In this guide
An audio mixer combines and routes sound sources while giving you controls for their levels. A hardware mixer can handle live inputs; software can mix recorded tracks. A mixer, an audio interface and a finished stereo mix have different roles.
Ready to combine recordings? Follow how to mix audio files for timing, levels and export checks.
An audio mixer combines and routes sound from two or more sources while allowing you to adjust their levels. A live sound mixer might balance microphones and instruments for speakers; a software mixer might combine recorded voice and music into a finished file.
Mixers range from physical consoles with input sockets and faders to controls inside a digital audio workstation or browser. Their capabilities vary: not every mixer records separate tracks, supplies phantom power or has built-in effects.
What does an audio mixer do?
Each source enters a channel or track. You adjust that channel, choose where it goes, and listen to the combined output. Depending on the device, you may also be able to shape tone, send a separate monitor mix or record the result. Shure's audio systems guide describes common mixer controls and routing.
| Control | Typical job | Practical check |
|---|---|---|
| Input gain or trim | Sets the level entering an input stage. | Test the loudest expected sound and avoid input clipping. |
| Channel fader or level | Changes a source's contribution to a mix. | Listen to its balance against the other sources. |
| Pan | Positions a channel within a stereo mix. | Check left and right and the intended mono playback. |
| EQ | Boosts or cuts selected frequency ranges. | Compare with the original and avoid masking or harshness. |
| Auxiliary send | Routes some channel signal to another mix or destination. | Confirm whether it feeds a monitor, effect or other output. |
| Master output | Controls the combined output to its destination. | Check the destination meter and the actual recording. |
The order and names of controls depend on the model. A fader cannot undo distortion that occurred at an earlier input stage. For input setup, see microphone gain; for level management across the chain, see gain staging.
Mixer vs. audio interface
A mixer primarily balances and routes sources. An audio interface connects audio equipment to a computer and typically converts analog input to digital audio and computer playback back to analog outputs. Their functions can overlap: some mixers have USB audio interfaces, and some interfaces offer software mixing and monitoring.
Do not assume a USB mixer records every input separately. Some devices send a stereo mix; others offer multiple independent channels. Check the product manual for input count, USB routing, supported sample rates and whether the recording software receives separate tracks. The audio-interface guide explains inputs and monitoring in more detail.
Example: mix narration and music
- Start with separate sources. Keep an original voice recording and an authorized music file. Separate tracks let you adjust their levels independently.
- Set the voice first. Listen to a quiet phrase and a loud phrase. If the source is already distorted, lowering its fader makes the distortion quieter but does not repair it.
- Add the music. Bring it up gradually while the voice plays. Check consonants and pauses; music that sounds modest alone can mask speech in the mix.
- Check the combined output. Listen through the beginning, transitions and ending. Watch the relevant meters for overload and test on headphones and a small speaker.
- Save and verify. Export the intended file, then play the actual export. Keep the editable project or originals in case you need a different balance.
For a short local example, the Saturalabs audio mixer combines two whole mono or stereo MP3/WAV files, with level and offset controls. Each input must fit five minutes and 50 MiB, and the output must fit the tool's limits. It processes files locally and is not a live hardware console or a full multitrack editor. If the summed sample peak exceeds full scale, the tool reduces the complete mix uniformly and reports the reduction; that is not true-peak limiting or loudness normalization.
Live inputs vs. recorded tracks
A live mixer accepts connected sources while a performance happens and may send different mixes to the audience and performers. Software editing usually works with recorded files on a timeline. A stereo recording of a live mix is not the same as separate original tracks: once speech and music are mixed together, turning down a fader on that file turns down both.
If you have a finished mix but need one source, source isolation can estimate it and may leave bleed or alter the sound. Original separate tracks offer more control when available. See stems vs. audio isolation.
Common questions
Do I need a mixer to record one microphone?
Not necessarily. A compatible interface or USB microphone may provide the required input and monitoring. Choose equipment for the number of sources and outputs you actually need.
Does every mixer record separate tracks?
No. Some send or record a combined stereo output; others support multitrack recording. Check the specific routing and software support.
Will an audio mixer remove background noise?
Lowering or muting an independent noise source can help, but a fader cannot independently remove noise already mixed into the same recording as a voice. Other processing has its own limits.