Mastering Heavy Metal Songs: The Ultimate Guide

As an audio professional and educator, I teach mastering to my students on a daily basis based upon my experience working in mastering studios and by my own practice. It’s a topic that is often regarded as a “dark art” amongst many, and I wish to dispel that notion.

Mastering doesn’t have to be ambiguous or a “secret.” It is a crucial part of our music reaching the masses. As a co-founder of Metal Mastermind®, it is our goal to share this information and to empower independent metal artists. Learning how to produce the best music is integral for being able to stand out amongst a crowded sea of other artists and to give us a better chance of bringing home that bacon! ?

Mastering is the process of finalizing a mix and getting it ready for distribution. The term mastering has changed over the course of decades within the world of audio engineering. Many have defined it as process in which the existing mix is “enhanced” or made to become “louder.”

While these are all true, mastering is really the optimization of a mix in order to hear it in its most translatable form. This is primarily guided by two important factors: objectivity and translation.

Mastering a mix requires great attention to detail and, in heavy metal, is especially important in creating a final copy that invokes an emotional impact from the listener without ripping their heads off and garnering the song unlistenable.

• The end-result of mastering starts with a workable mix.
• It’s paramount to understand that mastering doesn’t necessarily fix the mix.
• It makes the mix more of what it already is.

This post will expand on the premise of mastering heavy metal music and what to do in order to achieve an industry standard result.

Understanding The Heavy Metal Sound

While every artist has their own voice, it is common-knowledge to discern that heavy metal relies on a couple of predictable characteristics:

• Big guitars
• Punchy drums
• Growling bass
• Aggressive vocals

These are expected to be heard in the genre with some amount of familiarity as to how they are combined, meaning no matter what you do in your music there is still an expected sonic “profile” to the industry’s heavy metal sound.

These sonic profiles are integral to the structure of heavy metal music and leaning into them allows the consumer to relate and compare your music to some of their favorite artists in their favorite genre. Dismissing the fact that your music is different and should not adhere to these standards is a mistake that will make you less relatable and ultimately hard to market.

This doesn’t mean that we should make music that’s indifferent, it just means that we need to play to the expectations of our audience. That is what it means to be “industry standard.”

The challenge with mastering heavy metal music (or any sub genre of metal) is a mixed bag: we want loud guitars, but we don’t want to lose the definition of the drums. We want to have forward vocals, but we don’t want the guitars to trample them.

We want to have big bass, but we don’t want to lose low-end focus. It’s a game of sonic averaging, and understanding translation and how our master sounds across multiple facets is a moving target.

There’s also the case of loudness:

• How loud is too loud?
• Do I need to adhere to streaming loudness standards?
• What is true peak?
• What’s the difference between a clipper and a limiter?
• We’ll answer these questions in-depth.

Our goal is to preserve the song’s integrity, energy, intensity, and dynamic range during the mastering process.

Pre-Mastering Prep

I can’t overstate this enough: mastering does not fix a broken mix. If a mastering engineer receives a mix that needs a lot of work it is in their best interest to educate the mix engineer and provide feedback in order to get the most out of a piece of music.

Typically, the mastering engineer will be thanked for their objectivity in keeping the mixing engineer in check. After all, it is their names that will be printed on the release. They want to be proud of their work, as should you!

A well-mixed metal track has a couple of distinct factors. Here are some key pointers:

• Keep your drums and vocals at similar levels. The snare and vocals should be in the front of the mix.
• Your guitars will get much louder in mastering, so don’t overhype them in the mix. Lower them in order to emphasize the transients of the drums to make them punchier.
• Saturation can make your music unlistenable. When things get loud, the upper harmonics will become harsher, rendering your mix irritating to listen to. Be subtle about it, especially on the mix buss.
• Less compression on the overall mix buss is better. Don’t lose the punchiness of those drums! You’ll be chasing your tail if you do too much on the mix buss.
• Give plenty of headroom. In a world with 24-bit (144 dB of dynamic range) and 32-bit audio (1,528 dB of dynamic range), you should leave as much headroom as you can give. Peaking at -10dBFS is a really good place to be and you really shouldn’t exceed -6 or -3 dBFS, depending on the dynamic range of the mix. I like to use the Sample Peak meter in the mixing window of Pro Tools to view this (right-click the meter and select the appropriate option).

• Pay attention to RMS. RMS is the electrical average of a mix, usually associated to roughly 70.7% of the peak average. RMS is essentially the average electrical power behind your mix and is absolutely important when gauging a mix’s true loudness (before factoring in perception, as it is with LUFS). RMS is a significant factor when determining how well speakers will handle reproducing a mix, as it is directly tied to the amount of electrical excitation you use from your amplifier. Your average levels should be between -8 dBRMS and -9 dBRMS for less dynamic metal mixes and -12 dBRMS to -9 dBRMS for more dynamic metal mixes. I like to use the RMS meter in the mixing window of Pro Tools to view this (right-click the meter and select the appropriate option).
• Perform volume automation on the mix buss! This is a pro tip to help create momentum in your music in order to deliver a bigger impact to the listener. Mastering engineers do this often, but if you’re mixing this is something you can guarantee and easily do in the mixing stage and not leave anything to chance. The less variables, the better.
• Watch your reverbs. Don’t send distorted rhythm guitars to the reverb to create “size”. It actually muddies up the mix and softens the guitars. Keep those guitars clean and tight. You should also be EQing before the reverb to control what frequencies actually get treated with reverb. This is better than EQing after the fact, since EQing before the reverb removes frequencies from ever getting excited in the first place — a cleaner approach.
• Split your bass into two signals: One filtered above 250 Hz, and the other filtered below 250 Hz. Treat the high end of the bass differently than the low end. Keep the low end cleaner to hear the fundamental notes. You can side-chain the kick drum to the low end part of the bass without destroying the volume of its growl in the mids and highs.
• Listen to your mix at low and high volumes. A great study to review is the Fletcher-Munson curves (pictured below), which shows our perspective of frequencies at different volumes. At lower levels, in order to hear low-end evenly, we have to significantly increase the volume of bass frequency content. In essence, we hear high frequencies more clearly at quieter levels while at louder levels we hear bass and high frequencies more evenly. Therefore, check the balance of your mix at lower levels to see whether or not your listening experience is prioritizing the right things (drums and vocals). At louder levels, you should be able to feel everything without irritating your ears and making sure the energy feels right. It is imperative to do this with speakers and not headphones.

Technical Aspects of Heavy Metal Mastering

Mastering is the art of finesse. There is a motto we mastering engineers live by: “do no harm.”

We try to remind ourselves of this every day because mastering is such a critical step in the production process, but many times a mastering engineer is far removed from the attachment an artist has for their work. That artist may have been working on their album for years, and if you give back something that was worse than their initial mix, you’ve completely lost all trust and respect.

This is typically why mastering engineers are usually engineers who have a great amount of experience, whether that was in mastering or any other part of the production process in order to be in a position that grants them authority over how the final product should sound.

Note: Every mastering engineer has their own workflow. The following mastering chain is just an example of one you may use or derive inspiration from, but remember that every song requires a different approach. This is not a one-size-fits-all situation.

Let’s explore a workflow together. In this example, let’s take a look at a mastering chain from top to bottom:

• Dynamic EQ: Surgical, for corrective frequency balancing. Can be adaptive in multiple ways. A great plugin for this is the Fabfilter ProQ 3, which has an infinite amount of ways to do this.
• Multi-band Compressor: Surgical, for corrective dynamic balancing. The Waves C6 is a great example.
• Mid-Side EQ: Re-balancing the mix. Great for reducing the loudness of guitars against vocals and drums. The Chandler Limited Curve Bender or SPL PassEQ is a great option here.

• Stereo Compressor: Gluing mid-side corrections. For blend and typically very clean and transparent. The SPL Iron or Millenia Twin Topology is a good choice.
• Stereo EQ: The first process in subjective sonic enhancement. Set to taste. A Manley Massive Passive is a popular choice for something like this. Tubes sound sweet.
• Stereo Compressor: For additional color and addressing the first stages of loudness. Shadow Hills’ Class A Mastering Compressor is a fantastic choice. It adds a lot of girth and toughness to metal music with its two-stage compressor system (optical and discrete) and has several options for color using a selector switch to route the signal through different metallic components, giving subtle characteristic enhancements.

• Saturator: Energy enhancer. Set to taste. The iZotope Exciter or Newfangled Audio’s Elevate are great choices here.
• Transient Designer: Re-shaping the transients of the mix. This is critical for the next phase. Oeksound’s Spiff or Eventide’s SplitEQ are exceptional choices.
• Clipper: Does the heavy lifting for chopping off peaks. Clippers are a little different than limiters. Rather than lowering the volume significantly at the threshold, clippers literally chop off the wave form. Clippers typically have a more aggressive sound, which is why we love using them for heavy metal! We use a clipper to impart less work on the maximizer towards the end. Gold Clip is one of the best clippers around. It emulates a dream mastering converter, the Lavry AD-24-200, in which mastering engineers would hit the converter hard from the analog realm into the digital realm for its magical clipping “mojo.”

• De-Esser: Tames the edginess from cutting off those peaks. Keep it focused on high-frequencies rather than the broadband signal. The Maselec MDS-2 is the industry standard, but Oeksound’s Soothe2 is phenomenal and super effective here, too.
• Reverb: Restores dynamic range and softens the transients. This should never exceed 15% on the wet/dry knob. This is a very subtle addition to the chain. Set to taste.
• Maximizer: The last squeeze to get the most out of the track in terms of loudness. Maximizers like the Waves L2 or iZotope’s Ozone Maximizer account for maximum resolution. The point is to ‘capture’ the best possible quality audio into a shorter word-length file (a smaller bit-depth) from a longer word-length file (higher resolution). The human ear uses low level (quiet) information from a high resolution file to construct a mental image of the stereo soundstage, so any compromise in this area manifests itself as a loss of spaciousness and transparency.

As you can see, a mastering chain has multiple stages. The key here is that one device/plugin does not do too much of the heavy lifting (e.g. the clipper helps out the maximizer). The purpose of this is to be able to back-track and fix any gain staging between signal processors and help the engineer in the process of A/Bing the master against the mix. ADPTR’s Metric AB is a superb tool for doing this in order to check yourself.

Dealing with High-Gain Guitars and Distorted Sounds

Distorted guitars have a way of making a mastering engineer’s life miserable. Mainly because they are so limited in dynamic range that any sort of compression drastically changes their perceived loudness. This is an opportunity for mid-side to help balance the mix.

With mid-side, we can work with volume and frequency (or compression, depending on the processor you use) in order to help rebalance the changes that we impart with our mastering chain. When you limit hard, you will bring up the sides more, making the middle parts of the mix sound quieter comparatively. Mid-side processing is better used on a bad mix, so if there’s a good mix presented then less is more.

Now, distortion from a guitar is welcome but distortion in your master is absolutely not. On the phase meter, avoid the “diamond of death”. It is the outer energy of the master. If you are getting that, then you are having a lot of distortion!

To get rid of distortion, you can use masking techniques and tools, but first check if it’s you (review your gain stages in-between signal processors). If you’re using analog, your ADC/DAC stages are super important.

Gains are always cleanest in the digital realm. You should have clean gain right before a limiter so that there’s a clean make-up gain and not an already tampered signal as you put it into the limiter. In this case, distorted guitars are primed and ready for additional distortion, so take great care when processing them. If you’re questioning whether or not you are adding unnecessary distortion, check your meters and listen quietly to help discern those higher harmonic clips where distortion is more audible.

Adding “clean distortion” to a master usually equates to the concept of saturation. Just remember that oversaturating a mix leads to an unlistenable product.

Addressing Drum Dynamics

Drums are one of the trickiest to get right in mastering, because it’s one of the tell-tale signs that we are over-compressing the stereo mix. This is where a good practice of A/Bing your master to the mix is crucial.

Part of being a great mastering engineer is to be able to A/B well. Make sure to set-up your A/B path before starting anything! A great mastering engineer compares their changes.

Two ways to A/B are:

• To have the source and mastered playback delayed by a small fraction in time to compare transient points (example: snares. The original source could be first and when that first snare hits, quickly switch to the mastered to compare the two snares.)
• Play the two at the same time and alternate between them to hear the difference in sonic qualities.

While you do this, listen for the impact from the snare. Typically, if the snare is sounding weaker it’s usually because your attack and release times on your compressor(s) need adjusting. Go through your signal chain and bypass stuff to see what’s doing that.

With kick drums, fast and intricate double bass patterns have a unique issue in heavy metal. Some kick drums can play so fast that they actually create a frequency tone rather than momentary impact.

Think about it: if a kick drum is playing sixteenth notes at 200 bpm, that’s a little less than 14 kick drum hits per second. In frequency, thats a fundamental frequency generated at 14 Hz, which make tones at higher octaves (28 Hz, 56 Hz, and 112 Hz, etc… all key frequencies for kick drums) sound like single tones rather than individual hits!

This can be dangerous for a mastering engineer, since we would essentially be exciting standing waves and imparting muddiness rather than providing clarity and punch. Filtering and multi-band compression become inseparable tools here. You can tighten up the low-end by putting a high-pass filter to take away the rumble, but beware: the tricky part is when to stop carving out bass.

This is a case for multiple speakers and headphones. Headphones are great for hearing detail and bass information, but you don’t feel the bass like you do with full-on speaker excursion. Hearing the master on different sized speakers, with and without subwoofers, on headphones… they’re all important in discerning maximum fidelity and translatability.

Use the transient designer to your advantage here. Drums are heavily transient-dependent. It is there to either soften or accentuate this information into the clipper (or limiter, should you not have a clipper) so that you have total control over the impact and punchiness of the mix.

Vocal Processing in Heavy Metal Mastering

Vocals in heavy metal are some of the most interesting parts of the genre. Ranging from luminous opera to guttural roars, they are dynamic, extreme and most of all the element that tells a story. Therefore, this is an extremely delicate part of the process that we need to give our upmost attention towards.

In the midrange is where you’ll find the most vital vocal information. It’s the difference between making a voice sound nasally, honky, thin, clear or present. I look at this like pockets in a mix. Masking is very common place here, so lowering some frequency content near and around this range can be a technique that helps give a little more clarity here.

However, this is mastering… not mixing! You should never have to jump +/- 3dB in EQ. If you do, then it’s either to help/compensate for mix errors. A decibel is a lot! That’s one decibel to everything, not just the vocals!

Mid-side can also be helpful here, but use it sparingly. For background vocals and reverbs, the sides could use a dose of high end boosting to make them more exciting, but the mid-section should be a little more relaxed, otherwise you run the risk of emphasizing sibilance too much. That being said, this is a great way to keep those trampling distorted guitars separated from any vocal EQ.

In the mastering chain is the opportunity to use reverb. This can help give more spatiality to the master, but treat it with subtlety. You don’t want to lose the impact on those drums!

Finalizing the Master

A huge aspect to mastering is the marriage between tracks. This awareness is key, because it’s going to guide you as to what limitations you may have when it comes to the processing of every track.

Remember that they all need to sound like they’re congruent. Don’t go to crazy with EQ moves on one track that make it sound out of context with the rest of the album.

Be musical about the timing between tracks. Those fade-ins/outs are incredibly important! When it comes to digital, you can always hear the drop-out, which is hard to feather or smooth out. Analog is much smoother in that way, especially with loud music! “S” curves may be the closest thing you can get to the analog fade. Many mastering engineers prize themselves on artistic fades.

A good exercise to try when you’re starting a master is once you establish the setup, and the mix is a good one, your very first thing would be to try and see how loud it can get without changing timbre. This is a good gauge to see how much work you need to actually do. Here are some other tips:

• Listen outside and see if it balances. If you hear the bass nicely, then you probably have it right.
• When playing loud, your ear physically compresses and the hair follicles become less sensitive to the high frequencies so mastering the highs at low volumes with metal music will just have you chasing your tail because when it gets loud you’ll just lower the highs again.
• Listening loudness is very important. You want to feel the music like the consumer would. Metal? They’re probably cranking it. Country? Not so much. Let that be your guide for certain EQ moves (see last bullet point).
• Analog can shave off the highs and lows every time you pass through it, and in most cases affect transient response.
• Tubes can add a bit of saturation to your program, sometimes undesirably. It can sound like high frequency ticks!
• Some gear is better at certain frequencies than others. Or… that’s just a subjective thing!
• Analog gear deals with an infinite amount of frequency ranges in both low and high. This is the reason for some noise filtering parameters on high end gear (like high cuts at 70 kHz!) this is more apparent in situations with tape and vinyl.

So how loud should you master to? This is a common question that has many different opinions. In my experience, it’s better to master as loud as you need to in order to get the best tone. There’s something to be said about how loudness shapes and affects the tonality of the music.

How hard it hits a clipper, a maximizer, or stereo compressor all has something to do with it. In short, if you’re mastering to a number, you’re doing it wrong. Master with your ears.

You’re never going to satisfy every streaming platform anyway. If they want to turn your master down, let them do that. It is the nature of the world we live in. If you’re worried about normalization, check your master with normalization tools! iZotope RX is a really valuable tool that can do that and so much more.

A tool like RX can have a significant impact on your deliverable. Converting master files into their deliverable counterparts for distribution is a step you should never overlook or take for granted. This is your final chance to perform QC (quality control)!

iZotope’s RX was designed as an audio restoration and mastering suite in order to make sure files were delivered at their best. It’s the perfect place to check intersample peaking between sample rate and codec conversions and make the final consumer-friendly formats such as MP3 or FLAC. To prevent this, we master streaming formats to -1 dBTP (True Peak).

When you convert a file, rounding errors are resynthesized and sometimes peaks that weren’t clipping in the original file end up clipping in a re-rendered file (e.g. WAV to MP3). Back in the day, when we tried burning CDs to MP3s, I used to always wonder why the MP3 had distortion in it. Well… that’s why!

Taking into account everything we’ve spoken about, here are a couple of quotes I particularly like to remember whenever I master a track. They were passed on to me when I was learning my craft:

• “Always… and you’ll never…” – Andy VanDette
• “You are the judge. Nobody tells you what to do.” – Vlado Meller
• “Not everything sounds good… write that down.” – Randy Merrill

Be honest with yourself and your client. You’re both after excellence, so have some humility during the process. It’s a hard pill to swallow when you’ve passed your master through amazing plugins and analog gear and it actually sounds worse than the mix! Remember this, too:

“It’s the ear, not the gear.”

Metal music is an exciting genre, and as a fan of it you already have some instinctual tendencies. Listen to your gut. Mastering is a fun and rewarding process that ties a pretty bow on top of a mix. Take the time to make things right, because once it’s out there that’s it!

Don’t be afraid to experiment with different mastering techniques while remaining true to the essence of heavy metal music. Remember that creating your own sound also means competing against the industry standard.

Be unique in your composition, yet recognizable in your mix’s tone. These expectations were made because they work, and not everything needs to reinvent the wheel. Look at it this way: you’re standing on the shoulders of giants!

Here on Metal Mastermind® we help metal musicians and producers find their own way through the independent metal music space. Click below to enroll in Metal Producer Overlord, a course taught be a seasoned veteran, Nic Z, on mixing and mastering this incredible genre we know and love. He provides many examples, tips and tricks, and in-depth workflow demonstrations to show you exactly how to do it.

Are you ready to elevate your skills as a mixing and mastering engineer?