STEM MASTERING: HOW TO PREPARE THE STEMS
In this article, we are going to see what stem mastering is and how to get the stems ready.
There are a few tips that I would like to share with you to optimize the export of the stems and avoid common mistakes.
Remove any limiter plugin from the master bus.
Export the song in .wav or .aiff at 24-bit (or higher 32-bit/64bit floating point)
Use the original sample rate (don't upsample or downsample)
Make sure all the stems are synched together
Reimport the stems in your DAW and make sure their sum corresponds to the final mix
Mastering engineers usually accept up to 8 stems per song (make sure Drum, Bass, Main Voice, and Backing Vocals are all on different stems)
WHAT IS STEM MASTERING?
Stem mastering is a process to master a song from multiple stereo tracks containing consolidated groups of instruments (also called stems) of the mix. Providing the stems, allow the mastering engineer to manipulate the sound to a deeper level. That said, stem mastering shouldn't be confused with mixing where the engineer uses fx, automation, compression, eq, etc. to sculpt each sound. The goal of stem mastering is not to mix a song but to master it, having more flexibility when a problem needs to be addressed. It's important to notice that the sum of the exported stems must sound like the original mix (L-R mixdown). So, as a result, by importing the stems on their DAW the mastering engineer will have your final mix as a reference (we'll go more in-depth into this, later on, in this article)
WHEN GO FOR STEM MASTERING AND HOW THE MIX CAN BENEFIT FROM IT
You should go for stem mastering if:
You feel there are specific issues that can be improved: you are not sure of the overall balance, you can feel something is wrong, but you can't target the problem, You feel the mix is too muddy, boxy, etc.
You need a more "aggressive" approach to enhance the character of the mix.
You feel your mix lacks depth, width, warmth, and separation (yes, stem mastering can also help with this).
WHICH STEMS SHOULD I PREPARE?
Every song is different, but there are some groups of instruments that are always good to submit in separate stems due to the fundamental role they play in every song. These instruments are:
You can split the rest of the mix into sessions.
For instance: guitars, keys, background vocals, brass, and so on.
A good rule of thumb is to give an order of priority to the stems and eventually leave the last stem as "the rest of the instruments". If you are not sure about which kind of stems you should create, a very good idea is to talk to your mastering engineer.
At Master Your Track we accept up to 8 stereo stems.
We usually suggest splitting the mix into the following groups of instruments:
Back Ground Vocals
All the Other Instruments
Of course, every song is unique, so the stems might change according to the arrangement of the song.
Other potential stems might be Brass, Strings, Synths, and so on.
CREATING STEMS (CHECKLIST)
Remove any limiters from the master bus: the limiter reduces the number of options the mastering engineer has to manipulate the sound.
Leave some headroom: Someone recommend peaking at -3 dBFS, some others at -6 or -10 dBFS.The truth is that if you are mixing at least at 24bit (and all the DAWs today do), just make sure you don't hit the 0dBFS (digital distortion) on the master buss. The mastering engineer will be able to gain stage the song according to the mastering chain.
Leave one bar of silence at the beginning of the tracks: It is good practice to leave at least one bar of silence before the song starts. Some processing (some analog modeled plugin or if you bounce on tape) introduces noise. The mastering engineer can analyze this low-level noise and optimize the master accordingly.
Synch all the stems together: before exporting the stems make sure to select the whole length of the song. In other words, you want all the stems to start at the same point (bar 0) even if a group of instruments doesn't start to play at the beginning of the song. This ensures that all the stems are synched together.
Return fx: Make sure every stem includes the related return fx.
Mute or solo?: In order to create a stem mute all the tracks, you don't want in that specific stem. This will ensure that due to solo safe none of the unwanted track goes into potential effects return you have created during the mixing process.
File Type: WAV and AIFF are the recommended file types as they are lossless.
Format: Interleaved (this means that you are going to create a stereo file).
Bit Depth: 24-bit (or 32-bit/64-bit float). 16 Bit can be mastered but is not ideal.
Sample Rate: Use the same sample rate of the mixing project (44.1, 48, 88.2, 96 kHz). Don't upsample or downsample.
Dither: In some DAW, you can apply the dithering when exporting. The dithering process is used when reducing the bit depth. Since you don't need to do it, don't apply any dither. The mastering engineer will look after this.
Normalization: If your DAW gives you this option, don't apply any normalization as you want to keep the levels of your mix.
NAME THE STEMS CORRECTLY
Most people underestimate this point, while, it is essential to keep communication as smooth as possible.
If you need to ask for some change, you can refer to the stem using its name and the name of the song. Doing so the mastering engineer will exactly know which song you are talking about and which stem, as well as everyone else involved in the production process (Producer, Record Label, Mixing Engineer, etc.). The best advice is to create a folder for each song and put in each folder the relevant stems accordingly named.
It is usually good practice to provide a text document that includes at least track numbers, titles, artist names, album titles, and artwork. But if applicable you can also include the record label, publisher, ISRC codes, UPC/EAN, and all the ID3 metadata relevant to your project.
All or part of this information (depending on the final file format) can be embedded in the final file/delivery.
Knowing the tracklist is essential for sequencing: optimize the silences between the songs, create tailored micro automation to make the album/ep flow better, and improve the listening journey through the album/ep if there are climax moments. Make sure to provide the tracklist of the album/EP.
CHECK BEFORE THE SUBMISSION
Before submitting files to the mastering engineer re-import all of them in a new project and make sure all the mixes sound as intended.
Bear in mind that your mastering engineer is going to work on what you provide.
If you are not sure about something or you want your mastering engineer to look after some aspect of your album/ep/song, tell them before the session.
Remember that any mastering engineer is first of all a person who loves music at least as much as you do.