Buses, Auxes, Sends/Returns

Buses, Auxes, Sends and returns – What are they and how do they benefit me?  Well in this article I try to simplify it as much as I can so that anyone can really wrap their head around it.  Mainly because I cant explain it technically, haha.  I use them in every mix and you should too.  A little fact: you are already using buses in your mix you just may not know it.


A Bus is a single path for multiple sources to be routed and processed (compression, EQ etc).  The most common bus that you may know of is the “Master Bus”.  This is that one single fader in your session where all the sounds get meshed together to create a stereo track.  Another common method of bussing is to send the output of all your individual drum tracks to a single Fader.  This would be known as the Drum Bus.  Then the output of the drum bus would be routed to the Master Bus/fader.  I drew a sort of funnel type shape to sort of illustrate what a bus is.

Aux Bus (Sends and Returns)

If we look up the definition of Auxiliary we would find: Providing supplementary or additional help and support   So we can use that definition to try and apply it to the audio world of Auxes.  This means that an Aux Bus would be a sencondary source of the same signal.  So now we would have two sounds running in parallel.  So the send portion of an aux would be the fader before your insert/effects bin of the Aux Bus (aka input).  This is usually represented by a mini fader in most DAW’s.  The Return would be that fader after after the insert/effects bin of your Aux Bus. (aka the output).

So What’s the Point?

Well for starters buses allow the engineer to procces a group of sounds at the same time and control the overall output gain as well..  Haven’t you ever wanted to turn down ALL the background vocals at the same time?  Also by compressing and EQing, let’s say the drums, together it allows you to create something that sounds more ‘together’.

For Auxes it allows us to create, for instance, a reverb track where we can send multiple signals to the unit itself.  So instead of using 10 different instances of reverb, we can usie one instance and send all 10 at the same time.  We can also adjust the amount of reverb of each sound by turning the send level up or down.

Another reason to use an aux bus is for parallel compression.  We can split a vocal track into 2 and then heavily compress the second vocal and then mix it back in with the original.  This allows us to get some interesting textures.  It also allows us to get a more compressed and in your face sound with out give away too many of the precious dynamics, which we should all love, if we dont already.

YouTube Video Source: Busses, Auxillery Sends and Returns