Mixing console

A mixer (English Mixing Console, also briefly Mixer or Console ) is used to merge different electrical signals ( audio, video) and is found mainly in the areas of event technology and music production.

A mixer for video editing called also conventional cutting panel, but mostly mixers. The lighting control systems used for illuminating platforms are often colloquially referred to as a light mixer, although at no signals are mixed. Mainly used to the term mixer in conjunction with the audio engineering.

• 3.1 Input channel
• 3.2 Master section
• 3.3 Monitoring Section
• 3.4 Cable Connections

• 4.1 Split Console
• 4.2 Inline desk
• 4.3 sapwood console 4.3.1 Other concepts

• 5.1 phantom power
• 5.2 Faderstart
• 5.3 interception mute
• 5.4 effects
• 5.5 equalizer
• 5.6 Power Mixer
• 5.7 remote Control

Audio mixer

An audio mixer - as well as a sound mixer, Tonpult, mixer, blender or console called - used electrical sound signals from different sources ( eg microphones, music players or electronic tone generator) on two or more output totals or buses ( sub- totals multiple signals ), mostly after frequency response and dynamic changes to merge. For mixtures in Stereophonic sound, for example, all present at the mixer signals to the stereo channels "Left" and "Right" merged. Can be controlled using the appropriate mixers multi-channel surround mixes produce. There are different consoles for each sound engineering applications, such as recording and mixing in recording studios, live sound, DJ or program that can differ greatly in terms of size, functionality, ergonomics, sound quality and price of 50 euros to over one million euros. Audio mixers are available in versions analog mixer, digital mixer and powered mixers.

Function groups

A mixer is broken, in most cases in the different functional areas. The signaling pathways while most of the reading direction from above In the usual configuration, follow to bottom and from left to right.

Input channels

The first section forming multiple audio inputs. These are optionally further grouped by mono and stereo inputs.

Subgroups

On larger consoles himself subgroups enabling multiple input signals can be combined to simultaneously adjust the volume may be about to send them to different tracks of a recording device or a separate PA group ( PA group) find. For mixers, which are used for DJing also a cross fader ( fader ) between the subgroups is common.

Back channels / effects

Internal or external to the effect devices of the individual channels branched-off signals can again the sum signal, and sometimes certain subgroups are admixed.

Master / Total

The final mix will eventually be a master fader in a - fed PA, a recorder or transmitter - external or integrated with the power mixer.

The operator various points in the signal path can be selected for playback on the headphones or speakers in the listening room.

Technical structure

There are analog, digital and hybrid ( analog with digital technology combined) mixers. In analog mixing consoles, the signal is always an electrical image of the sound and is also processed so. In contrast, the digital consoles sound into a digital signal is converted and processed by processors ( DSP). Hybrid panels have a digital control and analog signal processing.

All these techniques have their advantages and disadvantages. Thus, a small mixer be made ​​cheaper in analog technology uses a low circuit complexity is necessary. With the number of channel strips and outputs of the circuit complexity increases and therefore the price increases. Large mixers can often be produced more cheaply in digital technology, because a basic equipment more expensive, an extension and distribution, however, is cheaper, because the digital signals are transmitted to a common data bus and not by separate electrical interconnects. It can also be saved in digital consoles on the number of operating as a knob or button with different functions can be assigned. It must not be present for all channels operating. The existing channel control strips can be used multiple times by Layer or bank switching. For channel numbers are possible which would not be realized in an analogous construction of pure space. In today's digital consoles, most settings (fader positions Kanal-Ein/-Ausschalter, sound and panoramic settings, etc. ) can be stored in so-called scenes or snapshots and call in a split second when needed. Often, effects units are already integrated such as compressors in digital consoles. This allows space and cost for additional devices can be saved compared to analog technology.

Furthermore, some models also store digital dynamic control processes such as fader movements and automatically drain out ( dynamic automation ). Hybrid consoles offer this possibility for analog signal processing. However, the circuit complexity and therefore the price for the coupling of digital control to the analog signal processing is compared with a purely digital approach is very high and is therefore rarely used today. Only a digital level control in an otherwise analog consoles is still in use. True hybrid consoles such as the Euphonix CS- series or the Lawo PTR are no longer made today.

Mixers can also be implemented on a computer. You are here generally integrated into so-called digital audio workstations (DAW ).

The main features of a mixer are the number of input channels, the number of output buses, the tone-shaping and ergonomic layout of the controls for the particular application. On the technical side, the key feature is the signal quality. The frequency response should be as linear as possible, and the dynamic range, ie the distance between the noise floor of the console and its distortion limit should be as large as possible.

Typical signal flow in the audio mixer

Input channel

At the beginning of the signal path in an audio mixer, the signal source is connected, depending on the level to either a line or a microphone input. Line Inputs are used for connecting audio devices, such as keyboards comparatively hochpegeliger and CD players, and are usually in the form of phone jacks, with simple devices also RCA, available. Microphone inputs, however, are usually made ​​in the form of XLR connectors and often have a phantom power for use of high-quality condenser microphones. About a knob ( input gain, gain ) of the input level of the signal source is adjusted to the optimum working range of the console. This can be installed for turntables, a special microphone or RIAA-Equalizer. For optical control of each channel level either a peak meter or a vu -meter is often present. In addition to the gain control is usually a pad switch ( Abdämpfungsschalter ), with the too loud input signal by a certain amount (usually 20 dB) can be lowered.

If it is a digital mixer, it follows that at this point the analog to digital conversion of the signal.

Discerning equipped mixers have next through a phase switch, with which the vibration direction of the signal can be rotated by 180 ° ( wave crest to trough is and vice versa). This is useful to correct Polungsfehler either in the wiring or adapt opposite polarity signals due to Mehrfachmikrofinierung a sound source (eg when miking the snare of a drum from above and from below).

Next, the signal passes through the EQ (filters, equalizer). The sound of a signal can be in different frequency bands (eg, bass, lower middle, upper middle, treble ) are processed. These bands can each raise or lower the level. The individual bands has the mixer further over a frequency controller, so can be moved if necessary, allowing more targeted adjustments to the actually occurring in the signal frequencies. Is also a quality control ( also called Q ) is present, the width of the impact of a tape can be varied. Are all of these control options available, then one speaks of a fully parametric equalizer. In addition, there may be for the bass and the high range also separate, very steep-edged high - and low-pass filters that allow above or below a certain cut-off frequency completely filter out all frequencies.

In some panels, the dynamics of the signal are affected by noise gate and / or compressor (switchable pre or post EQ optional). Some mixers have further via so-called insert jacks into the input sections of the channels that allow the insertion of external dynamics or effects devices in the respective channel.

In the further course of the channel strip then follow the power switch (On / Off, Mute) and run as an elementary component of existing in any mixer sliders for channel level, commonly referred to as fader, compact mixers do well as a rotary potentiometer.

In the signal after the fader of the panorama control follows (also called Panpot, contrary to the logic on the control panel above the fader arranged ) with which it can be determined how the signal is positioned in the stereo image of the mixer sum. He is a fader (like a cross fader ) and serves to distribute a signal after the channel fader to the left and right channels in the stereo output; the channel is a sub-group associated with the corresponding signal is fed thereto, the right-hand control position of the even-numbered sub-group corresponding to left odd. To achieve this overall constant loudness, the signal of a corresponding curve is next on the side facing away from the controller damped stronger on the side facing the regulator less. In the usual case in consoles intensity stereophony signals are not changed in their maturity or routed to the opposite channel.

The last link in the channel strip is the so-called routing. Does the mixer via subgroups, the signal on switch next to the fader can be sent depending on the version alternatively or simultaneously to the master signal to this. Likewise - especially with digital mixers - every single input channel can be assigned directly to a track of a multi-channel recorder.

The signal of one channel can be sent to different locations in the channel strip to so-called effects or monitor sends ( auxiliary paths = auxiliary paths). Mostly such auxes between "pre- fader" (signal is diverted behind the filter section, before the channel fader, so it is independent of its position) and "after " or "post- fader" (signal depends on the channel fader ) switchable. The controller this can be found on the control panel usually directly over the pan pot.

Master Section

Behind the routing follows the master section of the console, in which the mixture of signals and the output of the sum is carried to one or more master outputs. Be recorded Separate outputs to the PA - sum signal here mostly as two-track, abbreviated 2TK ( -out ), referred to; 2TK in a pathway serves to directly play the recorded signal without any further influence again.

Larger consoles in addition own subgroups, on which there is a mixture of several input signals. So sound sources can be summarized as drums, choral or orchestral parts and blinded with a single fader to the master signal. Likewise, the individual tracks of a recording device or different speaker systems can be recorded. When mixing consoles for music performance is the horizontal crossfader built a similar design available; Here, the left and right sides, one or more inputs are assigned to can be between them superimposed on a single controller.

Monitoring section

During production, the operator needs at the desk next to the master signal and the ability to preview individual channels or subgroups in the control room or on the headphones without affecting the output. With the pre-fader listening (English pre fader = before the volume control ) can (especially at live - production ) a new source will be examined during rest on the output of other channels. To this end, each monitoring point its own PFL switch, when activated, the console monitor system represents only the individual PFL switched signals. Similarly allows the Mixdown Solo mode (AFL, after fader listen = interception post-fader ), individual channels just listen to how they sound in the mix, so including their level and pan setting as well as they used effects. This is useful also for debugging or for the readjustment of filters during an ongoing production and inspection just recorded material, the " tape monitor ".

It is also important to give the active feedback, the so-called monitoring. If no headphones or in-ear monitoring systems used on which the master signal can run without causing feedback in the pickups, special mixes have to be created. This can be realized in the simplest case, the aux sends, but larger mixers have special ways to create headphone and monitor mixes and their distribution on the receiving spaces and acting persons. With great live performances and a private panel is for use on the stage.

Some consoles offer the possibility of communication between the sound engineer with the people in the receiving space ( Talkback ).

Cable connections

Professional mixers for fixed installation in large studios usually do not have individually executed and output connections more. The cabling is rather about multipin plug connections. This allows multicore cables also efficiently and clearly many analog audio paths are placed, such as in various studio rooms or from FOH to the stage, where the individual connections rest on stage boxes.

A patchbay (English patchbay ), installed in the control panel or in an external rack to which internally the inputs and outputs of all existing in the studio audio devices are connected, makes it possible to all devices very light and flexible by simply plugging short cables together connect ( " patch ").

Mixer concepts

Split Console

This concept can be edited with a channel only a signal, that is, the tape monitor can only take place via another own channel. The number of subgroups is fixed and can not be extended. Therefore, this mixer concept is today mostly used in the live arena as a FOH mixer. Before advent of in-line mixers Split consoles were also in the studio operating common large split consoles possessed for this purpose a separate monitor section with a corresponding number of channels. An advantage of this concept is the better overview of the signal flow, adversely the lack of flexibility and, especially for larger setups, the enormous space requirements.

Inline desk

The first mixer with the inline concept was developed by SSL and still is the professional standard in major music studios. The idea behind this concept is that you can simultaneously process two signals with one channel. On the one hand is due to the input signal of the recorded source at the main fader, and is used for tape recorder or DAW sent. At the same time, you can monitor the off- Tape ( rear belt ) signal on the "small" fader in the same channel strip. For blending you can change the assignment of the faders, import additional signal sources, define channels arbitrarily as sub-groups and split the filter and aux sends flexibly between existing signals of the same strip. An additional advantage is the enormous space savings. This is called inline concept as a " sandwich ".

Splint console

The concept of sapwood consoles is a mixture of the two previous mixer concepts. The number of subgroups, although limited as the split - panel, however, two different signals can be input per channel, of which the one on the main fader, the other is controlled by the "Small Fader", usually a small fader or potentiometer. The signals can also be connected flexibly to the equalizer or the aux sends on fader status switch between the main and the "small" fader, depending on the configuration of the console. One of the most famous desks of this type is the "8- bus " - console the company Mackie.

Other concepts

• Line mixer: This mixer concept usually does not have microphone inputs and is often used by keyboardists on stage for a pre - mix.
• Monitor Consoles: These consoles found in the live arena application and are used for the monitor mix on stage. Therefore, they have a large number of aux sends.

Additional functions

For special applications consoles are equipped with additional features that simplify either its own controls or by connecting to existing features work processes.

Phantom power

The condenser microphones primarily used in the study area require an operating voltage. These can be switched at most consoles as phantom power. If a mixer has phantom power, it is possible to switch a power supply module or a suitable preamp between the microphone and the mixer. The voltage is usually 48 volts.

Fader Start

Especially when transmitting mixers and sometimes even with DJ mixers can be started with the hoisting of a channel fader or pressing the signal (On ) switch the device connected to this channel playback device.

Listening mute

To avoid feedback, may in a studio space in which a microphone is in operation, the signal can not be reproduced. The muting can be configured so that when you open a microphone channel monitor speakers are turned off in the appropriate space and the signal is still available only through headphones.

Effects

In particular, digital mixers can be equipped with a more or less elaborate effects section (see also: Channel strip). This ranges from simple sum of effects ( eg, simple reverb, flanger or chorus ) devices in the lower price segment to high-quality effects and dynamics processing facilities for each channel strip in expensive consoles.

Equalizer

In addition to the filter options in the individual channel strips can be adapted to the conditions of the room and the speakers with the Master equalizer output signal. Similar to the built-in effects also satisfy this equalizer with cheap devices hardly professional standards, if only because of the limited space available on the front panel just so relatively broad filter bands can be offered.

Power Mixer

Power mixer combines a (usually somewhat simpler held ) mixer and a audio-power amplifiers together in one device. Devices of this type are mainly used for live performances in front of a somewhat smaller audience of about 50 to 100 people, for example, music combos, dance groups, for karaoke events, fairground advertising agencies. Hold as part of a sound system the total costs low, since essentially the only other speakers and the sound sources are needed.

Power Mixer are offered by various manufacturers and usually have the usual desk shape. They belong to their action principle also to the group of audio amplifier and are often, so a two-channel stereo technique. Simpler, usually not appearing in console form and use of the front panel of devices that are rarely two channels are generally considered " mixing amplifier ," but also called " Power Mixer" in the lower price segment. The definitions are therefore not precisely delineated.

Remote control

In networked production systems such as the ARD radio, many desks are remotely operated in the studios. The controller of the actual console to be moved by servo or linear motors. This remains the position of the regulator "current" and a manual on-site intervention is still possible. Typical applications of remote control are:

• Remote interviews, in which only the interviewee at the local studio sitting (no local technicians present)
• Complex live broadcasts from several studios that are "driven" by a central director
• Is broadcasts with computer controlled flow (typically at night), in which a computer runs the mixer and only a supervisor present ( even partially waived for private channels )
• " Shutdown" physical recording media ( such as tapes ) on distributed machines (Example: A live program is produced during HR in Frankfurt, a contribution is delivered from the studio Kassel and is there ready to tape ). However, these applications increasingly disappearing with the proliferation of server-based audio data storage.

Known mixer manufacturer

• Allen & Heath
• Behringer
• DiGiCo
• Digidesign
• Dynacord
• Lawo
• Mackie
• Midas
• Numark
• Pioneer
• Solid State Logic
• Soundcraft
• Studer ( Harman International Industries )
• Technics
• Yamaha