GB2276519A - Monitor matrix for audio mixer - Google Patents

Abstract

An audio mixer system for video editing is disclosed in which a plurality of audio source monitor signals are routed through an array of switches 11 - 44 to a plurality of monitor output terminals. Thereby, two or more audio channels may be provided to several different monitor output terminals in various combinations. Level control including monitoring of the monitor source signals are also provided. The output terminals may be connected to two or more loudspeakers. The signals applied to the switch array may be derived from microphone outputs, sound effect returns or playback signals from video recorders. These signals may be combined by pressing of buttons associated with the switches formed on a display or control panel of the mixer. <IMAGE>

Description

MONITOR MATRIX FOR AUDIO MIXER This invention relates to a routing scheme in an audio mixer for routing monitor audio channels to output jacks. More particularly, this invention relates to a routing scheme which provides a more flexible method for routing various combinations of monitor source signals in an audio mixer to a plurality of different output jacks.

In order to facilitate the use of an audio mixer, it is useful to monitor the various audio signals processed by the mixer. Such monitoring is typically achieved by routing selected source audio signals to one or more output terminals. The selected source signals may be, for example, line out signals, effect send signals or various external inputs.

Most conventional audio mixers provide for one channel (mono) or two channel (stereo) monitoring of selected audio signals. However, for some applications, for example video editing, it is known to use mixers which have a capability for supporting devices utilizing more than two channels, such as four channel VTRs. In such mixers, it is useful to offer more than two channel monitoring. However, at certain times it is more convenient to monitor the audio signals in these mixers with only a single speaker or only a pair of speakers.

Consequently, there is a need to provide a flexible way of routing the various monitor source signals to an increased number of output jacks serving as output terminals to monitoring devices. More particularly, there is a need to route various combinations of monitor source signals to different output terminals in such a way that a mixer may support different combinations of monitoring devices, such as one, two, or more speakers.

In view of the foregoing, it is apparent that prior art audio mixers lack a convenient method of providing a plurality of monitor output signals to a plurality of monitor output jacks.

A general object of this invention is to provide a routing system according to the present invention that enables the routing of any combination of selected output source signals to various output jacks in a simple, easy to use manner.

This and other objects and advantages are achieved in this invention by the use of an array scheme for routing the monitor signals to the monitor output terminals.

For example, according to an embodiment of the present invention, a four by four array of switches is used to route four simultaneous channels of a monitor output source to four monitor output terminals. The array consists of sixteen buttons arranged in four rows and four columns wherein each row corresponds to a single channel monitor source and each column corresponds to an output jack, whereby a user may conveniently route any of the four channels to any of the four output jacks by depressing the appropriate buttons. The invention may also include a monitor level output control for controlling the overall level of the monitor output signals routed to the output jacks. It may also be expanded to include any number of monitor sources and monitor output terminals.

The invention will be further described by way of non-limitativa xrnnle, with reference to the accompanying drawings, in which: Fig. 1 is an example of a typical application of a mixer in which audio signal monitoring is utilized.

Fig. 2 is an illustration of one embodiment of the invention.

Figs. 3A-3C provide three examples of various operations of an embodiment of the invention.

Fig. 4 is a more detailed drawing of an embodiment shown in Fig. 2.

Fig. 5 is a more detailed example of circuits used in the embodiment shown in Fig. 4.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, there is shown in Fig. 1 by way of example a mixer system for video editing, shown generally at reference numeral 125. As illustrated, various audio signals may be input to a mixer 100, such as microphone inputs 127, effect return inputs 129, and playback signals from a plurality of VTRs 131. In the course of editing, it is useful to monitor these various audio signals. For the four channel monitoring illustrated, two selected stereo signals 133 and 135 are being monitored. Thus, it is necessary to route two stereo signals to four monitor output terminals. However, it may at times be more convenient to use other combinations of monitoring devices, such as four monaural signals.

Accordingly, Fig. 2 illustrates an n x m array 150 of four n rows la, 2a, 3a, and 4a of buttons and four m columns lb, 2b, 3b, and 4b of buttons used to provide a routing scheme for coupling any of four selected monitor source signals to any of four output jacks. The array 150 is located on the display of a mixer, such as the mixer 100 shown in Fig. 1. The array 150 may include a monitor level control adjustor 250 for adjusting the overall amplitude of the monitor source signals routed through the array to the four monitor output jacks.

While a four by four n x m array 150 is illustrated, the number of rows n and columns m may be expanded to provide a greater number of monitor source signals to a greater number of monitor output terminals.

The four by four array 150 described herein may be used advantageously as part of a video mixer which supports a plurality of two or four channel devices, such as two or four channel VTRs, as illustrated in Fig. 1.

According to this embodiment of the invention, as best seen in Fig. 4, four monitor source signals 10, 20, 30, and 40 are selected in the mixer and are respectively coupled to four corresponding terminals in the mixer through sixteen switches 11, 12, 13, and 14; 21, 22, 23, and 24; 31, 32, 33, and 34; and 41, 42, 43, and 44. The switches are arranged in four rows la, 2a, 3a, and 4a, and in four columns lb, 2b, 3b, and 4b. Each row la, 2a, 3a, and 4a corresponds respectively to a monitor source signal 10, 20, 30, and 40. Each column ib, 2b, 3b, and 4b corresponds respectively to a monitor output terminal 1, 2, 3, and 4.By depressing any of the sixteen buttons illustrated in Fig. 2, a corresponding one of the switches 11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 33, 34, 41, 42, 43, or 44 closes, thereby closing a path for the corresponding monitor source signal 10, 20, 30, or 40 to a corresponding monitor output terminal 1, 2, 3, or 4.

Figs. 3A through 3C illustrate the use of such an array. In each example, a shaded button indicates a closed switch. Accordingly, in Fig. 3A, switches 11, 22, 31 and 42 are closed. Thus, a signal path is provided for monitor source signal 10 to monitor output 1, for monitor source signal 20 to monitor output 2, for monitor source signal 30 to monitor output 1, and for monitor source signal 40 to monitor output 2. That is, monitor output terminal 1 provides the sum of selected monitor output signals 10 and 30, and monitor output terminal 2 provides the sum of selected monitor output signals 20 and 40. No signals are available at monitor output terminals 3 and 4 for this exemplary switching state.

In Fig. 3B, switches 11, 22, 33, and 44 are closed. Thus, monitor source signals 10, 20, 30 and 40 are available respectively at output terminals 1, 2, 3, and 4. This arrangement could be used, for example, to provide two stereo monitor signals at four output terminals, as illustrated in Fig. 1.

In Fig. 3C, switches 11, 12, 21, 22, 31, 32, 41, and 42 are closed. Therefore, the sum of monitor source signals 10, 20, 30, and 40 are available at both output terminals 1 and 2. No signals are available at monitor output terminal 3 and 4.

Fig. 4 provides a more detailed illustration of the array 150. The buttons shown in Fig. 2 are illustrated in dashed lines surrounding sixteen corresponding switches 11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 33, 34, 41, 42, 43, and 44. These switches may be opened or closed by depressing the corresponding button. The switches are arranged in an n x matrix 150 of four rows and four columns, as shown in Fig. 2. Each n row la, 2a, 3a, and 4a corresponds to a previously selected monitor source signal 10, 20, 30, and 40, and each m column lb, 2b, 3b, and 4b corresponds to a monitor output terminal jack 1, 2, 3 and 4. By depressing the appropriate button, a signal path is closed coupling a monitor source signal 10, 20, 30, or 40 to an output terminal 1, 2, 3, or 4.

Monitor level circuits 201, 202, 203, and 204 and monitor mute circuits 301, 302, 303, and 304, are coupled to the array 150 between each column of switches lb, 2b, 3b, and 4b and monitor output terminals 1, 2, 3 and 4. The monitor level circuits 201, 202, 203, and 204 may comprise various signal amplitude adjusting arrangements known in the art. Similarly, monitor mute circuits 301, 302, 303, and 304 may comprise any suitable signal muting circuit known in the art. After passing through the respective monitor level circuit 201, 202, 203, or 204 and the respective monitor mute circuit 301, 302, 303, or 304, the routed monitor source signal(s) 10, 20, 30 or 40 is (are) provided to outputs 1, 2, 3, and 4.

By way of example, Fig. 5 shows a more detailed view of the circuit coupled to column ib of array 150 between switches 11, 21, 31, and 41 and monitor output terminal 1. Corresponding circuits may be used for the remaining three columns 2b, 3b, and 4b of array 150.

Such corresponding circuits are generally indicated by a block 500. These corresponding circuits are substantially the same as the circuit arrangement illustrated in Fig. 5.

In this embodiment, the monitor level control circuit 501 is coupled along the signal path starting with the four monitor source terminals lc, 2c, 3c, and 4c which provide monitor source signals 10, 20, 30 and 40, and terminating with monitor output terminal 1. The monitor level control circuit includes an operational amplifier 210, a variable resistor 212, and a capacitor 214, as well as resistors 206, 207, 208, and 209. The gain of the operational amplifier 210 may be adjusted with a variable resistor 212 through the monitor level control adjustor 250 (shown in Fig. 2) located on the display of the mixer. In this example, each of the four monitor level circuits 201, 202, 203, and 204 shares a single variable resistor 212, thus providing a master level control of all four monitor outputs.Accordingly, the monitor level circuits 201, 202, 203, and 204 are shown connected to each other in Fig. 4.

Fig. 5 also provides an example of the monitor mute circuit 301. In this embodiment, the monitor mute circuit 301 comprises an analog switch 310 coupled to the mute signal 320. The switch 310 provides for muting of the output terminal 1 when opened by a mute control signal 320. The remaining mute circuits 302, 303, 304 have corresponding switches in order to provide individual muting of the respective monitor output terminals 2, 3, and 4.

The example shown in Fig. 5 also includes an additional circuit 501 comprised of voltage divider resistors 514 and 516, a transistor 510, and a base resistor 518. The circuit 501 is coupled to a master mute signal 520, which also controls corresponding circuits similarly coupled between columns 2b, 3b, and 4b and the respective monitor output terminals 2, 3, and 4.

The mute signal 520 is further coupled to additional control circuits 600 controlling other signals in the mixer. The master mute signal 520 may be used to simultaneously mute all four monitor output terminals, along with other signals in the mixer (not shown).

The arrangement shown in Fig. 5 also includes a buffer circuit 401 which isolates the mixer 100 from monitoring devices attached to the monitor outputs 1, 2, 3, and 4. The buffer circuit 401 includes an operational amplifier 410, a resistor 412, a capacitor 414, and a resistor 416. Additionally, two filters respectively comprised of a resistor 602 and a capacitor 604 and a resistor 606 and a capacitor 608, are shown respectively between the monitor level circuit 201 and the monitor mute circuit 301, and between the buffer circuit 401 and the monitor output terminal 1.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the scope thereof, as defined in the claims, can make various changes and modifications of the invention.

For example, the embodiment described above can be expanded to any number of monitor sources or output terminals.

Claims (10)

1. An audio mixer system for monitoring a plurality of audio signals comprising: a mixer for providing selected audio monitor signals to monitor source terminals, a plurality of monitor output terminals for providing one or more monitoring audio channels from said mixer to one or more external devices; and switching means for selecting one or more of said audio monitor signals from said monitor source terminals to one or more of said monitor output terminals, said switching means including a matrix of switches arranged on a display of the audio mixer in a plurality of rows and a plurality of columns.

2. The audio mixer system of claim 1 wherein said mixer is coupled to one or more input devices providing more than two selectable input audio channels to the mixer.

3. The audio mixer system of claim 1 or 2 further comprising means for adjusting the output level of said audio monitor signals which are routed to said monitor output terminals through said switching means.

4. The audio mixer system of claim 1, 2 or 3 wherein said plurality of monitor output terminals comprises four monitor output terminals whereby up to four audio channels may be provided through said monitor output terminals.

5. A method of monitoring a plurality of audio monitor signals in an audio mixer system comprising: providing selected audio monitor signals to monitor source terminals in a mixer, and selecting with switching means one or more of said audio monitor signals from said monitor source terminals and supplying it to one or more monitor output terminals, said monitor output terminals providing one or more monitoring audio channels to one or more external devices, wherein said switching means includes a matrix of switches arranged on a display of the audio mixer in a plurality of rows and a plurality of columns.

6. The method of claim 5, further comprising coupling said mixer to one or more input devices providing more than two selectable input audio channels to the mixer.

7. The method of claim 5 or 6, further comprising the step of adjusting the output level of said audio monitor signals which are routed to said monitor output terminals through said switching means.

8. The method of claim 5, 6 or 7, wherein said plurality of monitor output terminals comprises four monitor output terminals whereby up to four audio channels may be provided through said monitor output terminals.

9. An audio mixer system constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

10. A routing switch array for use in an audio mixer according to any one of the preceding claims.