There are many different types of compressors that can be used for music production. Each hardware or software version implements 4 fundamental controls that can help you shape the sound. These are:
Set in decibels, the Threshold controls when a compressor should be activated. As soon as part of the signal exceeds the Threshold value, the compressor begins to reduce the gain according to the Attack, Release & Ratio settings.
The Attack control on a compressor affects the leading transient of the sound. It essentially determines how long the compressor will take to reach the maximum amount of gain reduction.
A fast Attack will start to compress the sound very early. This is helpful for controlling sound that may contain unwanted loud spikes in volume. Using a fast attack means the compressor will clamp down immediately on any part of the signal that exceeds the Threshold.
As many high frequencies are contained in the initial transient of a signal, using a fast attack can sometimes reduce these frequencies to the point where the sound becomes dull. This is particularly problematic if you are working with a very bright lead instrument that requires dynamic control. By increasing the Attack time, you should be able to find a balance between reacting to rapid changes in dynamics and preserving the transient of the signal.
The Release control determines how long it takes for a sound to return to its pre-compressed level after it drops down past the Threshold. If set too fast, the sound will immediately bounce back to the listener after compression, which can often result in an unpleasant gain pumping effect. In some types of music, introducing a pumping effect is actually desired (eg. Dance), but if not controlled correctly with the Release setting, it can often sound very unnatural and fatiguing to the ear.
They key is to find a Release time that works in tandem with the chosen Attack setting, so that any dynamic change that is imparted on the sound maintains or compliments the groove of the track.
Ratio controls the actual amount of gain reduction that occurs when a signal exceeds the Threshold.
A Ratio of 6:1 means that for every time the signal exceeds the Threshold by 6dB, the compressor allows an actual output increase of 1dB. The higher the Ratio setting, the more the compressor will squash the sound and hence impart firmer control. Lower Ratio settings typically result in a larger sound, however there is a risk that not enough dynamic control will be applied.
The author is a Progressive House DJ and Producer.
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