Using aux tracks

Aux tracks in Pro Tools let you route audio from multiple tracks into a single processing path. They’re commonly used to create shared effect returns like reverb and delay, or for parallel processing such as compression or saturation.

By sending signals to an Aux track, you can apply one effect to several tracks at once, keeping your mix consistent and reducing CPU load.

Create a Send

To create a shared effect or processing path, start by setting up an Aux track. This track will receive audio from your other tracks through sends.

Step 1. Create an Aux Input track

Go to Track > New and create a new Aux Input track. This Aux Input acts as your return track, where all incoming signals are processed together before being sent back to your mix.
For most effects like reverb and delay, choose Stereo, since these effects are designed for stereo.
You can also create a Mono Aux for something like parallel compression on a vocal or bass, where you don’t need stereo processing. You also have the option to create a Multichannel Aux if you’re working in surround or immersive formats.
This Aux track will act as your return track, receiving the audio sent from other tracks.
- Think of it like a shared effects lane: instead of putting the same effect on every track, you send them all here and process them together.

Step 2. Set the Aux input

On the Aux track, set the Input to a bus (e.g., Bus 1–2). This defines where the track will receive signal from.
Insert any plug-ins you want to use (e.g., reverb, delay, compressor).

Step 3. Open the Mix Window

Go to Window > Mix or press Command + = (Mac) / Ctrl + = (Windows).

Step 4. Send Tracks to the Aux

With your Aux track set up as the destination, the next step is to pick which audio or instrument tracks you want to send there. This is how you route individual tracks into the shared effects path:

On the track you want to send to the aux track, locate the Send section (A–E).

Click on an empty slot, then select the same bus you assigned to the Aux track (e.g., Bus 1–2).
A send fader will appear, letting you control how much signal is being sent.

Step 5. Choose pre- or post-fader

Pre-fader sends: Independent of the track’s volume fader (useful for headphone mixes).
Post-fader sends: Follow the track’s volume fader (best for effects like reverb or delay).

Adjust or Bypass a Send

Send fader: Move the send fader to control how much signal is sent.
Mute: Click the send mute button to temporarily disable it.
Remove/reassign: Right-click the send slot to clear it or assign it to another bus.

Tips for Using Aux Tracks

Shared effects: Use one Aux with reverb or delay and send multiple tracks to it for a unified sound.
Parallel processing: Send a track to a separate Aux with heavy compression or saturation and blend it with the original.
Headphone mixes: Use pre-fader sends to build custom monitor mixes that stay independent of your main mix levels.
Stay organized: Label your Aux tracks clearly (e.g., “Vocal Reverb,” “Drum Delay”) to keep sessions manageable.
Save resources: One Aux with a shared plug-in uses less CPU than inserting the same plug-in on every track.

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