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What Is Mastering and Why You Need It (or Don’t!)

What Is Mastering and Why You Need It (or Don’t!)

What is mastering?

Most people understand what mixing music is, but a lot less understand what mastering is and how it is different from mixing. I’ll start by saying mastering is very different from mixing. Mixing involves balancing all the individual elements in a song and ensures each element has its own space. These decisions are finalized and the mix is exported. Mastering takes this mix and enhances it by adjusting EQ, dynamics, stereo width, and volume. The album is then exported in the right audio formats for distribution. The purpose of mastering can be summarized as:

Mastering sweetens the audio of the final mixes and prepares the songs for reproduction and distribution.

Is it really that simple? 

Yes and no. There are a number of very important details that go into this mysterious process. Let’s quickly discuss what mastering originally was and what it consists of today.

The History of Mastering

In the early 1900’s, audio recording and mastering was essentially the same. Audio was recorded by playing instruments or singing next to an acoustic horn, which caused a diaphragm to vibrate. These vibrations were transferred to a cutting head that cut grooves directly into a disc, known as the master disc, which contained the audio. Magnetic tape was invented in the late 1940’s and made it possible to make master discs separately from the a live performance. The person in charge of transferring the audio from the magnetic tapes to the vinyl cutting machine was called the transfer engineer. This was the earliest form of what is now known as a mastering engineer.

Transferring audio from tape to disc was a difficult job! Sending a low level to the cutting machine resulted in a noisy vinyl disc, but too loud of a level could damage the disc or break the cutting lathe. It wasn’t long before record companies discovered that the loudest records sounded the best to customers. Transfer engineers learned that by manipulating the frequency and dynamics of the master recordings on the magnetic tape, a louder and better sounding record could be made. This increased the sales of records and established the need for separate mixing and mastering engineers. Thus the mastering engineer was born!

An Edison phonograph used to record audio in the early 1900’s. Source:

Most of these principles apply today, but with one huge distinction – we live in a primarily digital age where the limitations of a physical disc are less and less important. This provides us with more freedom to master audio in ways that were impossible in the past.


The Modern Mastering Process

As we mentioned earlier, mastering is the final step in the recording process. The final mix supplied by the mixing engineer is exported as a single file and sent to the mastering engineer. The mastering engineer adjusts the audio to sound great across all playback platforms (e.g. in your car, earbuds, club, or phone). The clarity and power of the audio is enhanced by controlling the dynamics and frequency balance. Mastering engineers also increase the sense of space and cohesion between the instruments by “gluing” or “gelling” the mix together. The volume is then increased to be competitive with modern music standards. Lastly, artist information or metadata is added to the digital files. If the album will be reproduced as a physical CD, a disc description protocol or DDP is usually made, which is essentially a virtual CD.

Modern mastering must now consider the multiple online streaming platforms when finalizing the masters. Conversion of high-resolution audio to lower quality “streamable” formats can introduce unpleasant sounding clipping and artifacts. Some mastering studios address this problem by making multiple masters specifically tuned for each playback medium. For example, separate masters can be made when submitting audio to Apple’s “Mastered for iTunes”, YouTube, Spotify and SoundCloud. All these platforms have different requirements and process the audio differently.


The main goal of mastering is to provide you with audio files that are pleasing to listen to and ready for distribution. This includes re-sampling and dithering audio to the correct bit-depth, indexing tracks, and for CD replication, adding PQ and other necessary codes to DDPs. To be competitive with currently released music, you can expect your masters to be louder, wider, bigger, and more powerful versions of your mix. They should also be enjoyable to listen to on multiple playback systems. Mastering also makes each song sound similar and more consistent on an album.


Think of mastering as quality control. The mastering engineer is the final stop before releasing your music. Usually, mastering is performed by someone not involved in the creation of the music, giving them a truly objective view of the songs in terms of instrumentation balance and the EQ curve of the mix. They are able to identify problems that were unnoticed during mixing because mastering engineers can react to the music as a whole instead of each element.

The mastering engineers increase the loudness of the track by compressing, limiting, or clipping the audio to a competitive level that will sound great on any playback system. Once these sonic adjustments have been perfected, the mastering engineer will export the audio to the correct format and apply dithering to minimize audio artifacts from the conversion process. Artist information (or metadata) for each track is added to the files if supported (e.g. .MP3s and .FLAC). The metadata also includes the international standard recording code, or ISRC. An ISRC is used to identify the specific recording, making it easy to prove you own the recording and simplify the royalty collection process for that recording. Lastly, depending on the distribution, different masters should be prepared based on the specifications requested by the audio platform (Soundcloud, iTunes, Spotify, etc.). This ensures the final master won’t clip when converted to their streaming format.


  • Flat or dull sounding mixes
  • Disconnected or highly separated instrumentation
  • Small stereo width or space
  • Noisey audio and clicks or pops
  • Low volume
  • Inconsistencies between tracks on an album


  • Poorly sung vocals
  • Out of time instruments or out of pitch notes
  • Poorly recorded instruments – they will sound even more poorly recorded after mastering!
  • Song dynamics if already heavily clipped, limited, or compressed


I hope this article demystified the dark art of mastering audio. I want to reiterate some of the most important take away points from this article. Mastering and mixing are very different. Mixing balances the individual elements of the mix and fits each instrument into its own sonic space.  Mastering enhances the mix by sweetening the audio, increasing the volume, and adding metadata to the audio files to identify the song ownership.

The mastering engineer is essentially quality control before your songs are released to the world. They make sure the songs all sound similar and coherent. Any problematic sonic issues are adjusted to make the audio as pleasing to listen to as possible. Mastering also provide you with a distributable version of your songs that are optimized for the platforms you plan to release your music on (iTunes, Soundcloud, physical CDs, etc.).

Mastering will have the greatest impact on well mixed and recorded songs so your results will vary. Remember, mastering engineers cannot perform miracles (even if they say they can)! Mastering can’t take a poorly recorded album and make it sound like it was recorded in a multi-million dollar studio – not even the best in the world can do this. Mastering a poorly recorded or mixed song might not make financial sense because the changes to the audio won’t sound better, but just different. If you can’t decide if your song should be mastered or not, call or e-mail a mastering engineer and ask for their opinion. Many will provide a free mastering sample – which will give you a chance to decide for yourself.

Do you master your own songs? Let us know in the comments below!

About The Author

Bobby Balow

I'm an audio enthusiast, entrepreneur, and owner of Raytown Productions – an online mixing, mastering, and production studio. I love challenging artists and musicians to create art that is honest and resonates with others.

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