They’d like to know in particular when a bus compressor must be applied. Without doubt in most cases it should be first included into the chain as it can insure to get more density of an audio and suppression of peaks without breaking disbalance. Consequently, it also insures more perceived loudness of the finalized project.
Nevertheless, there are situations when it isn’t first in the chain. The simplest situation is when the professional audio mastering engineer isn’t satisfied with the first step of compression and he makes up his mind to apply batch processing, one plugin of dynamic processing after another. Instead of the first step a limiter can be used as a version to cut hard all the peaks whereas the track sound is being compressed by the compressor put second. Any version is much more preferable than the attempt to level the dynamics of the track with too large peaks by one dynamics processor with higher reduction aggressiveness.
4. How far important is right setting?
Subtlety is a key concept during bus compressor adjustments. The engineer’s work is to select numbers so that after processing the sound will be as transparent as possible without a sign of an applied dynamics reduction.
Let’s keep in mind that mastering engineering is utterly focused on careful and gradual sound polishing of separate instruments and the whole track. This is the essence of the process when step by step you’re approaching perfectly balanced sound at the stage of track release from your mastering service. Disregard of this rule and the use of overaggressive settings during master channel compression don’t look promising and can bring on pumping effect and other artifacts.
To start with selecting ratio and threshold settings will be much better. Transparency and original natural character of a song are important to us and what mastering services clients expect for. So select a small term of ratio and set threshold so that the compressor hardly brushes peaks. In this case gain reduction will be the smallest and without any audible signs of interference with song dynamics - just like in mastering demos available on this website.