What Does The Damn Thing Actually Do And How Does This All Work? – Part 3: Routing And Processing

This is part 3 of our series of blog posts with simple explanations for the most common terms in audio, as well as features and functions found on recording studio equipment. The resource to end the confusion and help you focus on creating amazing music!


Fellow audio nerds, please note:

The explanations are as non-technical and simple, as possible. I want it to be practical and useful and I don’t care if everything is 100% scientifically correct. All that matters to me are the results that the people who read this will hopefully get.

It’s not meant to be an academic piece of work on audio technology and if you are an experienced engineer who thinks this is stupid, then I’m really sorry, but this is not for you then. And I can definitely understand your desire for accuracy and your love for nerdy discussions, because I’m a total freak in this regard, myself (just ask my wife). I just think inflating our egos by throwing around complicated terms and definitions is not going to help anyone trying to capture a great song.

Routing And Processing

Routing describes the distribution of audio signals between different “sources” and “destinations”. Basically sending signals from A to B. Or to B, C, D, etc. at the same time.

Processing describes the altering of a signal, so that the sound changes, or the technical specifications of the signal change.


A single audio channel where an audio signal goes through. A mixing desk or console is made up of many channels that each process an individual signal and then send them all to the “master bus”, where they are combined to a stereo signal. A channelstrip can contain elements like a gain stage to adjust the input volume, an Equalizer, a compressor, a gate, a limiter and various routing options to send the signal to different destinations.


Another word for volume. Mostly used for the input stage of a channel or piece of gear. Increasing the gain means increasing the input volume and “driving” the gear harder by feeding it a stronger level signal.


The pan control is used to distribute the level of a signal between two or more speakers. When set to “0”, the signal is distributed evenly and appears to come from “in between” the speakers. When set all the way to one direction, the signal only comes out of that speaker. And then there’s everything in between those extremes, of course. 


This is a place, most of the time right after the gain, where you can insert another piece of equipment or plugin to process the signal and then send it back to the channel. It goes out, gets processed and comes back in at the same spot. 

EQ (Equalizer)

This is a device designed to manipulate the frequency spectrum of a signal. You can adjust the volume of certain frequencies, or parts of the spectrum, like “lows”, “highs”, “mids”, or more specific, narrow frequency ranges. With an EQ you can drastically change and shape the sound of a signal, clean it up by removing unwanted “ugly” frequencies, or gently adjust the balance and “polish” an instrument track, voice, or the whole mix. 


“Dynamics” is often used not only to describe the dynamics of a song, but the dynamic processing section of a channel, a piece of gear or plugin. The dynamics section can contain a compressor, limiter, gate, expander, or de-esser.


A compressor is a plugin or piece of hardware that can alter the dynamics of a signal, by reducing volume peaks and making up for the resulting level difference, so that quieter parts get louder, while keeping the same peak dB values. That means, it reduces the dynamic range of a signal, makes it more “dense” and increases the perceived level (loudness). It can be used creatively to shape a sound by giving it more attack or reducing the attack, lengthen or shorten the sustain, or just adding a certain character to the sound.

Gate / Expander 

A Gate is used to eliminate everything below a certain level, so that only the useful parts of a signal can be heard and as soon as it drops below a certain level, it gets muted or significantly quieter. An expander can be viewed as a more gentle version of a gate or an “inverted compressor”. It makes quiet parts even quieter (but not completely silent) and loud parts even louder. So, it increases, or expands the dynamic range of a signal. 


A De-Esser is basically a high-frequency limiter, that limits or reduces the volume of certain (high) frequencies to make the signal sound smoother and less harsh. It reduces the “s” sounds in vocals, or can help tame the harsh frequencies in cymbals.

Multiband Dynamics

Multiband-dynamics are dynamic processors, like compressors, that are split up into different “bands”. Each band has an individual processor only affecting a certain frequency range. So there could be a low, mid and high band, or example. Each of those would work individually on their part of the spectrum and then they are summed back together. That way you can shape the dynamics of a certain frequency range without affecting the rest of it. 

Busses / Groups / VCAs

A “bus” is a destination on the mixer that many different signals can be sent to, to then be combined. This can be a subgroup and those can be processed individually and then be sent to another bus, where the groups are finally combined, or this could be the master bus, where all the individual channels and groups are combined. It can also be a bus that feeds many different signals to one effect or to a monitor-/headphone-mix. 


An Aux-send sends the signal to a bus that sums all the signals which are being sent into it and then that combined bus is sent out to an effect (reverb, delay, etc.). After the effect has been applied, it gets sent back to the mixer and ends up on an Aux-Return channel or fader, that can be mixed in and blended with the rest of the mix. 


A delay effect creates an “echo” effect by repeating the incoming signal a couple of times (or just one time, depending on how you set it) and some delays can also color the signal to give it character.


A reverb is an effect that either simulates a room, hall, or other realistic, reflective environment, or adds artificial, unnatural reflexions to a signal to give it length, depth and a sense of space.


Modulation effects alter the pitch, volume, phase or pan position of a signal automatically within a certain range and at a certain speed. This can create movement, depth, width, or doubling effects. Examples are chorus, flanger or phaser.


Distortion means overloading a circuit or piece of gear very hard to produce a lot of overtones, limit the dynamic range and get an aggressive, distorted sound. 


Saturation is just another term for distortion or overdrive, but it is used to describe a much more subtle form of it. Very slightly overdriving certain circuits or pieces of gear is called “saturating” the signal and can result in very smooth, warm, dense and slightly compressed results. Most commonly used for this are tubes, magnetic tape or transformers. And of course digital emulations of those things. 


Meters are devices that show you the numbers to what you are hearing. You can see levels, loudness, the distribution of signals across the frequency spectrum, width and panning, phase correlation, etc. 

These are the other posts in this series:

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