Getting Started With Mastering and EQ

At some point in your musical career, you may begin to wonder exactly why the CD of your favourite band just sounds so much better than the demo you recorded in your local studio. Some of this may be down to musicianship, extremely expensive instruments and high-end recording equipment, but a lot of it can be due to the expertise of a professional mastering and EQ engineer.

What is Audio Mastering?

Mastering is the process of taking a finished recording and adding the final sonic garnish to it. Mastering is not a way to compensate for a bad mix – if your mix isn’t right, then you shouldn’t be thinking about mastering yet. Actually, you should be thinking about it – you just shouldn’t be doing it. The art of creating a balanced musical recording involves placing each sound in its own place in the mix, so that everything sits together nicely and nothing is fighting for air. Each instrument will have a particular frequency range where it is dominant, and if two sounds share the same frequency range then they will interfere with each other, creating a muddy mess.

To fix this, you can use equalisation to change the frequency balance of one or both of these instruments, and/or you could pan them left or right – creating more space for them to co-exist. The act of increasing a particular frequency is known as boosting, and reducing it is called cutting. As a general rule, it is better to achieve your goal using cutting rather than boosting, if possible. This will give your overall recording more headroom.

Mastering From The Start

Songwriting, recording, mixing, mastering and EQ should ideally all be performed with the end result in mind. If a song is composed entirely of instruments operating between 30 and 300Hz, then it may be very difficult to make it sound balanced. However, if you have a recording which almost sounds great, an experienced sound engineer may be able to immediately identify that the rhythm guitar needs a cut at 612Hz to clean it up – and suddenly the whole track takes off.

Compressors and limiters are two devices that you will hear a lot about in the world of sound manipulation. A compressor basically takes an audio signal and squashes it so that the loudest and quietest parts of the signal are closer together in apparent loudness. How it does this can be controlled by the compression ratio, attack time and decay/release time. A limiter prevents the signal from going over 0dB, or clipping. Some limiters have a feature which introduces a mild, pleasant distortion to clipping signals – this is known as ‘soft clipping’. A ‘brickwall’ limiter stops anything from going over 0dB.

Learn More About Mastering

For some good introductory reading, try Vespers’ guides to bass, mixing, panning and equalisation. More excellent advice can be found in Tweak’s guides to EQ and mastering.

Bob Katz is a legendary sound guru and author of “Mastering Audio: the art and the science“. For some snippets of wisdom, check out his articles on audio at digido.

