Stem mastering and mixing are two distinct types of audio production which sometimes get confused for one another because they share one major concept in common: stems! As such, I thought I’d give a brief overview of and comparison between stem mastering vs mixing.
Stem Mastering Vs Mixing
As I just mentioned, stem mastering and mixing share one thing in common in stems. This is why the two oftentimes get confused with one another or even occasionally get used interchangeably.
The difference is the context in what the stems are.
In the world of audio mixing, the term stems typically relates to remixing or sampling.
In this case, we’re taking the individual tracks from an existing mix and importing them into our mix to use however we like. These tracks from another mix, typically from a commercially popular song, are referred to in this context as stems.
Someone doing a remix might just want the vocal tracks from a popular song, also referred to in this context as vocal stems.
They would then drag and drop them right into their mix, layering them over top of a marginally or completely different instrumental. They may also just want to use the chorus vocal in their song which is more referred to as sampling, a practice which is obviously very popular in the rap genre.
There are plenty of resources on the internet which house and either sell or give away for free huge databases of stems from popular and obscure songs all throughout the history of music.
Regardless, this is typically what stems refer to in mixing. The fact that they’re called stems is what makes people mistakenly conflate mixing (or better said remixing or sampling) with stem mastering.
Stem Mastering
Stem mastering, on the other hand, is a more granular level of audio mastering. Instead of mastering a single, mixed down song in say a WAV or AIFF format, stem mastering refers to taking groups of tracks which make up a song and which have been mixed down into single files, then applying some of the macro level touches associated with audio mastering both to each “group” as well as the master bus.
Compared to the stems I just covered as they relate to mixing, each stem in stem mastering can contain multiple tracks. Typically the tracks contained in a single stem in stem mastering are all related in terms of the type of instrument or role they provide in the song.
For instance, you might have all of your vocals on one stem, all of your drums on another, etc.
These tracks have already been mixed together to gel and work as their own cohesive unit with virtually all of the production already on them, certainly the track level production.
In stem mastering, the mastering engineer then applies additional production like EQ, multiband compression, glue compression, etc. on each stem to tighten them up as well as setting each stem’s volume relative to the others along with some possible automation to add a little extra life into the song.
The engineer will finally add additional master bus processing like stereo imaging, a maximizer or limiter, and a few of the components I just mentioned but on the master bus which those handful of stems are “summing” into and creating.
The appeal of stem mastering is that it’s a healthy compromise and affords musicians an additional option between the more expensive and time consuming process of audio mixing versus the more inexpensive but comparatively less impactful process that is audio mastering.
As you can tell from this comparison, stem mastering vs mixing are two different aspects under the greater umbrella of audio production. They’re commonly only misconstrued for one another because of that shared concept of “stems”.
As always, context is key, and that’s certainly true in mastering vs mixing.
