US2189161A - Sound reproducing apparatus and a wiring circuit therefor - Google Patents

Description

Feb. 6, 1940. R. E.'BOWLEY 2,189,161

SOUND REPRODUGING APPARATUS AND A WIRING CIRCUIT THEREFOR Filed July 5, 1938 2 Sheets-Sheet 1 INVENTORQT b- 1940- R. E.- BOWLEY 2,139,161

SOUND REPRODUCING APPARATUS AND A WIRING CIRCUIT THEREFOR Filed July 5, 1939 I 2 Sheets$heet 2 INVE NTOR iPatented Feta. 6, 1940 gleam PATENT oFFlCE s'omvn nnrnonucnvo APPARATUS AND A wmmo ,cmcurr 'rnnnuron Raymond E. Bowley, San Anselmo, Calif.

Application July 5, 1938,-- Serial No. 217,459

7 20 Claims. This invention relates to radio-audio apparatus in general and to sound reproducing appara-- tus in particular, and pertains to improved elec-. bro-magnetic O and electro-dynamlc circuit ar-- rangements included in apparatus of this character, and to improved combinations of elements in the circuit network, for efiectlng improved operating efficiency, particularly with respect to improvingtone fidelity over a wide band of audio frequencies.

In the principal feature of my invention 1 have provided an improved apparatus for sound communication or for sound reproduction comprising, in combination, power supply means h comprising electronic apparatus including an electrical and electro-magnetic circuit network for receiving radio frequency air waves and for translating radio frequency electric currents amplifyingsaid currents, having a radio frequency input circuit, an audio frequency output circuit and apower supply circuit network, a step-down audio frequency output transformer having a primary winding connectedto the audio secondary of the step down transformer, the transformer inductively coupling the loud speaker in operative relationship with the electronic apparatus, which is commonly called a 5 radio receiving set at least one inductance and impedance circuit network arrangement lncluded in the electrical and electro-magnetic circuit network comprising an inductance having a coil winding divided by tapping the winding, 9. lead 40 connected'to the winding atthe intermediate tapping point, a second lead connected to one end oft-he coil winding, the two leads connected to-suitable portions of the circuit network, and a circuit (consisting of a suitable impedance, which may be a fixed resistance unit, a, condenser, or both, one end of the impedance connected to the free" end of the coil winding and being the only connection thereto, the other end of the impedance connected to a suitable portion of the circuit-network having direct con- 'nection with the-coil winding ateither the intermediate t'appingipoint or at the opposite end of the coil winding, whereby the apparatus is into audio frequency electric currents audios electro-magnetic-induction, electro-magnetic, or other type, the speaker coll connected to the fidelityof reproduced sound waves over a wide band of audio frequencies.

The inductance and impedance circuit arrangement may be used in any circuit in the network that is used for, transmitting, translat- 5 ing or amplifying electrical currents having the characteristics of sound waves, which may be radio frequency currents, audio frequency cur- A rents or currents having associated frequencies, or in a radio frequency receiving or input clr- 1o cuit.

One feature of my invention is embodied in the inductance and impedance circuit network and the particular connections between the inductance and impedance network and the conla nected circuit, there being only two leads connecting the circuit to the inductance, one of the leads connected to an intermediate tapping point, the other lead connected to one outer end of the coil winding, leaving the opposite end of 20 the coil winding free except for the connection to the impedance circuit, as described and claimed.

Another feature of my invention is to provide animproved electro-dynamic loud speaker.

Another feature of nm invention is to provide an improved step down audio frequency output transformer.

An'object of the invention is to provide improved apparatus for sound communication,

soundreproduction or sound recording wherein an electrical and electro-magnetic circuit network is used embodyingan inductance and impedance combination operatively connected in the circuit, substantially as described, and as particularlypointed out in the appended claims, whereby the operative efilciency of the apparatus is caused to be improved. v Other objects and features of my invention more or less apparent and too numerous to re- 40 late in detail, will appearfrom the description of my invention in the following specification and accompanying drawings, taken together or separately. 7

For the sake of explaining the principles of 5 my invention, Iwill now describe illustrative embodiments thereof. The drawings are for il- .lustrative purposes only, the details of mechanical construction being left to the skill oi'the experienced .wo'rkman employing the apparatus 50 herein described and claimed.

In the drawings: H q V Fig. -1 is a portion of an electrical and electromagnetic circuit network embodying one'teature of-my'lnvention.

Fig. 2 is a portion of an electrical and electromagnetic circuit embodying another modification of the invention.

Figure 3 is a portion of electronic discharge apparatus including an electron discharge tube and an electrical and electro-magnetic circuit operatively connected to the input lead of the electron tube wherein another embodiment of myinvention is shown.

Fig. 4 is a portion of an electrical and electromagnetic circuit embodying another modification of the invention wherein a condenseris included in the arrangement.

Fig. 5 is power supply means, which may be invention, wherein a condenser is the impedance.

In all attempts made in the prior art to improve the fidelity of tone by using inductance and impedance shunts and combinations, the arrangements shown, described, and claimed are all confined to the audio frequency circuits, and they are not capable of functioning in the radio frequency or associated circuits, in fact none of the references in the prior art show, describe or claim apparatus for use in radio frequency circults, the circuits shown and described all are connected directly to the actuating coil of a loud speaker without the use ofa step down transformer, where a loud speaker is shown and is an element of the apparatus.

From the foregoing it has been learned that circuits have inductive effects upon each other and also that these circuits have inductive effects upon themselves, this being termed self induction or inductance.

Inductance is defined as: the capacity for induction possessed by an electrical circuit on itself or on neighboring circuits when the circuit is active. The term is also applied to coilsforming an inductance.

Impedance: Thetotal opposition to the passage of an alternating current through a circuit is grouped under the head of impedance. The

impedance includes the effect of the resistance,

inductance coil, and condenser, if all are present. The term is also applied to the apparatus forming the impedance.

My invention will be more clearly understood by reference to the accompanying drawings which illustrate various features'of the invention the 5A, 5B, 5C, 5D, or both, has one end connected to the coil winding at the free end 9 which has no other connection thereto, the opposite end of the impedance is connected to a suitable point in the circuit network having direct connection with either the intermediate tapping point 8 or at the opposite end of the coil winding at point I. A lead is connected to the winding at point I and to the circuit network in portion IP of the network, a second lead is connected to the winding at the intermediate tapping point 8 and is connected to the circuit network in portion OP.

The letters a and b in Fig. 1 illustrate magnetic lines of force inductively coupling magnetically the inductive impedance circuit formed by coil portion 3 and the impedance connected to the terminals 8 and 9 thereof.

When the circuit is active coil portion 2 will cause a magnetic fiux and induced currents to be set up in coil portion 3 and in the impedance circuit l etc., that react upon currents passing through the circuit network effecting improved resulting tones, or effecting improved operating efiiciency of the apparatus.

One coil portion may have currents oscillating in one group of frequencies while the other coil portion may have currents oscillating therein at another group of frequencies, such as harmonics and overtone frequencies of the funda mental tone current frequencies passing through the connected circuit network. The arrangement appears to cause the blending ofovertone currents with their fundamental tone currents so that sound vibrations reproduced by a loud speaker inductively coupled to the circuit through a step down audio frequency output transformer have improved clarity and timbre over a wide band of audio frequencies.

Coil portion 2 is shown having a relatively small number of turns, coil portion 3 is' shown having a relatively large number of turns, this arrangement appears to produce best results, but it is understood that other coil winding arrangements may be used without departing from the spirit of the invention or the scope-of the claims.

By determining the proper ratio of turns in each coil portion and the direction of their windings, it is possible to use this circuit network in electronic translating, transmitting and amplifying apparatus. for many useful purposes other than ,for improving tone fidelity, whereby the operative efflciency of the apparatus is caused to be improved.

:I have found that this circuit arrangement may be used in either the input circuit or the output circuit of an electron discharge tube or device for translating or amplifying currents havingthe characteristics of sound vibrations, which may be radio frequency currents, audio frequency currents or currents of associated frequencies. j i

In Fig. 2 a condenser 5A is shown connected in series with the circuit network in the output portion of the circuit arrangement.

In Fig. 3 the circuit network is shown connected in series with the input circuit of the electron discharge device or .tube E in either a radio receiving set or an amplifying device or other electronic apparatus for translating, trans mitting'or amplifying electric currents having the characteristics of sound waves, which may be radio frequency currents, audio frequency currents or currents of associated frequencies; a condenser 53 is connected in the impedance a condenser I! in series and connected to points circuit in series with the fixed resistance unit 53; numerals 2a, 3a, and letter Ca represent the same parts indicated by numerals 2 and 3 and by letter C in Fig. 1. The inductance and impedance circuit network may also be connected in the output circuitof the electron discharge device E, as shown in Fig. 6.

In Fig. 4 another modification of the-circuit network is shown connected to an electrical and electro-magnetic circuit network, wherein the ends of the impedance 4C are connected to both ends of the winding- Ca; points 7 and 9 are the outside ends of the coil Ca; 8 is the intermediate tapping point, 3 is the free end of the coil winding, having no direct connection with the connected circuit network. In this modification, the coil portions 2a and 3a are in parallel circuits, coil portion 3a and impedance dc forming one of said circuits, coil portion 2a forming the other circuit being directly connected in the connected circuit network at points 1 and 8. A condenser 5 is connected in the input circuit.

In Fig. 5 an apparatus l is shown, which may be for sound communication, sound reproduction, or for sound recording, comprising in an electrical and electro-magnetic circuit network, in combination, electronic apparatus for amplitying, transmitting or translating electrical currents having the characteristics of sound waves, which may be radio frequency currents, audio frequency currents or associated currents, in-- cluding an inductance Ca having a coil winding Ca divided by tapping the winding atv point 3, a lead connected to point 8, a second lead connected to point i at one end of the winding, the two leads connected to suitable points on the positive, plus, side of the circuit to suitable portions of the circuit, and the impedance circuit as hereinbefore described having one end connected to the free end 9 of the coil winding, the opposite end of the impedance ED connected to a suitable portion of the circuit having direct connection with the coil winding Ca at the opposite end at point I. In Fig. 5 the impedance is formed by resistance unit ti) and condenser 50 connected in series. Point 8 on the coil winding has no other connections thereto.

In Fig. 6 a complete apparatus for sound communication or for sound reproduction is shown embodying the principal features of my invention.

lA is an electronic apparatus for receiving radio frequency airwaves and for translating radio frequency currents into audio frequency currents and for amplifying said currents, and for transm'itting the amplified audio frequency currents through the step down audio output transformer 01 to the electro-dynamic loud speaker id. An inductance coil and impedance circuit network shown by numerals 2a, 8a., i'iE andt having connections at points i, 8 and 6 between elements of the circuit as described in Figures 1 to 5, is connected in series with the radio frequency input circuit A in the electrical and'electro-magnetic circuit network of device IA. G is the negative side of the circuit or the ground. it is the audio frequency output circuit; It is the field power supply circuit from a power supply circuit included in the network and adapted for connecting to an electric light or power circuit, or other suitable source for power supply.

The step down audio. frequency output transformer T has a primary winding P divided by tapping at point 8 into two coil portions 2a and 8a as described for the coils in Figs. 1 to an impedance 3F including a fixed resistance unit and 8 and 8 across the ends 01' coil portion 3a so as to modify currents passing through the coil portion 2a eifecting improved operating efliciency of the apparatus, particularly with respect to. improving tone fidelity over a wide band of audio frequencies. Leads from points I and 8 on the primary winding connectthe winding to the audio output circuit H of the electronic apparatus IA;

the secondary winding S of the transformer OT- has a relatively small number of turns for supplying a-comparatively low voltage output to the moving actuating coil VC carried by the substantially conical diaphragm i5 of the loud speaker or other sound translating device M.

The apparatus shown in Figure 6 is for the purpose of providing improved electrical and electromagnetic and electro dynamic circuits iii apparatus in the class described-and particularly for providing improved power supply means and circuits for the loud speakers described and claimed in my U. S. patent, Serial No, 20,467, filed Oct. 12, 1935, re-issue, of my U.. S. patent, Serial No. 1,93,693, filed Sept. 12, 1932; and in my re-issue U. S. patent, Serial No, 20,395, filed Aug. 5, 1936, re-issue of my U. S. patent, Serial No. 1,970,837, filed Jan. 9, 1933} and in my co-pending application for U. S. Letters Patent, Serial No. 247,865, filed Dec. 27, 1938; and in my co-pending application for U. S. Letters Patent, Serial No. 226,136, filed Aug. 22, 1938.; and to provide an improved electro-dynamic circuit for the sound translating apparatus described in my co-pending application for U. S. Letters Patent, No. 147,278, filed June 9, 1937, for the sound reproducing apparatus.

The device shown in Fig. 6 is a complete operative apparatus and when used in combination with a modification of the casing, cabinet or soundboard arrangements described in the above mentioned patents and applications for patents provides an improved apparatus for sound communication or'for sound reproduction.

In the loud speaker or sound translating device it, the electro-magnet il has a pair of concentric pole pieces forming a magnetic air gap as described in my co-pending application, Serial No.

A stationary electro-dynaim'c coil i6 is applied to the inner pole piece of the magnet i7 and is arranged in operative relationship with the moving coil VC and the field coil is so as to modify the action of the diaphragm i5 effecting improved resultant tones over a wide band of audio frequencies.

Coil it may be connected in the circuit with the voice coil V0 in various ways in order to obtain various modifications in the tones reproduced by the apparatus without departing from. the spirit of the invention or the scope of the claims. As illustrated in this modification, coil 56 is connected inthe speaker actuating circuit in series with the voice coil or moving coil VC and also with the secondary winding S of the step down transformer OT.

For best results I have found that .only a few turns are necessary for coil l6 and that the. turns may be arranged in numerous ways in combination with the magnet and moving coil and the permanent magnet loud speaker, or in a microphone of the electro-magnetic-induction type or of the electro-dynamic type without departing from the spirit of the invention or the scope of the claims.

In Fig, 7 is a step down audio frequency output transformer is shown having a secondary winding 8 of a relativelysmall number of turns adapted for supplying a comparatively low voltage output to. the coil of a loud speaker of any suitable type, the primary winding P has a relatively large number of turns for connecting to the high voltage output circuit from a radio receiving set, or

- from any other audio frequency source of supply.

. 'Iheaudiooutputcircuit from a suitable source is shown connected to the transformer at points I "and 2|,LtheLwiringof the transformer is substantially the same as hereinbefore described for the inductances comprising my invention and functions in like manner. In Fig. '7 a condenser 5D forms the impedance.

The embodiments of the invention illustrated and described herein have been selected for the purpose of setting forth the principles involved.

-The invention is, however, susceptible to being further modified to meet different conditions encountered in its use without departure from the inventive concept disclosed. I

Numerous ideas have been carried out in this invention, with recognition on my part that one or more novel elements or combinations can be employed separately, or the various elements or combinations can be employed collectively. While a certain arrangement of the inductance and impedance circuit network, or of the stationary electro-dynamic coil, in combination with apparatus in the class described will produce a certain result, a different arrangement or position will produce a different result.

I want it understood that I do not confine myself to the particular arrangement and modifications herein illustrated and described, for the obvious reason that different people have different tastes for music and demand different tone qualties.

I realize that other modifications of this invention are possible, therefore I say that my invention is not limited to the particular constructions shown and described, and it is my intention to cover all other modifications that can be made without departing from the spirit of the invention or the scope of the claims. I desire it understood that the claims hereunto appended are to be considered in defining my invention rather than the exact disclosures herein made.

I claim:

1. In combination, a step down audio frequency output transformer having a primary windin and also having a secondary winding and an electro-dynamic loud speaker comprising, a diaphragm carrying a moving actuating coil, a magnet having a pair of concentric pole pieces form- .ing a magnetic air gap applied to the moving coil,

a field coil applied to the magnet, and a stationary electro-dynamic coil applied to the magnet and connected in the audio frequency actuating circuit in series with the secondary winding of the step down transformer and in electro-magnetic relationship with the moving coil so as to modify the vibratory action of the diaphragm effecting improved resultant tones.

2. In combination, electronic apparatus for receiving radio frequency air waves and for translating radio frequency electric currents into audio frequency electric currents and for amplifying said currents and including a power supply circuit network having a field power supply circuit, a radio frequency input circuit, and an audio frequency output circuit having leads for coupling a loud speaker in operative relationship therewith, a stepdown audio output transformer having a primary winding connected to the audio output circuit of the electronic apparatus and also having a secondary winding, and an electro-dynamic loud speaker comprising, a diaphragm carrying a moving actuating coil, a magnet having a pair of concentric pole pieces forming a magnetic air gap applied to the'moving coil, a field coil applied to the magnet andconnected to the field power supply circuit, ands. stationary electro-dynamic coil applied totheimagnet and connected in the audio frequency actuating circuit in electro-magnetic relationship with the moving coil and in series with the secondary winding of the step down transformer whereby the vibratory action ofthe diaphragm is caused to be modified effecting improved resultant tones.

3. In combination, electronic apparatus comprising an audio frequency amplifying circuit network including an audio frequency output circuit and a power supply circuit network having a field power supply circuit; a step down audio frequency output transformer having a primary windingconnected to the audio output circuit of the electronic apparatus and also having a secondary winding and an electro-dynamic loud speaker comprising, a diaphragm carrying a moving actuating coil, a magnet having a pair of concentric pole pieces forming a magnetic air gap applied to the moving coil, a field coil applied to the magnet and connected to the field power supply circuit, and a stationary electro-dynamic coil applied to the magnet and connected in series with the moving coil and with the secondary winding of the step down transformer so as to be in electromagnetic relationship with the moving coil whereby the vibratory action of the diaphragm is caused to be modified effecting improved resultant tones.

4. In apparatus for sound communication or sound reproduction, in combination, a diaphragm carrying a moving coil, a magnet having a pair of concentric pole pieces forming a magnetic air gap applied to the moving coil, an actuating circuit connected to the moving coil and a stationary electro-dynamic coil applied to the magnet and connected in the actuating circuit in series with the moving coil so as to be in electro-magnetic relationship with the moving coil whereby the action of the diaphragm is caused to be modified effecting improved resultant tones.

5. In combination, in an electro-dynamic loud speaker, a substantially conical diaphragm carrying a moving actuating coil, a magnet having a pair of concentric pole pieces forming a magnetic air gap applied to the moving coil, a field coil applied to the magnet, and a stationary electrodynamic coil applied to the field coil and magnet in electro-magnetic relationship with the'moving coil and connected in the audio frequency actuating circuit with the moving coil.

6. In sound reproducing apparatus, in combination, a loud speaker which may be electrodynamic, electro-magnetic-induction, electromagnetic or other suitable type having a coil in an actuating circuit; and a step down audio frequency output transformer having a secondary winding connected in the audio frequency circuit with the speaker coil,and also having a primary winding divided by tapping the winding, a lead aisaiei 7 audio frequency output circuit so that the speaker is inductively coupled with the circuit without other connections between the primary winding of the transformer and the connected circuit.

7. An inductance and impedance combination for use in an apparatus for sound communication,

sound reproduction, or sound recording consisting of an inductance having a coil winding divided by.

tapping the winding, a leadv connected to the winding at the intermediate tapping point, a second lead connected to one end of the coil winding, the leads providing means for connecting the coil winding in a circuit network for transmitting, translating or amplifying electrical currents having the characteristics of sound waves, which may be radio frequency currents, audio frequency currents or associated currents, the opposite end of the coil winding'being free of leads for connecting to an associated network circuit, an impedance, which may be a' resistance unit, a condenser, or both, having one end thereof connected to the free end of the coil winding, the opposite end of the impedance connected to the coil winding and also to one of said leads at either the intermediate tapping point or at the opposite end of the coil winding. v

8. In an apparatus for sound reproduction, in

to the intermediate tapping point on the winding and a second lead connected to one outer end of the coil winding, the two leads connecting the said points on thewinding to a suitable portion of the associated circuit network, and a suitable impedance, which may be a resistance unit, a condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to the coil winding and also to one of said leads at either the intermediate tapping point or at the opposite end of the coil winding, there being no other connections between the impedance or the coil winding and the associated circuit connected to said leads. 1

9. In combination, electronic apparatus comprising an electrical and electro-magnetic circuit network for receiving radio frequency air waves and for translating radio frequency electric currents intoaudio frequency electric currents and for amplifying said currents, having a radio frequency input circuit, an audio frequency output circuit and a power supply circuit network, a loud speaker, which may be electro-dynamic electromagnetic-induction, electro-magnetic, or other type, a step down audio frequency output transformer inductively coupling the loud speaker in operative relationship with the audio frequency output circuit of the electronic'apparatus; at least one inductance and impedance circuit network arrangement included in the electrical and electro-magnetic circuit network comprising an in- 'ductance having a coil windingdivided by tapping the winding, a lead connected to the winding at the intermediate tapping point. a second lead connected to one outer end of the coil winding,

' the two leads connected to suitable points in the circuit network,and a circuit consisting of a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the free end "of the coil winding, the 'otherend of the impedance connected to a suitable portion of the circuit network having direct connection with the coil at either the intermediate tapping point or at the opposite end of the coil Y 10. In combination, power supply means comprising electronic apparatus includingan electrical and electro-magnetic circuit network for -1'eceiving'radio frequency air waves and for translating radio frequency electric currents into audio frequency electric currents-and for amplitying said currents, havinga radio frequency input circuit, an audio frequency output circuit ary winding for supplying a relatively low voltage output to the actuating coil of a loud speaker, an

electro-dynamic loud speaker comprising a diaphragm carrying a moving coil connected in the actuating circuit with the secondary winding of V and a power supply circuit network including a the step downtransformer, a magnet'having a pair of concentric pole pieces applied to the moving coil, a field coil applied to the magnet and connected to the field power supplyoircuit; at least one inductance and impedance circuit network arrangement included in the electrical and electro-magnetic circuit network comprising an inductance having a coil winding divided by tapping the winding, a lead connected. to the winding at the intermediate tapping point, 'a second 'lead connected to one end of. the coil winding, the two leads connected to suitable points in the circuit network, and a circuit consisting of a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the freeend of the coil winding, the other end of the impedance connected to asuitable portion of the circuit network having direct connection with the coil winding at either the intermediate tapping point or, at the opposite end of the coil winding.

11. In apparatus for sound communication or sound reproduction, in combination, a; suitable loud speaker, which may be electro-dynamic, electro-rnagnetic, electro-magnetic induction or other type having a coil inassociation with. a magnet, electronic audio amplifying apparatus including an electrical and electro magnetic circuit network having audio frequency output chcuit leads, a step down audio output transformer having a primary winding connected to the audio output circuit leads and also having a secondary winding connected to the coil of the loud speaker so as to supply a relatively low voltage output to said coil, and an inductance and impedance circuit network consisting of an inductance having a coil winding divided by tapping the winding, a lead connected to the intermediate'tapping point on the winding and a second lead connected to one outer end of the coil winding, the two leads connecting the said points on the winding-to a suitable portion of the associated circuit network,

- and a suitable impedance, which may be a fixed the impedance connected to the free end of the coil winding, the other end of the impedance connected. to the coil winding and to one of said leads at either the intermediate tapping mpe ei field coil of the loud speaker, an input circuit, and an audio frequency output circuit having anoint or a he pm ite' en io he-- there. beiirg no" other connections between the or the coil leads for connecting with the loud speaker, a step down audio frequency output transformer having a primary winding connected to the audio output circuit leads, and also having a secondary winding connected in an actuating circuit with the moving coil of the loud speaker; and at least one inductance and impedance circuit network included in the circuit network consisting of an inductance having a coil winding divided by tapping the winding, a lead connected to the winding at the intermediate tapping point, a second lead connected to one end of the winding, the two leads connected to suitable portions of the circuit network, and a suitable impedance,

7 which may be a fixed resistance unit, a condenser,

or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to a suitable point in the circuit network having direct connection with the coil winding at either the intermediate tapping point or at the opposite end of the winding.

13. In combination, in sound reproducing apparatus, power supply means comprising an electrical and electro-magnetic circuit network and electron discharge tubes for translating and amplifying electrical currents having the characteristlcs of sound waves, which may be radio frequency currents, audio frequency currents or currents of associated frequencies, including an inductance having a coil winding divided by tapping the winding,' a lead connected to the winding at the intermediate tapping point, a second leadconnected to the winding at one outer end thereof, the two leads operatively connecting the winding to suitable portions of the circuit network, a suitable impedance, which may be a fixed resistance unit, a condenser, or both, having one end connected to the free end of the coil winding, the opposite end of the impedance connected to a suitable portion of the circuit having direct connection with the winding at either the intermediate tapping point or at the opposite end of the winding, an audio frequency output circuit and a radio frequency circuit included in the circuit network; a loud speaker, which maybe electro-dynamic, electro-magneticinduction, electro-magnetic, or other type having a coil in an actuating circuit, and a step down audio frequency output transformer having a secondary winding connected in the actuating circuit with the speaker coil, and also having a primary winding divided by tapping the winding,

a lead connected 'to the intermediate tapping point on the primary winding, 9. second lead conmagn tic ail!!! nected to one end of the primary winding, the leads'connected to the audio frequency output circuit of the network, and a suitable impedance, which may be a fixed resistance unit, a condenser,.or both, having one end thereof connected to: the opposite end of the primary winding, the other end of the impedance connected to a suitable portion of-the circuit having direct connection with the primary winding at either the -intfermediate tapping point or at the opposite cndiof the winding.

f I 131. In'sound reproducing apparatus, in combi- -nat ion,-. a loud speaker, which may be electroeIectmFmagnetic-induction,, electroondary winding',.and power supply means for errergizi'ng" "theioud speaker comprising electron discharge ,tubes. and an electrical and electro-' magnetic circuit network for translating and amplifying electric currentsrhaving the characteristics of sound waves, which may be radio frequency currents, audio frequency currents or currents of associated frequencies, including a transformer in the circuit network having a primary winding and a secondary -winding, one of said windings divided by tapping the winding, a lead connected to the intermediate tapping point on the divided winding and asecond lead connected to one outer end of the winding, the two leads connecting said points on the coil winding to suitable points in the circuit network, and a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end .of the impedance connected to a suitable portion of the circuit having direct connection with the winding at either the intermediate tapping point or at the opposite end of the winding, the step down transformer inductively coupling the loud speaker in operative relationship with the circuit network.

15. In combination, in sound reproducing apparatus, a suitable loud speaker, which may be electro-dynamic, electro-magnetic-inductlon, electro-magnetic or other type having an actuating coil, an audio frequency step down transformer having a primary winding and a secondary winding, and apparatus comprising electron discharge tubes and an electrical and electromagnetic circuit network" for translating and amplifying electrical currents having the characteristics of sound waves, which may be radio frequency currents, audio frequency currents or associated currents, and including a radio frequency input circuit and an audio frequency output circuit, at least one inductance included in the circuit network comprising a coil winding divided by tapping the winding, a lead connected to the intermediate tapping point and a second lead connected to one outer end of the coil winding, the leads connecting said points on the winding to suitable portions of the associated circuit network, and a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to the coil winding and also to one of said leads at either the intermediate tapping point or at the opposite end of the winding, there being no other connections between the impedance or the coil winding and the connected cir- -0l'. -9ther type having a coil in an actu-- a =1 udi r q n y" step down? transformer a primary-windingand a seccuit, the step down transformer inductively cou- ,5 charge device, an input circuit connected to-the electron discharge device comprising, an inductance having a coil winding divided by tapping the winding, a lead connected to the winding at the intermediate tapping point'fa second lead connected to the outer end of the coil winding, the two leads connected to suitable points in the circuit network, and a circuit consisting of a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to a suitable portion of the circuit network having direct connection with the coil winding at either the intermediate tapping point or at the 0 opposite end of the winding.

17. -In combination, in an electrical and electro-magnetic circuit network, an electron discharge device, an output circuit connected to the electron discharge device comprising, an inductance having a coil winding divided by tapping the winding, a lead connected to the winding at the intermediate tapping point, a second lead connected to the outer end of the coil winding, the two leads connected to suitable points in the cir- 3o cuit network, and a circuit consisting of a suitable impedance, which may be a fixed resistance unit, a condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to a suitable portion of the circuit network having direct connection with the coil winding at either the intermediate tapping point or at the opposite end of the winding.

18. In combination with an electrical and elec-. tro-magnetic circuit network including a sound translating device, which may be electro-dynamic, electro-magnetic-induction, electro-mag'netic, or other type, an inductance having a coil winding'divided by tapping the'winding, a lead consuitable portion of the circuit network having -di-' rect connection with the coil winding at either the intermediate tapping point or'at the'opposite end of the winding.

nected to the intermediate tapping point'on the 19. In an electrical and electro-magnetic circuit network, in combination. electron discharge tubes for amplifying or translating electrical currents having the characteristics of sound waves,

. which may be radio frequency electric currents,

audio frequency currents or currents of associ-' ated frequencies, a radio frequency input circuit, an audio frequency output circuit and a power supply circuit network including a field power supply circuit, and an electro-dynamic loud speaker comprising a substantially conical diaphragm carrying a moving coil, a magnet having a pair of concentric pole pieces forming a magnetic air gap applied to the moving coil, a field coil applied to the magnet and a stationary electro-dynamic coil applied to the magnet and connected in an actuating circuit with the moving coil, a step down audio output transformer having a secondary winding connected in series with the stationary electro-dynamic coil and the moving coil, the transformer also having a primary winding inductively coupling the loud speaker with the audiofrequency output circuit of the electronic apparatus, the field coil connected to the field power supply circuit.

20. In an electrical and electro-magnetic cir-' cuit network, in combination. electron discharge tubes for amplifying or translating electrical currents having the characteristics of sound waves. which may be radio frequency currents, audio frequency currents or associated currents, a suitable loud speaker, which may be electro-dynamic, electro-magnetic-induction, electro-magnetic, or other type, a step down audio frequency output transformer inductively couplingthe loud speaker in operative relationship with the circuit network, at least one inductance and impedance circuit network included in the circuit network consisting of an inductance having a coil winding divided by tapping the winding, a lead connected to the winding at the intermediate tapping point, a second lead connected to one outer end of the coil winding, the two leads connected to suitable points in the circuit networlnand a circuit consisting of a suitable impedance, which may be a fixed resistance unit, a

condenser, or both, one end of the impedance connected to the free end of the coil winding, the other end of the impedance connected to a suitable portion of the circuit network having direct connection with the coil winding at either the intermediate tapping point or at the oppo site end of the winding.

aamonn n.

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