Updated: Mar 16
Mastering is the term commonly used to refer to the process of taking an audio mix and preparing it for distribution.
One goal of mastering is to correct mix balance issues and enhance particular sonic characteristics, taking a good mix (usually in the form of a stereo file) and putting the final touches on it. This can involve adjusting levels and general “sweetening” of the mix. Think of it as the difference between a good-sounding mix and a professional-sounding, finished master.
Think of mastering as the glue, varnish and polish of a piece of furniture. In that example, building the cabinet itself would have been the equivalent of composing and producing the track. Final carvings, placement of adornments, and sanding of the cabinet would be equivalent to the final mixdown. Applying tincture, polish and varnish would be equivalent to the mastering stage.
Mastering 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, peaks, 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.
This process can involve adding broad equalization, applying compression, limiting, etc.
Mastering also involves preparing the song or sequence of songs for download, manufacturing and/or duplication/replication. This step varies depending on the intended delivery format. In the case of a CD, it can mean converting to 16 bit/44.1 kHz audio through resampling and/or dithering, and setting track indexes, track gaps, PQ codes, and other CD-specific markings. For web-centered distribution, you might need to adjust the levels to prepare for conversion to AAC, MP3 or hi-resolution files and include the required metadata.
Here are two examples of mastering, (before and after) to illustrate the sonic differences involved in the mastering process.