EP0263177A1 - Systeme de melange audio et circuit de gain pour celui-ci - Google Patents

Systeme de melange audio et circuit de gain pour celui-ci

Info

Publication number
EP0263177A1
EP0263177A1 EP19870903109 EP87903109A EP0263177A1 EP 0263177 A1 EP0263177 A1 EP 0263177A1 EP 19870903109 EP19870903109 EP 19870903109 EP 87903109 A EP87903109 A EP 87903109A EP 0263177 A1 EP0263177 A1 EP 0263177A1
Authority
EP
European Patent Office
Prior art keywords
audio
signal
gain
signals
control console
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19870903109
Other languages
German (de)
English (en)
Inventor
John E. Juhasz
Daniel Kageff
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thermo Orion Inc
Original Assignee
Orion Research Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Orion Research Inc filed Critical Orion Research Inc
Publication of EP0263177A1 publication Critical patent/EP0263177A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/02—Manually-operated control
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
    • H04H60/02—Arrangements for generating broadcast information; Arrangements for generating broadcast-related information with a direct linking to broadcast information or to broadcast space-time; Arrangements for simultaneous generation of broadcast information and broadcast-related information
    • H04H60/04—Studio equipment; Interconnection of studios

Definitions

  • This invention relates generally to audio mixers and to gain circuits for audio systems.
  • Typical prior audio mixers have received plural audio input signals; have provided for selective signal amplification or other alteration, such as phase, pan, and the like; and have been able selectively to mix respective audio signals to produce one or more audio output signals.
  • Exemplary audio input signals may be derived or received from a microphone, an audio tape recorder, a video tape recorder and the like. The audio input signals usually are brought to a physically large console proximate which the operator sits and at which the audio signals are altered, mixed and used to derive one or more audio output signals, whether monaural or stereophonic.
  • the audio input signals typically are produced at different respectve levels.
  • a signal received from a microphone may be as low as from about -16 db to about -20 db.
  • a signal from a video tape recorder may be from about 10 db to 20 db. It would be desirable to amplify (either positively, i.e. to boost, or negatively, i.e. to reduce or to attenuate) the audio input signals to a nominal level of, say, 0 db so that effectively an equivalent control of each signal is possible, especially, according to the present invention, using generic control circuitry. By bringing all the audio signals to such nominal level, further signal level control of signals for mixing or other purposes would be facilitated.
  • an audio mixer system in which a control console at which an operator may sit is separate from an audio rack at which audio signals are amplified, etc., mixed, and output.
  • the audio signals are not generally transmitted to the control console.
  • using digital signal coupling between the control console and the audio rack which includes the actual audio
  • a visual display and a plurality of programmable analog and digital controls coordinated with the information displayed may be used to set certain functions or parameters in the audio rack, such as initial amplification gain for achieving the nominal level mentioned above, which signals are to be selected for control and/or monitoring, which signals are to be mixed, and so on.
  • An aspect of the invention relates to a selectable gain circuit capable of a relatively wide, say 40 db, amplification range.
  • Such gain circuit may be used to provide selective amplification of an input audio signal to derive an amplified audio signal at a selected nominal level, say 0 db, that can be conveniently further amplified, mixed with one or more other audio signals, and so on.
  • a selected nominal level say 0 db
  • the amplified audio signals will be at approximately the same nominal db level which will facilitate control of further amplification, mixing and other functions.
  • the gain circuit includes a loss stage and a gain stage which are cooperatively adjustable to bring the input audio signal to the desired nominal level.
  • Analog switches may be used to effect the selective adjustment of impedances coupled to such loss and gain stages to determine the degree of effective or overall amplification of the audio signal to achieve the desired nominal level.
  • Signals from the control console selected by the operator determine the setting(s) of the analog switches (open or closed) according to a program or table relating desired gain to, for example, input audio signal level to achieve the desired nominal level.
  • Another aspect of the invention relates to the time division multiplexing of the audio output signal(s) produced by the mixer at the audio rack to develop a bit stream carrying information concerning the amplitude level of each such signal.
  • the bit stream is coupled over a pair of conductors to the control console for processing, e.g. decoding or reconstruction per signal, and display via conventional vu (volume unit) meters.
  • Fig. 1 is a schematic block diagram of an audio system in accordance with the invention.
  • Fig. 2 is a schematic circuit diagram of a gain circuit useful, for example, in the audio system of Fig. 1. DESCRIPTION OF THE PREFERRED EMBODIMENT
  • an audio mixing system in accordance with the present invention is illustrated at 10 in Fig. 1.
  • the fundamental components of the audio mixing system 10 include a control console 12, an audio rack 14, and interconnection facilities 16 for coupling the control console and audio rack.
  • control console 12 and audio rack 14 are separate pieces of equipment, such separation being represented by the line 18. This separation permits the control console 12 and the audio rack 14 to be at different respective locations during use, while the interconnection facilities 16 permit communication and communicative operation between and of the two.
  • the audio rack 14 may be located quite close to the place where the audio signals are developed and mixed audio signals are used, and the control console 12 may be at a relatively remote (or proximate, if desired) location.
  • the control console 12 includes a visual display 20, a number of programmable/programming analog and digital controls 22 directly associated with the visual display, a quick response control portion 24, an output level control 26, and a vu signal processing and display 28.
  • the control console 12 may be physically located in a relatively small area in a control room separate from the area at which the audio rack 14 is located, e.g. the latter may be located directly at a sound stage, studio or the like.
  • Direct communications between the control console 12 and the audio rack 14 preferably is by way of digital signals sent between the two on one or more signal carriers, busses, discrete wires or cables, etc. of the interconnection facilities 16.
  • circuitry and programming information in the control console 12 causes the visual display 20 to display various information; and relying on the information currently displayed a user may manipulate one or more of the control buttons, knobs, etc. 22 to set relatively long term parameters of the audio system 10.
  • the controls 22 may be used to select two specific signals coming in to the audio rack to be mixed, one, say, from a microphone, and another. say, from a video tape recorder. Such signals may be received on pairs of lines 30, 32 as typical balanced audio signals, i.e. not referenced to ground, at the audio rack 14; and after appropriate operation performed on such signals the mixed audio output may be provided on one or more outputs 34, 36 of the audio rack 14.
  • Such adjustment of signals, parameters, functions, and so on are considered relatively long term variables or settings because they ordinarily would be set at the beginning of an audio session or the like and usually would not be changed during the session.
  • the display 20, controls 22 and associated circuitry also may be used to assign respective input audio signals, such as those received on lines 30, 32, to respective controllers or control strips 24a, 24b, etc. in the quick response portion 24.
  • respective input audio signals such as those received on lines 30, 32
  • controllers or control strips 24a, 24b, etc. in the quick response portion 24.
  • the coordinated useage of the visual display 20, controls 22 and associated circuitry permits the designating of a respective control strip 24a, 24b, etc. to act on a specified audio signal.
  • Such coordinated functioning also may be used to assign specific audio signals for output at a specific master or auxiliary output channel.
  • Each control strip 24a, 24b, etc. in the quick response portion 24 of the control console 12 may have a plurality of functions of the type typically available, for example, in conventional audio mixing systems. These may include level control, phase selection, pan balance control, "external input control (e.g. to send an audio signal to an external loop for usual purposes of signal delay or the like), filter control, muting, and the like. Such functions of the control strips are of the type that may require frequent or rapid change or adjustment during an audio session. Response to such changes or settings of the control strips 24a, etc. and of the display 20 and controls 22 may be placed in digital format and communicated digitally over the interconnection facilities 16 to the audio rack.
  • each may include one or more potentiometric circuits, e.g. a potentiometer and an amplifier with appropriate coupling circuitry together with circuitry for digitizing the output thereof and coupling the digitized information to the audio rack via the interconnection facilities 16.
  • Each also may include one or more buttons that may be pushed to mute or to unmute a signal, to determine the phase of the input audio signal, to couple in an external loop, etc., as generally is conventional in prior audio mixing systems but not in the separate console/rack environment of the present invention.
  • the output level control 26 of the control console 12 may include respective potentiometric devices 26a, 26b, etc. and associated amplifier and digitizing equipment to determine the level of the mixed audio output signal delivered, for example on lines 34, 36 at the output of the audio rack 14.
  • the vu processing and display 28 has a separate vu (volume unit) meter for displaying the level of each mixed audio output signal.
  • the vu meters 28a, 28b, etc. are conventional.
  • the audio rack contains processing circuitry 40 to effect time division multiplexing of representations of the mixed audio output signals, thereby producing a bit stream that can be reconstructed in the vu processor circuit 28' at the control console 12 for developing signals that can be displayed on the vu meters.
  • An advantage of such multiplexed transmission of signals is that they can be sent over two wires without requiring a separate pair of wires for each output signal.
  • the audio rack 14 itself, the same may contain conventional amplifier, mixing and like circuitry that is operative to effect the desired level control, signal mixing and like functions.
  • circuitry is responsive to the digital inputs from the control console 12 as was described in further detail above.
  • the audio rack 14 includes plural gain circuits 50, 52 (and possibly more— referably one for each audio input signal that is to be provided simultaneous control by respective control strips 24a, 24b, etc.).
  • Such gain circuits receive a balanced audio input signal from another device, such as a microphone, video or audio tape recorder, radio receiver, etc., for example on lines 30, 32.
  • the actual balanced audio signal ordinarily is not referenced to ground.
  • the balanced audio signal may be at various levels depending on the device at which it is derived; as was mentioned above, microphones typically produce low level signals whereas video tape recorders produce relatively high level signals.
  • the gain circuits can be selectively set, e.g.
  • the visual display 20 controls 22 and associated circuitry in the control console 12, to amplify the balanced audio input signals to produce therefrom a nominal audio signal output, which is represented on lines ⁇ 54, 56.
  • the signals on lines 54, 56 are provided the audio mixer 60 in the audio rack 14 for further amplification or level control, phase changing, pan balance adjust, mixing, and so on to develop the mixed audio output signals for delivery on outputs 34, 36.
  • the gain circuit includes two stages 60, 62, the former being a pure loss stage and the latter a pure gain stage.
  • the loss stage 60 includes a differential amplifier 64. Across the differential input terminals to the amplifier 64 is an input resistor 66; and to such terminals also are coupled respective input circuits 68, 70.
  • Each input circuit 68, 70 includes an input terminal 72, 74 across which the balanced audio input signal is received from another device, such as a microphone, tape recorder, etc.; a pad resistor 76, 78; and a selectively operable switch 80, 82 that may be opened or closed to determine whether or not the pad resistors are actively coupled in circuit with the amplifier 64 or are bypassed and, thus, out of the active circuit.
  • the selectively operable switches 80, 82 preferably are analog switches of conventional design.
  • such switches are represented as normally open contacts that can be selectively closed in response to an appropriate signal being sent to a relay coil or the like.
  • Other types of electrical and electronic switches such as relays, solenoids, electronic and/or solid state switches may be used for such purpose of bypassing or not the respective resistors generally in the manner shown in Fig. 2.
  • an electrical line 84 is shown to provide a selection signal to a driving amplifier 86 that in turn provides a signal to a coil 88 that can operate the contacts 90 for such selective switching purpose.
  • the line 84 is coupled to receive from the control console 12 a signal indicating whether or not the pad resistors 76, 78 are to be in or out of circuit with amplifier 64.
  • the resistors 76, 78 are selected to be of a size that create a socalled -20 db pad. Therefore, when they are coupled in the circuit with amplifier 64, the output of the amplifier 64 is 20db less than the balanced input audio signal. In the case that the resistors are out of such circuit relation, i.e. the switches 80, 82 are closed, there would be no pad and the output level of the signal from the amplifier 64 would be about the same as that of the balanced input audio signal received on terminals 70, 72.
  • a coupling resistor 92 couples the amplified signal output of the differential amplifier 64 to the input of the gain amplifier 93 in the gain stage 62.
  • the gain amplifier 93 may be an operational amplifier, and, as is well known, the gain of such an amplifier is a function of the impedances, such as the resistances, coupled thereto.
  • the gain determining feedback circuit 94 includes plural resistors 94a, 94b, etc., preferably of different respective resistances, and plural analog switches 96a, 96b, etc.
  • Such analog switches may be the same type as the analog switch 80 and may be selectively closed or opened according to control signals determined by the control console 12.
  • each analog switch may include the illustrated contacts associated with a respective resistor, a coil, an amplifier, and an input terminal, as was described above with reference to the analog switch 80.
  • the resistors in the feedback circuit 94 are of a size that allows the gain of the gain stage 62 to be varied select over a 20 db range at approximately equal increments.
  • the loss stage 60 and gain stage 62 should be coordinated such that when the gain stage has 0 gain, the pad circuit loss stage has the ability to attenuate the the largest expected level of balanced audio input signal to the nominal level of, say, a ⁇ db level.
  • the maximum gain of the gain stage 62 should be of a size that will amplify a minimum level of received balanced input audio signal to the desired nominal 0 db level.
  • buttons 22 indicate to the control console at the display 20 and button controls 22 the type of input signal (and possibly the usual level thereof) , as is evident according to known principles.
  • loss stage would bypass the pad resistors, and the gain stage would amplify the signal by about 16 db to achieve the nominal level.
  • the pad resistors would effect a -20 db pad being coupled in the loss stage, to produce a -4 db signal at the output of the differential amplifier 64, and the gain stage would amplify such signal by about 4 db to achieve the nominal level.
  • the present invention may be used to amplify signals to achieve the desired signal levels in a convenient manner and such s-ignals, especially when of the audio type, may be conveniently mixed, amplified, etc.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Control Of Amplification And Gain Control (AREA)

Abstract

Un système de mélange audio comporte une console de commande (12), un mélangeur de signaux audio, un mécanisme d'interconnection pour coupler ladite console de commande avec ledit mélangeur en utilisant la communication de signaux numériques, la console de commande comportant une visualisation (20) pour l'affichage des valeurs de paramètres choisis dudit mélangeur et un dispositif de sélection pour sélectionner les valeurs des paramètres affichés respectifs au fur et à mesure de leur affichage. Un circuit de gain pour les signaux audio comporte un amplificateur différentiel (64) qui amplifie un signal audio équilibré reçu (68, 70) afin de produire un signal de sortie amplifié par rapport à un niveau de signal de référence, un circuit atténuateur à utilisation sélective (60) permettant d'atténuer de manière sélective l'entrée dudit signal audio équilibré introduit dans ledit amplificateur différentiel, un amplificateur de gain (64) servant à amplifier ledit signal de sortie amplifié destiné à produire un signal audio amplifié, un dispositif (94) à impédance utilisable sélectivement pour établir le gain réel dudit amplificateur de gain, et un sélecteur (80, 82, 96a, 96b) pour l'utilisation sélective tant dudit circuit d'atténuation que dudit dispositif d'impédance à utilisation sélective afin de régler ledit signal audio amplifié à un niveau approximatif prédéterminé.
EP19870903109 1986-04-11 1987-04-13 Systeme de melange audio et circuit de gain pour celui-ci Withdrawn EP0263177A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US85076586A 1986-04-11 1986-04-11
US850765 1986-04-11

Publications (1)

Publication Number Publication Date
EP0263177A1 true EP0263177A1 (fr) 1988-04-13

Family

ID=25309055

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870903109 Withdrawn EP0263177A1 (fr) 1986-04-11 1987-04-13 Systeme de melange audio et circuit de gain pour celui-ci

Country Status (3)

Country Link
EP (1) EP0263177A1 (fr)
AU (1) AU7305487A (fr)
WO (1) WO1987006404A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2711460B1 (fr) * 1993-10-18 1996-02-02 Innova Son Système de commutation et transmission bidirectionnelle à multiplexage temporel pour des signaux haute-fidélité audio-analogiques et audionumériques et des signaux de commande et de contrôle.
GB2299493B (en) * 1995-03-28 2000-01-12 Sony Uk Ltd Digital signal processing
EP2372907A3 (fr) * 2010-03-24 2014-05-07 Yamaha Corporation Dispositif de réglage de niveau

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4357492A (en) * 1980-10-03 1982-11-02 Eugene Campbell Automatic microphone mixing apparatus
US4479240A (en) * 1981-09-29 1984-10-23 Mckinley Jr Robert H Audio mixing console with control element position storage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8706404A1 *

Also Published As

Publication number Publication date
AU7305487A (en) 1987-11-09
WO1987006404A1 (fr) 1987-10-22

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Inventor name: KAGEFF, DANIEL