What is the difference between mixing and mastering?
This is a question I often see.
Some of you send it directly to me via email.
Sometimes, I read it in Facebook groups.
Other times, I realize while responding to messages that the definition of mastering is not clear to everyone.
And to be honest, at first, it wasn’t clear to me either. Because, let’s face it, there is quite a bit of contradictory information online about this.
Or at least imprecise.
To finally explain what mixing is and what mastering is, which are two essential steps in the production of a track or an album, I decided to write this article. I hope it answers your questions in the best possible way 🙂
What is audio mixing?
Let’s start with a definition of audio mixing.
There are several steps in the production of an album. The main ones are represented in the diagram below.
As you can see, mixing comes right after recording, but before mastering.
Overall, this means that mixing will process all the recorded tracks from the previous phase.
For example, if you record a rock band, you might have 5 tracks for drums, 4 tracks for guitar, 1 track for bass, and 1 track for vocals.
In other words, several files that correspond to all the sound takes made.
Objectives of audio mixing
The objective of audio mixing is to produce, for each track, a unique audio file (usually stereo) that will be balanced:
- in terms of frequencies — with a harmonious balance of lows, mids, highs, etc.
- in terms of dynamics — to simplify, by adjusting the relative volume of each track compared to the others
- in terms of 3D space — ensuring that the position of different instruments in the stereo space is pleasant to listen to and meets creative needs.
To achieve this goal, a number of effects will need to be applied to the tracks. We are talking about:
- equalization
- compression
- distortion and saturation
- delay
- reverb
- etc…
When is mixing considered finished?
It is of course important to set a boundary between mixing and mastering (the next step).
In practical terms, to be considered finished, a mix must be perfect. Yes, perfect.
If you hear problems in your mix, it is not finished.
This means it must be a finished product, in the form of a single file, that is pleasant to listen to.
If you hear problems in your mix, it is not finished. If certain frequencies stand out too much or sound aggressive, or if you can’t hear certain instruments enough, it means you need to revisit the mix.
And that’s okay — take a break and continue the next day with fresh ideas! 😉
But don’t think that mistakes will be corrected in mastering. This is a completely inappropriate approach that will never yield good results.
A mix must be finalized at 100% before moving on to mastering.
(A little tip I read somewhere: if you start nodding your head in rhythm with the music, it’s a sign that your mixing phase is coming to an end.)
Definition of audio mastering
It’s difficult to write an absolute definition, but here is what the famous American mastering engineer Bob Katz says on the subject:
Mastering is the final creative step in the audio production process, it’s the bridge between mixing and pressing — your last chance to enhance the sound or fix issues […]
Mastering Audio: The Art and the Science – Bob Katz
Objective of mastering
The objective of mastering is, in fact, to achieve a file that is ready to be pressed in the form of a CD, or vinyl, or distributed on online music platforms.
It’s a bit like the cherry on the cake. Or, like the varnish you would apply to a painting, after perhaps a final touch of paint here and there.
In other words, to do good mastering, one must consider the corrections or adjustments that can be applied to the track.
Sometimes, no corrections will be necessary. Other times, additional effects will need to be applied to the entire mix for some subtle adjustments:
- on the frequencies with EQ
- on the overall cohesion of the mix, with compressors
- or, for example, on the stereo image of the track to widen or tighten it.
That’s why often, it is advised not to do the mastering of a mix that you have created yourself: it’s better to entrust this step to someone who will be more impartial and therefore make more relevant decisions.
Then, it is also during mastering that the final perceived volume of the track will be adjusted, for example using limiters or clipping plugins.
Of course, the goal of mastering is also to create a coherent set for the entire treated album. In terms of volume, but also frequency distribution. It’s hard to imagine having a first song heavily focused on bass, while the second is characterized by significant brightness in the highs.
Finally, once the audio aspect of mastering has been addressed, a number of less fun but equally important activities will need to be performed, such as putting the tracks in the order of the album and managing fades between tracks (fade in / fade out), ensuring that the exports comply with Red Book standards (standards for audio CDs), etc.
And when all that has been done, the album will be ready to be sent to a CD pressing plant to produce the final medium or to a radio for broadcast.
An example of mastering
To illustrate more precisely what can be done in the context of mastering, let’s take the example of this track by Chris Finegan (a very good Scottish artist whose music you can download for free on this Bandcamp page).
After mixing but before mastering, if we look at the waveform, we have something like this:
And in terms of sound, we will have this:
The mix is very nice and generally balanced. It is therefore ready to be mastered.
Here is an example of processing that I chose to apply:
- adding tape saturation with Tapedesk;
- overall compression to bring out the acoustic guitar a bit more, with Novatron;
- very light correction of the frequency spectrum with an EQ (for example, -0.65 dB at 850 Hz);
- subtle correction of the sibilance of certain “S” sounds with a de-esser set very lightly;
- and of course, adjusting the overall level to have a volume closer to what one might expect on a commercial master, thanks to the limiter Pro-L 2 from Fabfilter.
After mastering, we can see on the waveform that a limiter has been applied and that the overall volume has been amplified:
And of course, the sound has evolved, particularly in terms of perceived volume:
In conclusion
Ultimately, we realize that there are indeed two completely different stages, which do not share the same objectives:
- mixing, which combines several sound recordings and adjusts them relative to each other to achieve a balanced track;
- mastering, which adds a sonic polish, corrects the perceived volume, and ensures the consistency of the tracks across the album.
Therefore, distinguishing between the two is important.
Remember, before considering any mastering, make sure your mix is solid and sounds good. Mastering is not for correcting the mix. It is simply to refine it and prepare it for release.
► To go further: The Best Plugins for Mastering