Stems and Tracks and Channels, Oh My!

By: David Streit www.davidstreit.com

So you’re getting into recording music and you’ve heard people talking about stems and tracks and channels. What’s the difference? Are they all the same thing? It helps to know what you (and others) are talking about. While we’re here, we’ll also discus the basics of signal flow. Read on…

Tracks
Individual recorded items (like a snare drum, a guitar, or a vocal) are tracks. Often, one source (say, a microphone) is recorded to one track. A track is frequently represented as a horizontal lane in a DAW. (A DAW or digital audio workstation is a recording program such as Pro Tools.) You also might submix a few sources together and record the result onto one track. Tracks can be mono or stereo (or even multi-channel surround.) Picture a reel of 2 inch, 24 track analog tape. There are 24 tracks which together comprise the multi-track.

Channels and Mixers
The tracks are routed to the inputs of channels on a mixer and are mixed together with effects to make the mix which is often in stereo. So, a channel is a section of a mixer (frequently represented as a vertical strip) that comprises the controls for processing a track (or another source such as the output from a reverb) and controlling its level in the mix. In a DAW, each channel can host plug-ins that can process the sound on that channel. (Types of plug-ins include EQ, compression, and other effects.) The outputs from all of those mixer channels go to what is called a bus. The bus collects all of those sounds and combines them. The bus (in this case, it’s the master bus) is routed to the master channel where the whole mix is processed and controlled. The output of the master channel is the finished mix. Mixer channels can also have (auxiliary) aux sends that route signal from the channel through an aux bus to an aux channel (sometimes called an aux return.) If you put a reverb on an aux channel you can use one reverb for sounds coming from several channels. The output from the aux channel would go into the master bus.

Mix Versions and Stems
Once the mix is finished, you print (record) it to a track (or maybe just to a file on your computer.) There can be different versions of the mix, such as an instrumental (no vocals) or a vocal up (the vocal is slightly louder.) A TV mix includes background vocals, but not lead vocals. You might also print stems. A stem is a submix of the main mix that includes channel processing. To get the vocal stem, you would mute everything except the vocals and any vocal effects. You might also make a drums stem with all of the drum channels and associated effects, etc. You might include master channel processing in the stem, or you might bypass it depending on the situation. If the mix is in stereo then the stems probably should be as well. Generally, tracks are raw and stems have mix processing incorporated into them.

More Tracks
If you’re recording a drum kit and you submix the four tom drums onto two tracks, those would be tracks, not stems. You might send the finished mixes to a mastering engineer for mastering. Stem mastering is sending stems for mastering instead of sending a mix. It’s essentially mixing without the ability to really mix. I’m not a fan of this approach for music.

More Stems
Stems are common sources for final mixes for film and video. Stems are also useful for bands who will be performing live with “tracks” (which are technically stems.) Stems might also be used to tweak a mix after the fact or as components in a remix. A Remix is a re-working of the recorded song with new and sometimes very different parts added. Often, most of the elements of the original recording are discarded.

Hopefully, you now have a firm grasp of the meanings of all of these terms, as well as a basic understanding of the signal flow through a mixer.

Questions?
If you have more questions or there’s something I can help you with, don’t hesitate to contact me at www.davidstreit.com.

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