Ever wondered what happens behind-the-scenes to make your favorite songs sound so good? The answer lies in the art of mixing and mastering.

But what is mastering, exactly? It’s the final touch in the music production process that takes your tracks from raw to refined. This might seem like an intimidating part of the music production process to understand – which is why we’re breaking down mastering into its component parts! By the end of this, you won’t only understand what it means to master a song, you might even want to try it yourself.

Mastering, defined

So, what is mastering in music? This process is often defined as the ultimate quality-control measure before your music is released into the world. Anything from a single song to a full album can and should be mastered to reach its full potential.

Mastering engineers typically work with the stereo mixdowns of your songs, ironing out any imperfections, and ensuring they shine on any playback system.

Contrary to popular belief, it isn’t just about using fancy equipment to sweeten your material. In reality, it’s a complex process involving several important steps. Think correcting audio errors (like digital artifacts, clicks and pops), sequencing the songs into a working track order, and adding important metadata.

The benefits of mastering

Exploring the question of “What is mastering in music?” unveils a multitude of benefits for the artist and their creations. When a song is properly mastered, it will sound as close to perfection as it possibly can. Each song on an album needs to stand on its own, but it also needs to seamlessly fit within the flow of your overall project.

For instance, track 3 in a five-song EP needs to sound amazing in relation to tracks 1, 2, 4, and 5. But it’ll also need to sound perfect when compared to other songs in similar genres. This means if your song gets featured on a hyperpop playlist on Spotify, it should sound right at home.

Without mastering, your song will be kneecapped, as glitches can sneak into the mix during production, and even the most attentive mixing engineer might miss them. Especially if they’re churning out products in imperfect monitoring environments. A real mastering engineer will have a fantastic room, tailored to ensure translation across all media playback systems – from laptop speakers to high-end sound systems.

They’ll be able to catch imperfections, and ensure that every note, every beat, and every instrument is optimized for maximum impact. Plus, with metadata embedded in your songs, you can easily track your sales and ensure you receive the recognition and compensation you deserve.

Examples of mastering: Before and after

Let’s show you the incredible transformation that mastering can get you. Here’s an excerpt of a mix from Pete Mancini’s live album Alive in Patchogue:

Now, compare it to the final master:

The first thing you’ll notice is that the master is louder. But that’s a red herring: in an A/B comparison, the louder mix always wins. We’ll need to hear both examples at the same volume.

So here’s the mix again:

Here’s the master, level-matched to the original:

Can you hear the difference? The mastered version balances out the mix, allowing each instrument to shine with clarity. It also improves the depth and width of the soundstage, allowing the vocal to shimmer over the top of everything.

Sometimes a master will sound like someone took a blanket off the mix. Other times, the master will sound exactly like the original – because if the mix is already perfect, it doesn’t need more processing.

How to master a song

The process of mastering can be broken down into five essential steps: audio processing, editing/sequencing, metadata implementation, exporting, and quality-checking. Let’s dive into each of these stages.

1. Audio processing

Mastering engineers often apply stereo processing to the whole mix. This is where the fun begins! In this part of the process, masering engineers employ a variety of tools, like equalizers, compressors, and limiters, to help a song reach its full potential.

The equalizer balances the frequency content of the song to show it off in the best light. If the song has excessive bass that doesn’t align with the genre, the mastering engineer skillfully reduces those offending low frequencies. Similarly, if there are any irritating resonances, the engineer adeptly removes them as transparently as possible.

The compressor manipulates the dynamic range of the whole song. This can serve various purposes. If a tune requires more punch and aggression, a compressor can provide this in spades. If the instruments need to gel together more harmoniously, a compressor can achieve this objective.

To prevent distortion on a listener’s playback device, mastering engineers typically place a limiter at the end of the chain. Analog or digital playback systems share a common limitation: their capacity to handle volume without distortion is limited. The limiter is specifically designed to minimize distortion while allowing the song to reach the desired loudness.

Of course, mastering engineers use other tools like stereo-image manipulators, spectral editors, clippers, and more. Each of these tools could warrant a whole article or book dedicated to its usage in the mastering process. However, the equalizer, compressor, and limiter form the core of mastering, and they are undeniably the most enjoyable aspects of the craft.

2. Editing/sequencing

Say you’re mastering an EP or a full-length album. Your job as the mastering engineer is to ensure a seamless flow between songs.

You begin by setting up the right markers in your DAW that will define the start and end point of the songs upon export. This also entails skilfully applying fades that ensure the track emerges from silence and dissolves without any audible digital artifacts like clicks or pops.

If one song segues into another, you ensure the transition flows without any faults or failures. Should the proposed track order of the record not flow, it’s your duty to let the client know.

Sequencing can be approached at the beginning of the process or after the audio processing phase. Every engineer has their own preferred approach.

3. Metadata implementation

Songs have to be labeled by song title, album name, artist name, and more. If the song is intended for commercial release, the tune usually requires an ISRC code to help track its distribution. The client gives the mastering engineer the code, and it’s incorporated into the song’s data. In some cases, a UPC (Universal Product Code) is embedded to monitor album sales.

This might not sound particularly exciting, but it’s a sacrosanct part of the work. Mess this up, and the artist will not be able to track their songs – which means they won’t get paid!

It’s worth noting that most DAWs don’t provide you with the option to input metadata. Specialized mastering software is used to handle this specific task

4. The export

In this phase, the engineer exports the material into the desired file format. They create files for the CD plant (called a DDP file), individual files for streaming, high-res files, or any other format requested by the client.

All of these files are either encoded with metadata, or carry digital directions to the CD plant for the embedding of metadata within each track.

5. The quality check

When all is said and done, all is not said and done. The mastering engineer must still listen to the final files to catch any mistakes. This is called the QC – also known as the quality check, or quality control.

Only when this QC process is finished can the final files be confidently sent to the client. If any mistakes or issues are discovered, you have to go back and check your work from the top.

How would mastering fit into your workflow?

Now that we’ve uncovered the mystery of “What is mastering?” and witnessed its transformative magic on mixes, let’s explore how to make it an integral part of your workflow. Mastering should be done after the song, EP, or album is mixed. If you’re mastering your own material, you ought to wait until you’re positive that all the mixing is done.

Approach the process with a ruthless and intelligent mind. Allow time to pass between the mixing stage and the mastering stage, so you can develop a fresh perspective on the material.

It’s beneficial to have a full-range monitoring system that you trust completely. Mastering engineers pay upwards of $15,000 for the typical monitoring system. You might be able to get by on a pair of exceedingly good headphones, but you’d have to have intimate familiarity with how these headphones translate to stereo systems in the real world.

AI mastering vs. the human touch

You might have heard of AI mastering, where a computerized algorithm processes your mix to enhance its sound quality.

AI mastering has evolved into a distinct industry. Essentially, you provide your mix to a website, and their proprietary algorithm analyzes the material. It then attempts to deliver a product that’s ready for commercial release.

AI mastering has sparked some controversy among professional engineers, but it doesn’t necessarily have to be so. AI cannot fully supplant a human mastering engineer. It lacks the ability to sequence your record, discern errors like clicks and pops from musical materia, tag tracks with metadata, and export them in the required formats for various distributors. It cannot operate a lathe for vinyl releases either.

All AI mastering can do is apply stereo processing to your track, based on what it detects, and what the applicable genre usually calls for. It’s worth noting that if you run an AI-mastered track back through the same AI algorithm, it will churn out a second master on top of the first. Unlike a well-trained human, it won’t know when to stop.

That’s not to say AI mastering is without merit. It can still churn out a respectable result on a single song, given the right mix. In essence, it serves as an excellent tool for both mixing and mastering engineers to learn from.

If you run your mix through AI mastering and find it doesn’t match up to the competition, there may be balance or dynamics issues within your song that need to be addressed at the mix level. Knowing this can help you work backward to fix the problem.

Likewise, if you want to learn more about mastering, AI can serve as a great benchmark. Master your mix, and then compare it to the AI-mastered version. If the algorithm outperforms you, determine why and adjust your approach for further attempts.

How to use BandLab to master your track

If you haven’t heard, BandLab offers a free online mastering service that makes mastering your music a cinch. Unlike AI mastering, which relies on algorithms and data, this service enhances your mix with expertly-crafted presets developed in collaboration with Grammy-winning multi-Platinum artists.

Trying your hand at mastering for the first time? Watch this in-depth tutorial to master the basics, and follow the step-by-step instructions below to give it a go!

To start, simply drag and drop your track into the space provided.

Drag and drop your track into the BandLab Mastering tool to use it.

Once your file is uploaded on the platform, you can choose from four presets – Universal, Fire, Clarity, and Tape – to instantly enhance your track’s audio. This offers a quick and convenient way to prepare your for playback on all platforms. And the cherry on top? It can polish the audio quality in your videos as well.

BandLab's AI mastering tool will generate a few different options for processing your track.

Once you like what you hear, download the track! The results sound impressive, and the best part is it’s free and quick.

Here’s an example of a song we previously used, only this time it’s been processed by BandLab:

How does it compare to a human mastering engineer? You be the judge.

Now that you’ve got a better idea of what is mastering in music, don’t be afraid to go forth, explore, and experiment on your own!

About the author

Nick Messitte is a New York-based writer, mastering engineer, mixing engineer, post engineer, composer, producer, musician, and weapons-grade plutonium smuggler.