US3702901A

US3702901A - Volume, balance and fader control for four channel sound system

Info

Publication number: US3702901A
Application number: US100579A
Authority: US
Inventors: James R Cherry
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 1970-12-22
Filing date: 1970-12-22
Publication date: 1972-11-14
Anticipated expiration: 1989-11-14
Also published as: GB1317530A; CA941310A; IT953204B; DE2161474A1; JPS471120U; JPS512585Y2

Abstract

A volume, balance and fader control circuit is provided to control the translation of audio signals through a four channel audio system so that balancing of the output volume of the four channels is readily accomplished by a simple balance and fader control arrangement without causing changes in the total volume output of the four speakers. A single potentiometer is used for the left to right balance control and a second single potentiometer is used for the front to back fader control. The balance and fader potentiometers are operated to place the listener in the center of a surrounding field of sound without changing the total volume level of the four speakers.

Description

United States Patent Cherry [54] VOLUME, BALANCE AND FADER CONTROL FORFOUR CHANNEL SOUND SYSTEM [52] US. Cl ..l79/1 G, 179/1, VL, 179/1 D [51] Int. Cl. ..H03g 3/00 [58] Field of Search ..l79/l9,9A,9P,9VL,9D,

179/9 J, 9 A; 333/28 T, 18 T; 338/128 I [451 Nov. 14, 1972 2,148,030 I 2/1939 McLennan ..l79/1D Primary Examiner-Kathleen H. Claffy Assistant Examiner-Jon Bradford Leaheey Attorney-Mueller & Aichele [57] ABSTRACT A volume, balance and fader control circuit is provided to control the translation of audio signals.

through a four channel audio system so that balancing of the output volume of the four channels is readily accomplished by a simple balance and fader control arrangement without causing changes in the total volume output of the four speakers. A single potentiometer is usedfor the left to right balance control and a second single potentiometer is used for the front to back fader control. The balance and fader potentiometers are operated to place the listener in the center of a surrounding field of sound without changing the total volume level of the four speakers.

4 Clains, 3 Drawing Figures [56] p References Cited UNITED STATES PATENTS 3,397,286 8/1968 Prewitt ..179/1VE 2,474,191 6/1949 Reid ..333/28T 2,488,410 11/1949 Keizer ..333/28T 2,899,505 8/1959 Dresser ..338/128 CHANNEL 36 A-IN 5+ 35 BALANCE CHANNEL C-IN CHANNEL D-IN PKTENTEDNHV 972 3.702.901

FIGZ I FIGB CHANNEL 38 22 B-IN 5+ 35 LF -66 BALANCE 42 26 CHANNEL INVENTOR JAMES R. CHERRY ATTORNEYS VOLUME, BALANCE AND FADER CONTROL FOR FOUR CHANNEL SOUND SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to four channel sound systems and more particularly, to a volume,

balance and fader control arrangement therefor.

Audio reproducing systems such as multi-track tape players of the four track and eight track type are wellknown in the art for reproducing either monaural or stereophonic sound, whichever of these is desired by the user thereof. Recently a new development in four channel sound systems has made it possible for the listener to surround himself or herself within a field of sound emanating from four different speaker systems. Adjusting the volume or balance condition of such multi-channel sound systems is a rather difficult and tiresome task as it requires the adjustment of four independent sound channels.

Such four channel sound systems have been incorporated into the cartridge type tape player. Tape players of this type have found relative popularity for use in automobiles because of the ease with which a tape cartridge can be inserted into the tape player. A feature which lends this type of tape player readily to the safe operation of the motor vehicle, for instance, by the driver while he is driving, is that the cartridge can quickly and simply be inserted into the player, and this single act will initiate operation of the player system. Cartridge type tape players of this general charac teristic may include switch means which instantaneously actuate the tape reproducing mechanism upon complete insertion of the cartridge to effect operation of the system. To turn off the tape player, the operator merely pulls out the cartridge, either partially, or all the way, and in some instances, completion of the playing of all tracks on the tape within the cartridge will automatically eject the cartridge from the player and turn off the system. Despite the ease of operation of this particular type of tape player, the listening quality of monaural or stereophonic reproductions from corresponding channels or pairs of channels on the tape has provided only a limited increased listening pleasure as compared to an actual orchestra. However, by the empirical testing of listeners it has been found that four channels of sound, each independent of the other, substantially increase the listening pleasure as compared to monaural and stereophonic sound systems. The four channel sound arrangement allows the listener to feel that he is in the center of the field of sound, i.e. surrounded completely by sound and he can position himself accoustically to any desired location within the sound radiating pattern. But, as mentioned above, this is a relatively difficult process requiring the adjustment of many different control knobs.

SUMMARY OF THE INVENTION whereby the average total volume of the sum of the four channels is not affected by adjusting the balance and fader controls of the system.

Yet another object of this invention is to provide a simplified control arrangement whereby left and right balance control is obtained by moving a first control knob left to right or right to left, and forward and back fader control is obtained by moving a second knob in a plane perpendicular to said balance control knob, it being moved up and down or front to back.

A feature of this invention is the provision of a pair of variable resistance elements each having the movable contact thereof connected together and connected to a single volume control element which supplies DC power for setting the overall volume of the entire system. Adjusting the balance or fader control merely changes the division of DC power used to control the gain of the respective channels but does not appreciably change the sum or total gain of these channels.

Briefly, a four channel sound reproducing system is provided with an independent signal translating and amplifier stage for each channel and having an input terminal for receiving a discrete input signal from one of a plurality of transducer devices such as a pick-up element or portion on a four channel magnetic pick-up head. The output of each channel is connected to its respective speaker or sound reproducing means in any suitable manner. The amplitude of the sound translated through the respective channels is controlled by the signal gain within that particular channel. This is illustrated herein by a transistor connected in circuit with the respective channels'and ground potential and the transistors act as variable gain control devices. Each of listener can position himself in the center of the field of sound but the total sum of the gain of all four channels remains substantially constant. Therefore, not only is the user able to quickly and easily balance or locate himself in the center of sound within the area defined by the four speakers, but the relative total volume emanating from the four speakers remains substantially constant at all times while he is actually balancing a system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of a four channel eight track tape player wherein the volume, balance and fader control circuit of this invention can be used;

FIG. 2 is a top plan view of an automobile illustrating four speakers in four quadrants of its interior thus showing one advantageous use of the volume, balance and fader control circuit of this invention; and

FIG. 3 is a detailed schematic diagram of the preferred embodiment of the volume, balance and fader control circuit of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding of this invention, a particular environment is herein illustrated, but it will be understood that any signal translating system having four channels can utilize the balance and fader control circuit of this invention as being simply a gain sharing or dividing control circuit. Also, it will be noted that like reference numerals throughout the various views of the drawings are intended to designate similar elements and/or components.

Referring now to FIG. 1, there is seen a diagrammatic representation of a multi-track magnetic tape player designated generally by reference numeral 10. The tape player may include any suitable mounting brackets to permit mounting the player to the interior of an automobile, as seen in FIG. 2, in a conventional location to be easily reached and used by the operator of the automobile. In a known manner, the tape player 10 may include a tone control knob 12 and a volume control knob 14, or vice versa. An entryway 16 is provided to receive a cartridge 18 such that the insertion of the cartridge into the player 10 will cause automatic turn-on of the same and removal of the cartridge 18, at least to an unlocked condition, will cause automatic tum-off of the tape player 10. The cartridge 18 preferably contains an eight track tape wherein two programs are recorded and each program contains four independent channels of audio signal information. When the cartridge is of this type, it may be identified by a notch 180, or the like, and the volume, balance and fader control system of this invention is then utilized to best advantage to control the four independent channels of sound.

When the tape player 10 is used to reproduce four independent channels of audio signal information, the sound information ofeach channel is reproduced independently from four

separate speakers

20, 22, 24 and 26 here shown as being located in the four corners of the automobile of FIG. 2. This arrangement will substantially simulate surrounding the operator of the automobile within a complete field of music and the operator can then balance himself to be in the center of sound. FIG. 2 illustrates the automobile 15 as having the top thereof removed to more clearly show the location and arrangement of the speakers therein, it being understood that the automobile may be a sedan, hardtop or convertible, as desired, and the four speakers may be located in positions other than those shown in FIG. 2.

By utilizing the volume, balance and fader control circuit of this invention, the volume control knob 14 will function to set the overall volume emanating from the four speakers, this being the sum of the independent outputs of the speakers. The first control lever 28, which is here illustrated as the balance control for left and right balancing, extends through the housing of the tape player 10 through a horizontal elongated slot 28a and is attached to a potentiometer to cause balancing of the

speakers

20 and 22 with respect to the

speakers

24 and 26, they being on the left and right sides of the operator respectively. A second control lever 30, which is a fader control for front to back balancing, extends through a vertical elongated slot within the tape player 10 and is attached to a potentiometer to cause balancing of the

speakers

22 and 26 with respect to the

speakers

20 and 24. They being at the front and rear of the operator respectively.

For a better understanding of one preferred arrangement of this invention, reference is now made to FIG. 3 which illustrates a detailed schematic diagram of a volume, balance and fader control circuit which can be used in a four channel sound system.

The volume, balance and fader control circuit is designated generally by reference numeral 35 and is used'to control the relative output volume levels of the four channels driving the four

speakers

20, 22, 24 and 26. Connected to each of these speakers is a corresponding, independent audio signal translating channel, 36, 38, 40 and 42, respectively, each having an independent and isolated input terminal. The input terminal of each of these signal translating channels may be connected to a magnetic pick-up device, not shown, to extract audio signal information from discrete tracks of the magnetic tape within the cartridge 18. There is no intercoupling of audio signal information from one signal translating channel to the other and the only audio mixing that takes place will occur in the air space substantially centrally of the four speakers so that the listener is surrounded or substantially surrounded by sound.

Connected in circuit with each of the

signal translating channels

36, 38, 40 and 42 is a

corresponding transistor

44, 46, 48 and 50, respectively, each of which act as a variable impedance device in the circuit to control the gain of the audio signal passing therethrough. The

transistors

44, 46, 48 and 50 are here illustrated as NPN transistors with the collector electrode thereof connected to the signal translating channel and the emitter electrode thereof connected to ground potential. However, it will be understood that a PNP type transistor may be used and the opposite electrode connection can be effected in either case.

A first variable impedance element is provided by a potentiometer 52 which acts as a balance control and has one end thereof connected to the first and

second channels

36 and 38 and the other end thereof connected to the third and

fourth channels

40 and 42. A movable contactor 52a of the potentiometer 52 is readily adjustable between the ends of the potentiometer to effect a variable voltage divider network between the respective pairs of channels connected at the ends thereof. By so adjusting the position of the movable contactor 52a, the amount of DC voltage delivered to the respective pairs of channels, at the base of their associated transistor, is thus varied-but the total sum of such DC voltage remains the same. This causes balancing of the respective pairs of channelswhile at the same time maintaining a constant volume with respect to the total output of the pairs of channels because potentiometer 52 is connected only as a voltage divider and not as a limiting element or shunting device.

A second variable resistance element is provided by a potentiometer 62 and this potentiometer then acts as a fader control for balancing the audio condition between the forward and back sets of

speakers

22, 26 and 20, 24 respectively. The potentiometer 62 has one end thereof connected to the first and third

signal translating channels

36 and 40 and the other end thereof connected to the second and fourth

signal translating channels

38 and 42. The potentiometer 62 is, in similar manner, connected as a voltage divider element with the movable contactor 62a thereof dividing a fixed amount of DC voltage between the respective forward and rear sets of channels.

In the preferred embodiment illustrated herein, a fixed valued, series connected resistor is connected between the base electrode of the

respective transistors

44, 46, 48 and 50 to serve as bias current limiting devices in the circuit. However, it will be noted that these resistors, in some instances, may be eliminated. In this specific arrangement however, the top end of potentiometer 52 is connected to a pair of fixed valued

resistors

70 and 72 while the bottom end of the potentiometer 52 is connected to a pair of fixed value resistors 74 and 76. On the other hand, the top end of potentiometer 62 is connected to a pair of fixed valued

resistors

78 and 80 and the bottom end of potentiometer is connected to a pair of fixed

value resistors

82 and 84.

To set the overall volume of the system, which is the summation of the output of all four speakers, a volume potentiometer 64 has the movable contactor 64a thereof electrically connected directly to the movable contactors 52a and 62a of potentiometers 52 and 62, respectively. The potentiometer 64 is connected to a 8+ supply through a terminal 66 in any suitable and well known manner. Once volume potentiometer 64 is set so as to achieve a desired total volume level, this volume level is maintained during the balancing operation of potentiometers 52 and 62. Also, the balancing operation can be effected first without being upset or changed by an increase or decrease in the total volume of the four speakers. For example, the listener can adjust the levers 28 and 30 to effect movement of the contactors 52a and 62a, respectively, to center himself within the field of sound. After this adjustment is finished, he can then set the desired volume by adjusting the knob 14, which effects movement of the contactor 64a and such volume change will not upset the balance condition previously set by the balance and fader controls.

What has been described, is a simple and effective means of providing a control arrangement to center the listener within a field of sound so that he feels as though he is completely surrounded by sound. Additionally, the circuit arrangement illustrated herein maintains substantially constant volume of the system, once volume is set, despite respective changes in balance and fader perameters. Accordingly, variations and modifications of this invention may be effected without departing from the spirit and scope of the novel concepts disclosed and claimed herein.

I claim:

1. A volume balance and fader control circuit for a four channel sound translating and reproducing system, including in combination, first, second,third and fourth sound signal translating channels, each for translating a different sound signal, each sound signal translating channel including a gain control device for varying the gain therein in response to a direct current potential applied thereto, and output speaker means for reproducing the sound, a volume control including variable resistance means for providing a selected direct current controlpotential, a balance control including a first tentiqmeter having an input and first and second outg l its, said mput being connected to said variable resistance means, said first output being connected to respective gain control devices in said first and second signal n'anslating channels, and said second output being connected to respective gain control devices in said third and fourth sound signal translating channels, a fader control including a second potentiometer having an input and first and second outputs, said input being connected to said variable resistance means, said first output being connected to respective gain control devices in said first and third sound signal translating channels and said second output being connected to respective gain control devices in said second and fourth sound signal translating channels, whereby said variable resistance means of said volume control applies a selected direct current potential to each of said gain control devices to establish the overall gain of the four channel sound translating and reproducing system, and said first and second potentiometers of said balance and fader controls cooperate as a variable voltage divider for coupling said direct current potential from said volume control to each of said gain control devices to provide balance and fader control of the four channel sound translating and reproducing system without substantially affecting the overall gain of the system.

2. The volume balance and fader control circuit of claim 1 further including a transistor connected in circuit with each of said first, second, third and fourth sound signal translating channels, each transistor having the collector-emitter junction thereof connected in series with respective signal translating channel and ground potential and the base electrode of said transistors being coupled to said first and second potentiometer means.

3. The volume balance and fader control circuit of claim 2 further including a fixed resistor connected in series between said first and second potentiometer means and the base electrodes of the transistors connected thereto.

4. The volume balance and fader control circuit of claim 1 further including a first lever connected to said first potentiometer means, said first lever being movable back and forth in a first plane, and a second lever connected to said second potentiometer means said second lever being movable back and forth in a plane perpendicular to said first plane, said first and second levers being adjusted to effect a desired balancing condition of said first, second, third and fourth sound signal translating channels.

Claims

1. A volume balance and fader control circuit for a four channel sound translating and reproducing system, including in combination, first, second,third and fourth sound signal translating channels, each for translating a different sound signal, each sound signal translating channel including a gain control device for varying the gain therein in response to a direct current potential applied thereto, and output speaker means for reproducing the sound, a volume control including variable resistance means for providing a selected direct current control potential, a balance control including a first potentiometer having an input and first and second outputs, said input being connected to said variable resistance means, said first output being connected to respective gain control devices in said first and second signal translating channels, and said second output being connected to respective gain control devices in said third and fourth sound signal translating channels, a fader control including a second potentiometer having an input and first and second outputs, said input being connected to said variable resistance means, said first output being connected to respective gain control devices in said first and third sound signal translating channels and said second output being connected to respective gain control devices in said second and fourth sound signal translating channels, whereby said variable resistance means of said volume control applies a selected direct current potential to each of said gain control devices to establish the overall gain of the four channel sound translating and reproducing system, and said first and second potentiometers of said balance and fader controls cooperate as a variable voltage divider for coupling said direct current potential from said volume control to each of said gain control devices to provide balance and fader control of the four channel sound translating and reproducing system without substantially affecting the overall gain of the system.