Simon Gibson, mastering engineer, Abbey Road Studios

Audio mastering: inside the engineer's sonic laboratory

Mastering is the final phase for a recording before production, the last chance to fix any sonic issues. In this specialised role, what is required of mastering engineers today?

For musicians today, we appear to live in an age of boundless potential. From a time only 30 years ago, when the most portable recording tool a musician could hope for was a four-track cassette Portastudio, now anyone with a laptop, an iPad or even a smartphone can record a complete multitrack session at CD-quality bit rate and sample depth.

Your recording studio can now be anywhere: in your bedroom, in the garden, halfway up a mountain, in the back seat of your camper van – your preferred space is limited only by your imagination and accessibility. Musicians the world over are reveling in the creative freedom in being able to get their freak on any time, any place, anywhere.

However, there is still one phase of the music production process that requires - nay, demands - a room with exceptionally accurate acoustics, with some extremely expensive precision equipment on hand and with an exceptionally discerning pair of ears of the golden variety listening in: the mastering stage.

Mastering is the final phase in the production of any recorded work. It follows on from the furnace of creation that is the recording studio, and also from the moulding and shaping stage during which the recording gets mixed. Mastering is then the last-chance saloon for musicians to get everything right before the general public hears their latest magnum opus.

Whether a recording is planned for release on vinyl, CD or – as is increasingly the case - strictly as a digital download, mastering is an essential phase of the production process, covering not only the subtle sweetening and professional sheen it can add to a mix, but also important pre-production tasks for manufacturing and distribution.

As Pete Doell of Universal Mastering Studios, based in Hollywood, California, says, “Mastering certainly is more than just putting the cherry on top. Sometimes I’ve heard people compare mastering to going to your barber. They know what you like and how you like it styled and certain clients might like more bass or like a brighter sheen on their stuff. Everyone is entitled to their own little tastes and it’s certainly nice that I’m working in a room that if people have a certain predeliction towards one flavor or another that you can give it to their satisfaction right away and in a way that is accurate and musical and you’re proud to put your name on it.”

Doell has worked with dozens of internationally renowned, major-label artists, as well as with indie bands in equal measure, and he sums up the work of the mastering engineer as essentially being a two-pronged role.

“Basically you can lump it in to a couple of categories,” he says. “Let’s say everything on an album is done by the same person, there’s a uniformity as far as level and sound and all that and our mission there as far as aesthetically make everything flow and pay off musically the way that the artist desires, by making the colour, the tonal balance if you will, internally to each mix sound uniform, that there’s a flow from beginning to end of the record. You might even group songs together so they played almost like a set when you saw a live performance of a group or an artist of that kind.

Then the other thing we do is more along the lines of being important for the manufacturing work, in addition to PQ points – the start and stop points of the song, the internal timings for the CD – and also the metadata, like ISRC codes, which is a unique identifier for each and every version of a song, so when you have it in your database or your silo cloud in the sky you can tell exactly what it is, so you grab the right version of that song. It’s all about the royalties, so they can track the people who are due monies for publishing and mechanicals and all that good stuff. So in addition to the aesthetic musical concept, there’s the nuts and bolts manufacturing side of it that we also do.”

Loud and clear

Despite the aurally immersive nature of their work, it is interesting to note that often the first task of the mastering engineer when embarking on a new project is to understand the intent of the act or artist. Often, a mastering session may be attended by the musicians that made the record, in which case good old-fashioned people skills have to be at the forefront of the mastering engineer’s skill set.

Simon Gibson is a mastering engineer at Abbey Road Studios, London, and he illustrates this point: “Sometimes it’s easy and sometimes it’s incredibly fraught and one of the biggest skills you develop, if you haven’t already got it when you start, is your basic people skills: how to read people, how to communicate with them and how to know when it’s time to just put your head down and get on with it and not engage in conversation.”

Musicians that are open to polite and constructive criticism can benefit greatly from the mastering engineers expertise.

“If people are prepared to take comments on board, take some advice, then that works,” says Gibson. “Nevertheless, sometimes you just have to get on with it and work with something that’s less than perfect and you just have to do your best. With experience you know what’s going to work and what won’t and you can find a way through. You still have to try and create something finished from whatever you’re given. You can always say to a client that there are technical problems with it, which mean that if I master this it’s going to distort badly, I think you need to redo the mix and do this and resupply it. People have done that and they’ve come back and we’ve produced something in the end which they’re very happy with.

“Some people come in and don’t realise that what they’ve done will now cause problems. Often it’s down to poor quality recording chains and extra processing and they’ve layered it on to the recording or in the mix and it’s just muddied all the waters. The simpler, the cleaner, it can be from start to finish, the better the result.”

With this in mind, it is often ear-opening for clients to hear their work in a mastering studio environment. The high-precision nature of the mastering engineer’s equipment and the totally flat acoustics of the room that it sits in is often cause for revelation.

“It’s far more like a laboratory than a recording studio in that regard because it’s really not about a vibe and capturing the performance,” says Doell, who previously worked as a recording engineer before moving in to mastering. “It’s really about making the critical decisions to put it in a perspective that makes it sound finished and complete and very musical.”

When asked what is the most important piece of equipment for the work he does, Doell’s response is immediate: “The monitoring: the speakers and the room that you’re in. I am very, very blessed to be in a room that is so flat that I do not even have or even need EQ in the room. The speakers are totally a straight line from the console to the amp to the speakers. It’s so refreshing that not only myself can tell what I’m hearing right away, but my clients when they come in the room they’re not completely thrown a curveball. For so many years I would go to a mastering session for a record that I had personally mixed and you’d say to yourself, ‘Gee I hope that guy can tell what the hell he’s hearing. This doesn’t sound anything like what I remember!’ I’m very fortunate that my room here at Universal is spectacularly accurate.”

The room in question is the work of Delta H Design, utilising a technique called ZR, which stands for Zero Reflections. Doell explains the principles: “The usual acoustic treatment in any so-called professional audio room would have things to break up the sound waves so they don’t bounce around and build up in ways that cause anomalies of some kind. The way you do that is with diffusers or deflectors or absorbers or anti-parallel walls or bass traps – all those kinds of usual tricks to accommodate sound emanating from one end of the room. The technique [Delta H Designs] has got going on has a million angles in the ceiling and the walls and the net result is that my room has got to be 28-30 feet long – which is huge for a mastering room – and I’ve got people sitting at the back of the room on the couch, 20 feet behind me, and where they sit it sounds exactly the same, the colour, the image, everything, as it does where I am at the console. It’s spectacular to have clients come in and know this record sounds exactly like they remember it hearing and I’m making it sound better and we hit it out of the park the first time. You can hear exactly what is needed. Otherwise you’re perceiving problems that either don’t need fixing or need to be addressed in a whole other fashion.”

A good mastering engineer can also make it easy for themselves, as well as for their clients, by heading off potential problems right from the start. Doell and Gibson both paint a similar picture of how to approach a mastering job.

“We encourage people to come in and do a little show and tell, where they play their mixes here and we’ll discuss whether what they want is realistic in terms of the state of the mixes they’ve got,” says Doell. “We like to have them come in before they’ve wound up their mixing, so that if there is something kind of globally wrong with the room where they’re mixing that they can address that before they get to mastering and we have to spend unduly amounts of time and money and try to wrestle their mixes in to a good place.”

Gibson adopts a similar approach to understanding the music and the intentions of the artist – whether in conversation or by simply auditioning the tapes: “Everything boils down to your ears, what you’re hearing. You have to relate what you’re doing to the music. You’re listening to the music in the first instance and thinking, what’s the guy trying to say, what’s he looking for?

“With a client that comes and attends and sits in the room, obviously it’s more straightforward because you can have a chat about it. Quite often, the client will come in and simply say do what you can. A lot of people come in without really much of a clue as to what we’re able to do and are actually very surprised with what they end up with. They say, ‘Wow, I didn’t realise you could do so much’. I think that’s partly one of the dangers of mastering, in the sense that you can do an awful lot and you’ve got to sometimes exercise a little bit of caution. If it sounds good to start with, if it’s well recorded and well mixed, you shouldn’t really have to do much to it.

“What’s great is when somebody comes in and says, ‘Please tell us what we can do better’. I’ve given them some advice and they’ve come back, we’ve done another track and it sounds really good, better than the last stuff. They’ve taken on board stuff I said and they’ve changed the way they’ve recorded something and it’s had results. It’s a two-way process. That’s benefited both of us: it’s helped me in the mastering and it’s now helping them plan and make their recordings more successfully.”

The laboratory precision of the mastering studio is always a highly revealing environment in which to hear recorded music, a forensic examination that can cut both ways, elation and despair, as Doell dryly observes: “Sometimes you see people when they hear the first couple notes of their music, their face lights up and they go, ‘Man, that sounds just like I hear it at home!’ Sometimes you see them sink into the couch, and think, ‘Holy shit! It doesn’t sound like this at my place.’ It’s the whole, horrible truth!”

The loudness wars

One thorny issue in making records today that frequently crops up during the mastering phase is how loud a client wants the final result to be. In the eternal quest to have more impact than any of one’s competition, there has been a creeping arms race of loudness, as bands and record labels seek to squeeze every last decibel out their releases.

Ignoring the fact that virtually every radio and TV station in the world will apply further limiting for broadcast, thus compounding the problem of a sound already lacking in dynamics, there has been constant pressure on mastering engineers to go “one louder”. The net result is typically a near-solid wall of black when studying the overcompressed waveform of a typical “hot” modern production. The results can be so extreme, and so fatiguing to listen to, that listeners often find a whole album tiring to listen to.

One recent example of this is where fans of the rock group Metallica eventually started an online campaign to have the group’s recent album, Death Magnetic, remixed or remastered because it was considered that the aggressive nature of the album’s production was adversely affecting audio quality. To make matters worse, many fans also thought the Death Magnetic tracks included in the video game Guitar Hero offered superior audio quality over the standard CD. The online petition has attracted over 13,000 signatures.

Fortunately, engineers in the industry have long been aware of the diminishing returns in continuing to engage in “the loudness wars” and at the recent Audio Engineering Society (AES) conference in New York, a consensus was acknowledged amongst the producing and mastering community that the practice of slamming every mix as loud as possible was ultimately killing the music.

As Gibson points out, there is a requirement to make records sound exciting – just as there has always been – but that it’s all in context and is highly dependent on the quality of the mix.

“If it’s pop or rock, you’re probably looking to make it “hot enough” to have some impact on the radio or CD and it’s a question then of how far you want to go,” he says. “Of course you can make things absolutely full-blast in your face, but depending on how well it’s been recorded in the first place, that might not benefit the final recording.”

Considering the question of “the loudness wars”, Gibson remains skeptical that they’ll ever be completely over: “Because the technology’s there to allow anyone to just turn up the wick and compress things and make things as hard as possible, people will do it. With great respect, people perhaps don’t realise that just because you can doesn’t mean you should.

“When you overcook something like that, it really takes all the life out of the recording. For me, if somebody has spent a long time recording and mixing something and getting it sound really pretty good, it would be a criminal act to screw all that up just for the sake of getting something to be really really loud. If the recording has got something to say, let it say it. Don’t ruin it in the process.”

On the other side of the Atlantic, serving one of the major music markets in the world – the US record-buying public – Doell faces similar challenges.

“As you know, we’ve been suffering under the auspices of the “loudness wars” where every record has to be louder than the last thing you heard on the radio,” he says. “I’m happy to say that all that promulgation of listener fatigue by making stuff louder than loud, there’s a big trend to finally reverse that, to put the emotion back in music and take all the flatness out of the records we make these days. I can’t tell you how many times I master a record and they say, “Man this sounds great… Can I have it 2dB louder, please?”

A lot of the time, Doell perceives the demand for mastering as a result of a related shift in the recording industry.

“Because studios have been dying on the vine over the last bunch of years, and professional recording engineers as well, a lot more amateur stuff that is less professional or polished type of product comes our way and it’s much more often the job of the mastering engineer to “save the patient”, as opposed to just putting a little bit of window dressing on it. A lot more products need mastering in a way they didn’t before,” he says.

“Some of it is just metering and ways to know where the energy is and what frequency bands and for how long it exists so that you can get stuff to be apparently loud that isn’t so in your face from beginning to end and is much more musically dynamic.

“A lot of classical records and orchestral stuff for film and TV really don’t require the same type of dynamic reining in that pop and rock’n’roll records do. You might find - if you’re lucky - a 5dB dynamic range on any modern pop or rock’n’roll record. In classical stuff, even film score stuff, from pianissimo to fortissimo might be 40-50dB. We try to make it more like 20 or 25dB from the quietest to the loudest passages in mastering a classical or symphonic kind of record or film score. We try to let it have quite a bit of breathing room.

“Music should be medicine, right? It should make you feel good.”

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