Audio mastering can improve and enhance a final mix and make it sound good on as many playback systems as possible, so start with as high a quality source file (wav files at 24-bit will be okay). Remove any master bus effects and turn down your master output so your highest peaks hit at around -4 to -6dBFS.
Now render out your final mix at the same sample rate as the entire project, and at less 24-bit quality.
Where to start
Begin mastering in a new project so you have more CPU power and flexibility – and so you don’t get sidetracked by tweaking the mix.
When mastering, it helps to A/B your current track against great-sounding commercial releases to help guide your processing decisions. However, commercial releases are usually already mastered right up to 0 dBFS. RMS meters give us a more accurate picture of average levels – closer to how our ears respond to loudness, so use these when leveling. Lastly, use your ears to get the right loudness balance, then route your reference tracks to a separate stereo output so they don’t get processed too.
A frequency analyzer (such as the Voxengo SPAN) is a fantastic tool to help you keep an eye on your track’s frequency content when mastering. A stereo meter also helps you monitor the stereo and phase information in your audio (you can check Digital Peak Meter Pro DPMP).
Run some commercial releases through them to get a feel for how things should look, but don’t rely on them too much – your ears are the best analyzers at your disposal.
When mastering, it’s vital to know your EQ plugins characteristics and features so you can apply the right tool in the correct situation. Some mastering EQs are transparently clean and precise, while others are modeled on analog circuitry and can add flavor and/or excitement to a sterile mix.
A linear phase EQ will avoid phase shifts and transient smearing, at the expense of pre-ringing. One isn’t better than another, remember, so knowing your EQ’s idiosyncratic personalities means you can adapt to each tone-shaping task. Check here some of the best Free EQ plugins that can be used for this job.
Parallel compression is popular in mixing, but it’s also highly effective for adding RMS weight to a final mix. By balancing a heavily compressed duplicate signal with your original, you can add weight and power, ‘filling the gaps’ to add solidity without crushing your mix.
Mastering is largely about transparency!
So, try distributing processing actions across several plugin stages to make their effect less obvious. If you need to EQ or compress, remember that ‘many hands means an easy job’.
A single EQ cut can sound more noticeable than two smaller cuts on either side of an offending area, especially when applied to an overall mix. Similarly, a single limiter causing 6dB of gain reduction may ‘overreact’, while three limiters applying 2dB of gain reduction each may not.
You can easily test your plugins to see if they add harmonic distortion and therefore, gauge their suitability in mastering situations.
Load a raw sine Wave onto an audio track, then drop a frequency analyzer on its track. You will be able to observe the sine’s single fundamental frequency with no upper harmonics present. If you then add the plugin you want to test (before the analyzer in the effect chain) then you’ll be able to see if your plugin is adding upper harmonics to the sine wave.
Although you have a single stereo file to master, you can actually process its Mid (mono) elements and Side (stereo) elements separately. Re-level, EQ and compress these parts independently to give you full control over the stereo image, enhancing or “reining” in width where desired.
When setting your limiter’s output ceiling, it’s easy to assume that the maximum 0dBFS limit will give you the best master possible. However the process of digital to analog conversion and MP3 exporting may cause clipping and errors when this ceiling is too high, so shoot for about -0.5dBFS.
If you’re overcooking your track with excessive EQ and compression when mastering, consider revisiting your mix project and treating only the individual elements that require it.
Mastering is a delicate process!
You want to gently enhance a piece of music, not smash it to smithereens. If you are looking for the best mastering plugins, we recommend you FabFilter Plugins.