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Basic knowledge: Mixing consoles - structure / functions - effect routing

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Mixer channel strip


Masters section

Analog mixers

Analog totalizers

Inline and split consoles

Digital mixer

Routing I

Routing II

Routing III

Routing IV



Digital processors

Determine the effect share

Wiring of mono and stereo effects

Mixer glossary


Mixer channel strip

Entrances and exits

Phantom Power

Mic / Line

Stereo sum / monitor

PFL / mute monitor

Pan (panorama)

This divides the signal proportionally between two subgroups or the channels of the stereo mix. This determines the position of the channel signal in the stereo field.

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mutes a channel. This allows you to temporarily remove it from the mix without having to change the fader position.

A large mixer also has mute groups.


This switch enables the channel signal to be assigned to any pair of subgroups and / or the stereo master.

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This slider controls the volume of the channel.


Sub-groups make it possible to group individual signals. This is called “creating a sub-mix”, which is helpful, for example, to combine a drum kit with many microphones as a stereo mix. In the overall mix, the drums are easier to use.

But sub-groups are also needed when working with multi-track recorders.

In order to mix several signals together and record them on one track, you need subgroups. These represent their own mix in the mixer and have individual outputs that lead to the inputs of the multitrack recorder.

In the example shown, input channels 1 and 2 are routed to the stereo sum. Channels 7 and 8 are assigned to subgroup pair 1 and 2, with channel 7 being assigned to subgroup 1 and channel 8 to subgroup 2 using the pan control. The subgroups have outputs to the multitrack recorder, where tracks 1 and 2 are controlled. In addition, subgroups 1 and 2 are switched to the stereo master.

In the subgroup section of some recording mixers there are also the so-called tape monitors (see below), these are heavily slimmed-down channel strips to which the outputs of the multitrack recorder are connected. Here you can create a preliminary control mix of the already recorded tracks and switch it to the monitor boxes. This has the advantage that a full input channel is not required for each track. The operating options are mostly reduced to volume and panorama per tape monitor.

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Masters section

The overall mix (stereo sum) is controlled with the two master faders. Some mixing consoles only have one master fader that controls both stereo channels together. Differences in volume between the two channels can be corrected here with the help of a balance control. In the case of a live mixer, the outputs of the stereo sum lead to the PA, in the case of a recording mixer to the stereo master recorder, on which the mix is ​​recorded. The level is checked optically on the master level meters.

The controls for the aux sends are also located here, i.e. the outputs via which the signals for the effects devices and - in the case of live mixers - the stage monitor system are sent. The processed effect signals are fed back into the mixer via special stereo channels - the aux or effect returns - and can then be fed to the stereo mix for mixing or to the subgroups for recording. Some mixers do not have aux returns. In this case you have to route the effect signals back through normal input channels.

The master section also contains all the control elements for monitoring: The sound engineer can choose which signal he wants to have on the studio monitors or on the headphones: the stereo mix that goes to the master machine (or PA), the control mix for the musicians, thepfl bus, the aux paths, the outputs of the master machine for listening to the recorded final mixes, etc. As a rule, these signals are also routed to the level meter of the stereo master for visual control.

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Analog mixers

Analog consoles are still very popular. They are offered in all conceivable sizes and price ranges, with some models the number of channels can even be expanded. The sound properties are mostly excellent, the concepts are technically mature and the operation, thanks to simultaneous access to all channels, is unrivaled.

Since the computer is mostly used for recording today, numerous analog consoles for home recording and semi-professional areas of application have built-in analog / digital converters with Firewire or USB interfaces. Some models also have internal digital multi-effects units. Apart from a lack of mix automation, they often offer the same equipment and performance features as comparable digital mixing consoles.

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Analog totalizers

Analog summers are a special form of analog mixer: They only have high-quality level and panorama control options; microphone preamplifier inputs, EQs, effects paths and other sound processing are dispensed with. Connected to the outputs of a computer sound card or DAW, they offer the possibility of mixing a piece of music recorded in the computer on an analog level and thereby increasing its sound quality. This type of mixer has become more and more important in recent years, especially in the professional sector and in project studios. Advantages are mostly high sound quality with minimal space requirements.

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Inline and split consoles

Which mixer type is better suited for home recording?

The inline principle has established itself in the field of semi-professional studio consoles, and split consoles hardly play a role on the market. Digital hardware mixing consoles only comply with the inline principle. In the case of software-based mixers, the question of mixer type does not arise, as the mixer surface can be configured depending on the recording situation and space problems do not play a role.

Split mixer

Split mixers have the same structure as classic mixing consoles. The elements are input channels, subgroups and master section.

  • The input channels can be routed to the subgroups. These control the audio tracks of the multitrack recorder via the track send outputs.
  • The recorder outputs are fed back to the subgroup section via the track returns, where they are controlled by the tape monitors.
  • The tape monitor mix is ​​routed to the stereo mix.
  • For the mix, the track-outs are plugged or switched to normal inputs.

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Inline mixer

The inline concept primarily takes account of the requirements in the recording area. Each channel strip is divided vertically into two channels and, in addition to the line / mic inputs, also has inputs and outputs for the tracks of the multitrack recorder.

  • The signal to be recorded can either be routed via the direct output to the assigned input of the recorder or via the subgroups to create an intermediate mix.
  • The subgroups are in turn connected to the corresponding track sends of the channels. The tracks of the recorder can be listened to while recording is in progress via the B channels, which in this case serve as tape monitors.
  • In the mix, the input signals are then swapped with a flip or reverse switch and the track signals are routed via the A channels.
  • With the B channels, the line signals connected to the inputs, e.g. sequencer-controlled sound generators, can be mixed to the stereo mix.

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Digital mixer

Analog signal processing over many stages (pre-amplification, sound processing, mixing, etc.) requires considerable electronic effort if the signal is not to be falsified or is only to be inaudible. The quality of analog mixers achieved today is excellent, but still has its price - especially with mixers with numerous channels and high-quality equipment. Still prohibitively expensive until the mid-1990s, digital mixers are now enjoying wide acceptance, especially in the semi-professional sector.

Behringer X32 - Digital Mixer Put to the Test - Part 1

Behringer X32 - Digital Mixer Put to the Test - Part 2

Advantages compared to a similarly equipped analog mixer are the mostly smaller space requirement, complete automation of all functions and the low price. Against this, the generally less clear operation speaks against it, since mostly not all functions can be accessed at the same time.

Yamaha and Tascam are the market leaders in the field of semi-professional digital mixers, but Mackie, Presonus and several other manufacturers also offer corresponding mixers.

All the mixers mentioned are characterized by the fact that they have digital inputs and outputs (e.g. in Adat format) or can at least be retrofitted with them. Internally, the signals are processed completely digitally. Most consoles have built-in effects devices and dynamics processors. Automatic mixing is also included, as is the option of calling up complete mixer settings (scenes, snapshots).

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Mixer as software

The software mixer, as it is contained in a computer hard disk recording system (or DAW = Digital Audio Workstation), has played an extremely important role for some time. The most important system components are the computer itself, an audio / MIDI interface and recording software such as Apple Logic, Steinberg Cubase, Ableton Live, M-Audio Pro Tools or Propellerhead Record. It usually includes a software-based mixer.

It thus represents a special form of the digital mixer. The tracks recorded on the hard disk are internally mixed onto a stereo master track using software-emulated equalizers, dynamics processors and effect algorithms. The graphical user interface is based on a hardware mixer, the controls and switches can be controlled with the mouse or an external MIDI controller (e.g. Euphonix MC series, Korg nanoKONTROL, M-Audio UC33E, Novation Nocturn or special controllers such as Digidesign Command 8 , Steinberg CC121 or Akai APC 40).

The transition between DAW controller and digital mixer is now almost fluid. Some controllers offer an integrated audio / MIDI interface (e.g. Cakewalk Sonar VS-100, Digidesign Digi 003) or even an internal recording option (Zoom R16), while some digital mixers have the option of direct as an alternative to stand-alone operation Integration into a computer hard disk recording system (e.g. Yamaha N12).

The actual recording software is usually quite inexpensive, but in addition to a sufficiently powerful computer you need at least an audio / MIDI interface and, if necessary, a controller (see above) and additional software for sound processing in the form of EQ and effect plug-ins .

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Mixer accessories


At first glance, one does not suspect the vast amount of cables that “disappear” in a medium-sized home recording studio and on mixing consoles. A cost factor that is often underestimated: good cables are expensive, and using cheap “stripping” would certainly save money at the wrong end, because ultimately the sound quality suffers. Fortunately, there is a large selection of suitable cables, most brand manufacturers offer good products in various price ranges.

For the cabling of the mixer and other permanently installed devices in a studio, it goes without saying that the purchase of “multicores” is a good idea - these are cables with lots of small, shielded cables. This helps to keep the otherwise inevitable “cable clutter” as small as possible.

Hardware - racks, tripods etc.

So that the question of where to build the precious piece does not only arise after buying the mega mixer of all dreams, you should plan this cost center from the outset. First of all, it is important that the mixer has a secure hold and, ideally, that additional equipment (effects devices, monitors, etc.) can be installed. A wobbly X-tripod discarded by the keyboardist is definitely not the best choice and the studio outfitter around the corner usually gets really expensive.

Here's a little household tip: Take a look around the office and computer area of ​​a certain Swedish furniture manufacturer. There are a lot of parts that can be used in the studio. They are - 1, 2, 3 - built up (okay - not always). But they help save money that you can still invest in one or the other studio rack.

DI box (Direct Injection Box)

If you want to transport line signals (outputs from guitar and bass preamps, keyboards and expanders) over longer distances, you should first symmetrize them. The outputs of these devices are usually designed asymmetrically, which means that they are more susceptible to interference pulses picked up by the cable from the environment. Therefore the signal is first fed into a DI box; this is not a loudspeaker box, but a small box with electronics that convert the unbalanced signal into a balanced one. It can then be transferred from the output of the DI box to the mixer with practically no loss or interference.

Speaker emulator

A guitar cabinet has a very limited frequency response. A highly distorted guitar signal contains many overtones that would make the unfiltered sound very scratchy and uncomfortable. Only through the poor high frequency transmission of the guitar loudspeaker, which attenuates the overtones, does the sound become round and pleasant. Therefore, electric guitar tracks are usually recorded by a microphone placed in front of the loudspeaker. This is not always possible or useful with home recording. Instead of playing the guitar through loudspeakers, you can also connect a speaker emulator to the output of the amplifier or preamplifier, a device that simulates the frequency response of the loudspeaker and filters the signal. This signal can then be fed directly into the mixer or - if a computer-based recording system is used - into the sound card.

Recording preamp

A combination of guitar preamp and built-in DI box with speaker emulation. The output of the recording preamp is connected directly to an input of the mixer or the sound card.

Exciter / Enhancer / Psychoacoustic Processor: Devices of this type refresh the highs and sometimes also the bass part of a signal. However, they cannot be compared with equalizers, as they do not simply increase the underexposed frequency ranges but rather generate them according to psychoacoustic principles. When using a computer-based recording system, such devices can be used in the form of software plug-ins.

Frequency analyzer

In order to be able to correct unfavorable room acoustics, one must first know the frequency response changed by the room. The frequency analyzer is used to measure this. A broadband signal (pink noise) is sent over the speakers and this is picked up with a measuring microphone. The level is now measured in narrow frequency bands and visually represented by many individual level meters. Ideally, the analyzer should show an equally high level, i.e. a horizontal line, in all frequency bands. If the frequency response is wavy, it can be corrected with a graphic EQ, which must have the same bands as the analyzer.

Some analyzers are housed in one housing together with a matching graphic EQ. There are also automatic devices that carry out the calibration process automatically and even save various EQ settings, which can then be called up as required. When using a computer-based recording system, such devices can also be used in the form of software plug-ins.

When using effects - especially when integrating them into different systems - there are a few things to consider, because there are big differences depending on the application. The interconnection of an effects device with the outside world is called “routing”.

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Routing I

The simple variant - the direct way:

The effect is switched into the signal path between the instrument and the amplifier, i.e. one connects the orthe audio outputs of the instrument with the inputs of the effects device. From the audio outputs of the effect it goes on to the inputs of the amplifier.

... grind in the effect:

In addition, for guitars, for example, it can make sense to integrate the effect unit into the signal path of the connected amp via so-called loop-in paths, which has sonic advantages and requires certain settings on the effects device. Mixers offer effect inserts per channel for looping in.

... several instruments "share" one effects device:

If several effects devices are to be available for one or even different instruments, a mixer is required which, in addition to the instrument input channels, also offers connection options for the effects devices. Mixing consoles usually allow a relatively variable routing.

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Routing II

OR: Connect effects to the mixer, how effect sends and returns work and how to wire them to the effects device.

From the mixer to the signal processor

Mixing consoles offer special ways to feed effects devices, more luxuriously equipped consoles have eight or more of them, one speaks here of effects or aux buses. Each aux bus combines the signal components that are to be passed on to a signal processor. You only need one way to send the signals from many channels, each with a different proportion, into the reverb. The input channels are equipped with aux send controls for this purpose. These determine the volume at which the signal is fed to the effects device.

If a mixer has several aux paths, a reverb device can be connected to the first, a delay etc. to the second. In this case it would also be possible to connect an instrument to two or more effects devices at the same time.

To get the signal from the mixer into the signal processor, the aux path is the most obvious and convenient way. Almost all mixing consoles and multitracker are equipped with one or more such aux paths, which are also referred to as output, auxiliary or effects paths.

From the signal processor back to the mixer

Normally, the signal is returned to the mixer via the aux or effect return sockets.

When a Aux return level control is available, the overall volume of the effect signal can be adjusted with it. If not, the effect level is controlled directly at the output of the signal processor.

If the aux return does not provide tone control or there are not enough returns available, the effect signal can alternatively be fed back into the console via input channels.

In addition to the disadvantage of having to "sacrifice" valuable mixer channels for this, the whole thing has several advantages - here the most important:

  • Instead of the usual rotary potentiometer for regulating the return level, you now have a fader with which you can fade in and fade out the effect signal in a much more convenient and targeted manner.
  • The frequency response of the effect signal can be edited with the tone control in the input channel.
  • You can record the effect signal on a tape machine or on an HD recorder if required. This frees up the effects device again to create a different effect if necessary.

The effect signal can be sent back to another effect via another aux path, e.g. to fade away a delay signal.

Auxiliary feedback through channels can quickly create uncomfortable feedback. The reason: If the aux send of the effect input in the channel that is used to return the corresponding effect signal is turned up again, the signal path between the channel and the effects device forms a loop. In the worst case, this can even damage devices or kill the tweeters in the monitor boxes. To prevent this from happening, leave the corresponding aux send control of the channel that you are using as the effect return path turned down.

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Routing III

OR: Pre-EQ, post-fader, pre-fader, etc. Mixers offer several so-called tapping points from which the original signal is routed to the effects. This results in very different possible uses and modes of action of the effects.

Send points

There are several points in the signal path at which the aux send signal can be tapped. However, the selection is usually not free, but determined in the mixer. As a rule, there are corresponding switches in the channel strip. There are three main alternatives here:

Pre EQ / Pre Fader

The signal is tapped after the input amplifier, but before the tone control and the fader (volume control). The sound of the signal sent via the aux is therefore unprocessed.

In addition, the send level is independent of the position of the channel fader, which means that the signal from the instrument connected to this channel can be heard through the effects loop even if the volume of the direct signal is set to zero with the channel fader Has.

You can imagine that this may be less desirable in certain situations, e.g. if the drums are to be faded out from the mix by pulling down the corresponding faders.

Post EQ / Pre Fader

The level of the aux send signal is also independent of the channel fader, but is influenced by the tone control. Only the signal that has been sonically processed by the EQ reaches the effects device.

Post EQ / Post Fader

The aux signal leaves the input channel only after it has passed through the tone controls and the channel fader. When the channel fader is lowered, the aux send level is automatically lowered as well. When the channel fader is completely down, the signal disappears completely from the mix and can no longer be heard on the aux return path.

In connection with effects devices, the “Post EQ / Post Fader” position is usually the best choice.

On the other hand, it is sometimes desirable to fade the effect signal completely independently of the direct signal. For example, phasing, flanging or distortion can be used to generate two completely different signals from a guitar or synthesizer track. The volume can then also be dealt with separately. To do this, switch the aux path to Pre Fader / Pre Equalizer (if possible).

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Routing IV

OR: Integration of hardware / software effects in a computer-based recording environment.

Effects and software mixers

Of course, software mixers also offer the option of integrating effects devices. The routing there corresponds to that of a hardware mixer, because the structure and signal routing of a mixer window is usually based on a hardware mixer. However, there are two important alternatives, both of which can be used in conjunction with a computer-based recording system:

Effect plug-ins

The most obvious way to add effects to the mixer of a computer-based recording system is to use plug-ins. They can be easily called up in the mixer interface and are supplied with signals according to the various routing variants - but in a purely digital way within the computer and its host software.

Hardware effects

Even if the quality of the effect plug-ins today generally leaves nothing to be desired, it is a good idea to use certain hardware effects every now and then. Professional reverb devices and high-quality analog signal processors in particular are often used in conjunction with computer-based recording systems for more complex productions thanks to their uncompromising sound quality.

The hardware effects device is connected to the analog or digital connections of the audio card, depending on the equipment. In order to route the signal from the software mixer out of the computer, through the effects device and back into the computer, you have to select the corresponding inputs and outputs of the sound card in the mixer interface, depending on the routing used. The resulting latency may have to be compensated for.

Some current effects devices (such as the Lexicon PCM 96) can be connected directly to the computer via the Firewire interface. Additional audio cabling is not necessary; the host software integrates the external effect like a plug-in.

Devices such as the Lexicon MX series or the TC Electronic 350 represent a hybrid form: They are connected to the sound card on the audio side in a conventional analogue or digital manner, but they can be operated via a USB connection in the form of a plug-in surface in the computer.

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OR: What you should know about mixer effects inserts.

Integrate effects via inserts

Effects devices can also be looped in using so-called inserts, which not all mixing consoles have, however. In contrast to the aux path, looping in means that the signal flow in the input channel is interrupted before the tone control and the signal is first sent to the signal processor. The effect signal is then fed back into the channel via the insert socket. A special insert cable is used for this.

This type of routing is useful if you only want to connect a signal processor to a specific instrument. Devices that are suitable for looping in in this way are, on the one hand, special effects devices such as phasers or flangers. The classic use of inserts, however, relates to devices for dynamics processing such as compressors or noise gates, since there is usually no direct signal required.

By using the insert socket, the signal path of the channel is separated. If the signal is not fed back, the channel remains mute. With a small trick of the circuit, you can tap a send signal at the insert point without interrupting the signal flow.

Sum inserts

In many mixing consoles, insert sockets are not only found in the input channels, but also in the subgroups and in the sum bus. The inserts in the subgroups make it easy to add effects to entire groups of instruments (e.g. drums, vocals, instruments, etc.).

The inserts of the sum rail are primarily used to loop in level limiters (peak limiters), compressors or psychoacoustic processors (exciters).

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OR: Only correctly adjusted effects can develop their full potential ...

What you should consider when controlling effects devices

Adjusting the outputs and inputs of mixer and effects device is a popular source of errors. For example, if you control a 0 dB input with a -10 dB output, the signal-to-noise ratio deteriorates and the noise increases.

Conversely, connecting a 0 dB output to a -10 dB input tends to distort the whole thing.

Before connecting the effect devices, you should take a look at the manual or the labeling on the sockets. The levels of outputs and inputs can almost always be adjusted with switches on the back.

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Digital processors

There are of course no adjustment problems if the signal processors are already integrated into the desk. The current digital consoles show where to go. There is no cabling, you just have to route the desired effect to the appropriate path. Once configured, routings can be saved and called up conveniently at the push of a button if necessary.

The signal quality is also better in this case, since the whole thing takes place on a digital level. This eliminates the need for additional conversion between analog and digital at the effect input or between digital and analog at the effect output. In addition, there are no signal levels with components, cables and similar potential interference factors. The same naturally also applies to software signal processors, which are integrated in the form of plug-ins in computer-aided hard disk recording systems.

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Determine the effect share

In most cases it makes sense to be able to determine the relationship between the original signal and the effect signal. This is the only way to use nuanced effects. Most effects devices have a control option (“Mix” or “Balance”) that can be used to mix the effect component with the original signal as required (either as a whole or for each effect program).

If you control an effects device via the aux paths of a mixer, then it is advisable to only receive the effects signal from the effects device, since the original signal is already present on the mixer channel. In this case, you should turn the effects mix control of the effects device fully to effect (“Wet”).

The mix of “original” and “effect” then takes place on the mixer itself:

  • via the position of the aux send or aux send sum controls in the master section of the console
  • via the aux return controls or via the fader of a mixer channel, if the effects return has been assigned to a mixer channel.

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Wiring of mono and stereo effects

When it comes to signal processors, you not only have to differentiate between mono and stereo effects, but there are also mixed forms that require slightly different routing depending on the design.

Mono in / out: The simple way - here we connect the mono output of the instrument / mixer channel to the input socket of the effects device and then connect the mono output of the effects device to the return socket on the mixer.

Mono in / stereo out: It gets more complicated when the effects device conjures up a stereo signal from an incoming mono signal. Here it is called 1 x (= mono) in and 2 x (= stereo) out. Most mixing consoles, for example, offer stereo aux returns for connecting these effects devices, via which the left and right stereo channels of the effect signal can be fed back - otherwise, only the return via mixing console channels, which you set accordingly in the panorama, helps.

Stereo in / out: A distinction must be made here between whether effects devices only use the mono sum of the two input signals for the effect algorithms or whether these are “true stereo algorithms” that process the two stereo components discretely.

The advantage of the latter variant is that, for example, with a “real” stereo reverb, the instruments that are on the left or right in the panorama also retain their position in the reverb, while with mono-in / stereo-out effects, all instruments - regardless of their arrangement in the stereo image - are distributed over the entire base width of the hall.

If you really want to take advantage of these true stereo algorithms, you should also feed a real stereo signal to the effects device. To do this, you usually simply sacrifice two aux paths. For example, if you have the left stereo channel of a signal to be reverberated on mixer channel 10 and the right one on channel 11, you turn in channel 10 e.g. B. Aux path 1 on, in channel 11 the aux path 2. The aux send sum outputs 1 and 2 of the mixer are then connected to the two effect inputs of the true stereo effects device.

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Mixer glossary

DAC:Digital-to-analog converter; Converts a digital signal to an analog one.

Plug-in:Plugins are small programs that add to the capabilities of the host program. This is done with the help of an interface - also implemented in software - via which the plug-in is integrated into the audio system of the host program.

A distinction is made between real-time-capable and offline-working plugins. The plugins for the VST and AU interfaces (most widely used) work in real time. Offline plugins have become rare thanks to increased computing power. You are working with a preview: only a small section of the material to be processed can be listened to with the effect processing in order to find the right settings, then the effect must be included in the audio material.

Re-amping is often used in electric guitar recording. In addition to the mic guitar amplifier, the direct signal from the electric guitar is also recorded in parallel. This has the advantage that you can process the direct signal later in the mix session using an amplifier or an amp simulation and mix it with the amp signal.

Symmetrical: Feature of a circuit method which (with the help of some circuitry such as additional input and output transformers) allows largely interference-free transmission of electrical signals.

DI boxes: Adaptation adapter in order to be able to feed the high-impedance instrument signal into a low-impedance consumer (e.g. mixer) without loss of sound. In addition, there is a conversion from unbalanced to balanced signals.

A High pass filter lowers low-frequency signal components, while it allows high-frequency signals above the set cut-off frequency to "pass".

The Pad switch in the input stage of a mixing console is used to lower the signal level in the event that the GAIN control does not provide adequate reserves.

A AUX way is an independent busbar to which individual input channels can be sent.

A Equalizer is a control element in amplifiers or mixing consoles that allows sound corrections to audio signals by raising and lowering certain frequency ranges.

The Q value or “Q factor” describes the filter quality of a frequency band of a parametric equalizer.The higher the Q value, the narrower the set center frequency can be lowered or raised.

Compared to a parametric equalizer, the frequency bands are one graphic equalizers fixed to certain frequencies.

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