Basic mastering involves the changing of the sound wave using normalization, top and tailing, master equalization and loudness maximization.
Master for a Reason
Always master with purpose. Don't simply complete a process out of habit. Over-processing can destroy a mix. Remember that mastering is not a matter of applying a blanket set of rules. Treat each song as unique and work to optimize its own set of qualities.
A song that is clipping/distorting can never be fixed in the mastering process.
To master effectively, suitable equipment and a proper listening environment are required. Factors to consider include:
- Decent monitor speakers, including proper positioning
- An appropriate monitoring output level
- A reference track to compare your material against
- Where possible, an acoustically treated space
- Tools for the job - equalizer, compressor/limiter, exciter and anything else at your disposal
Master Equalization Technique
Adding equalization can mean the difference between a good and a great song.
- Use gentle, broad-stroke adjustments to help subtly change the perception of dynamics and loudness of the track. The goal is to make the sound better without it sounding like it’s been equalized
- Isolate any problem frequency by scanning the entire audio spectrum with a narrow bandwidth and cut any problem frequencies.
When equalizing, be sure to change the output of the gain to balance the loudness when A/B-ing its effect on the audio. If you don’t, your ear’s bias towards the louder version which will impair your judgment on the EQ curve you have applied.
Sometimes you have to accept that fixing something is beyond the scope of the mastering process; trying too hard to solve them can cause as many problems as you solve.
In order to make the track louder and give it more punch, it's important to apply loudness maximization (compression and limiting) to bring the overall average level up - the perceived volume of a song lies in its RMS (average) power and not its peak to peak power.
Not all music needs loudness maximization.
To achieve a louder sound, it is possible to add multi-band compression, which uses different amounts of compression across different frequency bands; usually the bass, mid-range, and treble.
There are many plugins and software packages that allow you to maximize the loudness using a couple of simple controls. Usually, there is a threshold and output ceiling.
While the threshold is lowered the volume of the song will increase. The output ceiling is usually set to 0dB or just under. If the threshold position is lowered too much, distortion will become apparent. It's all about finding the sweet spot; a decent increase in loudness without distortion.
How loud to go is of much debate between both amateur and professional producers alike. Use your instincts, listen to other similar-sounding songs, and, whatever you do, don't squeeze the life out of it by over-processing your master.