What does mastering a song mean?

Mastering a song involves taking a mix and putting the final touches on it by elevating certain sonic characteristics. This can involve aspects like adjusting levels, applying stereo enhancement, and monitoring for clicks and pops–anything that could distract the listener from the music. The end result is a polished, clean sound that is optimized for consistent playback across different formats and systems. 

Is mastering necessary?

Mastering makes the sound cohesive across the record and prepares the music for different distribution formats, such as Vinyl, MP3/AAC, streaming services such as Spotify, and broadcast. In today’s world, mastering is necessary to create that “finished” sound that you hear everyday in everything from television commercials to radio and streaming.

What’s the difference between mixing and mastering?

Mixing happens at the start of post-production, when a mixing engineer sculpts and balances the separate tracks in a session to sound cohesive when played together. Mix engineers reduce imbalances between instruments by adjusting balance and color, tighten rhythmic patterns, and emphasize important song elements with tools like EQ, compression, panning, and reverb. 

A mastering engineer then listens to the whole piece as a stereo mixdown. They’re thinking about the finished product and if there’s something they might need to do to improve the sound. This involves correcting and enhancing aspects of the mix including level and tone with tools like Ozone to ensure optimal playback quality across all systems and formats before distribution. In cases where a project contains more than a single track, Mastering engineers not only work to improve each individual track but also work to establish a consistent listening experience across an entire album.

The history of mastering

The earliest forms of mainstream recording technology did not require the recording, mixing, and mastering processes to be separate disciplines. 

Rather, the recording was cut directly to a wax disc via a stylus connected to a diaphragm, which was in turn driven by an acoustic horn through which the sound was captured. These wax discs were then used to make stampers, which themselves were used to press shellac-composite 78 rpm discs. 

The introduction of the 331/2 rpm long play (LP) vinyl record in 1948, and the 45 rpm in 1949 contributed to a change over time in the record making process. Recordings were being made to tape and engineers were tasked with preparing a master disc from the tape recording. When cutting master discs, these engineers now had to watch for and reduce loud transient peaks present in the tape recording. The energy of these peaks could potentially burn out the disc cutter head or cause the stylus to pop out of the groove when the record was playing. 

In order to detect and reduce these peaks, dynamics processing tools such as compressors and limiters were introduced. This was the first time sonic adjustments began to impact the audio after the recording and mixing processes. The need to monitor these tools and adjust the settings for an optimum playback experience without compromising the sound quality was the earliest form of mastering.

The introduction of the standardized RIAA curve meant that equalization (EQ) became part of the mastering discussion. Intended to allow records to be cut with narrower, tighter grooves (and thus, a longer playing time), one side effect of this curve was that the pre-emphasis curve applied to the recording could enhance high-frequency transient peaks, and the de-emphasis applied upon playback could cause a boost in low-frequency energy that would cause the stylus to pop out of the groove.

Slowly but surely, the necessity of these tools to ensure a positive consumer experience meant that the skills of those who could utilize them effectively became highly prized. Some engineers (notably Doug Sax, Bob Ludwig, Bob Katz, Bernie Grundman, and others) began to focus exclusively not just on the practicality of these tools, but also ways in which they could be used to further enhance the listening experience.

Now, many mastering engineers use plug-ins included in the Music Production Suite to achieve their desired sound.