Mastering is the final step of audio post-production. The purpose of mastering is to balance sonic elements of a stereo mix and optimize playback across all systems and media formats. Traditionally, mastering is done using tools like equalization, compression, limiting and stereo enhancement.
Think of mastering as the glue, varnish and polish that optimizes playback quality on all devices — from tiny iPhone speakers to massive dance club sound systems. Mastering bridges the gap between artist and consumer. The term itself comes from the idea of a master copy. All copies or duplications of the audio come from the master. These copies can be distributed on multiple formats like vinyl, CD’s or Tape, and streaming services like Spotify, iTunes and SoundCloud. Additionally, mastering allows for restoration of hisses, clicks or small mistakes missed in the final mix. Mastering also ensures uniformity and consistency of sound between multiple tracks on an album. Ultimately, what mastering does is create a clean and cohesive feeling across all your audio.
The goal of mastering is to ensure that your audio will sound the best it can on all platforms. Music has never been consumed on more formats and devices than today. Even if you are recording and mixing in a million dollar studio, or recording in less than ideal conditions, you still need the final quality check of mastering. This ensures that your sound will be heard the way you intended it to be.
A good mastering job makes an album consistent and balanced across all tracks. Without mastering, individual tracks can sound disjointed in relation to each other.
Though mixing and mastering do share similar techniques and tools, and are often confused, the two are indeed different. Mixing typically refers to a multitrack recording, whereas mastering is the final polish of a mixdown. Think of it this way:
Mixing is all about getting individual parts or instruments to work as a song. Think of it like building a car. All the parts of the car need to come together for it to run properly. The mixdown process is all about making sure all the parts are in place.
A good mix should easily flow into the mastering process. Check out this helpful post on how to prepare your tracks for mastering.
Now think of mastering like the best carwash ever. You want your new car to look as slick and shiny as possible. Mastering polishes everything to a perfect shine. It puts gas in the tank and oils up all the moving parts for the best possible performance.
In 1948 the first true mastering engineers were born. Due to the magnetic tape recorder changing the recording game. Before this, there was no master copy as records were recorded directly to 10-inch vinyl.
In 1957, the stereo vinyl record came onto the market. Mastering engineers began to apply techniques to make records louder. Loudness led to better radio playback and higher record sales. This marked the birth of the Loudness Wars that still go on today.
In 1982 The CD revolutionized mastering. Clunky vinyl masters were replaced by digital CD’s, although many of the analog tools stayed the same. That changed in 1989 when the first DAW, with mastering software, offered a mind-blowing alternative to the process.
Mastering is a complex process. Here are techniques involved:
This step fixes any hiccups in the original mix like unwanted clicks, pops or hisses. It also helps to fix small mistakes that stand out when un-mastered audio is amplified.
Stereo enhancement deals with the spatial balance (left to right) of your audio. Done right, stereo enhancement widens your mix, helping it sound bigger. It can also help tighten your center image by focusing the low-end.
EQing corrects any spectral imbalances and enhances elements that need to stand out. An ideal master is well-balanced and proportional. This means no specific frequency range is left sticking out. A balanced piece of audio will sound good on any playback system.
It's a bit like photography, you can make the sky bluer, the greens greener.
Compression corrects and enhances the dynamic range of your mix and keeps louder signals in check while bringing up quieter parts. This process gives the overall audio a better uniformity and feel. Compression helps glue together parts that might not be as cohesive as they could be.
The last process in the mastering chain is usually a special type of compressor called a limiter. Limiters set appropriate overall loudness and creates a peak ceiling. Limiting makes the track competitively loud without allowing any clipping that can lead to distortion.
Sample rate conversion or dither is dependent on the final output medium. For example, if you are planning to release on CD you will have to convert to 44.1kHz 16 bit and therefore, you may have to convert and dither your file to get to the standard of format.
Sequencing and spacing is one of the final steps in mastering. On an album or EP this process puts your audio in order. Spacing refers to how much silence (space gaps) you put between each track.
Think of mastering as the bridge between creation and sharing. After mastering, your audio should sound complete, uniform, professional and balanced. Whether you’re sharing online as a free download, or pressing a massive run of vinyl, good mastering allows you to release your work with confidence — no matter where it’s played.