US2221970A - Sound recorder - Google Patents

Description

Nov. l19, 1940. M. M. GRUBER Erm. 2.221,97

Y soUND RECORDER AFiled April 8, 19:58, :s sheets-sheet 1 Nov. 19, 1940. M, M, GRUBER -rAL 2,22,970

SOUND RECORDER f Filed April4 8, 1938 K' 5 Sheets-Sheet 2 Patented Nov. 19, 1940 PATENT "FFICE l SOUND RECORDER Morris M. Gruber, New York, N. Y., and George J. Salba., Englewood, N. J., assignors to Presto Recording Corporation, New York, N. Y., a corporation of New York Application april s, 193s, serial No. 200,926

11 Claims.

This invention relates to sound recorders, and

more particularly to a compact, portable apparatus for recording and reproducing disc records.

The primary object of the present invention is to generally improve sound recorders of the character specied. More particular objects center about the feed mechanism for feeding the cutting stylus over the surface of the disc being recorded, and are to provide feed mechanism which is comparatively simple, inexpensive, sturdy in construction, and positive in feed; which is readily releasable by the disengagement of parts of the feed gearing so that the cutting head may be moved over the disc to any desired point, thus making it possible to record parts of a disc or to continue a recording which was interrupted part-way through the disc; .and which automatically stops feed movement when theuseful part of the disc has already been recorded. In accordance with still another object of the invention, the parts of the feed mechanism are all located immediately beneath the turntable and above the plate on which the turntable and associated driving motor are mounted, for this simplifies the necessary feed connections between the turntable and the cutting head. Another and more detailed object of the invention is to provide convenient adjustments for the parts of the feed mechanism to compensate for inaccuracies which may arise in producing the bearings and other parts of the feed mechanism by die-casting methods.

Other objects of the invention center about the control of the driving motor, but this aspect of the invention is not claimed herein, itv being claimed in our copending application, Serial No. 243,104, led November 30, 1938, whichv is in part a division and in part a continuation of this application. l

To the accomplishment of the foregoing, and other more detailed'objects, which will hereinafter appear, our invention consists in the recording elements and their relation one to the other, as hereinafter are more particularly de- Fig. 4 is explanatory of the conversion of the cutting head for use with metal discs;

Fig. 5 is a section taken in elevation through the turntable feed arm and recording arm, with the feed mechanism engaged;

Fig. 6 is 'a similar view with the feed mechanism disengaged;

Fig. 7 is a section taken in elevation at the driving motor and. shows the motor control mechanism in driving position, this section being taken in the plane of the line 'I-l of Fig. 2;

Fig. 8 is a similar section, but with the parts in stopped position;

Fig. 9 is a section taken in the plane of the line 9-9 Aof Fig. 2, and is explanatory of the mounting for the driving motor;

Fig. 10 an elevation of the control handle with its associated cams for releasing the motor wheel and controlling the motor switch;

Fig. l1 is a detail of the feed segment;

Fig. 12 is a bottom plan view of the bearing for the recording arm; and

Fig. 13 is a. rear elevationof the audio frequency amplifier and loud speaker section of the apparatus.

.Referring to the drawings, and more particularly to Fig. 1, the recorder comprises a. turntable T, a recording arm R, ashaving collector S, a pick-up arm P, a feed release F, a motor control C, a microphone M, and audio frequency amplifier and loud speaker equipment located generally at the forward end A of the casing for the apparatus. The turntable T is driven by a concealed motor, the said motor being started or released from the turntable by the control handle C. The recording arm is moved over the surface of the disc D carried by the turntable, by appropriate feed mechanism subsequently described in detail. This feed mechanism is released or made inoperative by oscillation of the handle F, thus permitting the recording arm to be moved freely over the disc D so as to locate the cutting stylus at any desired point on the disc. Duringthe recording operation, a switch I2 is closed, thus energizing the amplifier, as is indicated by lighting of an appropriate pilot light I4, and a change-over switch I 6 is thrown to the recording position. There is a volume control I8 and a tone control 20. The Volume control I8 may be used to limit theamplitude of the. audio frequency wave being impressed on the disc, and for this purpose a meter 22 is provided to indicate the audio frequency amplitude.

After the disc has been recorded, it is merely and stopped and at the same time engaged with 35 necessary to release the feed mechanism at handle F, whereupon the recording arm R may be swung outwardly to a position clear of the turntable. The change-over switch I6 is thrown in opposite direction for phonograph reproduction, and pick-up arm P is lifted from its' rest pin 24 and applied to the record. The audio frequency wave, after suitable ampliflcation, is supplied to a loud speaker disposed against the inner side of the end wall 26, and the said wall is cut away as is indicated at 28 to form a grille for sound discharge.

Considering the mechanism in greater detail, and referring now to Figs. 2, 5 and 6 of the drawings, we shall first describe the feed mechanism for feeding the recording arm R and with it the cutting head 30, over the face of lthe disc. This feed must be properly synchronized with the turntable, and the drive for the feed is therefore preferably taken from the turntable shaft. Briefly, the turntable T turns a" worm 36 meshing with a small diameter pinion 44 carrying a larger diameter feed screw 46. 'Ihis engages the metal may be used in contrast with the soft dieperiphery of a toothed segment 58 secured at the end o-f a feed arm 60, the opposite end of which is connected to the recording arm R so that both oscillate together under the iniiuence of the feed screw 46. The release handle F moves segment 58 out of engagement with the feed screw and thus releases the recording armv from the feed mechanism.

In the present case the turntable T is a diecasting assembled with a force fit onto a turntable shaft 32. The upper end of shaft 32 is shaped and dimensioned to act as a record centering pin 34. Immediately beneath turntable T the shaft 32 carries a worm 36. The shaft then passes into a main bearing 38, the latter being closed at the bottom, as is indicated at 40, and carrying a ball 42 which receives the thrust of the turntable. No leakage of lubricant is possible, and a small amount of lubricant within- `bearing 38 lasts for many months.

cast metal of the turntable.

Worm 66 meshes with a relatively long, small diameter pinion 44. This rotates with a relatively large diameter feed screw 46. The assembly of pinion 44 and feed screw 46 is carried on bearing pins 48 and 56 which are: themselves received in upstanding bearing walls 52 and 54 which are cast integrally with the main bearing 38 and a top plate 56. 'I'his bearing assembly may be diecast, but in such case the soft metal is preferably cast around a thin sleeve of bronze forming a lining for the main bearing 36,

The feed screw engages the periphery of a segment 58. Segment 58 is secured to a feed arm 60 by screws 62 passing through slots 64 in the segment. Feed arm 66 is xedly secured to recording arm R. and they oscillate together about the upright pin 66. The arc of segment 56 is struck about pin 66 as a center, and the periphery of segment 56 is toothed` by a series of radial teeth68 best shown in'Figs. 6 and 11, these teeth having a pitch equal to that of the feed screw 46. In Fig.' 5 it will be observed that the end of segment 58 bears against the upper portion of screw 46, and -the parts are'ther-efore readily disengaged by elevating the segment slightly above the screw, as is shown in Fig. 6. This is done by oscillating the handle F, the said handle having diametrically opposite camming surfaces, one of which is shown at l in Figs. 5 and 6. 'Ihese camming surfaces bear against a pin 12 passing transversely through the upright shaft 66. Shaft 66 oscillatably carries recording arm R, the shaftI being freely received in the hub 14 of the recording arm in a manner which will be clear from inspection of Figs. and 6 of the drawings, and being held against axial movement by a cap I6 locked in position by set screw 18. The feed arm 60 is secured directly to the lower end of hub 14 of the recording arm, and the parts function as a single member although they are cast separately. 'I'hey are locked together by a pair of perpendicularly related set screws 80 which pass through the end of feed arm 60 and bear against hub 14 of the recording arm. The two parts are, of course, angularly related in proper manner so that the travel of the cutting head 30 will take place over the useful recording area of the disc, while segment 58 is moving in engagement with the feed screw 46. This angular relationis substantially as shown in Fig. 2, and it may be remarked that the section shown in Figs. 5 and 6 is fictional to the extent that the plane of the section through the recording arm Rl necessarily differs from the plane of the section through the feed arm 60, but these sections have been brought into a single plane for convenience in drawing.

The assembly of feed arm and recording arm is normally urged downwardly not only gravitationally, but also by means of a compression spring 82 (Fig. 5) housed within a bearing 84 and pressing at its lower end on a collar 86 which is secured to upright shaft 66 by a cross pin 88. The cross pin 88. projects beyond collar 86 and is received in slots 90 cut through the wall of bearing 84, as is shown in Fig. 12. This pre- `vents rotation of shaft 66 and consequently holds pin 12 against rotation when the feed release handle F is oscillated about shaft 66. In this way the handle F may be employed to elevate the feed arm 66, as is shown in Fig. 6, at which time therecordingarm may be swung freely over the entire surface of the turntable,

It is believed that the significance of the relative arrangement and dimensioning of the parts of the feed mechanism will now be apparent, for the segment 58 oscillates throughout its arc of travel either with or without engaging the feed screw 46, all without striking or interfering with the pinion 44 or worm 36 or bearings 52 and 54. This result is attained by making feed screw 46 larger in diameter than pinion 44, thus permitting the segment to ride freely over the pinion. The segment bears on the upper half of the feed screw so that it may be disengaged by upward movement, but it is preferably confined to the outer portion of the upper half of the feed screw in order that it may freely clear the worm 36. The relatively large diameter of the feed screw 46 together with the top location of the segment 58 causes the segment to ride over and to clear the bearings 52 and 54.

vIt lwas previously mentioned that the main bearing assembly together with the top plate 56. and bearings 52 and 54 are preferably diecast. Because of inaccuracies in the resulting casting, and in order to increase the tolerance in manufacture of the gears, the cone bearings 48 and 60 are preferably made adjustable. The center or cone of bearing 48 is located eccentrically with respect to its shank 92. and by rotation of shank 92 the distance of pinion M from worm 36 may be adjusted. The adjustment is locked by a set screw 94. The conical or center bearing 50 is not eccentric, but is formed at the end of a screw 96 which may be turned to adjusty the thrust of the bearings or to take up end play.`

' 50, while screw 05 is driven over one end 'of the pinion.

The peripheral length of segment 60 is made such as to correspond to the useful recording area of the disc and the location of the segment relative to the recording arm is such that when the cutting stylus reaches the minimum recording radius, the trailing end of the segment passes screw 46 and is thereuponv automatically disengaged from the screw, and no further feed' of the stylus takes place. Broken line position 60', 60' in Fig. 2 of the drawings shows the feed segment approaching the end of its range, and it will be understood that after some additional travel, the trailing end of the segment will leave the end of the screw. This presupposes that the feed is from the outside in, but with an oppositely threaded screw, the feed is from the inside out.

In such'case the automatic disengagement of the feed segment takes place at the opposite end of' the screw with the segment moving, counterclockwise as viewedfin the drawings.

The construction of the feed mechanism of the recorder is simplified by locating all of the parts above top plate |20 of the phonograph casing, yet the feed mechanism-is not at all exposed to View, it being fully concealed by the turntable T. The assembly of feed mechanism and turntable is kept compact in vertical dimension by elevating the segment 5B relative to the feed armv 60 so that the segment 58 is located within the hollow flanged turntable, as will be clear from inspection of Figs. 5 and 6. The total elevation of the turntable by reason of the introduction of the feed mechanism is limited to the introduction of the worm 3B between the turntable and the main bearing 36, and this is not enough to in any way affect the desired true rotation of the turntable, particularly so in view of the long and substantial nature of the main bearing 30.

The cutting head 30 maybe of conventional character, and requires no detailed description. It is mounted on a suitable bracket |00 pivotally connected to recording arm R at |02. The cutting head 30 is preferably made comparatively light in/weight so that it will be suitable for cut- ,ting acetate discs with a light cutting pressure.

30 with a forwardly projecting pin |06, and the machine is equipped with a weight |06 best shown in Fig. 4. This weight is center-bored to receive the pin |06, and may be. locked on the pin by means of a thumb screw H0. The mass is so selected and disposed relative to the cutting head 30 that the resulting recording pressure is suitable for recording on aluminum records. To again record on acetate discs, it is merely necessary to remove the weight |08.

'I'he motor control mechanism is next `de scribed with reference to Figs. '7 through 10 of the drawings, but' this control mechanism is claimed in our copending application'previously referred to. 'Ihe turntable T is given a broad machinetrued periphery H2, and this is frictionally engaged by a comparatively soft rubber motor wheel H4. Wheel IM fis mounted at the upper end of motor shaft H6, the motor H0 being disposed in upright position and being of the alternating current induction type which operates for the present purpose as a synchronous motor. The reduction ratio between the small motor wheel I M and the large turntable disc, together with the winding of the motor, is so selected as to produce a turntable speed of 78 R. P. M'., and no speed regulator or governor mechanism is needed or used. .The mctor is mounted in rubber cushions |22, as is best shown in Fig. 9, and is suspended from the top plate |20 on which all of the'parts so far described are mounted. More specifically, we provide a motor housing |20 best shown in Figs. 2 and 3. This motor housing is secured to top plate |20 by adjusting screws |26, one of which is received in a slot |28 (Fig. 2), thereby affording adjustment of the entire motor housing toward or away from the turntable. Thisdetermines the frictional driving pressure between the motor wheel H0 and the turntable.

` Motor housing |24 is provided with hollow frustroconical cups or seats |30 which receive the rubber sleeves or cushions |22. Motor i i0 is provided with upwardly projecting rods |32 which pass through the rubber pads |22 and the upper ends of which receive nuts |34 bearing on appropriate washers. The significant thing about this arrangement is not merely the provision of a soft cushioned'mounting' for the motor, but even more importantly, the provision of an oscillatable mounting affording bodily oscillation of the motor between the driving position shown in Fig. 7 and the disengaged or released position shown in Fig. 8. The motor is substantially upright in the driving position of Fig. '7, and thus the desired driving .force is obtained by reason of gravitational attraction on the body of the motor itself.

This driving. pressure may be increased by the use of a tension spring |36 connected between the lower end of the motor at 31 and any convenient point of connection on the plate |20.

The motor may be oscillated to the position of Fig. 8 by means of a motor release cam |38. Cam |30 is secured at the lower end of a pin |00 to the upper end of which the motor con-.

trol handle C is connected. Pin |00 passes through a suitable bearing in the motor housing |24 previously referred to. It will be manifest that by swinging the control handle C from the solid line position .to the broken line position shown in Fig. 2, the cam |38 will be shifted from the position shown in Fig. 7 to the position shown in Fig. 8, thus causing the same to bear against a. cooperating part of the motor housing acting as a cam follower, and thereby tilting the motor to the position shown in Fig. 8, at which time the motor wheel ||4 'is disengaged from the turntable T.

The motor housing |24 is made of a single piece of metal except for a small cover plate |42 which is secured in place by two small screws as is clearly shown in Fig. 9. This cover plate has been removed in Fig. 2 in order to expose the motor wheel ||4.

The control handle C also controls the'energization of motor ||8. For this purpose we provide an electric switch |44 mounted on plate by means of the conventional threaded bushing and nut construction, the body of the switch and the electric wires leading thereto being disposed beneath plate |20, while a plunger |46 for operating the switch projects upwardly through the threaded bushing above plate |20.

This switch is so designed that it is normally open, 'and is provided with resilient meansto keep it so. When plunger |46 is depressed and held in depressed condition, the switch is closed. In accordance with the present invention, this is done by the control handle C, and more particularly, by a camming projection |48 at one side of the control handle, as is best shown in Figs. 2 and l0. In Fig. 10 the switch is open, and the same applies to Fig. 8. In Fig. 'l the switch is closed, and the same applies to Fig. 2. In Fig. 2, however, when the control handle is moved. to the broken line position, the switch is,

opened. A momerts reection will show that as the control handle C is moved from the stop position shown in dotted lines, toward the starting position shown in solid lines, the switch is closed, thus starting the motor. ment of the control handle C is continued, the switch remains closed, and the motor release cam |38 is moved away from the motor far enough to permit the motor wheel to engage the periphery of the turntable. Because of this sequence of operation, the motor starts without any load and is already spinning when it frictionally engages the turntable. In stopping the machine, the motor is released from the turntable and there is no wear on the motor Wheel if the turntable is stopped quickly with the hand. Most importantly, it is impossible to neglect to release the motor wheel from the turntable when stopping the machine, and this prevents the motor wheel from being left pressing against the turntable over long periods of non-use with resulting production of a flat side on the periphery of the motor wheel.

The shaving collector S is particularly simple in character. Broadly, we provide means to wind up the shaving which is being cut from' the disc. This means is mounted at the center of the turntable, and more specifically, consists of a tube S which is frictionally slid over the centering pin 34 of the turntable. The tube S is preferably made by rolling a strip of metal'to tubular conguration with a slot or space between the edges of the metal, this being one way to obtain the desired frictional engagement between the tube and the centering pin. The manner in which the shaving collector operates will be understood if it is kept in mind that the shaving cut from the disc gathers in convolutions about the disc, but 'these convolutions tend to remain stationary rather than to rotate with the disc, because the cutting point or cutting stylus is stationary'. When the shaving reaches the shaving collector S, either in annular form or because of deformation and attening of the ring of shaving, it is wound up about the shav- As the moveat the center, where it does not interfere with 5 proper functioning of the recording stylus. The feed mechanism may be designed to cut from the outside toward the center of the disc, or from the center toward the outside of the disc,

depending upon which way the thread of the 10 feed screw is cut. We recommend the latter cut, because then the cutting head is constantly moving away from the previously cut shaving.

The turntable is desirably provided with a layer of sheet rubber of frictional character, indicated at |49 in Fig. 3, but omitted in Figs. 5 through 8 of the drawings.

The blank discs are provided with a center hole to receive the centering'pin 34, and are provided with one or more additional holes |50 (Fig. 1) to receive drive pins |52 (Figs. 527). Ordinary commercial phonograph records do not have the additional holes |50, and it is therefore desirable to make the pins |52 removable so as to make it possible to play ordinary records. In the present case this is done in very simple fashion by providing the pins |52 with threaded Shanks which are received in mating threaded holes in the turntable. When it is desired to play ordinary records, it is merely necessary to unscrew the driving pins or screws |52 from the turntable. Only one such screw need be used at any one time during the making of records, and this single screw may be expeditiously removed. When playing records which have been made on the machine, it is, of course, unnecessary to remove the screw, for the discs are provided with the extra holes |50.

The pick-up arm P may be conventional in character, and requires no detailed description. It is a channel-shaped arm formed of heavy gauge sheet metal. The magnetic pick-up head is received within the channel-shaped arm, and is secured in place by means of a screw |54 (Fig. 2). The stylus |56 (Fig. 1) may be changed by releasing a conventional knurled thumb screw |58. The opposite end of the arm is pivotally mounted on a post which in turn is secured to the top plate |20 by screws |02 preferably passing through substantial rubber pads or bushings |64. When not in use, the arm rests on a stationary rest pin 24, the lower end of which is secured to the top plate |20 of the machine, and the upper end of which isreceived within the side walls of the channel-shaped arm. This holds the arm elevated above the turntable and swung outside the turntable, as is shown in Fig. l. When the pick-up arm is raised over the rest pin 24 and moved `iust inside the rest pin, the stylus may be placed substantially at the edge of the turntable, as will be evident from examination of Fig. 2. The turntable in the present case is a twelve-inch turntable, and the pick-up is thus positioned to reproduce records up to twelve inches in diameter. R and its associated feed mechanism is similarly adapted to handle discs up to twelve inches in diameter.

Referringto Fig. 1, the casing comprises a bottom wall, not shown, side Walls |10, a rear 70 end Wall |12, a front end wall |14, a relatively large top plate |20, and a relatively small top plate |16, the large top plate being positioned substantially lower than the small top plate |16. The turntable and associated recording and pickf;

The recording arm supply, at |98.

up arms are mounted on the large plate |20, and the sides |10 and rear wall |12l of the casing are preferably cut away at plate |20 to afford free sideward access to these parts. The small plate |16 is located at substantially higher elevation to make room therebeneath for the audio frequency amplier and loud speaker equipment. The small plate |16 also functions as a panel on which the associated instruments and controls are mounted. The case is completed by a cover |18 provided with a narrow peripheral wall. 'Ihis wall is widened at |80 and |82 to compensate for the cutting away of the side walls |10 and rear wall |12 at the large top plate |20. The hinges of thecover are of the open type which permit complete removal of the cover when it is turned all the way b'ack, and this leaves the lower part of the case well open for use.A It is not essential, however, to remove the cover |18, and the apparatus may be used with the parts in the position shown in Fig. 1. When the cover is closed, it may be locked at |84, and dowels |86 are used to insure proper fit of the cover over the lower part of the case. The complete unit is portable, and may be carried by means of handle |88. The mounting of the controls on top panel |16 is especially convenient because these controls are fully enclosed and protectively housed when the case is closed by the cover |18. If the controls were mounted on the front wall |14, they would be exposed, or it' would be necessary to provide an additional protective wall outside the control handles, and this would increase the. size of the unit.

It has already been mentioned that the audio frequency amplifier and loud speaker equipment is located in the forward end section A of the case, and this -will be further claried by reference to Fig. 13, which is a rear View of this section looking in the plane of the line |3|3 of Fig. 1, but'with the chassis removed from the case. No attempt will be made to describe the same in detail, but it may be briefly pointed out that the chassis comprises a bottom plate |90 with the usual downwardly bent side Walls |92 forming a bottom space beneath which the wiring between tube sockets and various elements is disposed, as well as fixed resistors, capacitors, and the like. 'Ihe top plate or panel |16 is spaced above bottom plate |90 by appropriate vertical walls |94. The power transformer is in dicated at |96, and therectier tube for power In the present case this is the type known commercially as No. 80 rectifier tube. The tubes 200 are power amplifier tubes used in push-pull, and in the present case are of the type known commercially as No. 45 power tube. Voltage amplification is provided ahead of power tubes 200 by means of tubes carried within the shields 202 and 2.04. In the present case these are of. the type known commercially The change-over switch was previously referred to, and 1s indicated at I6. When this is thrown to the recording position, the microphone feeds into tube 202, then tube 204, then the power tubes 200, and then into the cutting head, the tube 204 having its second section used as a phase inverter for feed into the push-pull power amplification stage. When the change-over switch I6' is thrown to the phonograph or playback position, less amplification is needed, and the pick-up is connected' the second section of tube 202. the output o` Wllh is Afed t9 the tube 204, and thence -to the power amplifier tube 200 as previously described, and thence to the voice coil of the loud speaker.

The loud speaker is located in front of the tubes |98, 200, and is shown at 206. It is preferably of the electro-dynamic type, its eld coil being indicated at 208, and the transformer for the voice co-il being shown at 2|0. The remaining elements visible in Fig. 13 have already been referred to, these being the power switch'lZwith associated pilot lamp I4 visible in ruby lens I4, the volume indicator meter 2 2, the tone control 20, the volume control I8, and the receptacle 2|2 for the microphone connection.

It will be understood that the audio ampliiier'and loud speaker section described in connection with Fig. 13 isemployed only because the present unit is a completely self-contained portable unit, to operate which it is merely necessary to insert the plug 2|4 (Fig. l) into any convenient wall outlet. Many features of the invention may be used, however, withrecording and reproducing apparatus employed in association with a regular cabinet phonograph or radio receiver. In such case the audio amplier and loud speaker `of the radio receiver may be used, and the parts shown in Fig. 13 are unnecessary. More specifically, from the standpoint ctidentally, in speaking of radio receivers, it may be pointed out that it is possible to make a recording of a received radio broadcast feature. This may be done by simply locating the microphone in front o-f. the radio speaker, but

may. be done with greater fidelity by connecting l the audio output of the radio receiver, which would normally be supplied to the voice coil of the speaker, directly to the cutting head of the recorder. For this purpose, we provide a jack 2| B (Figs. 1 and 2) adapted to receive a plug which is connected to the voice coil of the radio receiver.

It is believed that the construction and operation, as well as the many advantages of our improved recording apparatus, and more particularly the improved portable recording and reproducing apparatus, will be apparent from the foregoing detaileddescription thereof. The feed -mechanism is simple, inexpensive, sturdy and positive in action. The segment is readily disengaged from the screw and the vcutting stylus may be positioned at any desired point on the disc. The segment is automatically disengaged from the screw at the end of the useful recording area of the disc. The parts of the feed mechanism are all located above the mounting plate and close to and are concealed by the turntable.

. The turntable is carried in a simple main bearing and may be removed by simply lifting the same upwardly, at which time the feed mechanism is fully exposed and accessible for service. The recording arm is located above the mounting plate and is readily removable from the upright pin, and the cutting head is readily removable from the recording arm for servicing. .The same applies to the pick-up arm, and in fact, even the electrical connections to both arms are made above thel mounting plate |20 so that the cutting head or pick-up may be completely removed from the apparatus for examination or replacement without having to open up the top plate |20 of the case. Most of the parts may be made comparatively inexpensively by die-casting, which has the additional advantage of permitting the use of very light-weight metals. The manufacturing tolerance is large Ibecause appropriate adjustments of the parts are provided for.

The motor control is especially convenient, and by simply oscillating a single lever, two different controls are caused to function in best time sequence. The softrubber motor wheel is normally disengaged from the turntable, and there is no danger of it sticking to the turntable or acquiring a iiat The motor is started before the motor wheel is brought into frictional engagement with the turntable. It is impossible to stop the motor without disengaging the motor wheel from the turntable because the motor switch is opened at the end of the movement of the control handle. 'I'he motor is suspended and cushioned in rubber, and the rubber mounting itself functions topermit the desired movement of the motor wheel. This is preferably accompanied by bodily movement of the motor itself, and the weight of the motor is used to provide the desired engaging force between the motor wheel and the turntable although this may be supplemented, if desired, by a tension spring.

An exceedingly simple and` inexpensive means is provided which functions effectively to collect the shaving when operating on an acetate or like composition disc from which a continuous threadlike shaving is cut. The same cutting head may be used to record on an aluminum or like metallic disc, and the necessary increase in cutting pressure is provided for in a convenient andl inexpensive ,mannen Driving pins in addition to the centering pin are provided on the turntable in order to insure positive rotation of the disc with the turntable during the recording operation. These driving pins may be left in place during-play-back of records made -in the apparatus, and are readily removable in' order not to interfere with reproduction of ordinary commercially manufactured phonograph records.

By the addition of audio amplifier and loud speaker equipment, the apparatus may be made as a panel on which the associated instruments',`

and controls are mounted, because in this way they may be protectively enclosedand locked against tampering when the main cover of the case is closed. There is no loss of accessibility to the turntable and recording and pick-up arms, because the side and rear walls of the lower part of the case preferably are cut away, and this is compensated for by increasing the depth of the cover at the cut-away portions.

It will be apparent that wliile we have shown and described our invention in a preferred form, many changes and modifications may be made in the structure disclosed, without departing from the spirit of the invention defined in the following claims.

We claim:

1. Apparatus for recording sound, said apparatus comprising a turntable, a cutting head, an

arm extending rearwardly from the same and oscillatably mounted at its rear end on a vertical pivot for movement across the turntable, and feed mechanism all located immediately beneath the turntable, said feed mechanism including a screw, gearing connecting said turntable and screw for rotating the screw, a segment extending rearwardly from and moved by said screw, said segment being in the form of a sector of a circle having the pivot of the arm as its center,

. said segment having teeth at the bottom of the periphery thereof engaging the top of said screw, the rear end of said segment being rigidly connected directly to the rear end of said arm for simultaneous bodily movement therewith, said arm and segment being vertically movable on said pivot, a feed release handle at said pivot, and cam means operated thereby to raise the arm and segment in order to disengage the segment from the screw.

2. Apparatus for recording sound, said apparatus` comprising a` horizontal panel, a main turntable bearing beneath said panel, a top bearing plate above said panel, a turntable above said panel having a turntable shaft projecting downwardly into said main bearing, a short worm on said shaft between said turntable and said main bearing, said plate having spaced bearing ears carrying a small-diameter pinion meshing with said worm, a' short large-diameterscrew secured at one end of saidpinion, a recording arm bearing secured to said panel outside said turntable, a recording arm having` a hub mounted on said recording arm bearing, a feed arm rigidly secured to said hub 'and extending between the turntable and the panel, a toothed sector carried by said feed'arm and adapted to rest on said screw and to clear said pinion and worm, cam means and an operating handle therefor disposed above said panel and beneath said vrecording arm hub for raising or lowering the hub and with it the feed arm and sector in order to disengageor engage the sector and screw, said worm and pinion and screw and sector all being concealed by' said turntable but exposed on lifting the turntable from the main bearing.

3. Apparatus for recording sound, said apparatus comprising a main turntable bearing, a bearing plate localized at the mai'nbearing, a -turntable having a turntable shaft in said main bearing, a worm on said shaft, said bearing plate having spaced bearing ears, a small-diameter pinion meshing with said worm, a short large-diameter screw at one end of said pinion between said bearing ears, conical center bearings carried in said bearing ears and receiving the ends of said pinion and screw assembly, one of said cone bearings being eccentrically mounted in its bearing ear for adjustment of the pinion toward or away from the worm, the other of said cone bearings being carried on a screw for axial adjustment of the center-to-center distance between bearings, a` recording arm above the turntable, a feed arm below the turntable connectedy to said recording arm, and a toothed sector on the feed arm adapted to mesh with the large-diameter screw and at the same time to clear the pinion and the worm.

4. Apparatus for recording sound, said apparatus comprising a horizontal panel, a main turntable bearing carried by said panel, a turntable above said panel having a turntable shaft projecting downwardly into said main bearing, feed mechanism including a feed arm 4located between the turntable and the panel and adapted to be l moved in response to rotation of the turntable shaft, a recordingarm bearing carried by said panel outside said turntable, a recording arm having a hub oscillatably mounted on a vertical shaft carried in said recording arm bearing, means to prevent rotation of the shaft but to afford vertical movement thereof, the aforesaid feed arm being rigidly secured to the hub of the recording arm, helical cam means and an operating handle therefor disposed above sad panel and beneath said hub, said cam means and handle being oscillatable about the vertical shaft and functioning to raise or lower the shaft, and with it the hub and recording arm and feed arm.

5. Apparatus for recording sound, said apparatus comprising a horizontal panel, a main turntable bearing carried beneath said panel, a turntable above said panel having a turntable shaft projecting downwardly into' said main bearing, feed mechanism including a feed arm located between the turntable and the panel and adapted to be driven by the turntable shaft, a recording arm bearing carried by said panel outside said turntable, a recording arm having a hub oscillatably mounted on a vertical shaft carried in said recording arm bearing, said shaft being provided with a transverse pinat its lower end to prevent rotation of the shaft, said pin be'ng received in vertical slots in the bearing to afford vertical movement ofthe shaft, the aforesaid feed arm being rigidly secured to the hub of the recording arm, helical cam means and an operating handle therefor disposed above said panel and beneath said recording arm hub for raising or lowering the recording arm and with it the feed arm, said cam means'and handle being oscillatable about the vertical shaft, and said vertical shafthaving a pin extending transversely therethrough and resting on said helical cam means for raising and lowering the shaft upon oscillation of the handle.. j

6. Apparatus for recording sound, said apparatus including a turntable having a shaft thereon, a cutting head, a pivoted arm supporting the same for movement over the turntable, and feed mechanism compactly localized at the axis of the turntable, said mechanism comprising a worm gear mounted on the turntable shaft for rotationv therewith, a pinion of small diameter meshing with said worm gear, a screw of substantially larger diameter than the pinion rotatable with said pinion, said screw being short in axial dimension and being located closely adjacent the worm gear, a segment driven by said screw and I secured to said arm for oscillation therewith, the

periphery of said segment being provided with teeth meshing with said screw, the large diameter of the screw relative to the small diameter of the pinion causing the segment to clear the worm gear and pinion while meshing with the screw, the central location of the screw near the axis of the turntable localizing the driving engagement between the segment and screw closelyadjacent the axis of the turntable.

'7. Apparatus for recording sound on a disk,

said apparatus including a turntable having a a screw of substantially larger diameter than the pinion rotatable with said pinion, said screw being short in axial dimension and being-located closely adjacent the worm gear, a segment driven by said screwand secured to said cutting head for oscillation therewith, the periphery of said segment being provided with teeth meshing with said screw, said segment beingof such arcuate length that it passes out of mesh with the screw when the cutting head reaches the limit of useful recording area on the disc, the central location of the screw near the axis of the turntable affording ample range of movement of the segpanel having a turntable shaft projecting downwardly into said main bearing, .a worm gear on said shaft between said turntable and said main bearing, a small diameter pinion above said panel and meshing with said worm gear, a screw-of substantially larger diameter than the pinion rotatable with vsaid pinion, said screw being short in axial dimension and being located closely adjacent the worm gear, a recording arm oscillatably mounted on said panel outside said' turntable, a feed arm connected to said recording arm above the panel and extending between. the turntable and the panel, a toothed segment carried by said feed arm and adapted to engage said screw, the large diameter of the screw relative to the small diameter of the pinion causing the segment'to clear the worm and pinion while meshing with the screw, the central location of the screw near the axis ofthe turntable localizing the driving engagement between the segment and screw closely adjacent the axis of the turntable, said turntable being downwardly flanged at-its periphery to rigidity the same, saidsegment being received in the hollow space within the turntable fiange thereby reducing the necessaryelevation of the turntable above the panel while keeping the feed mechanism above the panel. A

9. Apparatus for recording sound, said apparatus comprising a support panel, a main turntable bearing carried by and disposed beneath said panel, the lower end of said bearing being closed and provided with a thrust ball, a turntable above said panel having a turntablev shaft projecting downwardly into said main bearing and resting i on said thrust ball, a worm gear mounted on said shaft above the panel between said turntable and the main bearing and rotatable therewith, a small-diameter pinion above said panel and meshing with said worm gear. a large-diameter screw rotatable with said pinion, said screw being short in axial dimension and being located closely adjacent the worm gear, ybearings carrying said pinion and screw, said bearings being carried on a. plate localized at and so fixed in location by the main bearing as to maintain the desired center to center spacing v of the worm gear and the pinion, a recording arm above the turntable, a feed arm between the turntable and the panel and connected to said recording arm, a toothed segment carried by the feed arm and meshing with the screw, the large diameter of the screw relative to the small diameter ofthe pinion causing the segment to clear the wo'rm gear and 'pinion while meshing with the screw, the central location of the "screw near the'axis of the turntable localizing the driving engagement between the segment and screw closely adjacent the axis of the turntable.

10. Apparatus for recording sound, said appa.-

ratus including a turntable having a shaft thereon, a cutting head, a feedl arm therefor, and feed mechanism compactly localized at the axis of the turntable, said mechanism comprising a worm gear mounted on the turntable shaft for rotation therewith, a pinion of small diameter meshing with said worm gear, a screw of substantially larger diameter than the pinion rotatable with said pinion, said screw being short inaxial dimension and being located closely adjacent the worm gear, spaced bearings for said pinion and screw assembly, one of said bearings being adjustable with the pinion toward or away from the Worm gear, a segment mounted on the feed arm and provided with teeth adapted to mesh with said screw, said segment being adjustably secured to said feed arm for movement toward or away from the screw, screws to xedly lock the segment in adjusted position, the large diameter of the screw relative to the small diameter of the pinion causing the segment to clear the worm gear and pinion and bearings while meshing with the screw, the central location of the screw near the axis of the turntable localizing the driving engagement between the segment and screw closely adjacent the axis of the turntable.

11. Apparatus for recording sound, said app'aratus comprising a main turntable bearing, a bearing plate localized at the main bearing, a turntable having a turntable shaft in said main bearing, a worm gear on said shaft rotatable therewith, said bearing plate having spaced bearing ears, a small-diameter pinion carried by said bearing ears and meshing with said worm gear, a short large-diameter screw at one end of said pinion between said bearing ears and located closely adjacent the worm gear, said pinion extending through the screw and said screw being hollow to receive the pinion with a force-fit, a recording arm above the turntable, a feed arm below the turntable connected to said recording arm, and a toothed segment on the feed arm adapted to mesh with the screw, the large diameter of the screw relative to the small diameter

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