One of the most mysterious aspects of the music making process is mastering. Thanks to a combination of misinformation and good old-fashioned misunderstanding, a number of myths surround the mastering process, so we'll try and dispelthem here, as well as talking you through the equipment, processes and knowledge which mastering engineers use to add the finishing touch to your tracks.

So, what exactly is mastering? Simply put, it's the process of taking a complete mix and preparing it for distribution. Historically, the mastering engineer's job related very closely to the vinyl record manufacturing process. Vinyl discs had certain limitations which meant that mastering engineers had to be careful to get the balance right in order to create discs which would be loud and have enough bass Without causing the needle to jump or grooves to wear prematurely.

The same general principles apply to modem distribution methods, albeit with slight differences. A good master nowadays will sound good on any playback system, will be loud while retaining dynamic range, will have a good balance between all parts of the frequency range and will sound, for want of a better word, finished. Let's take a look at how it's done.

If you thought that recording studios paid close attention to acoustics and high-quality equipment, mastering studios take it to the next level. Given that the mastering process acts as a final check on the quality or tracks already mixed m recording studios, it stands to reason that the playback equipment and acoustic treatment of the mastering suite should offer an even more neutral, revealing sound to ensure that the finished product is of the highest sound quality. Studio acoustics are of vital importance to a mastering suite, and no expense is spared to ensure that the space offers a flat, neutral frequency response and is free of excessive reverberation, room modes, standing waves and other acoustic nasties.

It should go without saying that the monitors themselves must be of the highest quality. Debate rages as to whether subwoofers are preferable to full-range systems, but whichever approach is chosen the playback system should be capable of delivering a neutral, uncolored reproduction of the full frequency range. In these digital days, D/A conversion is also crucially Important so that the monitors are fed with a high quality signal, as is AID conversion to print the finished master back to digital. Some mastering engineers still choose to print the finished master to a top quality track tape machine, although tape's declining popularity m the trading process is mirrored in mastering.

The most important and perhaps most underrated, pieces of the mastering puzzle are something we all possess but not all of us use to their full capabilities: our ears! In order to carry out the mastering process, it's essential that the mastering engineer has a well-developed ability to listen to music and analyze it closely. Luckily, the hearing can be trained - although it's not really in the scope of this short article to explain how to develop your critical listening and analytical hearing skills - don't be put off if you feel that you don't have so-called 'golden ears'. With hard work and careful training using a wide variety of recordings, just about anyone can learn how to use their ears to a high enough standard. As with so many aspects of music making and production, practice makes perfect.

So, what's involved in the process itself? Firstly, the mastering engineer listens to the track and assesses its characteristics and requirements, including overall EQ balance, dynamics and stereo width and balance. At this point, consider the fact that the mastering engineer might decide that the track needs absolutely nothing doing to it. Although this is often not the case, it's a good reminder of the fact that there are no rules as to what equipment should be used In the mastering process, what processing should be applied or what settings should be used. Anyone who tries to peddle sweeping generalizations about processing and settings should be viewed with a healthy dose of skepticism!

Once the mastering engineer has a good idea of what's required, the sound can be processed in order to achieve the desired results. Taking a look at the typical outboard equipment used in mastering studios will give us a good idea of the kind of adjustments t hat might be made. The tools of the mastering trade are very closely related to equipment commonly found in recording studios and used for tracking, producing and mixing. The most commonly used gear like EQs, compressors, expanders and limiters should need no introduction, although the versions used here tend to be mastering-grade equivalents, designed with the intention of offering features demanded by mastering engineers and also providing the highest possible sound quality. Digital or analogue versions of each tool may be used.

Accurate and precise EQ is crucial to the mastering process and various options are available, with many offering mastering friendly features such as linear phase response, linked stereo channels and discrete switched settings rather than continuously variable rotary controls. The classic Pultec EQ and Manley Massive Passive are de facto industry standards here. Compressors and expanders are typically used to control dynamic range but may also be used to add a subtle coloration to tracks. Units including the Manley Vari-Mu, Chandler LTD-2, Pendulum OCL-2 and classic Fairchild 670 offer a variety of different flavors, including valve and solid state operation plus VCA, FET and optical circuitry. For the more aggressive forms of 'loudness maximizer'-style limiting, Waves' L2 digital hardware limiter is the top dog.

Together, these tools carry out the most important parts of most mastering jobs. Other tasks may include fixing problems with elements of the mix, for example by applying noise reduction or widening the stereo image some cases, mastering engineers may so choose to employ multi-band compression in order to control the dynamics of separate frequency ranges individually. Ail-in-one digital mastering processors are also produced by various companies, offering every type of mastering tool in a single unit. Software equivalents of just about all mastering tools are now available thanks to the likes of iZotope's Ozone suite, IK Multimedia's T-RackS, TC Electronic's MD3 and Brainworx's suite of MIS tools. Many will argue that sound quality in some cases may not match the hardware equivalents, but the lower price and ease of use of the software approach has seen it rise in popularity over recent years. Unfortunately, software also has the unwanted side effect of encouraging the use of presets, an idea which would be met with derision by any mastering engineer worth their salt. Presets will not be involved and appropriate settings should be determined on a case-by-case basis, even when using software.

Although the mastering process usually runs along these lines, there are a few alternative techniques, which some engineers might use when they feel it's necessary and appropriate. The most common technique in this case is for the artist or producer to supply the mastering engineer with separate stem files for different sections of the track. This could be as simple as providing a stem of the vocals and a stem of the instrumental or may involve splitting the mixed version into three or four component parts, all with the levels matched so that they simply need summing together to create the desired mix balance. The aim is not for the mastering engineer to carry out the mixdown for you, but to allow more freedom and flexibility during mastering. Processing the fully mixed stereo file of a track may be satisfactory in the majority of cases, but the ability to adjust the balance of elements or process separate parts individually may be preferable in some circumstances. Bear in mind that there comes a point where a higher number of stems is less convenient, and mastering engineers will certainly not thank you for handing over a disc full of unmixed stems!

A less common technique still employed by some is the idea of creating different masters for distribution by different methods. This is a real bone of contention among the mastering fraternity, with most mastering engineers arguing that it shouldn't be necessary to produce versions with different characteristics, and that a good master is a good master regardless of how you intend to distribute it. If you really feel that your track needs special treatment, discuss it with your mastering engineer and they'll be able to offer you the best advice. A good understanding of the theory behind mastering should help, but in next article we'll take a look at the DIY options and explain how you can try mastering at home.