• Music Mastering Toolsaudio producer image by Alfonso d"Agostino from Fotolia.com
  
  When mastering music, the primary goal is to adjust the sonic characteristics of the content to achieve a final product that sounds good wherever it's played back. The secondary goal is to boost the level of the content to achieve a "commercial" volume level. Mastering is best left to an experienced mastering engineer with a trained set of ears. However, when this is not possible, understanding the tools that they use is important when attempting to master your own music.
  
  

Equalizer

• An equalizer is used as a mastering tool in order to shape the overall spectrum of frequencies that make up the final mix of music being mastered. In mastering, equalizers are used to make subtle changes to the sonic characteristics of the music. This is accomplished by boosting frequencies by only a decibel or two in one area and cutting frequencies by a decibel or two in another area. When equalizing during mastering it is important to use a small "Q", or bandwidth, to boost or cut frequencies. This will ensure that the equalization adjustments sound transparent. A high "Q" of 10 or more will boost or cut a small bandwidth of frequencies that spans only a few hertz, whereas a small "Q" of 1 or below will boost or cut a large bandwidth of frequencies that spans a few hundred hertz.
  
  

Compressor

• When mastering, applying a compressor to the final stereo mix of music can act as the glue that holds the individual elements of the mix together. When using a compressor for mastering, the goal is to make the compressor sound transparent. To do this, adjust the compression ratio so that it is somewhere between 1.25-to-1 and 4-to-1. Then set the compressor's attack and release time so that the compressor smoothly turns on and off while compressing the music that you are mastering. After adjusting the attack and release times, adjust the compressor's threshold so that you achieve approximately 2 decibels of gain reduction. Then adjust the output gain of the compressor to make up for the volume lost in gain reduction.
  
  

Limiter

• A limiter is often inserted into a mastering chain in order to "limit" the levels of the music content from going over a certain level and peaking---which would cause unwanted distortion. A limiter is also used to maximize the volume levels of a recording. This is done by increasing the overall level of the music while limiting the peaks from going over the limiter's set peak level. Achieving a gain reduction level of 2 to 5 decibels will usually result in transparent sounding results when using a limiter for mastering.