An aux send is a fundamental feature on any mixing console, whether analog or digital, that allows you to tap a specific amount of signal from a channel and route it elsewhere without affecting the main output. This parallel path maintains the integrity of your original performance while giving you a separate mix to work with, making it indispensable for live sound and complex studio sessions. Think of it as creating a customized downstream mix that serves a purpose distinct from the feed going to your main speakers or record bus.
How Aux Sends Work in Signal Flow
The signal flow for an aux send typically occurs before the fader, meaning the level sent to the external processor is independent of your main mix fader position. This is crucial because you can drop the fader to kill the main mix during a verse, yet the singer still hears their preferred monitor blend via the aux. Most consoles feature a pre-fader tap, labeled "Pre" or indicated by a symbol, ensuring the amount sent to effects like reverb and delay remains consistent regardless of how loud or quiet the performer is on stage.
Parallel Compression and Creative Effects
One of the most powerful studio techniques involving aux sends is parallel compression, also known as New York compression. You duplicate a drum bus or a vocal group, send it heavily into a compressor on an aux, and blend the compressed signal with the dry source. This retains the transient punch of the original while smoothing out the dynamics, resulting in a sound that is both energetic and controlled. Similarly, you can use aux sends to create lush ambient pads by sending synth layers into granular processors or tape emulations, adding depth without cluttering the core sound.
Setting Up Effective Monitor Mixes
In a live environment, aux sends are the backbone of personalized monitor mixes. Each musician on stage likely has different needs; a drummer wants to hear the kick and toms up front, while a guitarist needs to catch the vocal harmonies. By adjusting the aux knobs, the engineer can build multiple sub-mixes on the fly, ensuring everyone hears exactly what they need to perform confidently. The goal is to provide clarity and separation so that the stage foldback acts as a focused tool rather than a noisy distraction.
Gain Staging and Headroom
When routing signals through aux sends, particularly to outboard gear, gain staging is critical. You want to hit the processor at its optimal input level to maximize headroom and avoid unwanted distortion. Check the meters on your compressor, limiter, or external effect unit and trim the aux send level accordingly. Maintaining a healthy signal chain ensures that the dynamics processing happens smoothly and that the return integrates cleanly into your main mix bus.
Modern DAW Implementations
In a digital audio workstation, the concept of an aux send translates to sending tracks to auxiliary mixer tracks, often called aux channels or bus channels. This allows you to apply a single plugin instance to multiple sources, which is not only efficient but also creates a coherent sense of space. For example, sending several vocal tracks to a single reverb aux allows you to automate the overall wash of the room, while sending individual tracks would make automation tedious and disjointed.
Advanced Routing and Automation
Advanced users leverage aux routing to perform complex tasks like sidechain ducking or multi-band processing. You might send a bass guitar and kick drum to a compressor on an aux to gently glue the low end, or send just the high frequencies to a de-esser to control sibilance without affecting the body of the vocal. Because the send is parallel, you retain the option to blend the processed signal subtly, preserving the natural tone while adding the desired corrective or creative effect.
Ultimately, understanding how to use aux sends transforms the mixing process from static correction into dynamic sculpting. It provides the tools to solve problems in monitoring, enhance rhythmic cohesion, and design immersive soundscapes. Treat the aux section of your console or DAW as a creative workspace, and you will find new ways to shape audio that feel intuitive and remarkably musical.
