Stem Mastering (stereo mastering from group tracks)
Stem mastering introduces another step in the process, which is actually more a part of mixing than mastering. Mixing up to 8 "level-correct" stereo groups such as lead vocals, background vocals, drums, bass, and other instruments, called stems, is recommended when the computer-internal mix conditions lack high-quality DSP resources for good compressors and high-end reverb, which would result in a mix lacking in power and depth. The individual groups should be exported or rendered with the levels they have within the mix so that the mastering engineer only needs to put all levels at 0dB to have exactly the same mix that the mix engineer has. The point of departure for the group tracks should therefore be 100% identical. In order to avoid errors, a stereo mixdown can be delivered for reasons of comparison.
This way of working has tremendous advantages for the end result, but also has some hidden dangers: Combining the mixing and mastering processes along with different listening and working methods (see Audio Mastering book) can lead to unsatisfactory results. I counter this problem by planning the mixing and mastering sessions on two separate workdays. The mixing session is carried out in Nuendo or Cubase, whereas I turn to the tried and tested WaveLab workflow for the mastering process.
- "Level-corrected" group tracks as stereo-interleaved files with identical starting point (stems).
- Stereo mixdown file for comparison
- read Tips for delivering files for mastering.pdf