What are stems? Stems are stereo recordings made from mixes of several individual tracks. For example, a drum stem is typically a stereo audio file that combines all drum tracks together (kicks, snares, claps, hi-hats, etc). In most cases, additional processing such as equalization, compression, and time-based effects are included to ensure the sound produced by the DAW is accurate.
Stems can be thought of simply as tracks from a final mix that have been isolated as their own stereo mix. These stems can then be combined in parallel and with the same starting point to create a similar version of the main stereo mix, but with minor changes as needed. It has always been common in film and post-production to work with stems – elements of the final mix that have been broken down into various subsets: dialogue, music, sound effects, background noise, and the like are all exported as surround or stereo tracks to facilitate mixing of the film to facilitate.
This allows control over the sound without having to control hundreds or thousands of tracks.
Why are stems useful?
Stems are useful for a variety of reasons. Stems are used in audio mastering to save time and money for the customer. Using stems saves the audio engineer from making small changes to the mix, thus saving time and production costs. For example, a common problem is that the vocals can be a little quieter in relation to the mix. When stems are provided, it’s easy to address them without having to ask the audio engineer to make changes to the mix.
Stems are also very useful for archiving mixes. As an audio engineer, when you’ve come to the end of a large project, you can create stems for the archive so that you don’t have to reopen the entire mix project and recreate the effects chains and every other configuration you used for the mix have to put together. By using stems that contain all of the original processing, you gain a great deal of flexibility. The other benefit is that by creating Stems, the archive files can be opened and reassembled in any DAW in the future.
Also read: Preparing a Track for Mastering
The difference between stem mixing and stem mastering
Stem mixing means looking for a more affordable audio mixing option. Sending a full set of tracks to an audio engineer that has not been edited would require a significant investment, so sending a smaller set of stems can save a lot of money. The more stems you provide, the more control the audio engineer has over the quality of the mix.
Stem mastering is often confused with stem mixing. Just like stereo audio mastering, stem mastering is much more subtle than stem mixing. It’s more of a quality assurance process where level adjustments are made between stems only for quality reasons (e.g. the vocal sits slightly lower than the rest of the mix). A mastering engineer will not typically make any obvious processing adjustments (dramatic EQ adjustments, heavy distortion, or obvious reverb, chorus, or other effects) as this is essentially a mixing task and not a quality assurance task.