Let’s take a look at the controls you’ll find on most compressor plugins.

Threshold - this determines the volume level (in dB) that a sound must attain before the compressor takes effect. When this level is exceeded the signal is reduced (gain reduction).

Ratio - this control determines the amount of gain reduction applied to the signal once the compressor has kicked in. A Ratio setting of 1:1 would mean that no gain reduction would be applied, where as a setting of infinity:1 would mean that the signal would never rise about the Threshold level (this is known as Limiting).

Attack – this control dictates the time that the compressor takes to reduce the gain. Fast attack times will reduce the gain immediately where as slow attack times will leave the first portion of the sound untouched fading the gain reduction in. This is a classic technique used to enhance the qualities of percussive sounds.

Release – this setting will determine the length of time that it takes the compressor‘s gain to return to normal once the signal has fallen below the Threshold setting.

Some compressors have an Auto attack/release button that selects suitable settings for the incoming sound.

Hard Knee/ Soft Knee – this control dictates the character of the compression used, a Hard Knee setting will instantly apply the full amount of gain reduction to the signal once it has exceeded the Threshold. Soft Knee will allow the effect of the compressor to be more gradual.

Side Chain – this function allows you to use an external signal to control the compressor. This effect is frequently used in dance music. For example producers will often feed the bass part from a song into a compressor whilst routing the kick drum sound through the compressors side chain input. This will have the effect of "ducking" the bass sound when the kick drum plays, producing a rhythmic pumping effect.

Many plugin compressors lack character and sometimes it’s hard to hear the effect they’re having. For instant gratification download Camel Audio’s excellent free plugin “Camel Crusher”. Disable the filter and distortion buttons and route a sound through the plugin. Now turn the Amount control up and notice the effect! We love using this plugin on bass lines and in tune with other Camel products it has an randomize buttom!

See our glossary section for explanations of many music technology terms.  

DMS