If you've been interested in audio and music recording, production and mixing, you've likely heard the term “multitrack” from time to time. The term goes back many decades in the world of audio technology and is still important today.
What are multitracks in audio? Multitracks are single tracks in a recording/mixing session or storage medium (tape, hard disk, etc.). They make up the basis of modern recording/mixing, giving the flexibility to overdub (record individual tracks at different times) and the freedom to mix with control over each individual element.
In this article, we'll discuss multitracks and their importance in more detail, taking a brief look at the history of multitrack recording and investigating the difference between multitracks and the commonly mistaken yet similar “stems“.
What Are Multitracks?
As mentioned earlier, multitracks are the single tracks that make up a recording or mixing session, either on a console, mixer or DAW or stored on multitrack tape or digital media.
Each element of the mix will have its own individual track that can be individually processed in the mix. This is true whether the multitracks feed the mixer from tape, hard disk, or otherwise.
Each multitrack of a specific project will have the same length, spanning the entire duration of the song. This way, a mix engineer can play back all the tracks in sync as he or she inputs the tracks into a mixer or imports them into a DAW.
These multitracks will make up an unmixed song, and it's up to the engineer and/or producer to add overdubs (if need be) and mix the session.
For more info on buses and aux channels, check out my article Audio: Buses Vs. Subgroups, Aux Sends/Returns, VCAs & Groups.
A Brief History Of Multitrack Recording
Multitrack recording came about in 1955 and has since become the norm in audio recording and music production.
Although stereo records were achieved before the advent of multitrack recording, they were relatively difficult to create, requiring two recording and playback heads.
Before multitrack recording, the musicians would gather in a studio to perform. The audio engineer would record them simultaneously as they performed into a microphone(s) or a horn (before the advent of electrical recording in 1925) in the studio.
The typical result would be a monophonic recording with little to no ability to mix the recordings after the fact. The signal chain would be carefully set up before recording to achieve ideal results.
Once multitrack recording became commonplace in the 1960s, musicians and engineers could overdub, bounce down, and mix multiple tracks into a final product (in mono or stereo).
To learn more about mono and stereo audio, check out the following My New Microphone articles:
• Is Stereo Or Mono Audio Better? (Applications For Both)
• How To Tell If An Audio Signal/File Is Mono Or Stereo
Multiple microphones could be recorded to multitrack tape (tape divided into multiple tracks parallel with each other to stay in perfect synchronization). Once recorded, the tape machine could playback the audio from the tape through the mixing console in order for the engineer to add additional tracks (overdubs) and mix the music.
Digital audio technology made multitrack recording even more streamlined with rapid advancements since the 1970s.
Today, multitrack recording is the norm and is largely taken for granted in the virtually limitless track counts of modern digital audio workstations.
However, it wasn't always this way, and we should be thankful for the many decades of technological advancements that have gotten us to where we are today in terms of multitrack recording.
Mixing With Multitracks
For simplicity's sake, let's assume we're working with digital audio, having a folder of multitracks that we're importing into our digital audio workstation. The same general process can be followed by routing the outputs of a multitrack tape machine into an analog console or audio interface (for DAW compatibility). Still, for this section, we'll focus strictly on digital.
So, we've received a folder of multitracks to mix. Hopefully, all recording has been completed, and all issues of phase/polarity, timing and tuning have been addressed appropriately.
We'll go ahead and import the multitracks into our session, adjust the session's tempo(s) and time signature(s) if need be, and ensure everything's looking good. Every multitrack should be the same length and sync up perfectly in the session.
We can then go about fixing any of the aforementioned issues if fixing is required (phase/polarity, timing and tuning).
Gain staging is a great next step. This sets each track/channel at the same level with faders at unity and allows for proper headroom, plugin performance, and even A/B testing throughout the mix. We can use gain/trim plugins for this process, inserting them on each track to adjust the gain as necessary (we can use the preamp gain control on hardware consoles).
From there, we're ready to get into the mix, using our multitracks!
The Difference Between Multitracks And Stems
The terms “stems” and “multitracks” are often confused. Let's clear up the difference.
The term “stems” actually refers to subgroups of instruments. For example, the “drum stem” would be a stereo audio file of all the drums in the mix, while the “background vocal stem” would be a stereo audio file with all the background vocals in the mix.
So, each stem will be made of one or (typically) more multitracks, while multitracks have each individual element of the mix.
To learn more about stems, check out my article What Are Stems? (Mixing & Exporting Audio).
Bouncing Down Multitracks
Bouncing out multitracks means recording each track (and potentially each bus and effects return) down to its own audio file, spanning from the beginning of the song's arrangement to the end.
This process is often referred to erroneously as “stemming down”, but we're technically looking to create multitracks. Again, multitracks refer to one track per channel.
All tracks will be of the same length, meaning there's a high likelihood there will be silence in sections of certain tracks.
Producing multitracks isn't necessary if you'll be the one mixing and are already familiar with the current session. However, it can help to clean up the session whether you'll be the one mixing or not.
If you're planning on mixing in a completely new session or want to send the session off to another mixing engineer, creating multitracks is warranted. Having a single audio file for each track (from start to finish) means we can import each “multitrack”, line them all up to the same starting point, and begin mixing. That said, it's probably best practice to multitrack your mix preparation tracks whether you're mixing yourself or not.
Depending on your workflow, you may want to keep the original tracks in the session just in case you need to reference them in the future. This can be a good strategy if you're mixing your own material.
In this case, you can bounce each track as its own audio multitrack and subsequently mute the original track, bypass or turn off its plugins, and hide it from view.
Bouncing Down Stems
Bouncing down stems follows pretty much the same steps as bouncing down multitracks. The big difference is that we'll solo specific groups of instruments/vocals and exclude the rest of the tracks.
We're still ensuring we're bouncing the entire session length, but we're combining several similar tracks for each stem.
- All lead vocals on one stem
- All adlib vocals on one stem
- All background vocals on one stem
- All bass on one stem
- All electric guitars on one stem
- All acoustic guitars on one stem
- All drums on one stem
We can go a bit further here and have separate stems for solo instruments (say, a guitar solo, for example) or split different percussion (drum kit on one stem, percussion on another, for example).
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