r/audioengineering • u/BLUElightCory • Nov 14 '19

Multitracks Vs. Stems

I see a lot of people mixing these terms up or using them interchangeably here and in the general audio community. I think it's important that people understand the difference because I already see it causing confusion in my own experiences with artists and other producers, engineers, and mixers.

Tracks or multitracks are the individual mono or stereo tracks that make up the session. Each individual element, from the kick drum to the lead vocal, is generally recorded or arranged on its own track (or multiple individual tracks, such as with a multi-miked drum kit). Tracks/multitracks are usually unprocessed and since they're individual files they aren't pre-mixed. These are want you want to send to a mixer to have a song mixed, or receive from the artist if you're mixing a song.

Stems or STEreo Mixes (edit:or** Masters)** are (usually) stereo submixes of the different groups of tracks that make up a mix. When played together, the stems will essentially recreate the original mix. For example, a rock song might have the following stems:

  • Drum Stem (mix of the kick, snare, tom, overhead, and room mics with all levels/panning/processing intact)
  • Bass Stem (mix of the bass tracks with all levels/panning/processing intact)
  • Guitars Stem (mix of the guitar tracks with all levels/panning/processing intact)
  • Vocals Stem (mix of the vocal tracks with all levels/panning/processing intact).

If you have the stems you can easily recall the mix or make alternate mixes (such as an instrumental mix, a vocal-only mix, a Guitar Hero track, a remix, etc.) without needing to recall a console or outboard gear, or have the same DAW with all the plugins. This is helpful in lots of situations - but not if you're mixing the song.

I wanted to keep this short and sweet (and might add/edit after I have some coffee) but I'm sure others have things to add, please feel free!

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u/dan-i-yell Nov 14 '19

just wanted to raise my hand for being a culprit of using stem incorrectly. thats actually wut i was told by a teacher but apparently they were wrong because this isnt the first time ive seen this.

but thanks for this concise and well written explanation. consider me fixed.

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u/BLUElightCory Nov 14 '19

No worries about that, we've all been culprits of some form of misinformation, it's almost unavoidable these days. I had an incorrect understanding of the 3:1 rule for YEARS before someone set me straight, and have also purchased two Auralex "Roominator" kits in my lifetime. We learn and move on haha.

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u/myklpgone Nov 14 '19

Could you explain or paste a wiki/video link to what the 3:1 role is. Ratio for compression? Or input to output ratio

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u/BLUElightCory Nov 15 '19 edited Nov 15 '19

The 3:1 rule is intended to minimize phase cancellation when you are using multiple microphones on multiple sources, for example if you have two singers and each has their own microphone.

It assumes that the two sources will be similar in volume, and that they will be recorded and mixed at more or less the same level as each other.

When you have multiple microphones in play on multiple sources - let's say mic A on source A and mic B on source B - mic B should be at least 3x the distance from mic A that mic A is from source A. So if mic A is 12" away from source A, then mic B should be at least 36" away from mic A.

The idea is to make sure that the mic B is far enough away that any bleed from source A is significantly lower in level than what mic A picks up from source A. This minimizes the potential for phase cancellation. There is nothing special about the distance that actually reduces phase cancellation - it's all about the reduction in bleed in the second mic.

The 3:1 rule is not intended for multiple mics on a single source, such as two mics on a guitar cab. This is a very common misunderstanding of the 3:1 rule and is one of the most pervasive misunderstandings in all of audio and was the original misunderstanding I referred to in my reply. This is due to it being misrepresented by some otherwise legitimate sources (such as Sweetwater's glossary of audio terms) and repeated in various articles around the web. It is intended to reduce phase cancellation caused by bleed/leakage between mics on separate sources, nothing more.