Low thresholds and high ratios give you more gain reduction, i.e.
The amount of compression is based on a relationship between the threshold and the ratio. In this graph a 45 o line represents equal input and output levels, ie no compression (1:1) ratio. (NB if the ratio is set as high as possible, usually infinity:1, the signal above the threshold is reduced to practically the same as the threshold and is referred to as LIMITING.
If the ratio is set at 2:1 the signal above the threshold is reduced to half its original, if the ratio is set to 5:1 the signal above the threshold is reduced to one fifth of its original.
The amount of reduction is relative to the level of the signal and expressed as a RATIO. Any parts of the signal louder than a certain THRESHOLD are reduced. (Don’t confuse this with file compression, which is used to make a computer file smaller). The aim of a compressor in recording is to reduce the range of dynamics of an audio signal.
