We’ve all made stems of DAW sessions before, but Native Instruments’ Stems file format refers to a new standard of packaged MP4 that compatible software can open as four individual stem tracks so that DJs and live performers can get more creative with mixing them. Stems files will also play back in normal stereo mode on any audio player that reads MP4.
[Editor's note: Native Instruments has recently expanded its support for Stems and made 1.5GB of Stems files available for free.]
Advantages of mixing with Stems can include muting entire parts of tracks, soloing a vocal track to mash it up live with another track, applying effects/ EQ only to certain parts of a track, looping one part of a song, etc. When you mix with Stems, each of the four parts is subject to all the DJing tools and tricks you’re used to on full tracks.
At launch, Stems only worked inside Native Instruments Traktor Pro 2, and the company’s Traktor Kontrol S8, S5, D2, and F1 controllers have instant plug-and-play integration with Stems’ controls. However, NI is releasing a Stems developer’s toolkit so that Stems can be an open format. Already, dance music stores like Beatport, Juno, Traxsource, and others sell Stems music at a premium. The more the format is supported, the more opportunities you’ll have to sell Stems of your own music at a tidy markup. This quick tutorial will help you prepare any of your new or existing DAW sessions as Stems files.
Before you create a Stem, you need to have a finished, mastered stereo file and four submixed Stem Parts that you can create in your DAW or audio editor. The Stems convention is to break down the four parts as: drums, basses, instrumentation (melodies, hooks, etc.), and vocals. Following that pattern assists DJs in mixing Stems. Bounce each the four submixed parts down to its own track, and open the stereo master into a DAW track to make sure that all five tracks are perfectly time-aligned, so that they play back correctly as a Stem file.
Fig. 1. The four Stem Parts (tracks 2-5) here are at unity gain, with no clipping, which must be the case before you import them to Stem Creator.
It’s suggested that you master all four Stem Parts with the same processes that are used on the full-mix stereo master. But you must play back all four Stem Parts together and make sure that when each one is at unity gain, there is no clipping in any individual track or master fader (Figure 1). Use limiting to eliminate any clipping, and then do not use level normalization when bouncing each part to an audio file (WAV, AIFF, or ALAC at 16 or 24 bits and 44.1 or 48kHz sample rates).
LEVEL THEM OUT
Fig. 2. In Stem Creator, use the compressor and limiter to match the levels of the Stem Mix to the Master File and to add metadata and artwork to the Stem. Get the free Stem Creator software (Mac/PC) at stems-music.com. Open it and drag your stereo master and four Stem Parts into the Stem Creator interface. There you can rename the parts and assign them colors that will factor into Stem-supporting performance software. But most importantly, you want to use the Dynamics section to make the Stem Mix equal the level and character of the Master File (Figure 2). Your pre-mastering of the four Stem Parts should have helped, but the Stem Mix may still need some attention.
Hit Play, and then use the switch to toggle from the Stem Mix to the Master File, listening for any differences. To adjust the Stem Mix, you can use the Dynamics Basic mode, which includes some presets and input, output, and dry/wet controls for the compressor. The Expert mode gives you access to the limiter and more compressor controls: ratio, attack, release, and highpass cutoff. If making adjustments to the compressor and limiter isn’t enough to match the Stem Mix with the sound of the Master File, you’ll have to revisit the Stem Parts in your DAW and make sure they’re being mastered in the same way as the main mix.
In the top section of Stem Creator, add your artwork image for the song, as well as relevant metadata. Now just hit Export to create the Stem .mp4 file. The software will save the new file with the same name as the Master File, except with the extension “.stem. mp4” at the end. Now you can live-remix your song in Traktor Pro 2, as well as future Stem-supporting software, and distribute it to others. Stems could be great add-ons to deluxe packages in your online store, ways to interact with fans through contests, or simply a new revenue stream.