954

VIBRATORY REED ELECTRONIC MUSICAL INSTRUMENT Benjamin F. Miessner, Harding Township, Morris County, N. J., assignor to Miessner Inventions Inc., Harding Township, Morris County, N. J

a corporation of New Jersey Application October 15, 1951, Serial No. 251,363

11 Claims. (c1. s4- 1.15)

2 This invention relates to electronic musical instruments utilizing clamped-free vibratory reeds as tone generators and more particularly to a novel arrangement of the translating devices associated with such reeds for the production of 5 desired tonal effects.

The complexion of the output tones of a tensioned-string piano is markedly affected by the natural frequency and energy-damping characteristics of the piano soundboard which effects are known as formant action or as formant efi'ects. These generally occur within a single cycle of vibration but may extend over a number of complete cycles before extinction by more or less string damping influences, in which case they are more properly classed as broad-band resonant effects. Both kinds are present in piano Soundboards but they will be referred to herein as formant efiects because of their tone quality forming action. In essence, this formant action generators and the introduction of the formant effect into the audible tones of such instruments must be accomplished without a soundboard as such.

An object of this invention is the provision of means for producing conventional soundboard effects in an electronic musical instrument utiliz- 1ing beam type vibrators as tone generators.

An object of this invention is the provision of a novel mounting arrangement for translating means associated with vibratory reed tone generators.

An object of this invention is the provision of novel and improved means for coupling vibratory reeds, in an electronic piano employing such reeds as tone generators, to provide improved output tones throughout a wide pitch range.

An object of this invention is the provision of means for producing formant effects in an elecerably, no direct sound radiation of the toneinvolves thegeneration of broad bands of vibration frequencies varying in mean or average value from one end of the piano bridge system to the other. Such vibration frequencies arise both by hammer impact action on the tensioned strings and by forced and resonant action and reaction between the strings and the bridge-soundboard structure. If, for example, a C key for a 130.8 cycle per second, lower register string be struck and the bridge-soundboard structure in the region of such string has a broad frequency response spanning 130.8 C. P. S., the bridge-soundboard structure will readily accept the 130.8 C. P. S. vibration partial I of the string. In fact, the structure willalso accept the higher numbered, integrally-related vibration partials of the string and will radiate all such vibration frequencies as long as the string continues to vibrate. Forth'ose vibration frequencies of the soundboard having the strongest coupling, together with efiicient radiation or other damping losses for strings having a group of partials within the soundboards strongly coupled band of frequencies, those string partials within this band will be relatively more rapidly damped than other partials of the string. Also, for these frequencies the bridge-soundboard structure will react back on the string to influence string vibration, in the manner of all coupled, resonant vibrators, mechanical or electrical. The net acoustical effect of the formant action is to make those vibration partials which are rapidly transferred to the soundboard of strong, initial amplitudeand shorter timeconstant.

In electronic musical instruments there is, preftronic piano employing vibratory reeds as tone generators together with means for selectively produce output tones of varying such effects to desired character. 26

\ predetermined manner.

An object of this invention acoustic means.

These and other objects and advantages of the invention will be apparent from the following description when taken with the accompanying It will be understood the drawings are forpurposes of illustration and are not to be condefining the scope, or limits of the invention, reference being had 'forthe latter purpose drawings.

strued as to the appended claims.

An object of'this invention is the provision of a tone-producing assembly for an electronic musical instrument said assembly comprising a reeds secured to a .reed rail, vibration-translating pick-ups associated with the reeds, pick-up supporting means secured to the reed rail, a vibratile support for the and electro-magnetic means for vibrating the vibratile support in a is the provision of a tone-producingv assembly for an electronic musical instrument and comprising a series of vibratory reeds and associated pick-ups mechanically coupled to a common reed rail, a rigid base, resilient members disposed between the reed rail and the base, mechanico-electro-acoustic means for translating reed vibrations into sound, electromagnetic means for vibratingthe reed rail, and an electrical feedback circuit connected between the electro-magnetic means and the electro- In the drawings wherein like reference characters denote like parts in the several views:

Figure 1 is a curve illustrating the relative amplitudes of the vibration partials of a tensioned string mounted on a massive, non-vibratile support;

Figure isipa curve :simwingstheavariationof; the amplitude of a soundboard (of a high quality, large-size, grand piano) related to the vibration frequency of the immediately proximate; tensioned string; 1-

Figure 3 is a fragmentary, top plan view of a reed and pick-up assembly made in accordance with my invention; 7

Figure 4 is a front elevationrnf the assembly shown in Figure 3;

Figure 5 is a cross-sectional view taken along the line A--A of Figure 3; w i

Figure 6 is a side view of in Figure 5 and including a diagrammaticshowing of my arrangement 'for vibrating the reedpick -up assembly to provide" desired formant eflects;

Figure flis similar toFigure'fi, with the-elec trical components omitted, and s'howing: a modi flcation of the invention wherein th plate sup-- porting the pick-ups is madec of non magnetic material;

Figure 8 is a plan view similar to Figurew3, and showing another construction of the pick-ups and their supporting posts;

Figure 9 'is a' longitudinal, cross-sectional view taken along the line A-A' of Figure 8; and

Figure 10 is a cross-sectional view similar to. that-of Figure 9, and showing-a2 single pickup and. supporting: post' of another iconstruction, drawn to an enlarged scale;

As is well, known, the initial: amplitudes of the r vibration partials of a tensione'd string mounted r on alrigidbase, are not-equal 'but,:rather, decrease T substantially; :uniiormyly as tha partial number-increases; Figured. lillustratessth'e relative vibration-amplitudes". ofcthe first mne vibra-r tion partials not 1a tensioned. stringnit iceingznoted that the partials are integrally related and' that the partials higherthampartialrIVlhave am amplitudeiess than'one-half that of the ifundamental partialaL The :decrease: in;v amplitude from. one ,to the nextghigher martial iswdetermined chiefly by the r characteristics r :of ithe string', the softness andlength of thevstriking hammeralong the string, and the specific point on :the string, where the hammer strikes, However, any one of I 1 these partials mayibe entirely, absent, or-of ab: normally lower amplitude, ,dueto the dampin action ,ofthe exciter, hammer during actual impact'with' the string, .yIna piano, the striking point, along the string, is sochosen that the Partial VI'I'is so "eliminated, crdamped. out:

' As "stated above the bridge-soundboard *structure'ofapiandhas abroad-bandirequency characteristicwhich" varies throughout *the scale of strings-from the lowerend of the bass bridge to the upper-endof the-'treblebrid'ge; "Many fac tors in-fiuence this frequency characteristic from point "to point along-the scale suchaspthe "distribution of the thickness; mass and iongitudinal stifiness of the bridge, the bearing"-pressure-of' the -tensioned-strings upon-the bridge, theproxthe assembly. shown ing rate'ofthe soundboard varies with humidity.

4 board for diiferent frequencies along its length from bass to treble ends, etc. Since the soundboard is, in effect, an upwardly and convexly arched membrane of irregular shape and variably loaded by the bridge, and since it is pressed wa d bathe pressure .of,a1i the,,strings into ram equilibrium p'psition aagainstg, its own upwardly acting compliance, its natural vibration frequency varies along the entir bridge in amanner that is difiicuit to calculate or, in fact, vclui'rlicaterin"arrygvgiren number of instruments.

pPiams made by the same manufacturer and which appear, outwardly, quite identical in design and-*cmistructicn-will sound differently in "1 .i .01 gch'ief, interest; here the. same .nitehiranges.

is the fact that the soundboard frequency and damping character- ,yistics mavkedly .aflect the complexion of the out- Duttones by formant action, and this tonal complexion varies, or shifts along the pitch scale of every such instrument-in a way which is detel-mined chiefly by these formant effects; In addition- 'to the net overa1l difference in the J formant effect as 'establishedbythe initial physical relationships of the coupled parts; the damp- For example, a piano with a soundboard having little or no -moisture content will sound bright and crispL With-.-continued exposure to highhumidity atmosphere the soundboard will absorb moisture and its it natural vibration frequencies" will-be -lowered due to -the-added loading effect of this water content and the rise in its; internal vibrational 'resistanca whereby the output-tones will have a- -higher damping rate and tvill sound dull and lifeless.

-Intests made ona small'grand -piano Ihave found that r the' natural vibration frequencies *of the soundboard varied smoothly from 90 to 550 cycles persecond; between the two-extreme ends +2. of "the bass and treble bridges. In the larger grand pianos the: drequency'range has"a larger spread and theatrequency variation is more uniform ovemthascalemangm (Figure 2 is a curv showing the vibration amplitude of. a soundboard, at positions immediate- 1ybeiowtstrings having:the indicated fundamentalrfrequencies, or a -largest size grand plane of Europeans.i'i'ianufacturei Superimposed -on such curve is a' similar curve-of anideal soundboard.- Ideally; ofrcourse; the soundboard should have a response frequency close to that of the adjacent strings .andsuch curve should be smooth; start ing at about 30 cyclesrper second and endlng at" 4,000 to-5,000 cyclesper -second. Then thecorwould bedepressedain amplitude. However; the;

vibration partial II n'fsuch-string. has a frequency 1 of 1,000 C. P. S; falling 'atithe relatively highpoint Ben the curve and, cons equent1y, thisvibration imity of "the bridge to--thefixed edges off thepartia1' is elevatedprelatively, lintoutput sound amplitude. .,Anotherstring.having, a fundamensoundboardy'the thickn'es'sgofthe soundboard and:

constants' oifithe: materialior LWIi'ic ifihese w rts;

tai,vibrationjrequencyof $50G. ,P. wouldhaye. a relatively, elevated amplitudefonpertial 1' (fa l ing at the point C)' while its partial II of: 900;,;,- are *made, 'the radiationempiencyzofithe sound-f JMCPR, vouldheneprassed (iauing. ,at- .the no1nt rectmimpedanceematching for uniform energy transfer: from the strings f to the soundboardwould "obtain- =and =there would "be no "regions of the: scale-where the tonequal-ity would b markexample; ii" a bridge-coupled D). Since the quality of a piano tone changes as the string vibration amplitude falls off, the first example tone, having its partial l1 damped out at a rate greater than partial I, will have a noticeably different quality than the second example tone subject to the reverse damping effect.

Sinc soundboards are strongly damped mechanico-acoustic transducers, their vibrations do not continue much beyond the time confines of a few cycles of string vibration and their action is very closely similar to that of the formant effects in the mouth, nasal passages, larynx, etc. of the human voice apparatus. These members, in different individuals, produce different tone qualities at the sam pitches due to the strongly damped but intra-oyclic resonant actions of these coupled resonators driven by the air puffs released by the vocal chords. In wind instruments, the formant action is varied from one instrument to another chiefly by the shape of the air column confined more or less within the boundaries of the instrument. In soundboard instruments employing the same kind of strings the formant action and output tone quality is varied from one to anotherchiefly by the soundboard design as to frequency and damping characteristics.

In electronic musical instruments having no soundboard, such as instruments employing vibratory reeds for tone generators, the formant effects must be provided by an added element whose vibration is induced by output of the tone generators and such induced vibrations is reintroduced into the translating system.

In order to provide formant effects, in a vibratory reed type of electronic musical instrument, simulating those of conventional instru ments, the vibrational characteristics of the formant-producing system must correspond to those of the particular instrument being duplicated. Since the frequency damping characteristics of soundboard instruments are not yet entirely known and since their damping characteristics are very difficult to measure by reason of their high absolute values, the duplication, in an electronic instrument, of a particular conventional instrument must be accomplished by cut and try methods. When, however, the formant-' producing system to be added to an electronic instrument is provided with variable frequency and damping controls along the scale of the tone generators the effects maybe adjusted independent- 1y, until the listening ear accepts the electronically produced tone as comparable to the tone of a conventional instrument.

In carrying out my invention, as applied to a clamped-free reed type of electronic piano, I provide. a vibratile support for the reed-vibrationtranslating pick-ups which supportis attached to the reed-mounting rail in such manner that. the reeds, when vibrating, tend to vibrate the pick-up support whereby the translating system will translate the combined vibrations of the reeds and of the pick-ups relative to one another.

Reference is now made to Figures 3, 4 and 5, Figure 3 being a fragmentary top plan view of one novel mounting arrangement for the pickups, Figure 4 being a front elevation thereof, and Figure 5 being a cross-sectional view taken along the line AA of Figure 3. Th vibratory reeds I I), I I I2, are clamped to the rail I3 by suitable, hardened set screws I4; I5, I 6, each such set screw being alined with a cooperating similar screw such as the screw I5 shown in the crosssectional view of Figure 5. The'reed rail I3 is v provided with transverse holes I1, l8,-'" l9 afford ing unrestricted vibration ofv the individual reeds. This particular reed-clamping arrangement offers numerous, practical advantages. Each reed is adapted for excitation, percussively or otherwise, by any suitable means and will vibrate in the direction indicated by the arrows a-a in Figures 4 and 5. The vibration-translating pickups, here shown as the capacitive type, comprise the individual metallic plates 20 to 21, inclusive, each plate being secured to the associated post to 31 as by the screws 28, such posts being made of suitable insulating material such as a plastic. It may here be pointed out that the posts are internally threaded to accept the fastening screws 28 and each of the pick-up plates is provided with an oversize hole whereby the spacing of the plate relative to the adjacent side of the reed may set to a predetermined value before the fastening screw is tightened. Further, if the plane of one or more of, the pick-ups is to be altered with respect to the plane of the associated reed, when the latter is in the at rest position, this can be done by driving the insulator posts in one or the other direction in the holes provided in the metallic plate 40. made slightly undersized relative to the outside diameter of the posts whereby the posts will be self-supporting when driven into such holes. Alternatively, the plane of each individual pick-up can be altered by placing shims between the pick-* up and the top of the supporting post. Each pair of pick-ups is so positioned that the transverse axis thereof coincides with nodal point for the vibration partial II of the intervening reed. Thus, when the reed is excited by percussive means, such second vibration partial, which is dissonant relative to the reeds partial I, is eliminated from the translating system.. The plate 49, preferably made of steel, is secured to the lower surface of the reed rail I3, by screws located between the reed-clamping screws, and is spaced from the plane of the reeds a distance suilicient to permit maximum amplitude of reed vibration. It will beapparent the pick-ups are electrically insulated from the reeds andthat all reeds can be connected into .an electronic circuit by means of a single lead. attached to any part of the reed base I 3 or plate 4i}, and that the pick-ups all can be connected by means of a lead secured to the ends of the fastening screws 28. Those skilled in this art will know the reeds and pick-ups form part of a radio-frequency circuit in which the oscillation frequency or amplitude is affected by the capacity between the reeds and the pick-ups and such frequency or amplitude will be modulated by the change in capacity brought about by vibration of one or more of the reeds relative to their associated pick-ups or of the pick-ups relative to the reeds. Such modulations are suitably amplified, demodulated, etc. to operate a loud speaker producing audible tones.

In order to superimpose desired formant eifects into the audible output tones of the instrument I mount the assembly, shown in Figures 3-5, on a relatively'thick, non-vibratil base and provide electro-magnetic mean rfor vibrating the assembly in a specific manner by feedback energy derived from the electrical output circuit of the pick-up system.

9 Reference is now made to Figure 6 which shows the assembly of Figure .5, comprising the reed rail I3, reeds II, pick-upsi24 and the supporting plat 40, secured to :the side of a thick n'onvibratile base bymeansof screws 46, washers 48. The'screws 46 pass through holes 46', see

The holes in the plate 40 are amvem amplitude lrelativeito that of the struck reed) 01 the platedmto ward andaway from "the reed; as: shown by: the? arrowsrc; c. Vibration of: the reed base: I 8'; iandioirl'the plateif W, :is reslsted by the compliance ot-ftne "bend in thezplatc 40, the com-'- pression'randzcompiiance niithe pad' fli as-well bysi'itsr internal viscosity ror vibrational resistano(=.-': Insamusical seriesi'or tunedii reeds- -the length of the? individual" reed'siwillivary; generailvtfrom' a maximumnini the low fre'quency'orbass section I to e: m'inimum'i in" the high -frequencypr treble increased whiteuortne'pomtsn to mandate G'i" the i'energwiossesmusthe decreased."-

Iriia' tensioned string: piano, each string has a series very nearly integrally-related fie quen'cy partials whereas. a clamped -free reed hasno such fortunate partlal frequencyrelationship;

The relationsliipof such partial frequencies to the fundamental frequency (partial 1) is as follows:

Freq. ofPartial to Fundamental rciamp'ed- L String section; Since it? is desirable to position each paiflofi'pickx-ups atathers-nodal point of vibrationpartial llxfort'the"interveningt reed, it is-apparent" therwidth ofdthepick up supporting: plate 40 will i varyfixi likezmanrier: I prefer to makethe width" of r the' plate". 40 2 about 80 of the length. of the innnediately above-disposed reed so that such platex width z'will also' be a:vmaximum at the low' frequency reeds-position and a minimum at the high: frequency? reedz position. The thickness of the plate andthe elasticity :of Y the material of whichrthnrplate is made are 1 so "chosen" that the plate s segmental :vibration period *is about equal to thefundamental frequencies of the immediate- 1y proximatetreedsi The-plate thickness for any 35 glverr pointi m'ay be found by forming such" a plate i'segmentzequal to thecentr-to-cehter spacingf of the'reedsy attaching-thereto a pair "of sup-'- port p0sts, iplck-ups and fastening screws to rep-- resent theieactualllplateiloa'd, clamping such arrangement in" a vice, vibrating the free end (ca-rryingthe picis-ups) land-actually measuring thevibration frequency: The plate -Ml preferably is made of steel, for purposes to" be 'explainedhereinbelow," ami itscorrect thickness is that which will give a frequency" response equal to that of the-moximate reed," with due consideration being given;to' -suclrliifaietors asathe': loading 1 provided by the :"pick ups and; their supporting structure. If necessary; holes may'be drilledthrough'the plate to raise the naturalvibrationi frequency *above "its normal value;- or loading-membersoflead brother material "maybe as specific points=to lower thewnaturai frequency; alltfo'r th'e purpose-of-pro-- ducing' a' particular and varying frequency chars acteristic: 1 -along' the p1atelength; thatfis', the dlmensionIin the longitudinal direction or the rail? la; 1 havezifoundi that'iforireeds havingwa thick nessrroi 0.032 winch; the: plate lil may be' =made-"of inchthiclc steel, in order to have the approxi mately correct frequency response alongthe scale" of reeds.

sincerithe damping" characteristics of an actual piano' soundboard; as shown bythecurve 'of Fi 1 ure 12 also varyi'alongItheapianobridgeathis fac tor imust'iialsolbe:rsiriiulatediintmy vibration= simu-= latingfi pick 'up'support' 'lil Forthls-upurposetthe width, :thicknesspr viscosity' of thelpad 41 maybe varied, along the length of the plate-"MT; these means the desired variation of: damping may; be obtained as distinguished from 5am other wisesmooth-curve such'asthe eurve ofwtheidealizedt soundboard shown-- Fomsuchi high-dampingmeal-chaosittieipointsm aad n'om? the curve thadainpingor energy lowes -mush When a? tensionedstrinsof a piano vibrates" with" varying pressure on an associated soundboard's hirldge each and all of its many and closelyespaced' vibration partials produce their owniiv'rbrating forceson the soundboard; -Also,

other neighboring and further distant Striiig-s havingrfone or? more-partial frequencies equal to one' or' more-partialsr of" th'e excited string; and' having more or less-coupling to it; will respond byiresonant vibration producing a complextone:

Also; thehhammer impact on the string is transmittedr to: the 1 soundboard producing a wide: and

continuous band of irequencies' resulting in the characteristic thump or rap."" In the* case of a: clamped-free reed" the vibration partials areim'uch further':'separated; frequency w is'e; and suoh partials areficompletely inharmonic; Thus,

the nearest reed; in'a musical scale series of tuned reeds; havinge- -near resonant vibration compo nent; equal' 'in frquencyto partial I of i an excited reed will beereinoved liva frequency spread of 6.27: times 'the fundamental frequency of the struck read; 1 Such frequency spread corresponds to about "2 /2 octaves above the struck reed 'or' a distanc'e equal 'to about 30' reeds along thereed ram 'riiis' compareawitn a spacing-of'about'lz strings in a" conventional piano. Consequently. the coupling irra 'tehsioned string piano is tighter thaniri an electronic piano utilizing clamped free vibratory reedsl Also, as alreadystated' partial" II of a vibratory reed 'is dissonant with partial I. Therefore, the partial vibrations of a reed flnd very'few, if any, resonant'partials, in a series of tuned reeds, to augment the transits-ml reed" vibrations; factors, theassemblvend arrangement thus far tru'e tonal eifectsbcorresponding' to those --of a given conventional musical instrument 'such" as, for'example: the piano. I'overcomesuch defij ciencyvbvintrcducing' into thevibratile pick-up support f many *integrally related vibration parmental: form, lam-adjustable polarizedcore' 50 surrounded by'a coili-h The =coil-is secured in fixed position within an. appropriate "aperture-in thebasa 45 am suitable means and the core Sm-ma be-threadedQto operaterwithimthe in: sulator tuberfl which;thacoilzisawound" 1 Sevenelmfo'suoh coils andecolte'r assemblienare :z' 'spaeedmt intervals talcum i the; longitudinatridh Because of these;

mension of the plate 40 and at different distances from the pick-up supports 34, as required.

the pick-ups and vibrating reeds are converted into corresponding electrical waves which are demodulated, amplified and fed to the speaker voice coil. As disclosed in my copending United States patent application Serial No. 169,714, filed June 22, 1950, the pick-ups can be sopositioned relative to the coacting reeds that the wave form of the amplifier output current will include a full series of Fourier series partials 1, 2, 3, 4, 5, 6, etc., times the fundamental vibration frequency of any one or more vibrating reeds. Such wave forms are fed to the coils 56 resulting in a vibration of the plate 40 (and the attached members comprising the reed rail, reeds, and pick-ups) in a manner corresponding to the normal frequency partials of the strings in a conventional piano. The phase of the feedback current may be made aiding or opposing, as referred to the partial I of the vibrating reeds, and of desired amplitude, by adjustment of the slider S on the potentiometer 53. Such adjustments will depend upon whether more or less amplitude of partial I is desired in the output tones of the loud speaker. It will also be apparent the magnitude of the feedback current can be made still further controllable, as by a separate amplifier and controls fed from the speaker amplifier. When the reeds and pick-ups are so vibrated, through the medium of the plate 46, a corresponding relative vibration occurs between the reeds and the pick-ups which vibrations are superimposed upon the translating apparatus to correspondingly affect the audible output, tones from the speaker.

With such an arrangement, then, the feedback currents contain all the component frequencies for setting up resonant vibrations not only in the octave-related reeds but also in those reeds having vibration partial frequencies of 1, 2, 3, 4 etc., or 4 etc., times the frequency of the excited reed. Furthermore, the broad, continuous band of frequencies of the vibratile pick-up-support plate provides innumerable other intervening frequencies corresponding to the roar of intermingled tones heard from a tensioned-string piano when played with the loud pedal depressed. Still further, the feedback-forced vibrations of the plate 40 will set up vibrations of the remaining, non-resonant reeds since such plate tends to vibrate, angularly, the fixed ends of all the reeds.

It is evident from the foregoing disclosure that the formant efiects characteristic of any type of soundboard instrument may be simulated. In electronic sustained-tone instruments, such as organs and the like, it is customary to use electrical formant circuits in an effort to simulate various conventional sustained-tone instruments of the direct acoustic type. Such circuits may also be used with my reed type mechanical vibrator instruments of damped or sustained tone type. It may here be observed that these prior electrical formant systems, having no direct coupling with the tone generating means and particularly no such coupling which varies note by note through the pitch range according to the formant frequency characteristics of conventional instruments, can only be efiective in the =10 particular pitch range for which they function. Such pitch range is only of a length of two or three octaves in the musical scale.

My direct mechanically-coupled electromechanical formant system can be so tuned and damped over its longitudinal dimension along the reed scale so as to secure any desired formant frequency effects in any or all parts of a scale having any desired pitch compass, or at least to a practical extent within the limitations imposed by the human ear.

While I prefer to make the vibratile plate, which supports the pick-ups, of magnetic material, the invention is not so limited. Reference is now made to Figure 7 wherein the pick-up supporting plate 40 is made of nonmagnetic material such as, for example, aluminum. Vibration of the plate is brought about by a plurality of soft-iron rivets 59, one such rivet spaced from each of the polarized cores 50.

In the Figures 3-7 embodiments of the invention the pick-ups comprise fiat, metallic plates secured to individual posts of insulating material. A preferred form of pick-up and mounting arrangement, from the standpoint of facility of assembly and adjustment, is shown in Figures 8 and 9. Here the individual pick-ups comprise a substantially U-shaped member 60 having offset ends 6|, 62 lying in planes parallel to that of the reeds H], II, H2. The pick-up 60 is secured to an insulator bushing 63 by means of a screw 64 which passes through a clearance hole in the bushing into a threaded hole in the base of the pick-up. The bushing 63 passes through a hole in the plate 46 and is secured thereto by a suitable nut 65. Thus, the pick-ups are insulated from the plate 40 and can be connected into the circuit by means of leads soldered to terminals disposed under the heads of the screws 64. It will be noted that a single pick-up is associated with two reeds and a slight amount of adjustment between the pick-up ends 6|, 62 and the reeds can be accomplished by appropriately bending the body and ends of each pick-up. The transverse center line passing through the alined ends of the pick-ups (such as the section line BB of Figure 8) coincides with the nodal points for the vibration partial H of the reeds, for purposes already explained.

Figure 10 shows another construction of the individual pick-up supporting post for use with a U-shaped pick-up of the type shown in Figures 8 and 9. Here the pick-up 60 is secured to an insulator bushing 61 by the screw 64. The bushing 61 is provided with an external thread which cooperates with a threaded hole in the plate 40 whereby the plane of the pick-up ends 6|, 62 can be adjusted relative to the reeds H], II. The bushing 61 is then looked in position by the nuts 68, 69 which may be made of metal and of a type such as those used for mounting conventional toggle switches.

Having now described several embodiments of my invention those skilled in this art will be able to make certain desired variations and modifications in the individual components and their assembled relationship without thereby departing from the spirit and scope of the invention as set forth in the following claims.

I claim:

1. In an electronic musical instrument of the class comprising a plurality of tuned reeds carried by a reed rail, reed-vibration translating pick-ups associated with the reeds and an electrical network for. translating relative vibrations aengzai between the: reeds pick-upsinto electrical combination, To'f felectroniafinetic means adapted. when .energized, to vibrate. the

reed. raiiandpickj-upa .andlfeedbackmeans enerkizin'ejthe saidielectroemagneticfmeans.from the Ictrica1...ritwork.

' IIn anjele'c'tronic. musicalfinstrument. of the class fcomp'rismga plurality of tunedlreeds carried by .a reed frail, reed-vibration translating piekeiips.associatedlwith'the reeds and an electrical'ntwork for translatingrelative vibrations between the .reeds and pick up's into electrical waves.thelcombinationof a vibratile plate mechanic allvcoupled'tof the. reed rail and pick-ups,

'lecti'o'-magnetic' means adapted when energized "the eieemem net wdrk.

3.. 'Tl'ie'f invention as recited'in claim 2, wherein the 'saidvibratile plate. is made of magnetic material,

4. "The. inventionfas recited in" claim .2, wherein the said vibrati-le plate carries "magnetic material members.inagneticallylcoupled to the said eIectro-m'agnetic. means.

r 5. A musical instrument .comprisingaplurality of'tiined reedscarried'by a' reed rail, avibratile plate secured to. .the. reed rail; reed-vibration pick=upsiassociated with. the reeds, said pick-ups being' carried by. and insulated from the said vibratilelplate; an electrical network translating relative vibrations between. the reeds and pickups into electrical 'w'avesj 'an electro-acou'stic deviceenergized, by th'elelectrical waves; .a nonvibratile"bas'e secured to the .vibratile p1ate,,said base havinga surface'spaced from thesaid. plate; electrof-magnetic means carried by said base and adapted. when energized, to vibrate the vibratile 'plate;. and a feedback circuit'connected between theelectrof-mag'netic device andthe said electiilcalfnetwork.

"6. 'Iheinvention as recited in claim 5,. include lug, a member .ofvi'sco-lelastic" material disposed betweenj'the said, plate a'n'dba'se'.

"'7. .Amu'sical instrument of the. class employing an"eiectrical"networkf including an output .circuit havingian electro ac'oustic device; .saidinstrue inentcoi'nprising .a'ree'd rail ;'f a plurality of .vibratory reed'secure'd to and. spaced alongthe reed railpa vibratile plate secured .to the reed rail and 'spacejdl'trornjthe reed's;* an ofiset end in the plate fin .the' regionqoflthe .reed rail; 51,1101)? vibratile'basehavinga surface spaced" from the saidplate; ineans' securing the offset end .of the plate to "the 'base; insulator members secured 12 to. thesaid vvibratilaplate; lreedevibrationetranslatin'gi. means carriedby .the insulator members,

. said .translatinglmeansiorming .part. of \the electrical .network .electroiemagneticmeans carried by the non-vibratile base and adapted,;.,iipon energization, to vibrate the .vibratil'ebase; and

. means energizing said electro'em'agnetic means from the output circuitjof the.- instrument. 8. The invention as. recited inclaim'l, wherein the 'vibratile .plate-isimade of magnetic ,material and said electro-magneticmeans includes anl a'djustable, polarized core-having an and spaced from the saidiplate. j

9. Theinventlon as recited in claim'l, wherein the vibratile plate islmade .0: .nQn-magnetiQmaterial .and including .a niaiineticematerlal men'1- ber. secured to. the said plate and in spacedaune ment with I said electro-m'agnetic means.

10. A musicalinstrument of the class employing an electrical network. including an output circuit having an ,electroeacoustic. device; said instrument. comprising a reed .rai1,".a plurality of vibratory reeds secured to and. spaced along the reed rail; a, vibrati-leplate secured to'.the...re'ed rail and spaced. fromthe reeds; anv offset end in the. plateinthe region ofthe reed rail; anon- -vibratiie .base 'havin'gea surface spaced from the .said plate; .means securing the offset end ofthe plate to the base; a visco-elastic member disposed between the. said .base. and plate; insulator. in'emibers secured to the vibratile plate; capacity pick- Bmamm immssrma; .2

References (liter! an *the me or: this patent UNITED" 'sTA'ijEs'ii'PAfrENTs

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