At our sister site, MusicGuyMastering.com, I provide audio mastering services for clients who want to release their music digitally, on CD, vinyl, even cassette tape in rare cases. In addition to all of that, I also provide stem mastering services, so I thought in the wake of covering how mixing is different from stem mastering, I thought I’d compare stem mastering vs mastering.
Stem Mastering Vs Mastering
First, let’s begin with mastering.
What is Audio Mastering
Audio mastering is admittedly a somewhat nebulous concept in audio production. Most people understand that audio mixing refers to taking the various individual tracks which make up a song – the bass, all the vocal, guitar, and drum tracks, etc. – and getting them to fit together like a puzzle (that’s the analogy I like to use, at least).
I would HOPE you’re familiar with the concept of audio mixing if you’ve been on this site at least once before, but yes this is what I talk about in every tutorial.
After we’ve fit all of those tracks together in setting the levels and panning positions of all the tracks relative to one another, we “bounce” or otherwise render that collection of tracks and “mix it down” to a single audio file, typically a WAV or AIFF format (see my overview of the types of audio formats).
That single audio file is then enhanced through the process that is audio mastering.
Ideally this is done by a different person than who mixed it as it always helps to get a second set of ears on a project, especially if you mixed it yourself.
In the mastering process, the mastering engineer applies a lot of the same effects used in the mixing stage but on a macro scale.
This is because any processing added to the single audio file understandably affects the entire mix all at once.
Any EQ, any compression, etc. which is applied to that mixed down file is simultaneously affecting the bass, vocals, guitars, drums, etc. all at once, but specifically that sum of tracks which has formed the collective unit of that mix.
Specifically, the typical effects used in audio mastering are (but not limited to):
Multiband Compression – This is a tool used to compress different frequency ranges. Some frequency ranges can be compressed (or expanded) more aggressively than others in order to achieve a better balance.
Stereo Imaging – Stereo imaging is about adjusting the width of the entire mixed down file. We can expand that width to make the mix feel larger and more spacious, or we can automate it even at the master level to emphasize the key moments of the song and give them more weight.
Maximizer – A limiter or maximizer goes at the end of the processing chain. There’s the old joke that all mastering engineers do is turn up the volume. While making a mix competitively loud so that it doesn’t sound quieter than other commercial songs when played side by side in a mix is important, it’s just as important to ensure that the song doesn’t get louder at the expense of its quality, and that’s part of the audio mastering process.
Beyond this, now more than ever mastering engineers have access to more surgical tools for correcting any unwanted artifacts on the mix, cleaning up pops/cracks or even seamlessly raising certain elements of the mix without sacrificing the quality of the recording.
The latter is invaluable in situations where the original tracks which made up the mix are no longer available and all we have access to is the single audio file.
In addition to simply ensuring the finished audio file/master is sounding its best and at a competitive volume, the process may also include getting it ready for whatever format the client wants to release it in. This is an important point, as releasing a song on vinyl versus digitally can sometimes require a different master.
The TL/DR of audio mastering is it’s the final step in ensuring your single mixed down file is sounding its best and ready for release.
What is Stem Mastering
Now that we’ve established what audio mastering is, what is stem mastering? In going back to my analogy of mixing is like putting together a puzzle, mixing isn’t just about sorting out the levels and panning.
It’s obviously also about the effective use of some of those tools I just mentioned in mastering but on a track by track level – sculpting frequencies, managing the volume dynamics, etc. on every vocal, every guitar, every drum track, every track in your mix.
There’s a lot of audio mixing in stem mastering, but that’s why I say stem mastering is a kind of happy compromise somewhere between audio mixing and mastering.
So what is stem mastering?
Stem mastering is about applying audio effects to GROUPS of tracks, arranged and grouped together sensibly before each group is mixed down to its own single file.
This typically means taking all of the vocals and rendering them to a single WAV or AIFF and doing the same for all the drums, guitars, etc.
Note that all of the individual mixing is still done on each group so that they sound good as a collective unit. So every individual vocal (for example) gets EQ, compression, even delay and reverb, AND is panned and level set relative to the rest of the vocals before all of the vocals are solo’d and bounced/rendered.
We then have our vocal stem.
This process is repeated for every remaining group of instruments. It doesn’t just have to be all the guitars or all the drums and so on in their own files, but basically just in a way which makes sense.
This typically results in around 5-6 groups/stems which are ready for stem mastering.
Stem mastering is then about applying the same effects covered a moment ago but to each of these individual stems, hence my calling this a compromise between mixing and mastering.
Not only does the mastering engineer improve the quality of each individual group/stem, but they apply those macro effects to the master bus as necessary to get the sum that is that group of stems sounding their best.
Stem Mastering Vs Mastering Reviewed
In summation of stem mastering vs mastering, stem mastering is a nice alternative for musicians who either want a more affordable hands on alternative to audio mixing but also want to have an impact on their own music in mixing the individual tracks before making the groups/stem tracks.
It generally is much more affordable than hiring someone to mix every single track of your song but understandably more expensive than sending a single mixed down WAV or AIFF file to the mastering engineer.
Stem mastering won’t be for everyone, but it’s becoming an increasingly popular midway option for those who want to mix their own music to a point but still recognize the value in that second set of professional ears on their music.
For more information, once again I’ll refer you to our sister site at MusicGuyMastering.com for my stem mastering services.
