console and mixer notes

Mixers and Consoles Mixers and consoles take input signals and amplify, balance, process, combine, and route them to broadcast or recording. Many consoles also store operational data. The differences between them are that a mixer is small, quite portable, and performs limited processing functions. The console is larger, substantially so in many models, more complex, and performs numerous processing functions. In many systems these functions are computer assisted. Their purposes and differences notwithstanding, mixers and consoles, from the most fundamental to the most elaborate, whether analog or digital, have at least three basic sections: input, output, and monitor.Signals from a sound source, such as the microphone, feed to the input section, which routes them to the output section. The output section routes the signals to a recorder or broadcast, or both. The monitor section enables the signals to be heard. Consoles designed for multichannels recording usually have a master section as well. In those consoles the output section routes signals to a multitrack recorder, and the master section routes the final mix to its recording destination.The console is simply a device for amplifying, routing, and mixing audio signals. Audio is the term used to refer to the electrical signals that are involved in the reproduction or transmission of sound. Sound is a vibration through air or another medium; audio is the electrical signal used in reproducing or transmitting the original sound.Functions of the Console1. Amplification. This is the boosting of a signal to a usable level. The tiny voltage produced by a phonograph is not strong enough to send to a loudspeaker or over the air. The console gives the operator convenient control over the volume of various signal sources such as microphones, turntables (professional-quality record players), and tape playback units.2. Routing. The console allows the producer to determine the path of the signal or, in other words, to route it. The console can send a signal either over the air or into a cue channel, which lets the operator hear an audio source without having the signal go over the air. In addition to routing signals through the console, the operator can turn signals on and off.3. Mixing. The signals can put two signals out at once – the announcer’s voice and music, for example. The console also allows the volume of both to be controlled separately, or mixed, so that the music doesn’t drown out of the announcer.Through amplification, routing, and mixing, the console operator can produce a final product that will be sent out over the air or routed to a tape recorder.Analog ConsolesThe basic differences between analog and digital consoles are in the way signals are processes and routed. Analog consoles come in a variety of designs to meet particular needs. Basically they fall into two categories:- On-air broadcast consoles- Production consolesIn on air broadcast consoles, the in-put, output, and monitor sections are usually separate. Consoles with separate input, output, and monitor functions are called split-section consoles. With production consoles the input and output, and some monitor, functions are located in a single module and are known as in-line consoles.The input section takes an incoming signal from a microphone, CD player, recorder, or phone-in caller. Each input channel is configured for either low level sound sources, such as microphones, or high-level sound sources, such as CD players and recorders. A fader regulates the loudness level of each channel. A delegation switch on each channel can either turn off the signal flow or route it to one of three destinations: program, which sends it to the console’s output; monitor, so it can be heard; or to a second monitor system, called audition or cue. The audition or cue system makes it possible to listen to programme material while preparing it for broadcast, without it being heard on the air.At the output section, there is a master fader to adjust the level of the combined signals feeding to it from the input channels. This is the last spot at the console before the output signal is sent on its way to transmission. Input and output signals are heard as sound through monitor loudspeakers. As they pass through the console, however, they are in the form of voltage. Therefore meters are necessary to measure the voltages in the input and output sections, respectively. By using the fader, these voltages can be kept within acceptable limits. A console designed for broadcast may be a production console as well and do double duty.Production ConsolesProduction consoles are used to produce a variety of demanding and complex audio applications for commercials, film and television sound tracks, sports, news, and music recordings. They therefore require a greater number of inputs, outputs, and signal processing functions than do on-air consoles for radio. They are also designed to meet specific needs. In film and television, automated panning facilitates the matching of movement to picture. A production console for music recording often requires a number of sub mixers to premix groups of similar voicing, such as strings, backup vocals, and the components of a drum set.Input/Output SpecificationsTwo indications of a consoles layout and capabilities are provided by the number of input sources it can accommodate at the same time and the number of discrete output signals it can send to its master bus. A bus is a common junction of several different signal paths. It can be accessed by more than one stream of audio, which can be sent to one or more destinations.He In-line Production ConsoleAnalog production consoles today are in-line consoles. The in-line console locates in each channel an output/output (I/O) module. The I/O module houses the input, output, and some monitor controls, bringing these functions vertically: in a line.”In most production consoles, the following are typical functions of each section. Some consoles may have fewer or more features and, depending on the design and manufacturer, the sequence of functions, signal flow, sections designations, groupings, and terminology may differ:1. Input/Output Section. During recording, the input/output section processes and delegates incoming signals and sends them to the multitrack recorder.2. Microphone-line input selection. Controles, which signals source, enters the input section.3. Microphone preamplifier. A microphone signal entering the console is weak. It requires a mic preamplifier to increase its voltage to a usable level.4. Phantom power. When activated it provides voltage for capacitor mics, thus eliminating the need for batteries.5. Trim. The trim is a gain control that changes the input sensitivities to accommodate the nominal input levels of various input sources. Trim boosts the lower level sources to usable proportions or prevents overload distortion in higher-level sources.6. Overload indicator. Tells you when the input signal is approaching or has reached overload and is clipping. In some consoles the LED flashes green when the input signal is peaking in the safe range and flashes red either to indicate clipping or to warn of impending clipping.7. Pad. Reduces the power of a signal. On a console it is placed ahead of the mic input transformer to prevent overload distortion of the transformer and mic preamplifier. It is used when the trim, by itself, cannot prevent overload in the mic signal.8. Channel Assignment. This is a group of switches on each I/O channel used to direct the signal from that channel to one or more outputs; or several input signals can be combined and sent to one output9. Direct Switch. Connects the channel signal to the channel output, directing the signal to its own track on the recorder, bypassing the channel CAN and thus reducing noise.10. Equalizer and Filter. An equalizer is an electronic device that alters a signal’s frequency response by boosting or attenuating the level of selected portions of the audio spectrum. A filter alters frequency response by attenuating frequencies above, below, or at a preset point.11. Dynamics section. High-end production consoles usually include a dynamics section in each I/O module for added signal processing. It often includes, at least, compression, limiting, and m=noise gating.12. Channel/Monitor Control. Switches the equalizer, dynamics, and usually selected send functions into the channel signal path to the recorder, or the monitor signal path to the monitor section.13. Polarity reversal. Sometimes referred to as phase, is a control that inverts the polarity of an input signal 180 degree. It is used to reverse the polarity of miswired equipment, usually microphones, whose signal is out of phase with the signal from a piece of similar equipment correctly wired.14. Pan pot. Short for panoramic potentiometer, is a control that can shift the proportion of sound to any point from left to right between two output buses and, hence, between the two loudspeakers necessary for reproducing a stereo image.15. Cue send (pre- or postfader). A monitor function that routes a signal from an input channel to the headphone, or foldback, system. Foldback is a monitor system that feeds signals from the console to the headphones. The cue send level control adjusts the loudness of the headphone signal before it is sent to the master cue sends in the monitor module. The pre- and postfade controls add flexibility in providing a suitable headphone mix to performers.16. Aux send (pre- or postfader). The aux (auxiliary) send control feeds the input signal to an external signal processor, such a reverberation unit, compressor, or harmonizer.17. Solo and prefader listen. Feeding different sounds through several channels at once can create an inconvenience if it becomes necessary to hear one of them to check something. Instead of shutting off or turning down all the channels but the one you wish to hear, by activating the solo control, located in each input module, you automatically cut off all other channels feeding the monitor system; this has no effect on the output system. The solo function is usually prefader. On some consoles, therefore, it is called prefader listen (PFL). In consoles with both solo and prefader listen functions, PFL is prefader and solo is postfader.18. Mute (Channel on/off). The mute function turns off the signals from the I/O channel. During mix down when no sound is feeding through an input channel for the moment, it shuts it down or mutes it. This prevents unwanted channel noise from reaching the outputs.19. Channel and monitor faders. Control the channel level of the signal being recorded and its monitor level, respectively. During recording channel levels to the multitrack recorder are set for optimal signal-to-noise ratio. On a VU meter, for example, levels would be set to reach or slightly exceed 0 VU. Level balances are made during mix down.20. Meters. Measures the electric energy passing through an input or output. Audio heard through a monitor system is acoustic, but it passes through the console as voltage, which cannot be heard, and therefore, must be referenced in another way. The only way to determine levels in mixers and consoles (and recorders) is visually – by watching a meter.The Virtual ConsoleDigital “virtual” consoles recreate the look of a standard console while offering some additional features. This allows you to use a mouse to raise or lower the levels of the “faders,” it also lets you assign sound sources to different faders, meaning a collection of circuits assigned to one fader. Advantages of the Virtual Console• It’s easy to assign sources to various faders. In some cases, you can accomplish with the computer what you would actually have to wire the console to do.• The computer “remembers” all this. Settings can be stored for later recall.• You can try different arrangements to your heart’s content. Suppose you have 30 different takes of an announcer’s voice over. You want to hear how they all sound in conjunction with the music you also have previously recorded. With a real console, you’ve got to run the tapes through the fader, recuing each time. With the virtual console, you can simply click on each take in sequence and try, try again.Advantages of the real console:• It is difficult to use your virtual console for actual recording. If you have an announcer in the studio, for example, it’s rally much simpler just to open the announcer’s mic on the real console and record, riding his or her level.• It is easier to run an air shift with a real console because the real console stays static. If you turn on a sound source and it’s too loud, it is much quicker to simply turn down a pot or fade down than to use a mouse to find the virtual slider.A broad conclusion: The virtual console is much better for doing complicated production of previously recorded segments. The real console is better for fast, simple jobs or putting material out live on air.

ALICE KARIUKI 08-0149