The next time you finish your mix, you may decide that you want it professionally mastered as it always helps to have a second set of ears in the mixing and/or mastering process. Before you opt for a conventional master, you may want to give stem mastering a consideration instead.
What is Stem Mastering
Stem mastering is a process which deals with groups of tracks or even the odd individual track rather than the entire mix.
Normally in audio mastering, you render your entire mix to a single audio file which gets enhanced in the mastering process and getting it ready for release.
With stem mastering, you render your tracks by logical groups. A few examples of stems for mastering might include:
- Drums – Your entire drum performance would oftentimes be output to a single audio file, let’s just say a WAV. Occasionally you might get the kick isolated as its own track, but this can vary from genre to genre. In hip hop when the kick plays arguably a bigger role, particularly in a sparser mix, so that might be its own track in stem mastering.
- Guitars – All rhythm guitars might be grouped together as a single track/stem. The solo/picked guitar parts might have their own group/stem, as well, and the acoustic guitar(s) might have their own group, too.
- Bass – The bass of a mix is typically represented by a single track, but this is left on its own track, as well.
- Vocals – Vocals might be separated by groups, with one for the lead, one for harmonies, one for backing or any other types of vocals, etc.
Note that these groups are completely mixed to taste. This includes any and all processing (EQ, compression, reverb, automation, etc.) whoever mixed the instruments put on them. This also includes all the panning within that group.
This might mean the guitars are split wide, the hi-hat and other cymbals are sent to each side, etc. Basically everything I recommend in my audio panning guide:
To put it another way, typically virtually all of the mixing within the song has been completed before a stem mastering project commences.
The idea is to get the stems sounding as good as possible as if they’re the finished mix themselves.
The various stems are then sent to the mastering engineer to work on and the engineer imports the stems into their DAW (similar to a mix).
Any number of types of audio processing might be added to each stem to slightly tweak and sculpt their frequencies, dynamics, stereo image, etc.
With each group being on its own dedicated track, there’s still a bit of room when it comes to striking a balance through relative level setting, as well.
Master bus processing is used similarly to conventional mastering to do the same thing we did on the stem level (sculpting frequencies, dynamics, the stereo image, etc.) but on a macro level.
This also includes applying some sort of maximizer or limiter on the master bus to boost the output level of the master to be commensurate with other commercial releases of the day (see what LUFs to master to).
This might also involve dithering to safely convert its bit depth or getting the audio ready for whatever medium its being released to (digital vs CD vs vinyl, for example).
Stem Mastering Vs Mixing
Stem mastering probably sounds remarkably similar to mixing, so let’s be clear on the differences.
Mixing involves assigning individual tracks for literally every instrument and oftentimes unique recording in your mix.
For argument sake, the 3 rhythm guitars all have their own tracks, every unique vocal has its own track, every drum and cymbal within your drum performance as its own track, etc.
Mixing is the starting point after recording when you just have dozens of raw and rough recorded audio tracks.
This is audio production at its most granular level and, as such, mixing is a much more involved and time consuming process than stem mastering.
Stem mastering, on the other hand, involves taking fully mixed track groups (each represented as a WAV) and fitting those groups together and adding processing to enhance them and make them sound their best together.
It’s worth pointing out that there’s an understandable amount of confusion between stem mastering and mixing because the term “stems” can also refer to individual tracks associated with a song.
People who like to remix songs get a hold of the individual tracks associated with that song, and they’re also referred to stems in that context. It’s the context which is the difference and determining if the “stems” are individual tracks (in the case of a remix or sampling) or track groups (in the case of stem mastering).
Stem Mastering Vs Mastering
What about how stem mastering compares to mastering in general?
If mixing is a more granular level than stem mastering, stem mastering ITSELF is a more granular level of audio processing then conventional mastering.
There’s still a decent amount of wiggle room when you’re working with multiple audio files in stem mastering and it’s a more involved process than conventional mastering.
In conventional mastering, it’s just taking a single fully mixed down audio file whether it be a WAV or AIFF and adding those last minute enhancements.
And just like with stem mastering, this once again involves ensuring it’s ready for a commercial release, so using a maximizer or limiter to make its average volume more competitive, adjusting the bit depth (if applicable) via dithering, and getting it ready for whatever medium, digital or physical, it’s to be released on.
Benefits of Stem Mastering
Let’s finish up by clarifying the reasons you might opt for stem mastering over conventional mastering.
As you might expect, there’s a greater financial cost associated with stem mastering because of the additional work involved.
Stem mastering:
- Is more involved than conventional mastering, allowing the engineer to work on groups of tracks rather than a single audio file.
- Is more cost effective than hiring a mixing engineer to mix your entire project from the ground up.
- Is a healthy compromise between mixing and conventional mastering. You can still do the majority of the work in getting the tracks where you want them on a track by track level while still getting the benefit of the enhancements in the stem mastering stage.
- Allows you to get a second set of ears on your song before its locked into a single file, typically yielding better results.
I offer stem mastering services at my sister site, Music Guy Mastering, so visit me there if you’re interested in stem mastering on your next project.
