What are Aux Sends in Audio? Exploring Their Function and Importance

In audio recording and live sound reinforcement, aux sends are crucial for routing and distribution. Also known as auxiliary sends or simply auxes, these functions allow sound engineers to create separate mixes for different purposes, such as monitor mixes for musicians on stage or headphone mixes for recording artists in a studio.

Aux sends, short for auxiliary sends, are essential to audio mixing. They allow audio engineers to create custom mixes by routing individual audio channels to separate outputs. These separated outputs can then be used for various purposes, such as creating monitor mixes for musicians or applying effects to specific audio channels.

Understanding how to use aux sends effectively can greatly improve the quality and creativity of audio production and the overall experience for performers and audience members alike. Aspiring sound engineers, musicians, and audio enthusiasts need to familiarize themselves with this vital aspect of audio technology.

Table of Contents

What are Aux Sends in Audio? Exploring Their Function and Importance

Understanding Aux Sends

Basic Functions

Aux sends can be found on analog and digital mixing consoles as knobs or faders next to each channel’s input controls. They enable the engineer to send a portion of a channel’s signal to another destination, such as an effects processor, a separate amplifier, or a different mixer.

This is done without affecting the main mix, providing flexibility and control over various sound sources.

By using aux sends, audio engineers can independently control each audio channel’s level, making it easier to balance and enhance the overall mix. This feature brings out desired aspects of each audio source, creating a dynamic and professional sound.

Types of Aux Sends

There are two primary types of aux sends in audio: Pre-fader and Post-fader aux sends. Both types serve different purposes and are crucial in achieving the desired results during a live performance or recording session.

  • Pre-fader Aux Sends: The signal is split from the audio channel before it reaches the fader, meaning adjusting the fader does not affect the signal sent through the aux send. Pre-fader aux sends are commonly used to monitor mixes, ensuring that the musicians can hear themselves and their bandmates consistently, irrespective of changes made to the main mix.
  • Post-fader Aux Sends: The signal is split from the audio channel after it passes through the fader, so when the fader level is adjusted, it directly influences the aux send output. Post-fader aux sends are often utilized to apply effects, such as reverb or delay, which must follow the main mix’s level adjustments.

Moreover, some audio consoles offer additional aux send variations, such as pre- and post-EQ or pre- and post-dynamics, providing even more control over the separated audio channels.

Applications of Aux Sends

Aux sends are an essential feature in various audio applications. They allow engineers to route and control signal levels according to their needs. This section explores the uses of aux sends in live sound, recording studios, broadcast, and podcast scenarios.

Live Sound

In live sound applications, aux sends are frequently used to create individual monitor mixes for performers. By routing specific instruments or vocals to separate aux channels, artists can hear the preferred mix that helps them deliver better performances.

Furthermore, aux sends apply external effects such as reverb, delay, or other processing. This set-up aids in creating a more polished and engaging live sound experience for the performers and the audience.

Recording Studios

In recording studios, aux sends are critical in signal routing and processing. They are often used for similar purposes as live sound applications, such as creating individual headphone mixes for musicians during tracking sessions.

Additionally, aux sends permit engineers to route audio to outboard gear or software effects, allowing for significant mixing and post-production processing flexibility. This flexibility helps shape the character and aesthetic of a recording, contributing to the overall production quality.


Aux sends are frequently employed in broadcast environments, including radio and television. They can route audio to different broadcast channels or external processors, such as compressors or limiters, to achieve the desired audio levels and quality in these settings.

Also, aux sends enable audio engineers to create customized headphone mixes for on-air talent, ensuring they can hear essential audio cues during their broadcasts.


For podcast production, aux sends benefit live-streamed and pre-recorded content. They allow podcasters to create individual monitor mixes and integrate additional audio sources such as sound effects, music, or remote guests.

Additionally, using aux sends for routing audio to external processing or software plugins can help enhance the overall sound quality and coherence, contributing to a professional and engaging final product.

Setting Up Aux Sends

Aux sends, short for auxiliary sends, are an essential component of the audio mixing process, allowing sound engineers to create separate mixes for monitors, recording devices, and effects processors. This section provides guidelines for setting up aux sends in various situations and using them with different mixers.

Optimizing Levels

Setting the ideal levels for aux sends is crucial to achieving a balanced mix. To do this, follow these steps:

  1. Connect your outboard gear (monitors, effects units, etc.) to the appropriate aux sends on your mixer.
  2. Choose a channel on your mixer from which you want to send audio to the outboard gear.
  3. Adjust the aux send knob or fader on the chosen channel to the desired level.
  4. Repeat this process for each channel you wish to include in the mix.
  5. Monitor the overall level and adjust to prevent distortion or overly loud signals for optimal performance.

For effects processors, setting the wet/dry balance to suit the desired sound is important. This can generally be adjusted on the effects processor itself.

Using Aux Sends with Digital Mixers

Digital mixers offer numerous advantages, such as improved audio quality and extensive onboard processing capabilities. While the basic principles of setting up aux sends remain the same, digital mixers provide additional flexibility and control:

  • Intuitive user interfaces like touchscreens can simplify routing audio to aux sends.
  • Assigning and labeling aux sends is often easier and more visually clear on digital mixers, reducing the risk of errors.
  • Digital mixers often offer a greater number of aux sends.
  • Advanced routing and processing options, such as discrete EQ settings for each aux send mix, enable more fine-tuned control over the audio signal.

Overall, the key to setting up aux sends on analog and digital mixers lies in understanding your specific mixer’s features and capabilities, carefully following routing procedures, and fine-tuning levels to achieve the desired sound.

Common Aux Send Effects

Aux sends in audio are used to apply effects to individual channels or sources without altering the original audio signal. Several common aux send effects can be divided into reverb, delay, and compression. These effects serve different purposes and can be combined to create a diverse and dynamic sound mix.


Reverb, short for reverberation, is the effect of sound reflections in a given environment. In an audio mix, reverb is used to simulate the natural reflections of sound in rooms or venues, giving the mix a sense of depth and space. Some popular reverb effects include:

  • Plate reverb: simulates the sound reflections from a large, flat surface like a metal plate.
  • Spring reverb: mimics the sounds created from the vibrations of a spring.
  • Hall reverb: recreates the sound of large, reverberant halls and cathedrals.

Reverb effects can be applied through aux sends by routing one or multiple channels to an auxiliary bus with a reverb processor inserted. This allows for varying reverb application to different channels without affecting the mix balance.


Delay effects are created by introducing time-based repetitions (or echoes) of the original sound. Delay can be applied to an audio signal to create effects like doubling, slapback, or even creative soundscapes. Common delay types include:

  • Tape delay: emulates the sound of analog tape machines with warm, organic tones.
  • Digital delay: provides clean, precise repetitions of the original sound.
  • Multi-tap delay: uses multiple delayed signals simultaneously, creating complex and rhythmic patterns.

By using aux sends to route channels to a delay processor on an auxiliary bus, the delay effect can be applied independently of the original signal, allowing for precise control over the mix’s blend of dry and wet signals.


Compression is an effect used to control the dynamic range of an audio signal. A compressor alters the volume of a signal by reducing the amplitude of loud signals while maintaining the level of softer signals. This results in a more polished and balanced sound. Key compressor parameters include:

ThresholdThe volume level at which the compressor begins to apply gain reduction.
RatioDescribes how much gain reduction is applied for every dB the input exceeds the threshold.
AttackHow quickly the compressor reacts to signals exceeding the threshold.
ReleaseHow long the compressor takes to stop applying gain reduction once the signal falls below the threshold

Utilizing aux sends to apply compression to specific channels or sources can be particularly useful for parallel compression. A compressed and uncompressed version of the same signal is blended to create a fuller and more dynamic sound.

Aux Send Troubleshooting

When working with aux sends in audio, diagnosing and resolving any issues that may arise swiftly is essential. This section provides valuable information on troubleshooting common aux send problems and offers helpful tips.

Common Issues

Issues related to aux sends can manifest in various ways, such as poor audio quality, insufficient signal levels, and feedback. Some of the most common aux send issues include:

  • No audio signal was sent to the aux bus.
  • Low audio signal level on the aux bus
  • Too much signal level causes distortion.
  • Improper routing of audio signals
  • Feedback problems when using monitor speakers

Any of these issues can disrupt the intended audio output or hinder the effectiveness of the aux send function.

Tips for Resolving Problems

Proactively addressing aux send issues can save time and improve audio output. The following suggestions guide fixing common problems:

IssueTroubleshooting Tip
Too much signal level causes distortionNo audio signal was sent to the aux bus
Low audio signal level on the aux busAdjust the aux send level, and check the routing of the input channels to ensure proper connection.
Too much signal level causing distortionReduce the aux send level or the input channel gain to avoid overloading the bus.
Improper routing of audio signalsConfirm the correct signal routing in the mixer or digital audio workstation (DAW) settings.
Feedback problems when using monitor speakersReposition the monitor speakers, adjust the aux send levels, or use graphic equalizers to suppress feedback frequencies.

Implementing these troubleshooting techniques allows aux send-related issues to be effectively resolved, ensuring a smoother audio experience.


Aux sends in audio are essential tools for sound engineers and producers, as they allow for more control over individual elements within an audio mix.

Some common applications of aux sends include:

  • Sending a mix to a performer’s monitor or in-ear system.
  • Applying effects such as reverb or delay.
  • Creating headphone mixes for individual musicians in a studio.

Using aux sends strategically makes it possible to create a more refined and professional-sounding mix. Understanding parallel and serial routing when working with aux sends is important to achieve optimal results.

Juan Louder
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Juan Louder

I started SoundStudioMagic to learn how to record my own audiobook at home, and now I'm addicted to all the latest techniques and gear.

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