Atmos mixing happens primarily from a couple of different sources:
From the multitrack, meaning all the tracks on your project, separately, with the processing (EQ, compression, etc.) baked-in, or not
OR
From stereo stems, which means, separate stereo mix-downs of just your vocals (with or without effects), just your guitars, just your keyboards, just your drums, just your effects, etc.
The more stereo stems the better. For example, you could have all the guitars in one stem,
OR
the “clean” rhythm guitars in one, the “dirty” rhythm guitars on another, the lead guitar on a different one, and so forth.
Multitracks provide the best mixing results since the mix can be constructed without any creative limitations on placement of objects in the 3D sound field. For example, you send us a stereo guitar stem we can only do so much, but when you send us each guitar, say you have 12 guitar tracks, separately then we can do so much more. Makes sense, right? The mix costs more though since it is more detailed and takes more time and effort.
Stems, 10-15 Stereo, are what’s used more often and they are the most cost-effective way to get an Atmos (or other immersive formats such as Auro-3D, or Eclipsa Audio for YouTube) mix.
EXPORTING
Exporting stereo stems of your project for Atmos mixing can be done in a few different ways but they all depend on the DAW you use.
There are many videos on YouTube that cover all DAWs. Here’s ours on how to export stems in Logic Pro:
