written by Damon Mapp
You’ve been gearing up for this new release for months. On top of the time it took to write and refine the songs, you and your band have spent countless hours rehearsing, testing the songs at shows, and playing every chance you’ve had to save up for the production of this project. Now that you’ve wrapped up at the recording studio, you can finally relax. It’s done… right?
Well, not quite. It’s time to dive into the last phase of finishing your album: mastering! This phase includes a final polish (adjusting volume, EQ, leveling, compression, spacing), adding the CD Text, submitting the content to Gracenote, and more.
If you read my last article, you should know that there are differences between recording, mixing, and mastering. But, did you know there are different types of mastering? Maybe you did. If not, though, don’t worry. Today, I’m going to explain two different types of mastering: stereo mastering and stem mastering.
Stereo mastering is the more common of these two types of mastering. It’s the final polish before mass production and distribution.
For stereo mastering, you take your final mixdown (or stereo track) that the mix engineer has produced, apply balance, EQ, and compression (if necessary), and tweak any other tonal enhancements or deficiencies that the track may have before it reaches its final place: on store shelves, on your merch table, or online for digital distribution. This mastered track is normally louder, punchier, and more articulate than the mixdown.
Compared to stereo mastering, stem mastering takes things a little further and offers more options to a mastering engineer. That’s because a stereo master starts with just two tracks (the left and right of the mixdown), but a stem master consists of the separated elements of a track.
I know, I know; some of you are saying, “Now I’m really confused. What do you mean separated? I thought we took care of all that in the mix process!”
Well, I’m glad you asked! For this type of mastering, things happen a little differently, starting in the mixing stage. Each stereo element—drums, bass, synths, lead vocals, background vocals, and sometimes other instruments—is recorded or bounced out as a group. For example, you can bus all of your drums—you know, the kick, snare hats, etc—to one group or bus during the mixdown process. After the drum bus gets EQ’d and compressed, it is re-recoded to a final mixdown track, which is known as a stem. Repeat this process for all of the other elements in the mix, and you’ll have stems for vocals, synths, bass, and so on. These stems are processed and recorded by the mix engineer and then given to the mastering engineer.
When working with stems, the mastering engineer has access to levels on the stems the mix engineer has created. This means that instead of trying to balance levels within one stereo track, the mastering engineer now has access to the separate stems, which can be processed independently of each other. In stereo mastering, if you made an EQ change in the bass region, it would affect the entire mixdown. But if you make that same change on just the drums stem, it would only affect the drum stem, leave the bass on the rest of the song as-is.
As you can imagine, this gives the mastering engineer incredible flexibility in maximizing the sonic potential of each separate stem.
So which one is better?
That is a decision for you, your band, and/or your mix engineer to make. My suggestion is to try both and see which one sounds better to you. They both have their technical advantages and disadvantages, but I will tell you what I always tell artists and musicians: use your ears!