Standard mastering involves equalising and limiting a stereo file to get the optimum sound and dynamics.
This process can work very well. However, as the eq is being applied and the levels are being adjusted, sometimes previously unheard issues can arise. The instrumental part may sound perfect but this may make the vocal sound too sibilant (or vice versa).
Trying to duck the sibilance on the vocal on a stereo file will have an adverse effect on other instruments in that particular frequency range. In compensating for one aspect of the sound others are adversely affected. In days gone by there were only stereo masters at hand and recalling and remixing songs would be impossible to do due to the constraints of time and budget. This meant a compromise at the mastering stage … e.g. turning down the vocal sibilance less than the ideal amount so the other parts of the tune are not too badly affected.
Stem Mastering can solve this problem.Using the example above, just a separate instrumental and vocal file will allow the engineer to adjust the vocal precisely while leaving the instrumental file as intended. No annoying requests for the engineer to recall the mix when he was over it last week and now working on a new project.
This process can be refined even more with multiple stems. Ideally grouped drums, bass, synths, guitars, keyboards and vocals.
Using the stem mastering process leaves us with big advantages for editing. From the finished session we can edit parts separately, guaranteeing seamless joins and giving the flexibility to create any kind of edit we need. Radio, TV, Extended, Instrumentals, adverts and snippets.