US2627555A

US2627555A - Method and apparatus for sound recording and reproducing

Info

Publication number: US2627555A
Application number: US155750A
Authority: US
Inventors: Luberoff Louis
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-04-13
Filing date: 1950-04-13
Publication date: 1953-02-03
Anticipated expiration: 1970-02-03

Description

L. LUBEROFF Feb. 3, 1953 2 SHEETS-SHEET 1 Filed April 13, 1950 phone Micro f agg Phone),

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METHOD AND APPARATUS .F OR SOUND RECORDING AND REPRODUCING Filed April 13, 1950 2 SHEETS-SHEET 2 LICI. 3

IZi/fbior Louis Zuberojj atented Feb. 3, 1953 UNITED Ni" OFFICE .SMETHOD AN D APPARATUS IFOR 'SOUND l RECORDING AND REPRODUCING This inventionrelates tothe recording and production of piano musiceither aloneorrincombination withother instrumentalities as hereinafter described.

The present 7 application is a continuation-inpart of my copending application .Serial No. 609,747, filed August 9, .1945, now Patent No. 2,530,251, issuedon, November 14, 1950.

One object of thepresent invention is to provide; an improved method and system. for recording piano, music.

fieretofo e, .it-has .beengthe practice to record piano music by means of a microphone; which receives sounds by air conduction from the piano and produces a corresponding electrical signal which is amplifiedand supplied to .a recorder. This method of recording -does notresult inaccurate sound reproduction of piano music. A predoim'nant characteristic of thepiano is that it has a rapid tone decadence, and because of such action, themicrophone method of recording is notwell suited for piano recording. Furthermore, thepoor acoustics of many auditoriums and studios adverselyafiect recording by themicrophone method, especially in the case of large auditoriums and studios where orchestra and piano concertos are performed and recorded. However, despite its disadvantages the microphone method has been used in the past forwant of a better method.

In accordance with one aspect of the-present invention, there I is provided .a method of piano recording which is entirely free of the shortcomings of the microphone method and which enables exact record reproduction of piano music. According to this method, the physical vibrations of the piano sounding board and for the associated strings are translated-directly into an electrical signal which is amplified and supplied to a recorder. .By this method, it, is possible to control the amplitude of the .signal through the use of hand or .kneeoperated volume control means as hereinafter described. Furthermore, it is possible to utilize a combination-ofthis'method and the microphonemethod, with individual gain controls for thesounding board pickupsand' the microphone. Further still, in the preferred embodiment of the invention provision is made for utilizing a small portion of the signal asan audible indicatin means duringcertainrecording operations involving other instrumentalities. .as hereinafter describedbesides an electrical .visual decibel meter.

Another object of theinvention iseto providewa novel-syst m and.no iel devices ior-improved re- '14 Claims. (Cl. 179-10011) 2 cording and production of .piano .music .either alone or in combination with. other instrumentalities.

The invention maybe fully understoodffrom-the following detailed description .with reference to the accompanying drawingswherein:

Fig. Us a front elevational view. of a'piano, embodying the present invention;

Fig. 2 is a diagrammatic illustration oftheelectrical system; and

Fig. 3 is a horizontal .sectionaleview showin .a preferred mountingof thepickeups.

, Referring firsttoFig. 1,.there is showna piano It whichmaybe of the character disclosed in my appending ,application .Serial .No. .5.3,808,';,filejd October 11, 1948. -Suchpiano-is oflthe spinet type and it is provided with lid-closed compartments I I andiZ within which there are disposed respectively a recorder l3 and a phonograph J4. The piano is also provided with radio receiving apparatus, the tuning section of which is centrally mounted as indicated at l5. Control knobs, designated generally by reference characterjfi, are provided to control the radio receiving. apparatus and alsoto control the.hand-operatedelements mentioned hereinafter. An audio frequency amplifieris represented at 11. .At least oneloudspeaker is is provided, and if desired two loudspeakers or more maybe arranged as shown in Fig. 1. A pair ofknee-operated levers l9 and 20 are also provided,the purposeof which ,wilLappear presently.

It should be understood thatthe presentinvention is notlimitedto any particulardesign or type of,-piano,.that illustrated in Fi g. 11being merelyan example.

Referring nowto Fig. 2, thepiano sounding board, aportionof which isshown at 2l,.has.associated therewith one or morepick-ups, there being two pick-ups 22 and 22a shown in the illustration These pickeup s may be. conventional electromagnetic or other type pick-upsandthey may be associated with thesounding board itself and/ or with the strings (not, shown) inanysuit- -able'manner so as to respond to thephysicalviconnected to a double-throw *switch 26;which=operates in tandem with a similar switch 21. The purpose of these switches is to render operative either a knee-operated volume control potentiometer 28 or a hand-operated volume control potentiometer 29. Switch 21 is connected to the input of audio amplifier l1, the output of which is connected to double-throw switches 30 and 3| which may be tandem operated. The sound reproducer or loudspeaker I8 is connected to the output of the audio amplifier |1 through stationary contacts of the switches 30 and 3| and through

resistors

32 and 33 connected as shown. The recorder I3 is connected as shown to stationary contacts of the switches 30 and 3| through a transformer 34. A recording meter 35 is connected to the recorder circuit. A power supply unit 36, controlled by on-off switch 31 serves to supply the necessary operating voltages to the amplifiers H and 25.

, It will be seen from the illustration that the switches 30 and 3| serve in one position to shortcircuit the

resistors

32 and 33, and in another position to connect the recorder l3 to the output of the audio amplifier H. In the first-mentioned or upper position of the switches, the loud-speaker I8 is connected directly to the output of the audio amplifier l1, and the entire audio output of the amplifier is supplied directly to the loud-speaker. In the second or lower position of the switches 30 and 3|, the recorder circuit is connected directly to the output of the audio amplifier, and at the same time the loud-speaker is connected to the output of said amplifier through the

resistors

32 and 33. In this position of the switches, a predetermined percentage, e. g. twenty-five percent, of the audio output is supplied to the loudspeaker, while most of the audio output, 6. g. seventy-five percent, is supplied to the recorder. The reduction of the output supplied to the loudspeaker is due to the fact that the

resistors

32 and 33 limit the current supplied to the loudspeaker. The purpose of this arrangement will be described presently.

If desired, the switch |3a which controls the driving motor for the recorder |3 may beganged with the switches 30 and 3| so that only one manual operation is necessary to condition the apparatus for recording.

As hereinbefore mentioned, an important objectof the present invention is to provide an improved method and apparatus for the recording of piano music. With the switch 23 closed, and with switches 30 and 3| in the recording position, physical vibrations of the piano sounding board 2| are translated directly into an electrical signal which is amplified and supplied to the recorder. This method of recording is a vast improvement over the microphone method heretofore used. The pickups are individually adjustable as to volume of their outputs by means of the potentiometers 24. This is particularly advantageous if the pickups are arranged to respond predominantly to vibrations of different frequencies, e, g. treble and bass. During the recording operation, the volume may be controlled by either of the

devices

28 and 29. With the

switches

26 and 21 in the left-hand position, the knee-operated volume control potentiometer 28 is efiective. This device is operated by one of the knee levers l9 and 20 (Fig. 1).. Thus the person playing the piano can control the amplitude of the signal supplied to the recorder by actuating the knee lever while observing the recording meter. The knee lever may be spring biased toward the zero volume position, and by exerting knee pressure on the lever, the user may control the volume at will. If desired, however, the volume may be adjusted by hand, in which cas the

switches

26 and 21 will be in the right-hand position and the volume control potentiometer 29 will be effective.

It should be noted that the apparatus as thus far described is also adapted to function as an amplified piano. With switch 23 closed and with switches 30 and 3! in the upper position, the vibrations of the piano sounding board 2| are translated into an electrical signal which is amplified and translated into sound possessing natural piano tone. In this case also the volume may be controlled as above described.

As shown in Fig. 2, the system is further arranged for use of the phonograph l4 and the radio receiver equipment l5, and a microphone 38 is also preferably provided. The provision of these devices greatlyincreases the capabilities of the apparatus, as will be seen presently.

The microphone 38 is connected through a volume control potentiometer 39 and through a switch 49 to the input of the pre-amplifier 25. Not only does the microphone make possible the recording of voice with Or without accompaniment, but it enables recording of piano by a combination of the microphone method and the method of the present invention, utilizing a common amplifier for both. While the microphone method is not entirely satisfactory when used alone, it may be used to advantage in combination with the pickup method of the present invention where the acoustics of the room do not seriously interfere.

The outputs of the phonograph l4 and the radio receiver equipment |5 are connected to a selector switch 6|, which in turn is connected to a double-throw switch 42, the latter being ganged with a second switch 43. Knee-operated and hand-operated

volume control potentiometers

44 and 45 are connected as shown to the

switches

42 and 43 for selective inclusion in the circuit. The device 44 is actuated by one of the knee levers l9 and 2|] in Fig. l. The switch 43 is connected to the input of the audio amplifier H which serves as a common audio amplifier for the various instrumentalities. The necessary power is supplied to the phonograph I4 and the radio receiver equipment l5 from the power supply 36 through onoff switches 46 and 41.

By means of the additional instrumentalities, the system is adapted for various uses in addition to the recording and reproduction of piano music. Thus, the piano may be utilized alone, either for recording or reproduction, or it may be used in combination with the other devices. For example, the piano may be played as an accompaniment to a phonograph record, either for reproduction or recording. In this connection, it should be noted that there are available phonograph records of piano-orchestra concertos and the like in which the piano part is omitted purputi-of-audio amplifier I -1f-isisupplied:to the loud speaker, and -the reduced -'-sound :output of :the loudspeaker provides low- "but audible reproduction of--voice,- radio program or phonographrendition being recorded. -At the same tim-e, this audible reproduction is insumcient to-cause mechanical feedback to the recorder... cutter head. Thus loud .voice, radio or phonograph passagesmre.reproduced at low #audible 1eve'1 Wi-thoutcausing mechanical feedback, forexamplelwhencplaying in conjunction .-with the piano in concerto style. Moreover the microphone control maybeset for high volume without causing howling dueeto acoustic feedback between the loudspeakerand the microphone, thus-.. permitting recording at high volume without I recording i any extraneous howling effects. Furthermore, with respect to piano the large lBdlICtlOIl *output'iof the loud speaker likewiseprevents mechanical feedback-to recorder.

The system as illustrated provided awide variety of waysin which a recording-maybemade. These are as follows:

1. Piano may be recorded bythepickupmethod alone utilizing either hand orknee-operated volume control.

2. Piano may be recorded by a-combinationof the pickup-and microphone .metho'ds utilizing either hand orknee-operated volume control.

3. Piano-and -either radio-or phonograph may be recorded, utilizing the pickup method alone for piano,- and utilizingeither hand or knee-operated volume control for-piano and'for radio or phonograph.

4. Piano and. either-'- radio or phonograph may be recorded, utilizing-a combination of the pickup and microphone methods for-piano.

5. The microphone maybe utilized torecord voice-alone ortorecord voice-in combination with any of the other instrumentalities,utilizing hand or knee-operated volume control.

6. Radio orphonograph may berecorded alone, utilizing eitherhand-or knee-operated volume control.

The various instrumentalities -andvolume-controls actually provide fourteen *ways in whicha recording may be'made.

The composite instrument provided by this inventionis usefulin aWa-riety of placesand for a variety "of-purposes. 'Th'uS, it is useful in'the h0me,in places of "entertainment, 'ineducational institutionsretc. -For-scme-uses,*itmay be desirable to provide-for-coin oontrolled use oft-he instrument atcertain ti-m'es. --As shownin Fig."2, a conventional coin-control mechanism 48 maybe connectedin the-manner indicated, the switch 31 being-a double-throw switch which may be placed in either position. When placed in the righthand position, this --switch "will include the coin mechanism so that the instrument can be used only by insertion of a coin to -close-a switch in the coin mechanism.

A further feature-of theinventionresides in the pick-up -arrangement and- 'mounting shown in Fig. 3. A portion-ofthe'soundingboarddfl-adjacent the-'pick-up SDiscoVered-witha layer 51 of acoustically-absorptive soft material such as felt. This arrangement materiallyafiects the action of the pi'ck-upand provides improved tonal quality. The resultis the preduction'ofa' predominantly pronounced fundamentalwith less corroborating harmonics'related'to this fundamentaL-and also the lessening of prolongation 'of-the point of decadence. The-system and pick-up arrangement provide-a* very -flexiblemeans for obtaining the 6 most-Inaturalipianoftone byls'ele'ctively mixingzthe frequencies and amplitudes. of the pick-cups.

As. shown in Fig. $3, the pick-.aupsfifl and 1 52 :are firmly held respectively .againstithelayer :51 and the sounding board "49iby:means;of;

rigid brackets

53 and 54 secured to the .piano posts 55,;56rand

Eland carrying adjustablescrews

58 and 59 which engage disks fifl andfil. .Eachofithe pickaupsis enclosed a resilienturubbenhousing 62'- :or-63 against which .the disktil or; filtbearstto hold the pick-up firmlyv in place. .Inzoperatiori thppick-np armature is actuatedbyithe soundingboardewhile the rubber housing holds the pick upin placeby virtue of its'being compressively heldbetween the board. and .the backing disk or .plate. The housing also serves to'protect'thepickeup. .By virtuezof'its resiliency the housing-.doesmot sinterfereiwith the board vibrations.

'Thei ab'ove described*mountingtofvthe picksups eliminates so-called .wows which have been;encountered with priorvtypesof pick-.uptmountings, especially in notesof long sustainingaduration. Furthermore zthiS arrangement enablesreadyiadjustment'of frequency. As .the.screws 5 81or159 are tightened, the pick-up respondsincreasingly to higher frequencies and .decreasingly to lower frequencies. Suchadjustment enables; selective change of .the harmonic structuresofutheproduced sounds, and enables the :productionzoifdifferent tone characteristics.

From the foregoing description;itiwillzbei-zseen that .the invention provides a IIOYGL'QmBthQd and apparatus for piano recording, .and it: also provides a composite musical instrument whichhas wide capabilities. It will beunderstood, of course, that the invention is-notlimited tothe particular embodiment shown but 'is capable of various modifications and other embodiments.

I claim:

.1. In a system for ;electrically reproducing .or recordingmusic of a piano,'atleast'one-pick-up on the piano sounding board assembly fortranslating physical vibrations directly into an electrical signal, means for amplifying:saidsignaLza sound'reproducer connected to said amplifying means,'resistance means includedin circuit'with said reproducer, ;a recorder, and switch :means adapted in one :position to short circuit said resistance means and in another position to connect said .recorderto said amplifying means.

2. In a system 1 adapted ;for electrical grreproducing or :recording of piano music, and also adapted for electrical reproducing orxrecording of radio, phonograph or.microphonerenditions; pick-up means on the piano sounding board-assembly for translating physical vibrations directly into an electrical .signal; yradio :receiving equipment; a phonograph; ami-crophone; :azcommon audio amplifier; meansxfor'selectively:connecting said pick-up means, saidradio receiving equipment, said phonograph and said microphone to the input of said amplifier a recorderya sound reproducer; and means :for supplying :the .audio output of said amplifier either to said recorder or to said reproducer; knee-operated volumecontrol means for controlling the signals from said pick-up means and said microphone; and other knee-operated volume control means for controlling the signals from said radio receiving equipment and said phonograph.

3. In a systemadapted for electrical reproducing or recording of piano music, and also adapted for electrical reproducing or recording ofradio, phonograph or microphonerenditions; pick-up means on the piano sounding boardassembly for translating physical vibrations directlyinto an electrical signal; radioreceiving equipment; a phonograph; a microphone; a common audio amplifier; means for selectively connecting said pick-up means, said radio receiving equipment, said phonograph and said microphone to the input of said amplifier; a sound reproducer connected to said amplifier; resistance means included in circuit with said reproducer; a recorder; and switch means adapted in one position to short circuit said resistance means and in another position to connect said recorder to said amplifier.

4. In a piano having a sound board, two selectively adjustable electrical pick-ups mounted in cooperative association with said sound board for picking up mechanical oscillationsthereof and converting said oscillations into electrical impulses, means for amplifying said electrical impulses, a sound reproducer connected to said amplifying means, means for mounting one pickup so as to effect translation of the said mechanical oscillations into their equivalents in electrical impulses, means for damping the mechanical oscillations of a portion of said sound board cor-responding to the mounting location of the second pick-up, and means for mounting said second pick-up in cooperative association with said portion of said board so as torespond to the damped oscillations of said portion.

5. In a system adapted for electrical reproduction of piano music, and also adapted for electrical reproduction of phonograph renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a common audio amplifier; means for selectively connecting said pick-up means and said phono graph to the input of said amplifier; a sound reproducer connected to the output of said amplifier; knee-operated volume control means for controlling the signal from said pick-up means; and other knee-operated volume control means for controlling the signal from said phonograph.

6. In a system adapted for electrical reproduction of piano music, and also adapted for electrical reproduction of phonograph or microphone renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a microphone; a common audio amplifier; means for selectively connecting said pick-up means, said phonograph and said microphone to the input of said amplifier; a sound reproducer connected to the output of said ampliplifier; knee-operated volume control means for controlling the signals from said pick-up means and said microphone; and other knee-operated volume control means for controlling the signal from said phonograph.

7. In a system adapted for electrical reproduction of piano music, and also adapted for electrical reproduction of phonograph renditions; at least two pick-ups on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; means for varying the frequency response of each pick-up; a phonograph; a common audio amplifier; means for selectively connecting said pick-ups and said phonograph to the input of said amplifier; a sound reproducer connected to the output of said amplifier; knee-operated volume control means for controlling the signal from said pick-ups; and other knee-operated volume control means for controlling the signal from said phonograph.

8. 8. In a system adapted for electrical reproduction or recording of piano music, and also adapted for electrical reproduction or recording of phonograph renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a common audio amplifier; means for selectively connecting said pickup means and said phonograph to the input of said amplifier; a recorder; a sound reproducer; means for supplying the audio output of said amplifier either to said recorder or to said sound reproducer; knee-operated volume control means for controlling the signal from said pick-up means; and other knee-operated volume control meansfor controlling the signal from said phonograph. V

9. Ina system adapted for electrical reproduction of piano music, and also adapted for electrical reproduction of phonograph renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a common audio amplifier; means for selectively connecting said pick-up means and saidphonograph to the input of said amplifier; a sound reproducer connected to the output of said am plifier; and knee-operated volume control means for controlling the signal from said phonograph. 10. In a system adapted for electrical reproduction of piano music, andalso adapted for electrical reproduction of phonograph renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a common audio amplifier; meansfor selectively connecting said pick-up means and said phonograph to the input of said amplifier; a sound reproducer connected to the output of said amplifier; hand-operated volume control means; kneeoperated volume control means, and means for connecting either of said volume control means in circuit between said phonograph and said amplifier for control of the amplitude of the signal from said phonograph.

11. Ina system adapted for electrical reproduction of piano music; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; an audio amplifier; means for connecting said pick-up means to the input of said amplifier; a sound reproducer connected to the output of said amplifier; hand-operated volume control means; knee-operated volume control means; and means for connecting either of said volume control means in circuit with said pick up means and said amplifier iorecontrol of the amplitude of said signal.

12. In a system adapted for electrical reproduction of piano music; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a microphone; an audio amplifier; means for selectively connecting said pick-up means and said microphone to the input of said amplifier; a sound reproducer connected to the output of said amplifier; hand-operated volume control means; knee-operated volume control means; and means for connecting either of said volume control means in circuit with said pick-up means, said microphone and said amplifier for control of the amplitudes of the signals from said pick-up means and said microphone.

13. In a system adapted for electrical reproducing or recording of piano music, and also adapted for electrical reproducing or recording of phonograph renditions; pick-up means on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; a phonograph; a common audio amplifier; means for selectively connecting said pick-up means and said phonograph to the input of said amplifier; a sound reproducer connected to the output of said amplifier; resistance means included in circuit with said reproducer; a recorder; and switch means adapted in one position to short circuit said resistance means and in another position to connect said recorder to said amplifier.

14. In a system adapted for electrical reproduction of piano music; at least two pick-ups on the piano sounding board assembly for translating physical vibrations directly into an electrical signal; an audio amplifier having its input connected to said pick ups; a sound reproducer connected to the output' of said amplifier; means for varying the frequency response of each pickup; and knee-operatedsvolume control means for controlling the signal from said pick-ups.

LOUIS LUBEROFF.

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

UNITED STATES PATENTS Number Name Date 260,214 Mason et al June 27, 1882 1,616,416 Fessenden Feb. 1, 1927 1,689,524 Fortin Oct. 30, 1928 1,863,841 Fessenden June 21, 1932 1,893,895 Hammond Jan. 10, 1933 1,915,858 Miessner June27, 1933 1,994,889 Hammond Mar. 19, 1935 2,001,724 Hammond May,21, 1935 2,028,630 Stark Jan. 21, 1936 2,038,995 Hammond Apr. 28, 1936 2,073,071 Nernst Mar. 9, 1937 2,201,232 Helberger May 21, 1941 2,239,042 Kleber Apr. 22, 1941 2,307,454 Demuth Jan. 5, 1943 2,323,232 Miessner June 29, 1943 2,334,744 Benioif Nov. 23, 19-13