In Summary

Successful masters come from successful mixes. Although sonic sweetening in Mastering can happen, the source mix needs to be as complete as possible. Here we talk about some of the artistic considerations as well as the more practical things to have in order for the master to happen smoothly.

Going Deeper

Although many micro productions see artists’ own mixes hitting platforms such as Spotify and Bandcamp, a great number of releases still go to Mastering before being unleashed on the world. There is a lot of talk about the processing that is or isn’t used in mastering, but fundamentally it is the final quality check and file formatting before distribution.

The expertise and judgement of an experienced dedicated third party is golddust for any release, and for productions with the budget, the human mastering engineer can shed light on problems that would have gone unnoticed by tired ears that are still invested in the mix being a certain way.

Putting aside the benefits or pitfalls of automated ‘machine’ mastering, if nothing else these services can also perform number crunching tasks such as loudness compliance or file formatting. There’s no doubt that some of these can deliver a net benefit over the non-engineer’s bounce making it all the way to air.

Both traditional human mastering engineers and automated cloud services do have one thing in common, and that is that neither will return the best results without a great mix to work with. There are also technical mix aspects that are also best dealt with before the master is done. Here are our six ways to make sure that your mix evolves into the best master it can be, regardless of who or what is doing the work. Some equate to good mix hygiene whether or not mastering is on the horizon.

1 - Know Your Monitoring

Although the mix’s intent will arrive baked into the file, occasionally Mastering may request a remix where obvious balance problems have got through. These can sometimes arise from inaccurate monitoring (some are new to mixing and/or are working in unknown or uncalibrated environments) rather than from any ‘inappropriate’ mix decisions. One of the best ways to avoid mixes coming back is to be able to trust your monitoring chain including and pivoting on the room you’re working in.

Whether a studio B or C pair, a car system, earbuds, boomboxes, or even the dreaded laptop or phone speaker, things like vocals and basses can have their prominence skewed a great deal depending on the medium. Mono checks are also invaluable for picking up on big shifts in balance that listeners might hear.

Related to levels, balance is also the question of the mix’s overall tonal makeup. Any jumpy notes in the bass will need to be dealt with (either from the instrument itself or in the monitoring). Mastering engineers can apply EQ to help fundamental notes, although this will affect anything else occurring in the same band.

2 - Mix For Mastering

If the aim of the mix is to be as good as it can be, if achieved that means that no further action should be needed further downstream. Many engineers prefer to mix into a bus compressor from the outset. Although it might be tempting to add a little compressor gloss after the mix is completed, nine times out of ten this will simply fight many of those carefully chosen fader moves and pull up the level of effect returns depending on settings. As for mix EQ, it could be argued that unless a specific unified treatment is wanted, EQ across the mix simply isn’t needed when the mixer has access to the individual tracks in a multitrack project.

With any bus compression in place, engineers need only do what they do best to get the mix exactly where the artist and song need it to be. William Wittman puts it another way:

Most important is that my goal is to have it sound complete before I think about going to mastering. Nothing is ‘left for’ mastering except levelling.

3 - Deal With Dynamics

It’s often said that mixes should be as dynamic as the music needs. While this can mean huge variations in level between song sections (or especially between classical movements), it doesn’t mean that controlling these differences should be avoided. Just like the overall balance, the mix as received by Mastering should already contain the mixer’s intent for how much dynamic swing should exist. Certainly too much dynamic movement for the title is almost as bad as too little, the only difference being the amount of information left for Mastering to work with.

If mix compression concentrates on ‘microdynamic’ changes that are too fast for a hand on the fader, then macrodynamic adjustments can help with the big picture, for example between sections of a song. This is natural fader territory, and it’s not against the rules to automate the mix bus fader during the song! Small rides can reduce massive dynamic chasms between sections to give Mastering a more prescribed starting point.

4 - Control Quality

Although Mastering is the final arbiter of technical quality, does any mix engineer really want to send files that contain clicks, pops, noise, or clipped audio? Checking for these and busting them when needed frees up the Mastering Engineer’s energy to concentrate on the music instead.

Clicks and pops from edits will hopefully be absent anyway, but double checking zero points and crossfades can’t hurt if it’s possible to do so. Check to see if your DAW supports a ‘Snap To Zero Point’ function or similar when editing. Other subsonic thumps going up mic stands can be easily filtered out; using a filter across groups of suspect elements like drum mics or vocals can be high enough to be effective and low enough to be under the music. Start from 20Hz up to around 40Hz.

Virtually all engineers know that red lights in the DAW are bad. This can extend to plugins as well as channels, but the thing that will send your mix straight back to you is a clipped mix bus. Limiting for clip protection should be in place for those times when the mix is the master. However it really isn’t wanted or needed for mixes that will be mastered (more on which in a minute), although a limiter can be in place if there is any possibility of the odd red light. Settings of 0dB on the Threshold and a high ceiling such as -1dBTP can do the trick.

Certainly, any machine-mastering service will not know or care if your mix is compromised in these ways, so good mix hygiene has never been more important.

5 - Learn Levels

Headroom

Virtually all services will ask for a 24 bit file with lots of headroom. Although a 16 bit file will hit at the same level as the same audio at 24 bit, what Mastering really wants is all of the practically bottomless footroom that 24 bit files have. By leaving a generous amount of headroom, the engineer is giving Mastering a much larger sliding scale to work with at both extremes.

Some Mastering services will specify a peak level for bounced files which could be as low as -18dBFS, however technically there’s no need to keep peaks at -18dBFS when you’re mixing. This is because the often-quoted level of -18dBFS (depending on territory) more accurately pertains to an analogue lineup level. This would accommodate much higher musical peaks without overloading analogue gear.

Loudness

Although different to headroom, loudness should still be a consideration. With the crazy levels of the loudness war behind us (referred to as “toothpaste” audio by some on the team…), virtually all pros will deliver mixes that hit at around a given loudness. While this can be an absolute spec for post mixers, music mixes can regard loudness targets as the aim rather than the rule. This is because whatever the destination, mix loudness will be compensated for - mixing to loudness makes sure that mixers are reducing (or hopefully eliminating) any unwanted downstream changes.

Some engineers will get the mix to the right loudness simply through experience; knowing how loud a given number will sound is key to this. Steve DeMott explains:

I don’t mix to a target, but my mixes tend to land in the -18/-17 LUFS naturally... That’s probably a result of my obsessive calibration of my monitoring system.

6 - Bounce Well

Once everything is in place, it’s time to commit in the correct format for the destination. This will hopefully be after any tweaks or anything after that ‘just one more thing’! If you’ve been in a project for days, weeks, or months, it can pay dividends to do the bounces to be mastered when you’re feeling fresh after some time away doing some of the best mix therapy out there: sleep.

So-called stem mastering can divide opinion, however if there is only one shot due to a deadline or other ‘hard stop’, making stems available as a backup to Mastering can be a good insurance policy if nothing else. Any alternate versions with vocals up or down for example should have already been decided on by the time the final candidate makes it to the master.

Titles’ files should be clearly named and numbered if there is to be an album sequence. Including a text file with any bounces is the standard way to detail anything that Mastering should be aware of. This could include details of fades or hidden tracks for example. If in any doubt, check with your service. Tracks can be bounced with ‘handles’ that allow Mastering to do the final topping and tailing, although machine services will need edits and fades to be in place.

On the subject of song fadeouts, the flow of the sequence is a big part of album mastering. Bouncing without fadeouts allows experienced ears to enhance the ebb and flow of an album with fades that are musical and in context with the sequence. Again, notes and communication are key.

Final Checks

Hopefully this guide has de-mystified the process of preparing mixes for Mastering. It’s true that a machine service will return masters that will include any oversights at the mixer’s end, so care is needed. That said, human mastering engineers also need quality to work with, following the well-known mantra involving what you put in and what you get out…

Do you master records? What are the things that make your life easier when receiving mixes? Are you a mixer who has ever had to re-mix or re-bounce for some reason that was picked up in Mastering? Let us know in the comments.

A Word About This Article

As the Experts team considered how we could better help the community we thought that some of you are time poor and don’t have the time to read a long article or a watch a long video. In 2023 we are going to be trying out articles that have the fast takeaway right at the start and then an opportunity to go deeper if you wish. Let us know if you like this idea in the comments.