How to Prep a Mix for Mastering: A Practical Handoff Checklist

A mix is ready for mastering when it has enough headroom to avoid clipping, no unintended processing on the master bus, correct file specs (usually 24-bit WAV at your session's native sample rate), clean silence or tails at the start and end, and a clear file name. Send that, plus a reference track and short notes, and most mastering engineers can get to work without emailing you back.

That's the short version. Here's the full checklist, in the order engineers actually check it.

What "mix-ready for mastering" actually means

A mastering engineer isn't judging your song at this stage - they're judging your file. They need a mix that's musically finished but technically open: no brick-walled limiter, no baked-in loudness war, and no guesswork about what processing is already on there.

If they have to ask "is this the final mix?" or "why does this clip at -0.3dB?", you've added a round trip before the real work even starts.

The technical checklist before you export

Sample rate and bit depth

Export at the sample rate your session was recorded and mixed in - don't upsample or downsample unless the engineer asks. Bit depth should be 24-bit minimum. Never bounce down to 16-bit yourself; that's the mastering engineer's job, done at the very end with proper dithering. Dithering twice (once by you, once by them) adds noise you can't undo.

Headroom - how much and why

This is the number one thing new mixers get wrong. Turn off any limiter or clipper on your master bus before you export. Your mix should peak somewhere between -6dB and -3dB, with no clipping anywhere in the signal chain.

A mix that's already slammed to -0.1dB gives the mastering engineer nothing to work with. They can't add punch or loudness without distortion, and if the mix has issues, there's no room to fix them without pulling everything back down first.

File format and naming

Send WAV or AIFF, not MP3. MP3 compression is lossy and audible once you start EQing or compressing further - it will show up in the master.

Name the file clearly: song title, mix version, and date. Something like midnight-drive_mixv4_2024-06-02.wav. Avoid generic names like Mixdown_1.wav - if the engineer has five songs from five artists in their inbox, generic names get lost or overwritten.

Tails, silence, and fades

Make sure reverb and delay tails ring out fully before the file ends - don't cut them off. Leave a small amount of silence (roughly half a second to a second) at the very start and end of the file rather than starting right on the first transient. This gives the mastering engineer room to work with fades and avoids clicks.

Don't add a fade-out yourself unless it's a creative effect you want kept exactly as is. Fades are usually cleaner done at the mastering stage.

What to include besides the audio file

Reference track

Send one or two commercial tracks that represent the tone and loudness you're going for. This matters more than a paragraph of description - it gives the engineer a sonic target instead of a vague instruction like "make it punchy."

Mix notes

Keep it short and specific:

• Any known issues you didn't have time to fix ("snare a bit thin in the chorus")
• Whether this is the final mix or still open to small tweaks
• Tempo, key, and song length, if relevant
• Whether you want the master brighter, warmer, louder, or more conservative than the reference

Don't write a wall of text. A mastering engineer reads dozens of these; three or four bullet points get read properly, a full page often doesn't.

Alternate versions

If you need an instrumental, a clean version, a radio edit, or a TV mix, say so upfront and send those files at the same time as the main mix. Asking for an instrumental after the master is already done means a second round of work and, often, a second invoice.

Common mistakes that make mastering harder

• Sending an MP3 because the WAV was "too big to email." Use a file-sharing link instead.
• Leaving a limiter on because it "sounded better." It sounds louder, not better, and it removes headroom the engineer needs.
• Not checking mono. Extreme stereo widening on the master bus can cause phase issues that only show up when a mix plays on a mono speaker or phone. Check it before you export.
• Sending the wrong version. If you've been through several revisions, double-check you're exporting the approved one, not an earlier bounce still sitting in the export folder.
• No notes at all. Even a single line - "final mix, please keep dynamics close to the reference" - saves back-and-forth.

A simple pre-master export checklist

Go through this list before every handoff, even if you've sent files to the same engineer a dozen times. It takes five minutes and it's the difference between a one-round mastering job and three rounds of "can you resend without the limiter."

How Waves fits into a mastering handoff

Once you're happy with a mix, you can drop the final WAV into the song's project in Waves alongside the stems and earlier mix versions, so the approved file is easy to find later even if you keep revising. Waves detects BPM and key automatically, which is handy for the notes you send along with the file.

When it's time to hand off to a mastering engineer, invite them to just that song, point them to the right version, and leave your notes as a timestamped comment on the mix itself instead of a separate email that gets buried. It won't replace a proper mastering brief, but it keeps the file, the notes, and the reference all in one place instead of scattered across your inbox.