What is Mastering? A quick Walk through History
I have refered to mastering as a dark art, because there is a lot of confusion around this topic and what mastering actually is. Historically speaking, mastering used to describe only the process of producing a master medium that would then be replicated for distribution. In the early 1900’s, this meant recording a live-band directly to a master-disc, which then would then be pressed to vinyl. Because of the nature of vinyl records, equalisation had to be applied to the signal to prevent exessive bass from cutting too deeply into the vinyl. To compensate for this missing bass, a bass-boost had to be applied during playback. By the 1930’s it was also already established, that boosting high frequencies during cutting would improve playback of details that where otherwise drowned out by the hiss.
Keep in mind, that in the early 1900’s radio was a relatively new thing, and there were no standards or norms on how music should be produced and sound until the late 40’s. This presented a problem in so far, that everybody producing records figured our their own way of equalizing them, leading to records sounding vastly different from each other during playback.
By the late 1940’s magnetic tape recordings became widely avaliable and changed the music industry forever. Instead of recording directly to a disc, people now had the opportunity to record songs at different times and in different places, and then later transfer those recordings from the tape onto a master disc. It was at that time, specifically 1948 with the introduction of the Ampex 200 tape recorder, that the job of the “transfer engineer” was born. The transfer engineer specialized specifically on the process of transfering the recording from tape to vinyl while retaining the best possible quality. [Read more about the history of the Ampex Tape Recorder]
In 1954 the RIAA Equalisation Curve was established as a global standard and dictated the curve of the corrective EQ in playback devices. Having a predictable playback slowly morphed the rather technical job of the transfer engineer into the more creative and artistic profession of the mastering engineer. By the use of EQ and compression, early mastering engineers improved and matched the sound of recordings before transfering them to the master, ensuring a more standardized sounding playback from different playback devices. Their musical influence further increased when stereo-recordings were introduced in the late 60’s.
In the 1980, the music industry was disrupted yet again, by the introduction of digital audio and CD’s. The technology removed many limitations that vinyl and analog music reproduction intrinsically had, and paved the way for a new era of music: the digital era. Trying to press a louder playing vinyl record was not feasable and resulted in a bunch of problems. Given the high theoretical fidelity of a CD however, engineers slowly figured out ways to make the songs on CD’s play back louder and by the mid 90’s the loudness war was in full force. It became the main objective of a mastering engineer to find ways to make the music play back louder than the competition. This frency also gave rise to aspects of what we nowadays percieve as a “finished” sound in modern music.
The latest paradigm shift in the music industry was the shift that occured from digital mediums like CD’s to online steaming services. Most providers have introduced loudness normalisation, where they analyze the dynamic range of uploaded songs to play them back at a coherent sounding level. In some cases they even apply limiters at -1dB to prevent clipping after level-matching albums. What does this mean for mastering engineers? Contrary to popular belief it does not mean that you should master at significantly higher dynamic range to maintain the full range the provider normalizes to. It means that you should master at the level of dynamics that give the best sound subjectively, without worrying about the playback level of your song. You will find that in Pop music that range usually lies between a modest 8-12dB of dynamic range.
What makes a great Mastering?
By reading this article, you have probably noticed that the true definition of mastering is slightly elusive. I’d like to describe it like this: while mixing is the process of adjusting everything that happens within the song, mastering is the process of shaping the overall impression of it. Here inlies the theoretical advantage of using a different mastering-engineer, someone who has never heard the song before and can make an unbiased judgement. Mastering tries to turn the “mix” of signals into a coherent and “as one” sounding whole. It tries to give the entire frequency spectrum an equally felt presence, and balances the dynamics so the music sounds loud but not “squashed”.
What is Stem-Mastering?
Another source for confusion is the practice of stem-mastering. Stems are different from multi-tracks, because stems usually contain fully mixed groups of intruments or vocals. The advantage of stem mastering is the ability to adjust the levels and responses of these groups while hearing the finished master. It can also be used specifically to make use of analog summing, which in some cases leads to a more balanced and “glued” sound. For more information check out our post about stem-mastering.