A compressor is an electronic sound processor designed to reduce the dynamic range of the signal. All pedal compressor can be used as a limiter. However, in rack format and mixing and mastering we can find these separate effects. In the world of the guitar, it is very unusual to find a pedal that only limits. Always we discuss compressors. A compressor acts, so that attenuates the electric signal in a certain amount (typically measured in decibels) and from a given input level.