Stem Mastering – Part 1: Definition and Operating Principles(Letto 32 volte)

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Stem Mastering

We could also call it Multi Track Mastering and define it as a cross between a simplified mix and the more common Single Track Mastering.

Instead of manipulating a single stereo mix, we will also use various tracks of sound sources into which the mix has been divided.

This process is certainly not a cure-all, but it can be decisive in many cases where single-track mastering fails to produce satisfactory results. For example:

• volume errors attributable to soloists or other “critical” sources”
• tonal imbalances of one or more sources in comparison with the tonal context of the entire mix
• soloists too compressed
• distorted tracks
• others

A competent mixing engineer will now provide a number of stems to accompany the mix, which they deem to be useful in case of need.

If you do not do so, it would still be advisable to make yourself available in case of request.

In this case, after carefully analysing the mix, the mastering engineer will decide which additional tracks to request from the mixing engineer.

The division into tracks will allow for some additional corrective measures that cannot be performed in single track mastering, offering greater scope for correction of any imbalances.

The mastering engineer will thus have the opportunity to tweak certain sound elements (volume, equalisation, compression, effects) should the need arise during the mastering process.

Addition and subtraction

Each stem can be used additively or subtractively with respect to the complete mix.

In order to ensure the correctness of the following processes and obtain maximum effectiveness from them, it is absolutely essential to verify that the DAW is perfectly correcting the latencies induced by the filters that will be installed on the tracks during the mastering process. This is important for additive processes but even more so for subtractive ones.

Additive use of a stem

To increase the volume of a source in the mix, you must:

1. In the DAW, place the mix on the mastering session timeline; set the mix track volume to 0 dB (Unity Gain).
2. in another track, place the stem corresponding to the source we want to highlight in parallel; keep the volume of this track completely turned down
3. raise the volume of the stem referred to in point 2 as much as necessary to obtain the desired degree of prominence of the source

Subtractive use of a stem

To decrease the volume of a source in the mix, you must: 

1. In the DAW, place the mix on the mastering session timeline; set the mix track volume to 0 dB (Unity Gain).
2. in another track, place the stem corresponding to the source we intend to attenuate in parallel; keep the volume of this track completely turned down;
3. reverse the polarity of the track itself (the polarity reversal command, when not available directly on the track, is generally offered by a gain or EQ plugin that can be installed on the track itself)
4. raise the volume of the stem referred to in point 2 as much as necessary to achieve the desired degree of attenuation of the source

I use “Post Subtractive Additive” through two identical stems.

After subtractive use at the maximum level (i.e., giving the stem a volume of 0 dB, causing the total cancellation of the source involved), it will be possible to re-enter the same source into another track (this time without inverting its polarity) in order to mix it from scratch with the possibility of filtering it independently with tonal, dynamic, and ambient processes.

Note

Of course, there are many other observations on the stem mastering process, which will be discussed in a subsequent article.

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The topic continues in a second article entitled: Stem Mastering - Part 2: Selecting and Exporting Stems

 

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For more information on Digital Audio Mastering