CD mastering is the process of taking a song or audio file, editing out the bad bits and increasing the quality of the good bits! It is generally done by professional editors as it is a very complicated and technically advanced process involving editing each individual layer of the song. Mastering a CD can make a good song into a great one, giving you a final master CD that is ready to be sent off for duplication!
Generally, CD mastering takes place in three main stages:
Assembly Editing – This is the stage at which the layers of the track are aligned with one another. The technician will place proper spacing between the cuts and ensure that the song plays through with perfect timing. The places where you tend to get most noises, pops and clicks, the beginning and end of each cut, are generally faded so that the flaws cannot be heard, and any other unintentional sounds are also removed. The different layers can also be cross-faded, to create a marvelous disc ready for printing.
Sweetening – In this stage, the layers of the track are enhanced with special effects. You can apply echo, reverb, and many other effects to the song to make it sound just that bit better. This improving of sound, making the song sound more perfect than perhaps it really was, is known as ‘sweetening’. Many famous pop artists have been criticised for the degree to which the ‘sweeten’ their songs until their voices don’t actually sound like their real voices, but generally technicians only sweeten to a sensible level.
Output – Depending here on whether you are duplicating or replicating, this final process involves two different things. If duplicating, the technician produces a final CD-ROM copy of the disc which can then be played on a normal CD player. However, if replicating, a glass master disc must be created, which can be used on the replication machines almost as a stencil for further copies. The final mastered version of the song if usually ‘auditioned’ for the client to ensure they approve of the sound created.
Because of the high levels of technical knowledge involved in mastering a CD, it is generally advisable to get a professional company to do it for you. However, many disc duplication companies provide mastering as a part of their service, so you can master and duplicate all at the same time!