Mixing and Mastering — The Last Two Steps

Mixing is subtraction inside a balance; mastering is compromise inside constraints

Related

Dynamic MarkingsWhat Is a Musical Sound

Mixing and mastering are two different jobs, though they get treated as one. One line separates them: mixing is subtraction inside a balance; mastering is compromise inside constraints.

Mixing: turning N tracks into one whole

Mixing takes separate tracks in and delivers a finished piece. It has three core moves:

1. Placement (space)

Each track gets placed at "a position":

• left/right — who sits where;
• front/back — depth implied by reverb amount and high-frequency content;
• room size — reverb implying "hall" versus "small room".

The first example is the clearest case: two pianos are not "two parts" but two positions inside one space — which is nearer, which is further, whether they share a room.

2. Balance

Each element's share of the whole:

• lead vocal usually centred and forward;
• drums centred but not dominant;
• bass providing low end without masking;
• harmony parts filling the outer edge.

Crucially, "the whole" is alive — the balance may differ every second (buses push forward in loud passages, sit back in quiet ones).

3. Subtraction

The bulk of mixing work is removing things:

• congested frequency ranges are opened up;
• elements fighting each other are pushed down;
• unnecessary decoration is dropped.

The reason for subtraction: multi-track layering naturally accumulates mud. If every track is audible, nothing in the mix is.

The second example is a principled reminder: for a live recording, the mixer's job is not to perfect it but to preserve "this happened" — the small mistakes are evidence, not defects.

Mastering: responsible for other people's devices

Mastering takes a finished piece and returns a finished piece, but the audience changes.

Its judgements come down to three:

1. Dynamics

The most direct effect of mastering is dynamic range:

• squashed too far → no sense of shape across sections;
• left too wide → unintelligible in a noisy environment.

This is a trade-off with no optimal answer, and it depends on the delivery channel (see the piece on loudness normalisation).

2. Overall level

Producing different level versions of the same piece for different channels is routine.

3. Making the top and bottom survive

Mastering addresses what breaks elsewhere:

• top end too harsh (especially obvious on a phone);
• bottom too muddy (turns to paste in earbuds).

The third example says exactly this: for an old recording with wide dynamics, the first mastering decision is often not aesthetic but "make it playable anywhere". That is compromise, not improvement.

A usable dividing line

Beginners blur the two. A practical distinction:

• Mixing is a creative decision — it changes the music itself;
• Mastering is a translation decision — it turns a fixed piece into one that holds up under varying conditions.

If after the mix you can still say "I'd like to try a different approach", that is mixing. If you can only say "it's harsh on my phone", that is mastering.

Listen: a demonstration of subtraction

Below are five notes. Imagine first treating them as ten tracks stacked (everything sounding at once, masking each other), then subtracting: pushing the low end down, moving the middle notes back, keeping the landing note forward. What you get after subtraction is far clearer than "everything at once".

Next

• The final stage: Dynamics.
• What mixing adjusts: Timbre.
• Who makes these decisions: roles in the studio.
• The knock-on effect of level: loudness normalisation.

Sources

• 本文为混音与母带工序职能的通识性介绍；具体技术标准、交付规格与平台要求不在本文范围
• 涉及的曲目均标注来源与许可档位，可在线试听

Used for fact-checking only; all prose is original.