Mastering can fix small problems. It can't fix a bad mix. Here's the 12-point checklist to run through before you pay for mastering — or before you master it yourself.
mastering mixing checklist workflowMastering is the final polish. It's where your mix gets louder, wider, and more cohesive. But here's the thing — mastering engineers can't fix a muddy mix, a thin mix, or a mix with a buried vocal. They work with what you give them. If you give them a broken mix, you get a polished broken mix.
I've seen producers spend money on mastering only to get back a track that still has the same problems, just louder. The fix is simple: check your mix before you send it out. Here's what to look for.
1. Frequency balance is even. No frequency range is way louder than the rest. The low end isn't booming, the mids aren't muddy, the highs aren't harsh. Upload to MixDiagnose to verify.
2. No clipping on the master bus. Your mix output should peak no higher than -3 dBFS. Leave headroom for mastering. If the master bus is hitting 0 dBFS, you're already clipping.
3. Mix is between -18 and -23 LUFS. This gives the mastering engineer room to work. If your mix is already at -14 LUFS, there's nothing to work with — you've already compressed it.
4. True peak is below -1 dBTP. Make sure no inter-sample peaks are sneaking through. This prevents clipping when the track gets converted to MP3/AAC for streaming.
5. Vocals are clearly audible on phone speakers. If you can hear the vocal clearly on your phone, it'll cut through everywhere. If it disappears, push the vocal up 1-2 dB or check the 2-5 kHz range.
6. Kick and bass are balanced. Solo them together. Both should be audible and distinct. If they blur into one sound, you have masking. Fix with EQ or sidechain.
7. Stereo image is wide but not broken. Check in mono. If stuff disappears in mono, your stereo width is too aggressive. Elements should still be present in mono, just centered.
8. Dynamics aren't crushed. Your mix shouldn't be compressed to death. The chorus should feel louder than the verse. If everything is the same volume, you've over-compressed.
9. No unwanted noise or clicks. Listen for digital clicks, background hiss, sample rate artifacts, or plugin glitches. Check the beginning and end of the track for clicks.
10. Reverb tails are clean. Let the reverb decay naturally. Don't cut it off. But also make sure there's no low-frequency rumble in the reverb tails.
11. The mix sounds good on at least 3 systems. Monitors, headphones, and a phone or car. If it only sounds good on one system, it doesn't translate.
12. You compared it to a reference track. Level-match a commercial track in a similar style. How does yours compare? What's different? Fix the differences before mastering.
Don't do all 12 at once. Work through them in order. The first four are technical checks — numbers you can verify. Items 5-8 are mix decisions. Items 9-12 are quality control.
For the technical checks (1-4), you can use MixDiagnose to verify frequency balance, LUFS, true peak, and dynamics in one upload. It takes about 10 seconds and gives you a report you can screenshot and send to your mastering engineer.
If your mix has any of the "cannot fix" problems, go back to the mix. Don't pay for mastering hoping it'll save you.
If I could only do one check before mastering, it would be uploading my track to MixDiagnose. The report covers frequency balance, dynamics, loudness, and stereo width in one pass. If any of those are off, I know exactly what to fix before sending to mastering.
It's free. It takes 10 seconds. And it'll save you from paying for mastering a mix that isn't ready.