Audio Amplifier Arrangement

1. Field of the Invention

The present invention is concerned with an audio amplifier arrangement, and more particularly it relates to an audio amplifier arrangement which enables the user to operate the arrangement either directly or in a remote-control mode as desired.

2. Description of the Prior Art

In stereophonic system or like audio systems, those of the so-called component style which are of the arrangement that a record player, an amplifier, speakers and like parts are selected and assembled in accordance with the taste of the user are now being used widely.

It is usual that these component parts are arranged together and that the position at which they are installed is different from the position at which user listens to the sounds produced from the speakers of the assembly. As such, in case the listener intends to adjust the sound volume, sound quality, balance of sounds or like items, the listener has to depart from the optimum position at which he has been listening and to move over to the site at which the assembly is installed to accomplish these purposes, and this is quite inconvenient to the listener. Recently, it is often the case that the user employs a plurality of speakers of different makes so as to switch from one speaker to another so as to select a most suitable speaker for certain kind of music. In view of the fact that these speakers could be different from each other in acoustic pressure, it would be necessary to adjust the loudness level control for the respective speakers. In such a case also, the aforesaid inconvenience arises. Furthermore, when it is intended by the user to confirm the difference in sounds which are produced from these speakers while listening to the sounds, it is important that the listener keeps staying at the optimum position of listening. Such a convenience cannot be expected from the audio systems of the prior art.

Also, indication of output level is carried out frequently on the amplifier, especially on the power amplifier. However, under the circumstance that the assembly is set at a considerable distance from the listener, it is difficult for the user to visually confirm the indications on the indicators provided on the power amplifier at such a distance therefrom.

It is, therefore, a primary object of the present invention to provide an audio amplifier arrangement which can be controlled directly as well as remotely as desired by a simplified structure.

Another object of the present invention is to provide an audio amplifier arrangement of the type described, which enables the mechanical as well as electrical separation and coupling of the manipulation unit and the amplifier unit to be performed easily and freely.

Still another object of the present invention is to provide an audio amplifier arrangement of the type described, which enables the coupling of the manipulation unit to the amplifier unit in their separate mode to be accomplished by the use of a connector-equipped cable means.

These as well as other objects and the features of the present invention will become apparent by reading the following statement when taken in conjunction with the accompanying drawings.

The drawings show examples of the audio amplifier arrangement according to the present invention.

FIG. 1 is a perspective view of the audio amplifier arrangement of the present invention in the state that the amplifier unit and the manipulation unit are directly coupled together both electrically and mechanically.

FIG. 2 is an explanatory front elevation of the amplifier unit shown in block style.

FIG. 3 is an explanatory top view of the manipulation unit shown in block style.

FIG. 4 is an explanatory illustration of the connector-equipped cable means.

FIG. 5 is a wiring block diagram, showing in general the respective circuits of the amplifier unit and the manipulation unit in their coupled state.

FIG. 6 is an enlarged partial diagrammatic top view of the manipulation unit, showing an example of the movable projection.

FIG. 7 is a perspective view of the amplifier unit with an adapter unit attached to the front side of this amplifier.

FIG. 8 is an explanatory top view of the adapter unit.

FIG. 9 is a wiring block diagram, showing the respective circuits of the amplifier unit and the adapter unit in their coupled state.

Like parts are shown by like reference numerals and symbols for the sake of simplicity throughout the drawings.

In FIG. 1 which shows an audio amplifier arrangement for two-channel stereophonic sound reproduction embodying one aspect of the present invention, reference numerals 1 and 2 represent an amplifier unit and a manipulation unit, respectively.

A casing 3 of the amplifier unit 1 contains such elements as a transformer, a power amplifier, and other necessary parts for constituting an amplifier circuitry. The general arrangement of the essential parts or elements incorporated in the casing 3 of the amplifier unit 1 corresponds, for example, to the regions locating outside the block of dotted line in FIG. 5.

As shown in FIG. 2, on the front side of the casing 3, there are provided a terminal connector 5, position-determining holes 6 and apertures 7 both of which are used for mechanically coupling the manipulation unit 2 to the amplifier unit 1, a first recess 8 for accommodating a connector-equipped cable means 9 shown in FIG. 4, and a second recess 10 for receiving a protruding connector guide 11 shown in FIG. 3.

On the other hand, a casing 4 of the manipulation unit 2 contains manipulation elements for controlling the operation of the amplifier unit 1. The general arrangement of the essential elements or parts incorporated in the casing 4 of the manipulation unit 2 corresponds, for example, to the region enclosed in the dotted line in FIG. 5. On the front side of the casing 4 of the manipulation unit 2, as shown in FIG. 1, are arranged a power switch S.sub.P, a filter switch S.sub.F, indicator lamps L.sub.1 and L.sub.2, output level meters M, speaker selector switches S.sub.0, S.sub.1, . . . , S.sub.5, volume control variable resistors R.sub.1, . . . , R.sub.5 (refer to FIG. 5). And, with reference to FIG. 3, there are provided the protruding connector guide 11 mentioned above, spring-like movable projections 12, position-determining bulgings 13 and a pin-terminal connector 14 on the rear side of the casing 4.

The manipulation unit 2 can be detachably directly coupled both mechanically and electrically to the amplifier unit 1, with the rear side of the casing 4 and the front side of the casing 3 abutting each other, as shown in FIG. 1. This coupling and locking is performed by bringing spring-like movable projections 12 of the manipulation unit 2 shown in FIG. 3 into engagement in apertures 7 of the amplifier unit 1 shown in FIG. 2. The movable projections 12 are provided at two corners on the rear surface of the casing 4 which is to abut the front surface of the casing 3 and each is of a generally tapered configuration and has a stepped portion 12a formed intermediate of its length. The projections 12 are urged laterally outwardly in FIG. 3. This urging may be had either by manufacturing the projections 12 with a flexible material such as a plastic material and fixing it at one end to the body of the manipulation unit 1 so as to have a habit of normally tilting laterally outwardly in FIG. 3. Or, the urging may be materialized by the construction shown in FIG. 6. In FIG. 6, the projection 12 of a rigid material is supported rotatably about a pin 15 with one end of the projection 12 protruding out of the manipulation unit 2, and the other end of the projection 12 is pressed by a spring 16 so that the one end of the projection 12 is urged laterally outwardly of the casing 4 of the manipulation unit 2. When this manipulation unit 2 is required to be coupled to the amplifier unit 1, the tips of these projections 12 are advanced progressively into the apertures 7 of the amplifier unit 1 while contacting those walls of the apertures 7 which are positioned closer to the lateral ends of the amplifier unit 1 shown in FIG. 3 and while thereby being pressed inwardly toward each other by said walls. As each projection 12 advances up to a position at which its stepped portion 12a is aligned with the edge of the aperture 7 of the casing 4, the projection 12 is urged laterally outwardly so that its stepped portion 12a will be brought into locking engagement with the edge of the aperture 7. Thus, the casing 4 of the manipulation unit 2 is locked to the amplifier casing 3. However, by this locking alone, there can occur that the terminal connector 5 is not correctly coupled to the pin-terminal 14. In order to avoid this, position-determining means are provided on both the casing 3 of the amplifier unit 1 and the casing 4 of the manipulation unit 2. The position-determining means comprises four bulging 13 which are provided at four corners of that surface of the casing 4 which is to face the front surface of the casing 3, and four bulging-receiving holes 6 which are provided at corresponding positions on that surface of the casing 3 which is to face the rear surface of the casing 4. These position-determining means, as the bulgings 13 are engaged in the bulging-receiving holes 6, serve to inhibit the vertical as well as horizontal play of these two casings 3 and 4 which would occur at the time that they are coupled together. More specifically, by bringing the bulgings 13 into engagement with the bulging-receiving holes 6, the manipulation unit 2 can be securely coupled to the amplifier unit 1. Along with this, the protruding connector guide 11 and the second recess 10 for accommodating the protruding connector guide 11 will both serve as the guiding means for correctly coupling the pin-terminal connector 14 to the terminal connector 5, as will be understood from FIGS. 2 and 3.

When it is intended to remove the amplifier unit 1 off the manipulation unit 2, the projections 12 shown in FIG. 3 are pressed inwardly toward each other by fingers of the user. Whereupon, the stepped portions 12a of these projection 12 will be released from their engagement with the bottom edges of the apertures 7 and the projections 12 will be able to be withdrawn from the casing 3. In this state, the casing 4 of the manipulation unit 2 is pulled toward the user, and this unit will be removed from the casing 3 of the amplifier unit 1. Along with this, the pin-terminal connector 14 of the manipulation unit 2 will be detached from the terminal connector 5 of the amplifier unit 1, and at the same time the bulgings 13 will be disengaged from the bulging-receiving holes 6.

When it is intended to use the amplifier unit 1 and the manipulation unit 2 in their separate state, this desire is satisfied by the use of the cable means which is generally indicated by 9 in FIG. 4. This cable means 9 is composed of a cable 9a having at one end a connector 9b adaptable to the pin-terminal connector 14 and at the other end a connector 9c adaptable to the terminal connector 5. The cable 9a may have a length of, say, five meters as required. Such a length of the cable means does not affect the characteristic of the amplifier 1. The connector 9b of this cable means 9 is coupled to the pin-terminal connector 14 of the manipulation unit 2, whereas the connector 9c is coupled to the terminal connector 5 of the amplifier unit 1, so as to electrically couple two units 1 and 2.

The electrical connection between the amplifier unit 1 and the manipulation unit 2 will hereunder be described by referring to FIG. 5. FIG. 5 shows either of the "left-" and "right-" channel circuits of the stereophonic amplifier arrangement. The region enclosed in the dotted line in FIG. 5 represents the manipulation unit 2. The regions outside the block of the dotted line represent the amplifier unit 1 except for a pre-amplifier A.sub.0 and speakers SP.sub.1, . . . , SP.sub.5. Reference symbols a.sub.1, . . . , a.sub.16 represent the pin-contacts of the pin-terminal connector 14 and reference symbols b.sub.1, . . . , b.sub.16 represent the contacts of the terminal connector 5 to be connected to the corresponding pin-contacts a.sub.1, . . . , a.sub.16. The symbol IN represents an input terminal to which an audio input signal is inputted from a signal sources such as a phonograph, an FM radio, or a taperecorder via the pre-amplifier A. The output signal of the pre-amplifier A.sub.0 applied to this input terminal IN is fed to a filter amplifier A.sub.1 which functions as a rumble filter (low-cut filter). This function as a rumble filter can be attained by turning either the rumble filter switch S.sub.F or S'.sub.F "on".

The filter switch S.sub.F of the rumble filter is provided on the front side of the manipulation unit 2 and the filter switch S'.sub.F (not shown) may be provided at a desired place of the amplifier unit 1, to render the rumble filter element on and off. The output or the input signal as required of the filter amplifier A.sub.1 passes through the connector 5 and 14, and via switching circuits, it is applied to a plurality of volume control circuits housed in the manipulation unit 2. The speaker selector switches S1, . . . , S5 each has three interlocked contacts S1-1, S1-2, S1-3, . . . , S5-1, S5-2, and S5-3. In FIG. 5, the switch SP1 is turned "on". Therefore, the variable resistor R.sub.1 is rendered to its operative state by the contact S1-1. The signal which is adjusted of its level by this variable resistor R.sub.1 which is shown only by its knob in FIG. 1 passes through the contact S1-2 and therefrom the signal is led via connectors 5 and 14 to the input terminal of the power amplifier A.sub.2 contained in the amplifier unit 1, where the signal is power amplified to be derived as an output of the power amplifier A.sub.2. Now, the contact S1-3 also is actuated, so that a relay Y.sub.1 connected in series between the output terminal of the power amplifier A.sub.2 and a first output terminal O.sub.1 to which the first speaker SP.sub.1 is to be connected is accordingly actuated, thus rendering the circuit of the speaker SP.sub.1 "on". Thus, the output of the power amplifier A.sub.2 is led to the speaker SP.sub.1. The output signal of the power amplifier A.sub.2 contained in the amplifier unit 1 is delivered from the output terminal of this power amplifier A.sub.2 and, via the connectors 5 and 14, it is led to the input terminal of an output level meter amplifier A.sub.3 housed in the manipulation unit 2 where it is amplified. The signal level is then indicated by an output level meter M which is connected to the output terminal of said output level meter amplifier A.sub.3.

Description will hereunder be made in connection with the power switch S.sub.P provided in the manipulation unit 2, to the filter amplifier A.sub.1, the power amplifier A.sub.2, the meter amplifier A.sub.3 and the relay circuit in FIG. 5. The A.sub.C supply cord plug A.sub.C is connected to a power source, and the primary of a sub-transformer T.sub.S is connected to the output terminals of said AC supply cord. One line of the secondary of the sub-transformer T.sub.S is grounded, and the other line is connected to the input terminal of a relay actuating circuit A.sub.4 of which the output terminal is grounded via the coil of a relay Y.sub.6. The control terminals of the relay actuating circuit A.sub.4 are connected via connectors 5 and 14 to the power switch S.sub.P housed in the manipulation unit 2.

When the power switch S.sub.P in the manipulation unit 2 is turned "on", a voltage for driving the relay Y.sub.6 appears at the output terminal of this relay circuit A.sub.4, causing the contact of this relay Y.sub.6 to be rendered "on". Whereupon, an AC voltage is supplied to the transformer T.sub.P provided in the power supply section, thus supplying a power to the audio amplifier circuitry.

The manipulation unit 2 is provided with the overload indicator lamp L.sub.1 and the thermal indicator lamp L.sub.2 as mentioned above. These lamps are connected to the output of a protection circuit A.sub.5 so that, in case there develops an overloading in the audio amplifier circuitry particularly in the power amplifier, the overload indicator lamp L.sub.1 is lighted up. More specifically, the voltage and the current of the amplifying elements of the audio amplifier circuitry are monitored by the protection circuit A.sub.5, and in case there is a disorder therein, the overload indicator lamp L.sub.1 is caused to be lighted up for warning by said protection circuit A.sub.5. The thermal indicator lamp L.sub.2, on the other hand, is connected to the output of the protection circuit A.sub.5 so that the temperature of the amplifying elements is monitored thereby. In case a disorder is sensed, the thermal indicator lamp L.sub.2 is caused to be lighted up in the same way. At the same time, in order to protect the amplifier circuitry and the speakers SP.sub.1, . . . , SP.sub.5, the protection circuit A.sub.5 sends protection signals to protecting switching circuits A.sub.6 and A.sub.7 provided in the output current paths of a power supply circuit A.sub.8 so as to open these output current paths, and ceases the delivery of actuating power for the relays Y.sub.1, . . . , Y.sub.5, resulting in the speakers SP.sub.1, . . . , SP.sub.5 being disconnected from the power amplifier A.sub.2.

Description will next be made on the accommodation of the cable means 9. This cable means 9 is not needed in the mode of operation of the audio amplifier assembly in which the manipulation unit 2 is mechanically directly coupled to the amplifier unit 1. In order to accommodate this cable means in the aforesaid mode of operation, there is provided the recess 8 as shown in FIG. 2 in the front surface of the amplifier unit 1. The cable means 9 is accommodated in this recess 8. Thus, in case the amplifier unit 1 is mechanically directly coupled to the manipulation unit 2, the whole assembly will give the appearance as if the two units are formed integrally into one piece apparatus. On the other hand, by placing the manipulation unit 2 at a desired distance from the amplifier unit 1, and by connecting the cable means 9 to each of the two units 1 and 2, it is possible to operate the amplifier unit 1 in the so-called remote control mode at any desired position of the user. Such a mode of operation will be quite convenient for the user who intends to listen to the sounds from one speaker for a certain kind of music and to switch over to another speaker for another kind of music and so on while sitting at the optimum listening position. This arrangement is also convenient for a mode of operation wherein the user installs only speakers in a listening room separate from the room in which the amplifier is installed, since the user can operate the whole assembly while he is sitting at the optimum position in the listening room.

Description will hereunder be made, by referring to FIGS. 7, 8 and 9, on still another aspect of the present invention in which an adapter unit 20 is employed. This adapter unit 20 is intended to be attached to the amplifier unit 1 for permitting the amplifier unit 1 to obtain the necessary least functions of an audio amplifier arrangement without the manipulation unit 2.

This adapter unit 20 is composed, for example, of a panel 21, a pin-terminal connector 14, a protruding connector guide 11' provided on the rear side of this panel 21, and in addition thereto, volume control variable resistors R.sub.6, a power switch S.sub.P, and indicator lamps L.sub.1 and L.sub.2 which are contained in the protruding connector guide 11'. The guide 11' is insertable into the second recess 10. On FIGS. 7 and 8, only the knobs of the variable resistors R.sub.6 are shown. The adapter unit is attached, by screw 22, to the front surface of the amplifier unit 1 as shown in FIG. 7, and the electrical coupling of these two units 1 and 20 is accomplished by coupling the pin-terminal connector 14 to the terminal connector 5 of the amplifier unit 1.

The electrical connection between the amplifier unit 1 and the adapter unit 20 will hereunder be described by referring to FIG. 9. The region enclosed in the dotted line in FIG. 9 represents the adapter unit 20. The regions outside the block of the dotted line represent the amplifier unit 1 except for the pre-amplifier A.sub.0 and speakers SP.sub.1, . . . , SP.sub.5. In this case, the output of the filter amplifier A.sub.1 is applied, via the connectors 14 and 15, to the volume control circuit of the variable resistor R.sub.6, and without passing through any selecting circuit, this output is applied directly to the input terminal of the power amplifier A.sub.2 through the connectors 5 and 14. Out of five relays Y.sub.1, . . . , Y.sub.5, the first relay Y.sub.1 only is actuated by the protection circuit A.sub.5 so that the output of the power amplifier A.sub.2 is fed to the first speaker SP.sub.1. Thus, the amplifier unit 1 can perform the necessary least functions of an audio amplifier assembly without the manipulation unit 2.

Description has been made on the present invention with respect to an instance wherein the manipulation section of a power amplifier for changeover of speaker connections is separated from this amplifier. It should be understood, however, that the present invention is applicable equally effectively also to various kinds of manipulation units such as for performing volume control and tone control.

As will be understood clearly from the above statement, the audio amplifier assembly according to the present invention is arranged so that the manipulation unit equipped with various operation elements can be either detachably directly coupled to the amplifier unit both mechanically and electrically, or the manipulation unit can be used separately from the amplifier unit by electrically connecting these two units with a cable means. Thus, only the manipulation unit can be moved to any desired place for a remote control operation. Thus, in the relation with the place of installation of the record player and the speakers, it is possible to freely select the place of installation of the manipulation unit separately from the amplifier unit, which is quite convenient to the user.

It will be understood also that the locking means described above may be replaced by a wellknown hinge means.