Sometimes frequency analysers can be used in mastering. Of course your ears should be the ultimate decision maker, but an analyser can be useful as a ‘second opinion’. It can help sway you one way or another if you’re unsure about something.
There are, however, some issues to keep in mind when using frequency analysers when mastering:
- There are differences between analysers. Different analysers have different options and defaults for frequency tilt, time constants, resolution, etc. What one analyser shows as a straight line may look like a gradual rolloff on another. One analyser might show show short-term peaks differently to average level, whereas another might only show the peaks, and yet another might smooth everything out to show only averages. Configurations options might appear similar in some cases, but it can be difficult to know exactly how they’re implemented ‘behind the scenes’. Solution: If you’re going to use a frequency analyser (or, really, any kind of analyser) make sure you pick one and don’t use any others. Get to know how it responds to different signals. Don’t get distracted by comparing its readings to the readings from other analysers.
- There are differences between songs. Just because your reference song has a certain shape in a frequency analyser, it doesn’t mean your song must have the same shape. Different voicings and dynamic behaviour will cause two songs to sound different with the ‘same’ frequency balance, and sound the same with a different frequency balance. Further, non-technical aspects of music (such as structure, pace, harmony, etc) will also have an impact on how the audio sounds, which affects the frequency balance that is required in order for the song to sound balanced. Solution: Recognise that frequency analysers only measure some technical aspects of audio, and that music is much more than what can be revealed by a frequency analyser. The analyser is not a source of truth.
Ultimately, the only ‘analyser’ you should trust is your ears. Your tools can be helpful in some situations, but only if you understand their limitations.