Sending the correct files to your mastering engineer helps protect the quality of your music and allows the mastering process to begin without unnecessary delays.
The main requirement is normally a final, full-resolution stereo mix for each song. Reference tracks, metadata and additional versions can also help the engineer understand your creative goals and prepare the correct final deliverables.
This guide explains which files should be included, which formats are preferred and when stems or complete session files may be required.
What Should You Send for Mastering? #
Most mastering projects require the following essential files, with several additional items supplied where relevant.
Final Stereo Mixes #
One clearly named WAV or AIFF file for every song being mastered.
Project Information #
Artist name, track titles, running order and required delivery formats.
Reference Tracks #
Commercial releases or previous versions that communicate the intended tonal direction.
Alternate Mixes or Stems #
Instrumentals, vocal alternatives, stems or session files where the project requires additional control.
Full-Resolution WAV or AIFF Files #
The main file supplied for mastering should normally be an uncompressed WAV or AIFF file. These formats retain the full quality of the exported mix and are widely supported by professional mastering systems.
WAV and AIFF can provide equivalent audio quality when their sample rate and bit depth are the same. The choice between them is primarily one of compatibility and workflow.
WAV #
Widely used across professional recording, mixing, mastering and digital distribution systems.
AIFF #
A full-resolution audio format commonly associated with Apple-based recording and production environments.
Recommended Technical Settings #
Keep the export at the native resolution of the original mix session wherever possible.
For example 44.1, 48, 88.2 or 96 kHz.
Avoid reducing the resolution before mastering.
One file containing the left and right channels.
The exported file must not contain clipping.
One Final Stereo Mix for Each Song #
The stereo mix should be the final approved version of the song, with the intended balances, automation, effects and creative processing already in place.
Each song should be exported as a separate file rather than one continuous file containing the complete album or EP.
Final Mix Balance #
Confirm that the vocals, instruments, bass and effects have been approved before exporting.
Complete Song Length #
Include the complete beginning and ending, including any natural reverberation, delays or intended silence.
No Digital Clipping #
Ensure that the final bounce remains below 0 dBFS and does not contain clipped or overloaded peaks.
Reference Tracks #
Reference tracks help communicate the tonal direction, impact and overall presentation you would like the master to achieve.
A reference does not mean that your music will be copied or made identical to another release. It provides useful context for qualities such as bass weight, brightness, vocal presence, dynamics and perceived loudness.
Tonal Balance #
Demonstrates the preferred relationship between bass, midrange and high frequencies.
Dynamics #
Helps communicate whether the desired presentation is open, controlled, powerful or highly energetic.
Vocal Presence #
Provides context for how forward, smooth or integrated the lead vocal should feel.
Low-End Weight #
Indicates the preferred depth, tightness and impact of bass and kick drums.
Stems and Session Files #
Standard stereo mastering normally begins with the final stereo mix. Stems or complete session files are only required when additional mix control or revision work has been agreed.
Final Stereo Mix #
The complete song is supplied as one left-and-right stereo file.
- Normal mastering workflow
- All balances already approved
- Efficient and straightforward delivery
Grouped Audio Stems #
The mix is divided into groups such as vocals, drums, bass, instruments and effects.
- Provides additional balance control
- Must begin from the same timeline position
- Should recreate the approved stereo mix when combined
Complete Session Files #
DAW session files may be requested when mixing or detailed corrective work is included in the project.
- Not normally required for standard mastering
- Plug-ins and audio files must be available
- Software compatibility must be confirmed
Metadata and Project Information #
Clear project information allows files to be identified correctly and helps avoid mistakes in track titles, running order and final delivery.
Additional Versions You May Be Asked to Supply #
Some projects benefit from alternate mixes that give the mastering engineer limited additional control.
No-Limiter Mix #
A version without the final loudness limiter or clipper.
Vocal Up #
A mix with the lead vocal raised slightly where vocal balance remains uncertain.
Vocal Down #
A mix with the lead vocal reduced slightly as an alternate option.
Instrumental #
A version without the lead vocal for alternative release or performance use.
Clean Version #
A broadcast or family-friendly alternative with edited lyrical content.
Acapella #
A vocal-only version where required for distribution, remixing or performance.
Name and Organise the Files Clearly #
The file name should identify the artist, track and version without requiring the engineer to open the file first.
Artist_Name_Track_Title_Final_Mix_24bit_48k.wav
Suggested Project Folder #
Keep the delivery simple and easy to navigate.
What Should You Not Send as the Main Mastering File? #
MP3 Files #
MP3 uses lossy compression and should not replace the original full-resolution mix.
Clipped Exports #
Digital clipping may create distortion that cannot be completely removed during mastering.
Unlabelled Versions #
Files called “final 2”, “new final” or “latest mix” create unnecessary confusion.
Changed Sample Rates #
Avoid unnecessary sample-rate conversion before the mastering stage.
Incomplete Bounces #
Do not cut off reverb tails, count-ins or other audio that forms part of the intended presentation.
Every Session File #
Do not send complete sessions unless the mastering engineer has specifically requested them.
Files for Mastering Checklist #
Sending Files to a Mastering Engineer #
Should I send WAV or AIFF files for mastering?
Either WAV or AIFF is suitable when exported at the correct sample rate and bit depth. Both can provide full-resolution uncompressed audio.
What sample rate should I send?
Export the mix at the sample rate used in the original recording and mixing session. Avoid converting it to a higher rate only for delivery.
Should the mastering file be 24-bit or 32-bit float?
A 24-bit file is suitable for most mastering projects. A 32-bit floating-point export may also be supplied when it is supported by the mastering workflow.
Should I send stems or the stereo mix?
Standard mastering normally uses the final stereo mix. Send stems only when stem mastering or additional mix control has been discussed and agreed.
Can I send an MP3 for mastering?
An MP3 may be used as a reference, but the main mastering source should be the original WAV or AIFF file wherever possible.
Should I include commercial reference tracks?
Yes. A small number of carefully selected references can help communicate your preferred tonal balance, dynamics and overall presentation.
Does the mastering engineer need my complete DAW session?
Not for normal stereo mastering. Complete session files are generally required only when mixing, revision or detailed corrective work is part of the project.
Send the Best Available Source #
The most important mastering file is the final approved stereo mix supplied as a full-resolution WAV or AIFF file.
Reference tracks, project notes, metadata and clearly labelled alternate versions provide useful context and help ensure that the correct master is created for the intended release.
Careful preparation protects the quality of the music and allows the mastering engineer to concentrate on tone, dynamics, translation and the final presentation.
Send the final stereo mix as WAV or AIFF
Keep the original sample rate and resolution
Include references and clear project information
Send stems or sessions only when requested
