Preparing For a Mastering Session

What’s every mastering engineer’s worst nightmare. Probably losing their ability to hear or their speakers not working very well. Other than those things, there’s nothing worse than receiving a “mixed” file that’s already at the point of clipping the master bus. That’s exactly what happened to me the other day. Definitely not the best way to fill an engineer with confidence that good practice has been observed in the mixing process before they get stuck into mastering your track.

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The mix was hitting -0.1 dBFS at -12.7 LUFS before any mastering processing

In the case of the track I was working on, I was able to go back to the mix engineer to see if any processing had been applied to the mix bus pre-bounce. Lo and behold, they confessed to adding mix bus compression and about 6dB of gain before they bounced the file down (the tell-tale squashed wave form was also a bit of a give-away). Problem identified, I received a new version of the mix, minus mix bus processing which was much more dynamic sounding and had the headroom I like to work with when mastering a track.

But What Is Mastering Anyway?

Great question, and one that if you asked 100 people, you’d probably get 100 different answers to. If anyone is going to give you a good response though, it’s the author of the go to text on the process of mastering – Bob Katz. In his book Mastering Audio – The Art and The Science, he opens up on the introduction with the following:

“Mastering is the last creative step in the audio production process, the bridge between mixing and replication (or distribution).”

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A nice summary, but there’s a whole lot more to it once you get in to the detail. If you’re serious about mastering and want to learn more about how it is done at the highest level, Mr Katz’s book is definitely worth a read. If you’re new to the field then it probably goes in a bit deep. Chances are for the beginners out there, you’ll be mastering in-the-box. Our recommendation for those of you who are, is to search for some tutorials that are specific to your DAW so you can familiarise yourself with the tool kit available to you. Then get some practise by using those two things on the side of your head (your ears in case you were wondering) to compare the tone and balance of professionally mastered tracks against your efforts.

Back to the matter in hand, a few pointers about how best to prepare for sending your freshly mixed track off to the mastering engineer.

Before You Bounce

Headroom

The mastering process will in almost all cases involve an element of tone shaping through the application of subtle final EQ tweaks, and loudness processing to bring the track up to the appropriate playback level for the destination medium (vinyl, CD, YouTube, Spotify etc.). To give the mastering engineering the scope to do their thing in these two areas they need headroom. In simple terms, some spare decibels on the master bus.

Digital

In the digital domain this means keeping the peak level of your mix comfortably below 0 dBFS, above which you will start to hear distortion effects creeping in due to the squaring off of the output waves. We recommend targeting values on the mix bus between -10 and -5 dBFS for mixes that are being sent for mastering. Don’t worry yourself too much about hitting that mark on the nose. If the mix sounds good and you’ve left sufficient headroom, you’re heading in the right direction.

Analogue

In the analogue world you may monitor levels using a VU meter. The level to aim for on the VU meter really depends on how you have your equipment calibrated so it’s not easy to give a definitive value. However, at standard calibration 0 dBVU = +4 dBu = 1.228 volts RMS. As a general rule of thumb this value equates to around -18 dBFS RMS in the digital domain. But again, this varies depending on the analogue to digital converter you use and how your DAW is set up.

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Understand how your VU meter has been calibrated

At standard calibration, most analogue equipment allows around 16 dB of headroom before audible clipping. So a mix that gets the needle on the meter dancing around the 0 VU mark should serve you well when you print the mix for mastering or send it into your computer for bouncing.

Beyond the Mix Bus

The headroom story doesn’t stop at the mix bus, you can extend the theory back to the individual tracks you’ve recorded as well. If you ensure that no individual track is peaking above -6 dBFS or pushes the needle on the VU meter above the 0 VU line for too long, this translate into sufficient headroom on the master bus when it comes to bouncing your track ready for mastering.

Bouncing

Don’t be Normal, Do be Consistent and Don’t Dither

That heading sounds like instructions your grandma might give you about living life to the full based on her many fun filled years of experience. Convert that to the audio world and it’s a pretty simple trio of rules to run through when you’re about to bounce a file for mastering.

The first one’s easy. If you are bouncing out of a DAW, do not normalise your track. End of story.

If you’re working in-the-box, check the sample rate and bit depth you’ve recorded at, and make sure you bounce down your file at the same rates.

Also turn off any dithering when you bounce. Leave that to the mastering engineer.

Silence is Golden

Leave a little bit of silence at the beginning and end of the audio that you send to the engineer. This gives them more scope to add fades and allow for any reverb tails to decay naturally. A couple of extra bars at the start and maybe double that at the end never hurt anyone.

Get Naked

We mean the mix bus, not you! Think of the mix engineer as the sous-chef that combines all the ingredients the artist has provided them with. They plate up the music onto the mix bus and hand it over to the head chef who does a final inspection and maybe adds a presentational sprinkle of EQ and compression to make sure the song is taken out to the restaurant in the best possible format.

For those engineers who like to mix into a compressor on the mix bus to get the tone and effect they like, that’s totally fine. There’s no harm in bouncing a version of your mix without this processing and sharing that with the mastering engineer too.

References

Following good mix and bounce discipline when preparing for mastering is one thing, but the engineer is doing nothing more than shooting in the dark unless you provide them with some guidance about where you want the track to end up.

One of the most helpful things for a mastering engineer (in our experience anyway), is receiving some pointers from the artist / producer about the style they are trying to emulate or other tracks in their genre they would like their song to compete with. Armed with this information, the mastering engineer can listen to the mix critically and make more focused processing decisions to move the finished track closer to the desired sound in terms of tone and dynamics.

If there’s an engineer with a good reputation for adding the finishing touches to songs in your genre, try and get them on board. But as is often the case with those who develop a reputation for being good in their field, the popular mastering engineers can be pricey. A good engineer should be able to dial in a competitive sounding master across a range of genres, providing they have the right references to compare their work against.

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Try to give your mastering engineer the highest quality references possible

The track I recently got to work on was in the “Latin Urban” space with “Kizomba” (a dance style originating in Angola) influences. I’d heard tracks from this genre in passing on TV and radio, but not taken the time to critically assess them for mastering purposes before. Fortunately, the artist really knew their market and sent me some great reference material (I took it as a given that anything Pharrell Williams was willing to put his name to was going to have been mixed and mastered to a pretty high standard). I also checked to see if the tracks sounded noticeably different on streaming platforms like Spotify and YouTube to see if multiple masters might be called for. From this, I was able to pick out the key features that felt would make the artist’s track stand out against the big boys.

I have a good understanding of the loudness levels I need to work towards for different playback platforms, the features I was listening out for when referencing were more to do with tone for final EQ purposes and dynamics for compression and limiting.

Final Thoughts

From what looked at the outset to be a mastering mission impossible, turned out to be a really good mastering experience, and most importantly the artist was really pleased with the result.

The moral of the story, if you’re kind to your mastering engineer by following the points above and provide them with some good quality references, you’ll end up with a much better end product.

Now get out there and make some great music, record it, mix it superbly and send it off for that final mastering sheen. Oh, and let us have a listen too!

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