What's the difference between mixing and mastering?

Mixing is deciding the relationship between the elements of a song; mastering is treating that finished mix as a single piece, so it works on any system and sits alongside the rest of the record. They're separate stages with similar tools: in the mix you have forty tracks, in the master you have one.

Can I master my own mix?

You can, and for most independent releases it's perfectly reasonable. The drawback isn't technical but a matter of perspective: you've been hearing that mix for weeks and your ear has adapted to its faults. If you master it yourself, leave it a few days and work with references in front of you.

How much headroom should I leave in the mix?

Peaks around -6 dBFS is fine. It doesn't need to be exact: what matters is that it doesn't arrive touching the ceiling or with a limiter already on the master, because that leaves mastering nothing to do except make something already flattened worse.

What order does the chain go in?

The usual arrangement is correction first and level last: corrective EQ, gentle bus compression, colour EQ, saturation if it adds something, and the limiter right at the end. The logic is that the limiter should meet an already balanced signal rather than fix one.

Are automatic mastering services any good?

For a demo or a quick reference, yes. They get level and general balance reasonably right and they're cheap. What they don't do is make judgement calls about what should stand out in your particular song, which is the part that justifies paying a person.

Can a bad mix be fixed in mastering?

No. It can be disguised, sometimes considerably, but with a single signal there's no way to turn down a guitar that's burying the vocal. If the problem is the relationship between elements, the fix lives in the mix, and going back is always faster than fighting it at the master.

Mastering11 min read

Mastering: what it is, what it isn't and what you can do yourself

The real difference between mixing and mastering, the usual chain order, how much headroom to leave, and when it's worth handing it over.

What mastering really is

Mastering is the last stage before release, and it means taking a finished mix — one stereo signal — and preparing it for the real world: making it hold together in a car, on a phone and on headphones, arrive at the level each platform expects, and sit alongside the other songs on the record.

Two ideas are worth dismantling up front. The first is that mastering means «making it louder»: that's a consequence, not the job. The second is that it's a mysterious process reserved for unreachable studios: the tools are the same ones you already use in the mix, applied with far more restraint and to material that should already be right.

What the mix has to bring

Headroom: peaks around -6 dBFS, with no limiter or maximiser on the master.
Nothing at the edge: if an element already distorts in the mix, mastering amplifies it.
Checked in mono and on several systems. Phase problems don't get fixed later.
Exported at the project's sample rate and at 24 bits or more. Don't bounce to MP3 to master.
Rested: listen the next day before calling it finished.

The headroom point is the one most often broken, usually because a limiter went on the master during mixing «to get an idea». It's understandable but it has a cost: every later decision was made while hearing something compressed. If that's you, have a look at the gain staging guide, which is where it gets solved at the root.

The chain, and why in that order

Corrective EQ: gentle wide cuts to fix imbalances from the mix. You work in single-digit dB here, nearly always under 2.
Bus compression: low ratio (1.5:1 or 2:1) and 1 or 2 dB of reduction. It isn't for control, it's for cohesion.
Colour EQ: the wide boost that gives character, usually air on top or some weight underneath.
Saturation, if it helps: it adds harmonics and makes the track feel louder without raising the level.
Limiter, last: it sets the ceiling and reaches the delivery level. Never before the signal is balanced.

Quantity is what separates a master from a second mix. If you're moving 6 dB of EQ or seeing 5 dB of gain reduction, you aren't mastering: you're trying to fix the mix with one hand tied. Go back to the mix session, correct it there and bounce again.

References: the only reliable calibration

Mastering without references is deciding blind, because after hours with the same material the ear loses any absolute standard. The fix is having two or three commercial tracks in the style loaded into the session, level-matched to your master, and switching constantly.

Level matching is essential and it's where nearly everyone slips: if your master is louder than the reference it will always seem better, and you'll keep pushing until it's crushed. Bring your master down until both feel equally loud, and only then compare low end, sheen and width.

What level to deliver at, and why pushing no longer buys you anything, is in the LUFS and loudness guide. And if you want an objective read on your frequency balance against genre references, the mix analyser makes that comparison.

Frequently asked questions

What's the difference between mixing and mastering?: Mixing is deciding the relationship between the elements of a song; mastering is treating that finished mix as a single piece, so it works on any system and sits alongside the rest of the record. They're separate stages with similar tools: in the mix you have forty tracks, in the master you have one.
Can I master my own mix?: You can, and for most independent releases it's perfectly reasonable. The drawback isn't technical but a matter of perspective: you've been hearing that mix for weeks and your ear has adapted to its faults. If you master it yourself, leave it a few days and work with references in front of you.
How much headroom should I leave in the mix?: Peaks around -6 dBFS is fine. It doesn't need to be exact: what matters is that it doesn't arrive touching the ceiling or with a limiter already on the master, because that leaves mastering nothing to do except make something already flattened worse.
What order does the chain go in?: The usual arrangement is correction first and level last: corrective EQ, gentle bus compression, colour EQ, saturation if it adds something, and the limiter right at the end. The logic is that the limiter should meet an already balanced signal rather than fix one.
Are automatic mastering services any good?: For a demo or a quick reference, yes. They get level and general balance reasonably right and they're cheap. What they don't do is make judgement calls about what should stand out in your particular song, which is the part that justifies paying a person.
Can a bad mix be fixed in mastering?: No. It can be disguised, sometimes considerably, but with a single signal there's no way to turn down a guitar that's burying the vocal. If the problem is the relationship between elements, the fix lives in the mix, and going back is always faster than fighting it at the master.