What is Stem Mastering?
In the last decade, stem mastering has soared in popularity - especially among self-mixing home recording artists. Unlike normal mastering, in which the engineer processes a single stereo file, stem mastering is when multiple instrument-group tracks are treated to achieve a master.
It allows the engineer more control and typically results in a more complex and balanced final product. It’s a cost-effective option for those who aren’t entirely satisfied with their final mix, but at the same time, don’t want to hire an outside mixing engineer.
Stereo and stem mastering are different means to the same end, but each offers its own advantages and disadvantages. In this brief guide, I’ll go over their key differences and how to know which one is right for you.
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Stereo vs Stem
Normal mastering, or “stereo mastering”, is the process of delivering the final mix as a single stereo file to the mastering engineer for them to treat and prep for commercial release.
Stem mastering, on the other hand, is when you deliver to the mastering engineer multiple “stems”, or instrument group mini-mixes, for them to individually treat and combine back into a final master. You could deliver anywhere between 2-8 stem tracks and create stems out of whatever instrument groupings that make sense for your song.
By separating your instrument groups, you allow the mastering engineer more control over how they treat your song. Additionally, you’re empowering them to more easily identify and fix any mix issues that might have slipped by.
For example, in stereo mastering, it’s difficult to isolate and treat overly present vocal sibilance (“s” sounds) without also killing the cymbals or the “air” of the synths. But with stem mastering, that’s no longer an issue. Another common mixing trouble spot is the relationship between the kick and bass, where, again, the same idea applies.
Below are examples of how each stem might benefit from being processed individually, resulted in a stronger final product...
Drums - Punch, tightness, and clarity without affecting the rest of the song
Bass - Fullness without the mud; clarity in the high end "action" without having to boost everything else
Guitar - Solid mid-range impact with crowding vocals; reduced low end mud without affecting the bass
Keyboard - Bright high-mids and highs without pushing cymbals or vocals harshness
Vocal - Clear, full, upfront sound that sits neatly within the mix
When preparing to deliver your stems for mastering, you should leave on all of your effects and processing - keep all of your compression, EQ, reverbs, delays, and anything else you’ve mixed in. If you have any processing happening on your mix bus/stereo bus, however, you’ll want to turn those off.
For hip-hop, it’s not uncommon to simply deliver a “music” and a “vocals” stem. For rock bands, you might send over stems for drums, bass, guitar, keyboards, synths, and vocals. Combine your tracks into stems in whichever way most compliments your song and arrangement.
When to Go With
If you’re happy with your mix overall and you’d just like help bringing it to that next, commercially-competitive level, then stereo mastering might be the way to go. Additionally, if your budget is tight or you’re up against a tight deadline, the stereo mastering is always going to be more affordable and have a quicker turnaround.
Stereo mastering is also appropriate if you’ve collaborated with a professional mixing engineer on a larger project, like an EP or a full-length album. You’ve likely already gone back and forth with them on mix revisions for a while, and stem mastering might only confuse or disrupt your carefully crafted vision.
But if you’re a self-producing, self-mixing artist with a new single, then stem mastering is your best choice. Especially if you’re struggling to nail the mix - if overall, you feel okay about it, but something isn’t working quite right and you aren’t sure what it is or how to fix it.
The best way to ensure that your less-than-perfect mix will be transformed into a full, impactful, and polished final master is to deliver stems to the mastering engineer rather than the summed stereo mix.
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