US2072803A - Reproducer for phonographs - Google Patents

Description

March 2, 1937. uc- 2,072,803 I REPRODUCER FOR PHONOGRAPHS Filed Dec. 51, 1954 TEFL.

INVENTOR Joseph M L aca relle w, I WW A ORNEYS Patented Mar. 2, 1937 UNITED STATES PATENT OFFICE REPRODUCER FOR PHONOGRAPHS Application December 31, 1934, Serial No. 759,916

10 Claims.

This invention relates to acoustic reproducers for phonographs and more particularly to improved means for modifying the sound transmitted thereby. An object of the invention is to provide an efficient reproducer and modifier device of simple and compact form and construction. A further object is to provide a sound modifier effectively operable gradually to vary tone and intensity of sound transmitted thereby.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of the various possible embodiments of my invention:

' Fig. 1 is an elevation partly in section showing an embodiment of the present invention;

Fig. 2 is a plan View of the device shown in (Fig. 1, showing in dotted lines the position of the g5 modifier parts when adjusted for loud sound transmission; and

Fig. 3 is a cross-section taken on line 33 of Fig. 1 showing the modifier parts adjusted for medium intensity sound transmission.

Similar reference characters refer to similar parts throughout the several views of the drawing.

As shown in the accompanying drawing, the carriage IU of a transcribing phonograph is pro- 35 'vided with an opening II in which fits the reproducer and modifier unit, indicated generally by I 2. This unit comprises a shallow annular sound-box l3 and an upwardly projecting cylinldrical hub I4. The sound-box of the reproducer 40 is provided with a vibratory diaphragm IE to which is connected a link l6 for actuating a stylus carrier, not shown, the stylus of which is adapted to track the sound groove of a phonograph record. The vibrations of the diaphragm 45 produced by the phonograph record set up in the air chamber ii of the sound-box a succession of sound waves of substantially the same character as those which were recorded on the phonograph record.

In practice it is usual to connect the air chamber of the sound-box by means of a passage of relatively small diameter compared with the diameter of the sound-box, with suitable hearing devices adapted to bring the sound waves into 5 effective relation to the ears of a listener; and it has been usual to provide at some point in the transmission passage means for modifying the sound waves during transmission to adapt them to the ears of the listener even though the vibrations transmitted by the diaphragm may include many difierent frequencies and differ greatly in intensity.

The invention in its illustrated embodiment includes a modifier in the form of a valve member l8 comprising a, cylindrical portion l9, rotatably seated in snug relation to the walls of a cylindrical chamber 20, which chamber extends part-way through the hub I4 and is open at the upper end thereof. This chamber is connected to the air chamber I! in the sound-box by means of an inlet passage 2| of restricted diameter relatively to the diameter of the air space I l. The cylindrical portion IQ of the valve member is provided with an axial passage 22 of substantially the same diameter as the passage 2|, arranged coaxially therewith and forming a direct continuation of the passage 2|. This passage 22 extends upwardly into the valve memher a sufiicient distance to intersect with a radial passage 23 which is adapted to be brought into alignment with an outlet passage 24 provided by a tubular member 9 extending through the peripheral wall of the hub It. The tubular member 9 may be connected in the usual manner with hearing devices by means of rubber tubing. 7

Before continuing the description, it should be pointed out here that the sound passage, constituted by passages 2|, 22, 23 and 24, is substantially free from enlargements or extensions in the form of pockets or resonant chambers. The usual practice has been, somewhere along the sound passage to provide a relatively large resonant chamber from which, if desired, excess energy could be released by venting to the atmosphere. It has been found, however, that such resonant chambers should be avoided since they tend to have a mufiling effect upon the transmitted sound. In the present structure the sound passage throughout the modifier avoids this objectionable feature and other beneficial features have been attained which tend greatly to improve the quality of sound reproduction.

The valve member I8 is provided at the upper end of the cylindrical portion IS with a cap 25, which, covering the upper end of the hub [4, extends beyond the peripheral walls thereof and provides efficient means for rotating the modifier valve. Occupying predetermined angular positions upon the upper surface of this cap appear the index markings Soft, Med. and Loud, to indicate the appropriate positions of the valve for loud, medium or soft sound transmission. These index marks are adapted to be brought respectively into line with a pointer member 26 mounted upon the hub l4. Prior to inserting the valve l8 in the hub M, a spring washer 27 is disposed at the bottom of thevalve chamber 20. The valve member is then inserted and positioned so that the valve passage 23 exactly registers with the outlet passage 24. In this position the spring washer 21' being slightly compressed will offer sufficient resistance to rotation-to maintain the valve in any position of angular adjustment. The

valve is held against axial movement by means ofa screw 28 threaded through the wall of hub l4 and having at its inner end a portion adapted to fit closely between the side walls of an annular groove 29 formed in the valve cylinder l9.

Stop pins 30 and 3B seated in the groove 29 engage the screw 28'to limit rotation of the valve memberin-one direction at the loud position, andin theopposite direction at the soft position.

Centered in the plane of the horizontal axis of the passage-23 isa V-shaped groove 3|, cut in the peripheral wall of the valve cylinder l9 which, starting with a predetermined depth where it intersects the port 23-, extends away from the port 23*in-a-counter-clockwise direction and gradually grows shallower until it runs out at a predetermined point" indicated in Fig. 3 by the reference number 32'.

In many sound modifiers it is customary to restrict the passageway between the sound-box and'thehearing devices when it is found desirable tobrin-g the sound waves to the ears of the listener with less' intensity, the restriction of the passage serving to choke back and reduce the energy of the sound wavestransmitted. A certain amount of restrictionmay take place without greatly changing the tonal quality of the voice sounds received by the listener. However, where very loud sound waves are set up by the diaphragm, since the major portionof the energy of those sound waves reside in the lower frequency elements thereof (those below 1,000 cycles), it will happen if the restriction'is carried far enough that the sounds of low'frequency will predominate. To offset this condition, means have'been provided in the present construction-for-providing a variable vent to the outside air, thus permitting part of the energy of the low frequency sound waves to dissipate itself 'exteriorly 'of the sound passage.

Referring to Fig. 3, a vent opening 33 is providedi'n-the wall of the hub M, in the sametransverse plane-as the'groove 3 i and in order to provide -a passage of variable area connecting the opening;33-with the valveport 23, a second V- shaped groove 34 isformed in the periphery of the valvemember. This groove is shallower than groove 3| and extends in the opposite direction from the port 23, gradually becoming less deep until it'runs out at a poi-ntindicated by 35 in Fig; 3."

Animportant feature of the present invention is thev shaped groove 3| which in the position shown in'Fig. 3 provides an indirect connection betweenthe passages 23-and 24. This is approximately the-position that the parts would have for mediumdoudness of reproduction. In this position-of the parts; in order-for sound to reach the listener, it must follow a path making a sharp angle at the beginning-of the groove 3! and another sharp'angleinto the passage 24'. The efiect produced upon the frequency characteristics of the sound waves by sharply bending the sound channel is to reduce the high frequency response as the lower frequencies tend to mask the higher. But this tendency to mask the higher frequencies may be compensated by a partial elimination of some of the lower frequency energy. In the present construction this is accomplished by increasing the effective area of the vent-passage 34 as the area of the'sound passage 3| becomes more constricted. Thus the V-shaped groove 3| provides a very superior means for accomplishing a gradual modification of sound in respect to loudness while the V-shapedgroove 34 by providing an efiicient means for gradually increasing the venting as the sound channel is constricted, makes possible the maintaining of a tone of constant quality, whether the modifier be set for loud or soft transmission or at any point therebetween.

Thus the present invention provides two marked advantages over modifiers known to the prior art:one is the construction whereby the passage through the modifier is of substantially uniform area, thus eliminating resonant chambers or pockets; and the other, the means for producing gradual changes in the tone and intensity of the sound received by the listener as the modifier is changed from one position to another.

A further advantage'ofthe present construction' resides in the fact that the modifier comprises a short rotatable annular member mounted coaxially with respect to the sound passage 2! and sound-box air chamber l1, thus making possible a compact construction, easily adjustable to meet various conditions of use and of high efiiciency.

It will be seen that there is provided a construction of an essentially practical nature in which the several objects of this invention are attained.

As many possible embodiments may be made of the above invention without departing from the scope thereof, it'is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a reproducer, in combination, a soundbox having an upwardly extending hub, a cylindrical-valve'chamber formed in the upper end of said hub and communicating by means of a coaxial inlet passage with the interior of said sound-box, an outlet passage extending laterally through said hub into communication with said valve chamber, a cylindrical modifier valve rotatably mounted in said valve chamber having formed therein angularly connecting passages the first of which is coaxial with and of substantially the same diameter as said inlet passage'and the second of which is of substantially the same diameter as said outlet-passage and adapted to be brought into registry therewith, said valve having a peripheral groove adapted to connect said'outlet passage with said second valve passage when said passages are moved out of registry with one another, and means for rotating said valve about its cylindrical axis.

2. In a reproducer, in combination, a soundbox having an upwardly extending hub, a cylindrical valve'chamber formed in the upper end of said hub and communicating by means of a coaxial inlet passage with the interior of said sound-box, an outlet passage extending laterally through said hub into communication with said valve chamber, a cylindrical modifier valve rotatably mounted in said valve chamber having formed therein angularly connecting passages the first of which is coaxial with and of substantially the same diameter as said inlet passage and the second of which is of substantially the same diameter as said outlet passage and adapted to be brought into registry therewith, and means for maintaining communication between said outlet passage and said second valve passage comprising a peripheral groove in the modifier valve of gradually decreasing depths.

3. In a sound modifier of the character described, in combination, a pair of relatively movable members provided with registrable sound passages, means for providing gradually decreasing communication between said passages upon further relative movement of said members after the registrable sound passages have been moved entirely out of registry, and means for relatively moving said members.

4. In a sound modifier of the character described, in combination, a pair of relatively movable members provided with registrable sound passages, means for providing gradually decreasing communication between said passages as they are moved out of registry comprising a V-shaped groove of gradually diminishing depth formed in the contact surface of one of said members, and means for relatively moving said members.

5. In a sound modifier of the character described, in combination, a pair of coaxial relatively rotatable contact members having radially aligning sound passages, means for providing gradually varying communication between said passages as they are moved out of alignment comprising a groove of gradually varying depth cutting the contact surface of one of said members, and means for rotating one of said members.

6. In a sound modifier of the character described, in combination, a cylindrical valve mem ber containing a sound passage having respectively axial and radial branches, a housing member for said valve member having an inlet passage in coaxial alignment with said axial branch, and an outlet passage adapted to communicate directly with'said radial branch, means on one of said members for providing indirect communication between said outlet passage and the sound passage in said valve member, and means for rotating said valve member to render said indirect means of communication effective.

7. In a sound modifier of the character described, in combination, a cylindrical valve member containing a sound passage having respectively axial and radial branches, a housing member for said valve member having an inlet passage in coaxial alignment with said axial branch and an outlet passage adapted to communicate directly with said radial branch, means on one of said members for providing indirect communication between said outlet passage and said radial branch, means for rotating said valve member to render said indirect means of communication effective, and means for venting said inlet passage to the atmosphere.

8. In a sound modifier of the character described, in combination, a cylindrical valve member containing a sound passage having respectively axial and radial branches, a housing member for said valve member having an inlet passage in coaxial alignment with said axial branch and an outlet passage adapted to communicate directly with said radial branch, means on one of said members for providing indirect communication between said outlet passage and said radial branch, means for rotating said valve member to render said indirect means of communication effective, and means providing a variable vent connecting said inlet passage to the atmosphere.

9. In a sound modifier of the character described, in combination, a pair of relatively movable members provided with registrable passages, means for providing gradually decreasing communication between said passages as they are moved out of registry, means for simultaneously providing gradually increasing communication between one of said passages and the outside atmosphere, both of said means comprising V- shaped grooves of gradually diminishing depth cutting the surface of one of said members, and means for relatively moving said members.

10. In a sound modifier of the character described, in combination, a pair of coaxial relatively rotatable contact members having radially aligning sound passages, means for gradually varying communication between said passages as they are moved out of alignment comprising a groove of gradually decreasing sectional area formed in the contact surface of one of said members, and means for rotating one of said members.

JOSEPH M. LUCARELLE.

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