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Making Metal: How to Master Metal with Ian Shepherd

September 4, 2019
Ian Shephard, photo by Mike Banks

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Mastering metal is tough.

In fact, I'd probably go so far as to say it's one of the most challenging genres to get truly great results in. It is certainly possible though.

My name is Ian Shepherd and I’ve been a professional mastering engineer for over 25 years. I run the Production Advice website and The Mastering Show podcast, where I try and help other people get great results mastering their music. I’ve worked on a seriously diverse range of metal over the years, from bands like Darkthrone, Anathema and Cradle of Filth, through to Deep Purple, Anthrax and Porcupine Tree.

If you’re struggling to master your own metal mixes, consider these tips and tricks to help you sound loud without being turned down, balance your EQ, and achieve a great master.

Why is mastering metal difficult?

There are several factors—here are three of the most important:

1. It needs to sound loud

You might be thinking that this applies to every genre, but metal often has very dense arrangements, which can be particularly challenging to get working at very high levels. 

2. Metal is incredibly diverse

The sheer quantity of different sub-genres and "cores" of metal can be bewildering. The ultimate goal can be different in every one. Dense or dynamic, clean or distorted? Current trends in metal mastering cover all these extremes—and everything in-between.

3. Online streaming keeps moving the goalposts

The louder you master your metal, the more it's likely to be turned back down by YouTube, Spotify, TIDAL, and the rest. Loudness has a crucial impact on the way things sound to us, so this is another factor that needs to be considered when mastering metal in the 21st century.

All this can sound pretty daunting, but thankfully there's a common thread running through all these points—and the tools you need to achieve the results you're looking for are more affordable than ever.

No matter the genre, you need a high-quality, accurate monitoring and listening environment for mastering, plus some time and space after mixing to help you get a clearer perspective. Having said that, let's look at each point in more detail.

1. Metal loudness—hitting the wall

It almost seems too obvious to say, but metal needs to sound loud. And that's not just a case of slamming everything through a really good limiter. Don't get me wrong, that will lift the level, but there's far more to sounding loud than just raw LUFS—I'll talk more about this later.

In particular, metal often has very dense textures, typically including real instruments—vocals, guitars, bass, and acoustic drums. Often all those instruments play at the same time, and all playing loud. This makes for a classic "wall of sound" texture, which can be one of the hardest things to get sounding loud, because loudness is all about contrast. Without quiet, there can be no loud. And when the elements of the "wall" are heavy guitar riffs, pounding bass, thrashing cymbals and searing vocals, there's even less room to maneuver. All these sounds have a wide frequency spectrum, and often overlap with each other.

For me, the key to making this work is achieving enough clarity and separation between the elements, while keeping them glued together. The very best approach is via a great arrangement and mix, of course, but even so, there's plenty we can do to enhance this in mastering.

The golden rule—optimal EQ

Probably the most important factor is a great overall EQ balance. In metal there’s often already a lot of distortion and "flavor" in the sound already, so for me, the EQ typically requires precision and detail, rather than "character"—the Digital Surgical Mode in Ozone's EQ is ideal for achieving this kind of result. 

The goal when the music is going full tilt is to achieve a balanced response across the entire frequency spectrum, without "hot spot" build-ups or under-represented frequencies. Listen for these and identify them—Ozone's built-in frequency meter is ideal for this, although you may want to increase the averaging time in the Spectrum Settings to help get a slower response than the realtime default. This makes it easier to see the big picture without being distracted by sudden changes, and usually gentle, broad boosts and cuts will give the best results.

Be prepared to experiment with tiny tweaks as well, though—something that still surprises me about mastering is how a small change over the whole mix can transform the apparent details. Maybe a small reduction to tame harshness in the upper mids of a vocal, say, or a narrow boost in the low mids to add extra weight to the snare. This can be especially true in a dense metal “wall of sound” master.

Living on the edge

Using mid/side processing can be an extremely powerful strategy in metal mastering. Often guitars are panned hard left and right for example, so it's possible to add extra muscle by boosting the low mids only in the side signal, without cluttering the vocal or bass sound in the center. Or, perhaps there's a build-up in the snare, and precisely cutting it in the mid signal only can help reduce this, without affecting the warmth of the synth pads or guitar tones near the edge of the image. 

Again, Ozone's EQ makes these kind of adjustments straightforward—take care not to get carried away though, as too much mid/side EQ can quickly cause very unnatural results.

Compression or Limiting? Know the difference and choose wisely

First things first, achieving high loudness is not just about heavy limiting. Limiting and compression are actually both the same thing, in fact, a limiter is just a compressor with very high ratio. Often limiters also have very fast attack and release times too, especially digital mastering limiters as opposed to analogue “character” limiters or their plug-in emulations.

All this means that limiters are typically very good at almost invisible control of extremely fast transient details, but much too aggressive for the musical “body” of the sound. Compression can help shape the tone, add density, and “glue” the sound together, but probably won’t catch the fast transients effectively enough to prevent clipping. Whereas limiting will ruthlessly control the transients, but if it starts cutting into the musical tone of the sound you’ll probably end up with distortion or wild pumping.

This is a crucial distinction, especially when you’re mastering metal. Heavily pumping or distorted results might be a valid creative choice for sound design and mixing, but my goal in mastering is to be “invisible”—to get the best possible results without anyone knowing how it happened, so artefacts like this aren’t acceptable unless the client asked for them. 

The solution in my experience is to use a little of both. Share the load between the compressor and the limiter, so that neither is working too hard. This approach with a balanced EQ is highly effective at achieving higher levels with minimal side-effects.

2. Know your genre and metal "core" when mastering

The metal scene is incredibly rich and diverse. Mainstream metal is typically cleaner and more melodic, whereas doom metal is often far slower and more atmospheric. Technical genres favor super-precise, accomplished musicianship, whereas the exact opposite might be true for a Black Metal band, and so on. Dealing with this kind of variety can be a real challenge in mastering!

To a large extent, you can take your cues from the material, but it can also be invaluable to choose suitable reference songs. When you do, make sure you balance the LUFS loudness before making any comparisons—again, I'll talk about this more in the final section of this article.

Even with references, it can be tricky to get the balance right with tracks that are "meant to sound bad." My own approach is to retain as much of the original character as possible, but control anything that might affect the way the material translates. So for example, there's a point where intense upper mid-range in the guitar sound goes from being aggressive to simply painful on any playback system—I want my masters to be on the right side of that line!

Clean or dirty? The delicate, dangerous delights of distortion (Is that you, Trash 2?)

Distortion is a crucial element in almost all metal. Even the most precise technical genres can be aggressively distorted, whereas some mainstream or progressive metal can sound exceptionally clean and clear.

Maybe the most important point to make is that distortion doesn't have to depend on loudness. A limiter like the one in Ozone's Maximizer can achieve fearsome LUFS levels without distortion, if that's what's called for, but creative use of the Exciter module can give you incredibly detailed control over exactly how much crunch, fuzz, or grit you choose to add to the sound, and still retain plenty of dynamics. This is a more flexible, powerful approach, in my opinion.

Low effect percentages in selected bands

Something I particularly like about the Ozone Exciter is its multiband capability, and the option to blend in the exact percentage of the effect in each band that I like. Often even very low percentages can make an invaluable difference. Adding Ozone’s mid/side capability to this makes it even more powerful. So, for example, I can choose to add bite to the upper mids of the vocal while keeping the guitars clean, by choosing to blend in some distortion in the 2–5 kHz region for the mid signal only—or vice versa!

As always, take care with this type of processing, it's easy to go over the top—the example above will also probably affect the snare and upper registers of the bass, plus any centrally panned guitars. But the ability to shape the level of aggression in the sound in this way, without thrashing the overall level, is really liberating if you haven't tried it before. 

One important point is to always enable the over-sampling option in the Exciter if you're planning to use it at 48 kHz or lower—unless aggressive digital hash is the effect you're going for, that is!

3. Online loudness: sounding loud without being turned down 

The topic of loudness keeps coming up in mastering, and that's because it is fundamental to the way we hear sound (psychoacoustics!). Simply turning something up, even by a small amount, can make it sound more exciting to most listeners, even though nothing else in the sound has changed.

So, louder is always better, right? Well, yes—and no. 

Beyond a certain point there are inevitable compromises to achieving super-high LUFS levels, that might even make your music sound less exciting. The higher you push the LUFS, the less room the music has to breathe, and the harder it becomes to maintain clarity, space, depth, and impact.

This is especially important since so many people are listening online these days. Most major streaming services have been using loudness normalization for years now—turning songs with the highest loudness down to prevent users from being "blasted" by sudden changes in level—and Amazon Music recently made the move, too.

You've probably heard about this already, but watch out—it doesn’t mean that these are “targets” we need to “aim” for . That approach doesn't make musical sense (why would an acoustic ballad want to be as loud as a Thrash Metal track?) and it also isn't 100% effective because of the different ways each platform measures and adjusts loudness. That’s OK though—streaming platforms will balance the loudness for us, and that’s a good thing, because it means we can concentrate on achieving the perfect musical balance instead.

The best loudness strategy for mastering 

So how do you do that, exactly? My first suggestion is to start using LUFS monitoring—in Ozone you can enable this by going to the I/O Options and changing the Type from RMS to Short-Term. Then keep an eye on the LUFS levels, and avoid going higher than -9 LUFS at the loudest moments. Everything else can be balanced musically in comparison. 

What do I mean by that? In a nutshell, use automation. If the verses seem to lose energy or lack intensity in comparison to the chorus, don't push the whole song up and risk crushing the loudest moments too much—automate the level of the quieter moments up a little instead, prior to the Dynamics module. If there isn't enough contrast, reduce their level slightly. Of course, in an ideal world, the mix will be perfect and not need this kind of tweak, but in practise it's a highly effective way to achieve the energy and consistency you're looking for, without having to keep pushing the overall levels up and up.

Is this really loud enough?

The level I’m suggesting is conservative by modern mastering standards—many current releases push up to -6 LUFS or even higher—but then they immediately get turned down 5 or 6 dB by all the online streaming platforms! This doesn't necessarily matter if it still sounds good to you, but in my experience following the -9 Short-Term guideline, combined with a balanced EQ response as I described above, allows you to get the best of both worlds. Achieve all the aggression and intensity you need using the Dynamics and Exciter modules, and take full advantage of the peak headroom available online.

You may have read that some genres “need” higher levels to get “the right sound,” but in my experience this simply isn’t true, even in genres like metal or EDM. If you do decide to push ahead with higher LUFS levels though, the most important thing is to check how the result sounds once it’s been normalized. This is easy to do using the Insight meter, or by temporarily changing Ozone’s I/O Option Type to "Integrated." Simply adjust the playback loudness of your song after mastering and adjust all reference tracks to -14 LUFS Integrated before comparing to get an idea of how they’ll sound when normalized by TIDAL, for example. 

And whatever you do, make sure you enable the "Gain Match" icon in Ozone's Bypass section so you can preview all its mastering processing without being fooled by any change in loudness it causes!

Summary

Mastering metal is tough. You need the right reference tracks for the style of music, loudness-matched for a fair comparison; plus you need a great EQ and the perfect balance of loudness, dynamics, and distortion to achieve the power and aggression you're looking for without squashing all the life out of the sound. There's incredible variety out there—some metal releases are among the most dynamic masters you'll hear these days, others are limited to within an inch of their life, and only you can decide what's best for the material you’re working on.

But mastering metal is also incredibly rewarding. The satisfaction when you get it right and achieve the results you're looking for, taking a mix from good to great, or even great to outstanding, is second to none. Hopefully, something in this article will help you get closer to that goal!

 

Featured photo by Mike Banks

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