Manuel's here from masteryourtrack.com
Working with many independent producers I have noticed that sometimes there is a bit of confusion about the differences between Stereo and Stem Mastering.
In this article, I'm going to explore the signalflow of these to way of processing the audio when mastering.
Hope this can be helpful.
For this article, I've taken some screenshot of Logic Pro X only for the purpose of explaining the signal flow of the two types of mastering. The same signal flow can be reproduced with any software and hardware.
What's the difference betwen Stereo and Stem Mastering?
From the mastering engineer point of view, the real difference between stereo and stem mastering is the signal flow and the flexibility.
Let's start from the beginning
Mastering is the final step of the music production process. At this stage the mastering engineer will look after the final polishing of the song, correcting some minor problems if needed, applying an overall enhancement to the song and get it ready for the distribution.
When a client provides the L+R mixdown (one stereo file) we talk about stereo mastering.
When instead the client provides multiple stems, we talk about stem mastering.
But...what are stems?
As I've explained in the article STEM MASTERING: HOW TO PREPARE THE STEMS stems are multiple stereo tracks containing consolidated groups of instruments of the same mix. In this article, I've also talked about when you should go for stem mastering and how a mix can benefit from it (it might worth to have a read).
Stereo Mastering Signal Flow
From the stereo mixdown, the mastering engineer will apply his/her mastering chain. This can be digital, analogue or a mix of both. Usually, this process includes equalisation, compression and limiting, but can also include other kinds of precesses like saturation, multiband compression, mid-side processing, etc.
Stem Mastering Signal Flow
Providing different stems will allow the mastering engineer to work more in detail. In fact before going to the main mastering chain, s/he'll be able (if needed) to work on each stem to improve at a deeper level some aspect of the mix like the intelligibility, depth, frequency distribution and the dynamic.
At this level is also easier to fix problems like muddines ore resonances for instance. The mastering engineer, in fact, can work only on the problematic groups of instruments leaving the rest unchanged. The overall texture, glue and enhancement are then applied to the main mastering chain.
As you can imagine, stem mastering is more expensive but also give much more flexibility and ability to work on a deeper level. That said if you have a good mix there is no reason to go for the stem mastering and a common stereo mastering process will do the job excellently. On the other hand, if you are not 100% sure of your mix and you feel it can be improved at the mastering stage it worth to talk with your mastering engineer and discuss with him the possibility of stem mastering.
I hope this article clarified some doubt about stereo and stem mastering.