Compressors / Limiters: A compressor is a device that reduces the dynamic range of program material. This is useful in the case of vocals or an instrument that changes from low levels to very high levels. Reducing the dynamic range causes the high levels to be reduced, which prevents distortion and makes it easier for you to set optimum levels. Properly applied compression allows an instrument or vocal to “sit” better in the mix and allows for louder average levels and punchier-sounding mixes.  A limiter stops the output of a signal path from exceeding a predetermined level.