While mixing focuses on making an individual tune the best it can be, mastering focuses on the CD as a whole and how the individual songs interact. When you listen to a poorly mastered CD, you may find yourself on a roller coaster with each song approached in a different way. It may sound as though the music were recorded by different bands, or by the same band but in different locations, or with different sound engineers putting different effects on each of the tunes.
The production of a CD incorporates the blending of two different ideals. One ideal is trying to make each tune different to vary the palette of the listening experience. Much of this effort is done in the mixing process. The second ideal is trying to maintain a sound that is representative of the artist across the CD. Is there a continuity of sound across the CD? Can the CD be approached as a whole, or is it just a collection of random songs? I can remember listening to a CD that was tracked and mixed at three different locations, at three different times, with three different mix approaches. The CD sounded like three different CDs patched together.
The mastering process involves a number of variables, such as…
- Volume. There needs to be continuity of volume on a CD. An example of poor mastering (on purpose) is when you are watching television and are blasted out when a commercial comes on. When listening to a CD you do not want to be blasted out. Some songs are going to be quieter by nature, but you want them all to be within a range.
- Continuity of sound. Is the same instrument EQed in a similar way across the CD? This does not mean there are not some differences from song to song, but that there is a recognizable sound across the CD. Does the bass have the same relative strength on each tune?
- Continuity of structure. The gap between songs should be consistent, for example. In addition, the CD should meet RedBook standards. RedBook remains the gold standard regarding precisely how audio is written to a disc. Basically, all music CDs are RedBook discs. [ More on RedBook ]
- Effects. Are effects such as reverb and compression consistent throughout the project? Reverb, for example, can provide the background sound that one hears when listening to a CD; when consistent, it should sound as though all the songs on the CD were recorded at the same location, in the same environment, under the same conditions. In acoustic CDs, reverb is often added to produce a more natural sound. Often the studio room is dampened for sound, and the natural reverb you normally hear is added as desired. Compression provides volume control, keeping a track from getting too loud, while cutting back on that track will also boost sounds that are under the cut-off. This allows a tune to be played louder without distortion and have a richer, warmer sound.
- Tune lineup. There are a number of rules of thumb when it comes to song order. It seems best to separate songs of similar tempo. In most cases, varying the tunes of tempo provides an experience that keeps the listener from getting stuck. It’s best to separate tunes played in the same key. Often, tunes in the same key will play similar notes and deliver a similar listening experience, even with very different melody lines. One should also separate song focus in the same range; songs played in the highest range of the instrument or vocals provide a similar experience. We also like to separate songs that are of the same genre; for example, putting all the the Celtic songs together might make the listening experience seem repetitive. The key is to make the listening experience fresh and variable, not boring and repetitive.
- Editing. Editing is the removal of all unwanted sounds, buzzes, clicks, and the like.
- Cleaning up fades and intros.
So, one of the goals of mastering is to provide a continuity of sound throughout a CD. This is the process of looking at the CD as a whole and making sure the listening experience is fresh while still having some sense of the project as a whole.
During this process of these articles, I have approached tracking, mixing, and mastering as three separate processes. In reality, there are aspects of each process in each of the others. Different sound engineers will often focus on aspects in an order that works for them. Our sound engineer works on the the EQ right after the tracking, attempting to get as pure a sound as possible while the music is still fresh in his mind. One bit of advice I have from my limited experience is to have a concept of what you are attempting to do in the recording and try to focus on that goal while in the process of tracking, mixing, and mastering.
Resources: The art of mastering in music production
There are number of excellent resources for those interested in learning more about mastering. These resources will take you much farther into the whole recording process and can provide you with lots of useful information.
- The Berklee School of Music has a website with both webinars and technical information.
- Another excellent source for knowledge on all aspects of recording is the online recording magazine Sound on Sound (which we’ve mentioned before and will likely mention again). [ Preparing Your Music For Mastering – Sound On Sound ]
- Another source of wisdom for all aspects of recording is British music engineer Ian Shepherd’s Production Advice website. [ How to master your own music: The basics – Production Advice ]
- Audio mastering – Wikipedia