Mastering is the very final stage of processing that your music should go through. After mastering, it should be ready to be released to the outside world. It’s also the answer to the question that is often asked: “Why don't my tracks sound as loud as tracks I hear on CD or on the radio”? Leaving aside the fact that many commercial tracks have huge amounts of money spent on them, the main difference is that they have been mastered, and your tracks may not have been.
Mastering shouldn’t be confused with mixing, since the two are very different processes. Mixing is the technique of balancing every element of a piece of music, every track and channel so that everything sits together as well as it can. At the mixing stage you're not worrying too much about the overall punch and loudness of the track but rather whether it sounds like everything is well matched in terms of relative levels, EQ and effects. Mastering is something that is performed across a stereo mixdown – a whole file, not individual tracks. As such your mix needs to be as good as it can be before you go to the mastering stage. Some people think that you can ‘fix’ a bad mix by mastering and while you can certainly make changes, it’s a far better idea to fix the mix at the mix stage, going back and doing it again if necessary.
Mastering is about tweaking and sweetening the sound of the whole track, and applying compression, limiting and possibly even stereo widening to give it a ‘radio-ready’ sound. Your music will be played on an ever-expanding list of devices from CD to car stereos, iPods, FM radio and more, so it’s important to try to achieve a consistency across these devices. This is the holy grail of mastering. As ever, it’s important not to go overboard, as too much processing is even worse than not enough. And although professional mastering facilities produce great results, they also cost a lot of money. The great news is that today, with just a little practice, you can create excellent masters using specialised plug-ins and applications in your own studio.
Why master with software?
Studios historically used hardware for mastering, but for many people this is simply impractical. Apart from the cost, hardware uses space and if you are working mainly inside a DAW, it’s better to avoid lots of external cabling and mixing desks unless you already happen to have it to hand.
Like any software instrument or effect, mastering software uses no space and can travel with you wherever your laptop goes. They can also store presets, a feature that's uncommon in hardware effects units, and enable you to A/B and test different mastering treatments at the click of a mouse. Software is easily updated or modified, and you can use multiple instances with different settings, which is impossible with hardware. As mastering usually involves multiple processing stages, software is able to take advantage of the multi-core, high-spec computers that many producers run, as well as up-to-the minute technology such as 64-bit.
Mastering software requirements
Some mastering applications are 'suites', with multiple stages carrying out separate processing tasks. Others are plug-ins or applications that let you load chains of plug-ins to achieve the same thing.
There are some ubiquitous processing tasks that are key to any mastering activity; the first is compression, and this is used gently to even out the dynamics of the stereo mixdown track. Compression makes quiet parts louder and loud parts quieter. Used carefully it creates a nice even track with no unexpected peaks in volume or conversely, inaudibly quiet sections. Some mastering tools allow multiband compression, which is able to selectively compress different frequency bands using different amounts of compression.
EQ is also a key process in mastering, used to carefully draw out or damp down specific frequencies across the whole track. The idea is that you can sweeten the overall sound using gentle applications of EQ. If you’re having to make dramatic EQ changes during mastering, your mix probably isn’t right.
Limiting is the process of driving a track’s input gain, while leaving its output level at or very fractionally below 0dB. This 'squeezes' the level so your sound is bigger, louder and punchier, but never clips by going above 0dB. Limiting should be used carefully, since too much of it is very tiring on the listener’s ears. An over-limited track can sound 'crushed' with no dynamic range left, which is not a good thing.
Some people also like to use a little stereo widening during mastering, though this should be approached with care since too much can totally unfocus your sound and adversely affect the mix. All bottom end, for example, should sit firmly in the centre of the stereo field, though it’s OK to widen the top end a little in some cases.
Plug-in or app
There are two main kinds of mastering software: plug-ins and applications. Steinberg’s Wavelab comes in a variety of flavours to suit your budget and is a whole audio editing environment with advanced analysis and processing tools. It even has CD burning capabilities, and bigger versions included things like DVD-Audio authoring, video track support, Red Book CD mastering standards and multi-channel and surround support.
Wavelab also includes an Audio Montage feature that lets you overlap and blend tracks for more creative track listings. Also featured are a number of Steinberg’s own dedicated mastering plug-ins that you can mix and match to create your masters, as well as a range of spectral analysis views and tools so you can really get the lowdown on what’s going on in your music.
IK Multimedia’s T-RackS 3 Deluxe is a rather different proposition, and is a standalone app with modules that also work as plug-ins inside your DAW. You can load up to twelve processors from a selection of nine available models, mixing and matching. There are also a range of compressors, EQs and limiters on offer as well as advanced analysis tools, including one that helps you master appropriately to specific styles of music. You can create playlists of files for your album then apply presets to them, auditioning them as you go to see which work best.