Mixing and mastering music are two separate but equally important parts in the audio production process that can often become blurred and hard to differentiate between. Basically, mixing is the step before mastering that involves adjusting and combining individual tracks together to form a stereo audio file after mixdown. The stereo file is then mastered, which ensures that the various songs are clearly polished and form a cohesive whole on an album. This defines mixing and mastering in their simplest forms. Let's take a deeper look at the numerous other differences between mixing a mastering.
After all of the individual tracks of a song have been recorded, a mixing engineer steps in to work their magic. They begin by labeling and organizing the tracks into their similar groups. The song is often Normalized to ensure that the tracks are all at similar volume levels and no tracks peak. The engineer will then EQ each individual track to get the best tones out of the instruments and use high and low pass filters to eliminate any unneeded frequencies. The general goal of EQing is to make adjustments that allow all of the tracks to inhabit their own frequency areas. This allows the song to be clear and each instrument distinguishable. The same idea is also applied to panning the tracks to get a full, wide sound. Compression, reverb, delay, and other processors can be added to each track to get the desired tones for the instruments as well. Manipulating fades and effects throughout the songs with automation can help the engineer control the emotion of the song sonically. A lot of engineers will switch between headphones and the studio reference monitors to get a consistent sound for their mix on various sources. After hours of tweaking knobs and faders, and the song sounds as best as it possibly can: It's time for the mastering engineer to step in.
The mastering engineer receives the stereo track along with some notes and reference songs from the engineer and/or the artists. This will help give the engineer an understanding of the sound that they are going for and so that the mix isn't altered in areas that are intended to sound a particular way. Then, the finishing touches are added to the song by making slight adjustments primarily to the EQ, compression, limiting, and stereo enhancement. All of the songs mastered on an album are brought to similar levels so the album flows and is cohesive throughout. Spacing and fades are added to the beginning and endings of the songs. Usually the Red Book standard of 2 seconds is added in between songs unless otherwise specified. Audio mastering engineers often offer sequencing services for albums to put the songs in the desired order, label track names, as well as encode the tracks with ISRC. The mastering engineer's primary goal is to provide a high fidelity, high clarity, professional sound that can be enjoyed by listeners on any source.
You could have a great mix without a great master, or vice versa, and still be unable to achieve a professional sound that can compete in today's music world. The line between mixing and mastering should never be blurred. Attempting to combine these two steps into one will only hinder your music and prevent it from reaching its full potential.