US1771323A - Attachment for electric amplifiers - Google Patents

Description

July 22, 1930. B. WASHINGTON ATTACHMENT FOR ELECTRIC AMPL-IFIERS Filed Oct. 20, 1926 A lNvENToR 'Bowden Washington,

yTORNEY tionpresent in the audio frequency ampli-l Patented July 22, 1930 UNITI-m STATE-sf PATENT `@rari-lcs :soWnEN WASHINGTON,

0E NEW vomi, N. Y.,'Ass'1eNoE or ONE-TIALE To EoEEaT s. ALLYN,`0E NEW Yoan, N. Y.

i l y ATTACHMENT Eon ELECTRIC AMPLIEIERS Application filed October 20, 1926. Serial No. 142,978.

will 'greatly improve the volume and tone; quality of existing talking machines or vphonographs. -Another object is to produce a simple device which may be readily attached to an existing talking machine and will con*4 vert said machine into a so-'called electrical phonograph.' Another object is` to provide lmeans whereby the high quality amplificaiers 'of many 'radio receivers may be applied to reproduction from records to a phonograph making use of the tone arm and tone chamber of said phonograph and ofthe volume control present in many ampliers.

` Another object 1s to provide an attachment of this character by means of which an ordinary phonograph horn may be also readily used on the loud speaker of a radio receiving set by a shift of one connector or the use of a switch. n y

As is well known the ordinary mechanical phonograph has no means of providing amplification. In other words, the energy applied to the needle by the wavering groove in the record is the maximum amount of enmust. be well within the range'of'the fre' querfcies to beV reproduced. Thisbeing so the response ofthe diaphragm to this fundamental frequency and to the various harmonics of this frequency will be too high inamplitude, thus causing distortion of-themusic or voice. If the needle operatedstructureis given aA period somewhat higher than the highest .desirable harmonics of the'instruments usually recorded, this distortion will not'be present, but the device will be eX- tremely insensitive.

If an eiiicient, well designed and faithful i electron tube amplifier be inserted between ythe pick-up device and the reproducing de vice, an ineiiicient but faithful pickup de vice may'jbe used-and efficiency may; be'v sacrificed for faithfulness inl the 'reproducing b device as well. This, I believe, to bev the main reason for the extremely high quality of reproduction from so-called electrical phonographs a y means of my invention anyone possessing a phonograph. and a highrquality audio frequency amplifier, either' alone or within a radio receiver, may convert y'said-phono graph into 'a highv grade electrical phonograph within a few minutes and without the use of tools.

Referring to the drawing, Fig. 1 is a verticalysection of one embodiment of my in'- vention. p l

Fig. 2 shows a front view of the embodiment disclosed in Fig. 1 vwith the cover partially broken awayF Fig. 3 is a diagrammatic view of my invention attached to a phonograph and toan audio frequency amplifier with its auxiliary apparatus.y l

In Figs. 1 and 2,'10 is the casin for the needle actuated pick-up member." t has at its base the flange 1l, this flange having four perforations such as 12 and 13.` The'cover 14 of the casing' 10 may be secured by the screws such as 15 and I16. 17 is the armature Whichis preferably constructed ofhard mavnetic material and preferably having a hig natural period.` This armature 17 is actuated by the needle 18 through the lever 19:` and the link 20. The lever 19 is pivoted between the two pivot screws 21 and 22 held in the hangers 23 and 24, which are prefers ablyintegral ,with thevcover 14. The coils 25 and 26 areheld by the L-shaped pole pieces;

27 and 28. lThe outer ends "of lthese pole pieces are clamped 'beneath the built upfper-- manent magnet structure 29 as at 30 andl. The casing l()` is secured tothe back of the casing: 32 by screws isuch as 33 and 34. 'Between the two casings is inserted a soft .p

rubber disc-35 and under ithe heads of. and

around. the screws 33 and 34 are inserted soft rubber bushings -36-and 37. l,

The structure of the stationary magnetic system 38 of the reproducing unit is identical with that described for the pick-up, unit,` alf` though the number of turns andlsiz'e ofiwire onthe bobbins 39 and 40 may differ from l thewindings of 25. and 26.- `The cover 41 bears the nipple 42 which may be designed to't theend of the tone arm of the'particular make of talking machine to which theV device -is to be applied. This cover 1s selcured to the casing 32 by the screws such as 43 and 44 and 'contains the diaphragm 45 which is held in place by the threadedl locking ring 46. The armature 17 maybe held in place against the casing 10 by the resilient blocks 47 and 48. n

In Fig. Bisshown my `combined pick-up device .and reproducer 55 attached-to the tone arm 56 of the phonograph 57. 'The terminals 58 and -59 of the pick-up portion-are connected lto the in-put of the vacuum tube,A

amplifier 60 which may have the' gain or volume control 63. The out-put of this amplifier is connected to the terminals 61 and 62 of the reproducing device. The cathodeheating and anode batteries for the amplier currents are thus induced in the windings l so' areV shown lat 66, 67, 68 and 69. yInoperation the armature 17 is moved to and from the'poles27 and 2S by the action of the needle 18 in the groove of the phonograph`v record. Substantially proportional 25'l andl 26. These currents are ledV by the fleadsA 58 and 59 to the in-put of the ampli,- VVIier 6,0V andthe greatly amplified out-put is .returned by the lead 61 and 62 to the windf "ings'39 and 40 of the out-put unit.

.I prefer to provide somemeans to prevent direct-transmission of mechanical vibration or mterference between the "1n-put and output'portions of the device, as if this vibration was present to any extent an overall oscillation, .howl., or squealvmight occur.v

4For this reason I have shown 'the cushion members 35, 36 and 37. It is preferable ythat the casings 10 and 32 and the covers 14 and 41 be formed of some light and strong material'such as, die-cast aluminum or molded phenolic insulation.

- my device, "the pick-up and the reproducer, may be manufactured and adjusted separatemicrophonic or condenser type of pick-up device may not be substituted.v

It will vbenoted that the two elements'of i 1,771,323 f l i Iclaimzf l 1. An attachment for a phonograph comv .prising a housing -formed oit: two parts, one

part having means for securing it to the tubular tone arm of said'phonograph, a needle operated electro-magnetic current modulator mounted in the other part ofsaid housing .a current. operated sound producer, means for connecting said current modulator to an elec-- tronic amplifier and meansfor connecting.

the out-put of -said amplifierl to said current operated sound producer mounted inthe first mentioned part of the housing, and non-interfering `means of connecting the parts of said housing.` 2. As an article-of manufacture a phonograph., attachment comprising a housing havingtwo enclosing chambers, means for acoustically shielding one from the other, a needle operated electro-magnetic'.current modulating device in onesof said-chambers and an electromagnetically operated sound producing devicein the other chamber, said latter device having a diaphragm and' said chamber having an outletadjacent thereto adapted tobe attached to the tone arm of a phonograph. i Y

3. An attachment for the tone. arm of a phonograph kcomprising a housing having two parts,a resilient damping means between saidA parts, an electro-magnetic pick-up in one'partof the housing having a stylus holder, an electro-magnetic sound reproducer inthe other part of the housing, a tubular device extending from said latter part of the housing-and adapted to be slipped on to the tonearm of the phonograph, and means for connecting a vacuum tube amplifier between said pick-up and said sound reproducer.

4. An attachment-'for a phonograph tone arm comprising two Qcup-shaped casing members, with their closed bottom wallsspaced ap t by damping means, v.means for clamping said members together, electromagnets mounted in said members and secured to the bottom'walls thereof, an armature and a projecting stylus for the electromagnet in one casing member, a cover member for holdy ing the armature and stylus 1n place and a diaphragm and an outlet plate secured to the other casing.

5. A phonographattachment comprising two casings one of which has means for securing it on the tone arm of a phonograph, an electromagnet and a diaphragm mounted in said casing, an electromagnet and an armature mounted in the other casing, a needle' stylus carried by the latter casing, resilient damping means mounted between said casings and means for clamping said casings to- .gether so that they may be handled as a.l unit.

6. A phonograph construction comprising a movable tone arm, an'electro-magneticreproducer removably carried by said tone arm and movable therewith, and including a housing, an electro-magnetic vibrator' mounted in the housing, an electro-magnetic pick-upA detachably secured' to and supported by said housing, and including a casing and electromagnetic means Within said casing, a stylus cooperatively connected with the electromagnetic pick-up and means yfor preventing vibratory interference between said casing and said housing.

7. In a phonograph a movable tone arm, an electro-magnetic reproducer detachably secured to the tone arm and movable therewith, and including a housing, an electromagnetic unit mounted within the housing, n

an air vibrating diaphragmy interposed-between said unit and the tone arm chamber, an electro-magnetic pick-up mechanism having a casing mounted co-axially with the housing of the reproducer, means for connecting said casing to said housing, damping means located between said casing, and said housing, and a pick-up'stylus carried by said easing.

i 8. In a phonograph a movable tone arm, an Aelectro-magnetic reproducer having a housing provided with a 'tubular extension secured to and movable with. the tone arm, an electro ma netic pick-up including a casing having a flange, damping means between said flange and said reproducer housing, and

screws for securing said flange 'to said i housing.

BOWDEN WASHINGTON

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