Compressors/Limiters - TREHB Ch.3

Compressors/Limiters

Compression
To change the tonal qualities of a sound/even level

Limiting
Control of dynamics to prevent overloads

Primary Controls

Threshold
- Sets the point (Db) at which automatic gain reduction (GR) is triggered

Attack Time
- Determines the time taken for the unit to respond to the threshold breach. Too slow and overloads may still breakthrough. Fast attack times guarantee overloads are kept at bay.

Release Time 
- Determines the time taken to return the volume to its nominal level. Setting release time to a fast response will give an audible motion to the sound, an on/off effect referred to as 'pumping' or 'breathing'
- Setting release time to a longer duration eliminates this movement/near oscillation sensation

Compression Ratio
- Determines the amount of compression that will occur
e.g. a 1:1 ratio will produce no effect
      a 2:1 - for every to 2Db beyond the threshold, the compressor will only increase output by 1Db
      a 10:1 - for every 10Db beyond the threshold, the compressor will only increase output by 1Db

Breach of threshold > 10:1 < resultant output increase
                                   (Db)
Setup 

Ratios of 2:1-9:1 are considered compression, as they keep level even and produce tonal adjustments
Ratios of 10:1 + are considered limiting and serve predominantly for dynamics control and overload prevention

Outstanding examples : Vintage