Adventures In Audio with Audio Masterclass

How much mastering does acoustic music need?


An Audio Masterclass visitor asks whether be should master his acoustic track. What kinds of process should be used, and how much?

Here’s a question from an Audio Masterclass website visitor…

How much signal processing should be done on an all acoustical session when mastering? Should compression be applied?

How I hate that word ‘mastering’. In the old days of recording, pre-CD, mastering was a necessity. The finished stereo mix was on analog tape and it had to be transferred to vinyl for release.

Vinyl has certain technical limitations and requirements, so active mastering was an essential stage. And of course also, then as now, individual tracks of an album will have different levels and EQ balances, which need compensation.

These days however, the digits that comprise your stereo mix can be transferred directly to CD with no adjustment or alteration (other than, of course, level and EQ balance adjustment as before).

So there isn’t any need for a mastering stage in the sense of ‘improving’ the mix.

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But we seem to feel the need for mastering. After all, everyone else is doing it, are they not?

But what exactly is mastering? Surely the process of mixing will bring the track to the very best it can be – so why an extra stage?

Let’s go back a little in the recording process…

In any recording there will come a point where the producer says, “That’s it!” and the track is finished. There is nothing more to add, no more overdubs or tweaks. Done.

At that point the track is ready to mix.

So the mix engineer will balance the levels, EQs and dynamics of all of the individual instruments and voices, applying great care and musicality. Over the course of anything from a couple of hours to a day, the mix will take shape.

Often a mix engineer will listen to the mix next day with fresh ears and apply further fine tuning.

At that point the mix is finished. It is as good as it can be. So why should it need further mastering, other than moderate adjustments to level and EQ balance to fit with the other tracks on the album?

One answer would be to make it louder. Clearly the mix engineer has this in his or her power. But it may be that although the engineer has achieved a wonderful balance and optimum loudness, the A&R manager of the record label wants it louder still. That happens.

But there’s another way of looking at this, which involves further defining the terms ‘mixing’ and ‘mastering’.

I would say this…

‘Mixing’ is the process of blending the individual tracks of the mix, with individual processing of those tracks.

‘Mastering’ refers to any process, such as EQ or compression, applied to the stereo mix as a whole.

So if there is no processing in your master inserts you are simply mixing. If there is some processing in the master inputs, you are mastering as well.

Also, if you don’t use master inserts, but you come back to your stereo mix some time later and process it, then that too is mastering.

And now back to the question. My advice on mastering is…


Mastering is a powerful tool that can completely ruin a track. If you are not capable of achieving a really good mix yourself, then it is hardly likely that your mastering abilities are going to improve it in any way. But an experienced mastering engineer can often ‘salvage’ a less-than-perfect mix. As long as it has not been mastered previously.

But I know that people do want to master themselves. And yes, sometimes it is appropriate.

You SHOULD consider mastering your tracks if you plan on CD release.

You SHOULD NOT master your tracks if your music is intended for TV – mastering makes the track harder to manipulate later on, and therefore less versatile and less usable. You’re throwing potential money away.

Also, you SHOULD NOT master your tracks if there is a possibility that they could be mastered by an experienced mastering engineer. You could of course make mastered and unmastered versions of your mix. That would be a safe thing to do.

But the acoustic instruments referred to in the question. If you are going to master, what should you do?

Firstly, you have to have in mind the sound you want to achieve. Find a CD of similar music that sounds good to you. That will be your benchmark and a standard to achieve.

It is likely that you will want to EQ the stereo mix. Of course you may also have EQed the individual channels. But often although this can result in a well-blended mix, the overall frequency balance isn’t quite right. You could adjust the individual channels, but it is easier to EQ the mix.

EQing the mix therefore is likely. Compare your balance with the reference CD.

Compression is less likely and less desirable in this case. If you are working with acoustic instruments, then you know what they should sound like – exactly as they sound when you are standing in the room with them. They were not compressed then, and there is no reason why the mix should be compressed either.

Unless of course you want to achieve a ‘processed’ sound. But this would be something you had in mind right from the start. You shouldn’t apply compression just because you think it is ‘the thing to do’.

Mastering consists of other processes besides EQ and compression. EQ and compression can be mild. But then there is limiting, soft clipping, hard clipping and multi-band compression. All of these are used by professional mastering engineers.

These are all DANGEROUS processes. In inexperienced hands a track can easily turn from perfectly listenable to an atrocious mess.

In fact, even pro mastering engineers sometimes create an atrocious mess – but that’s because they did what the A&R manager told them to and made the track obscenely loud!

But dangerous though these processes are, there is no reason why you should not experiment and learn. But always keep a clean, unmastered, version of the mix.

My thoughts with acoustic instruments though would be to EQ, perhaps compress a little, but go no further than that.

David Mellor

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David Mellor