The Difference Between Buses, Auxes, Sends, and Returns


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How do returns contribute to the audio signal process and how are they different from buses, auxes, and sends in PAA?

Understanding the different terminologies in the world of audio mixing is critical to achieving excellent mixing results. Among the terms that are often used in audio mixing are buses, auxes, sends, and returns. While they play crucial roles in the mixing process, their functions can get a bit confusing, especially for beginners. In this article, we’re going to break down these terms, discuss their functionalities, and how they relate to each other. Let’s begin!


A bus, in audio mixing parlance, is best defined as the path through which audio signals flow inside a mixer. You can visualize it as a highway that carries audio signals from one point of the mixer to another. There are different types of buses; each dedicated to a specific purpose. For instance, there’s a bus for all the output channels, a bus for all the input channels, and so on. Each bus can carry multiple signals concurrently without each signal affecting the other.

Auxes (Auxiliary Sends/Outputs)

Next on our list are auxiliaries or auxes. Auxes are auxiliary sends/outputs on a mixer that can dispatch audio signals to external effects units or monitors. They are like gateways that redirect signal clones to different sources without affecting the original signal’s pathway. Auxes enable the application of effects to a signal or a group of signals in a controlled manner.

The use of auxes becomes incredibly beneficial when you want to apply the same effect to different channels. Instead of duplicating the same effect across multiple channels, which could lead to a CPU power drain, you can employ an aux send to deliver the effect to all the desired channels.


Sends play a function similar to auxes, but their application is slightly different. Sends are used to channel a portion of the audio signal from a track to an auxiliary track/bus. They’re quite useful for adding effects to a specific track or group of tracks. For instance, if you want to add reverb to a vocal, you can setup a send to carry the signal to an aux track with a reverb effect.


Returns are the final part of this chain and serve the purpose of delivering processed audio signals from the auxiliary track back to the main mix. The term ‘return’ is often interchangeably used with ‘aux return’. They fetch the modified signal from the aux output and bring it back to the main mix or another intended destination.

Understanding how to manipulate buses, auxes, sends, and returns can elevate your mix to professional sounding levels. They provide increased control over the application and modification of audio effects, enabling more refined and polished sound outputs.


While the use of buses, auxes, sends, and returns can initially be confusing, frequent practice and use will make these terms and operations second nature. As each one plays a unique role in the journey of your audio signal, mastering them will certainly pay dividends for your production and mixing skills.