definition 1.

mastering is the process of producing a master copy of a recording

Well, that seems pretty straightforward - but it doesn’t tell us much. We can dig in deeper, but first a little history…

Back in the days of vinyl a master would be cut on a lathe which could then be used to stamp all subsequent copies of the record (or until it wore out and needed to be recut). The process is a little more involved than that, but essentially the mastering engineers job was to ensure the format faithfully reproduced the studio recording (which was likely on tape).
This would involve challenges such as getting the bass levels right and width between grooves so they didn’t run into one another.

Nowadays we can produce digital recordings without any of those considerations - the final bounce can be the one all subsequent copies are made from. You might want to consider including any relevant metadata to formats that allow like mp3 too. But that’s about it.

So what does a mastering engineer do then?
Well, vinyl is still produced. Although likely done by a specialist these days.
Mastering has taken on a new role over the years that you could describe as adding the final ‘polish’.
For an album the tracks will be adjusted so the levels flow smoothly from one to another. Although this equally can be done in the studio.
It may also involve adjusting the overall tonality of tracks so they match each other and bear up well to reference recordings.
Then there’s ’loudness’ to consider too. Compression can be applied to reduce the dynamic range and thus increase the overall volume.
Sometimes even additional reverb may be added if a track requires it.

But really a mastering engineer is there to lend another pair of ears and usually some very expensive equipment to apply the finishing touches to a recording.

Do I need to get tracks mastered?

If you have the budget for that then absolutely you should find someone who has the working style that suits your music.
Which could take quite a bit of shopping around.
And if you don’t have the budget, well…

Can I master my own tracks?

As we have said the mastering process is simply a case of producing an artefact that all subsequent copies can be made from, so yes, you can.
This could be as simple as:
ffmpeg -i inputfile.wav outputfile.mp3
to make an mp3, and add the tags using eg. id3v2.

but it’s not that simple, right?

Well, yes and no. Are you confident that the tonality (high vs low frequencies) and the levels are all balanced? If you’re not than you probably need a mix engineer. But then again this is something you can do yourself.

nah, I don’t have the ‘golden ears’

The thing that makes this difficult is monitoring. Ideally you need low distortion reproduction that covers the whole frequency range and that is not coloured by room reflections and resonances. But this could be as simple as getting a decent pair of headphones. Even some earbuds might be adequate.

but what is the secret sauce to making something sound like a record? How can I do this myself?

okay. Listen carefully. Not to me, to your music. The things are all there. Don’t listen too much, if it’s not immediately obvious just stop.

When we’re talking about ‘mix polish’ it starts when you start writing the track. Is it too busy, too empty, does it engage the listener?
I wanna push back against the idea of polish though, it’s not helpful at all. Think in terms of energy.

My only advice regarding ‘mixing’ tracks is that 90% of it is chorus and reverb. You can never have enough really. Regarding setting levels of things - that’s all about tonality. Is the mix too bright (treble)? or too dull (bass)? Switch between your track and some reference material to compare. Turn down high frequency sounds or turn down low frequency sounds.
I’ve eliminated this process as Syntə sets levels based on a heuristic. I’ve also calibrated it by ear against different playback systems - club, car, headphones etc.

Don’t be drawn into plugins, equalisers I would avoid especially. Perhaps high-pass filter some sounds to take out muddiness. I prefer to adjust amplitude envelopes than compress sounds. Assume every process is a creative, not technical one. The ‘mix’ starts and ends with sound design.
I got a lot from reading Sound On Sound magazine back in the day, but fell out of the habit in the pandemic.

What about LUFS?

The Loudness Units Relative to Full Scale is a way to measure perceptual loudness, mainly for use in broadcasting. I would say it’s designed for consistency rather than accuracy, not that it matters. If you’re playing different types of music you don’t want certain tracks to jump out in volume so this is a way of avoiding that. It has since been adopted by streaming services for the same reason.
It would be useful if you had a whole load of tracks that you didn’t have time to listen to and you wanted to normalise the levels. But it can equally be done by ear - and this is the most important thing - all of this will be judged/experienced by ‘untrained’ ears!
So imagining you need to be somehow special when the listener is not (the listener is very special just not in any technical way) is not helpful.

If you listen on speakers that don’t have the full range of bass to treble, you won’t be able to judge because those parts will be missing. You also need them to reflect the average tonality of playback systems (whatever that is) or at least know how they sound relative to that ‘average’. Within a few dBs is fine.

I like to think of it as cooking. Start with amazing ingredients, keep it as simple as possible (yes!), try out different techniques and recipes, don’t burn things if that was unintended, be safe with knifes and equipment, but otherwise do not be intimidated by the kitchen.
On the subject of knives I would say keep them very sharp and treat them with a lot of respect. Which would be analogous to having low distortion ‘flat’ monitoring while understanding that being careful and methodical is crucial? Am I making any sense?
Btw, yes I will warn you in a condescending way that my kitchen knife is sharp - most domestic ones are not! I was (almost) a chef in another life.

I hope that gives you confidence that you can make music and publish it. The aim is to demystify :)

bonus content

Cave Theory

We briefly mentioned earlier about chorus and reverb and how they make everything sound lovely.
I have a theory about this.
For millions of years (about two of them?) humans spent a lot of time in Africa, Europe, Indonesia etc living in caves with a bunch of other humans.
So we love the sound of an echo-y space filled with many voices, it makes us feel warm and nice.
And that is exactly the effect that chorus (the clue is in the name) and reverb create.
‘Richness’ or ‘fullness’ of sound often translates to exactly those effects, that we experience as layers of slightly differing pitches. Chorus is not the only way to achieve this - subtle detuning of layers of sounds can be done directly - as in the infamous supersaw we mentioned in the previous post.

Well there you have it. We’re all still cave peoples floundering about in urban environments doing our best to figure out what everyone else is doing and trying to go along with it, mostly. But I digress…