PSP Impressor is an incredibly accurate, full-featured, high-precision compressor designed to process entire mixes, buses or individual tracks. PSP Impressor emulates the magical classic characteristics of valve and optoelectronic compressors, as well as classic modern compressors. PSP Impressor also has an easily customizable side-chain. The side-chain filter has a significant impact on the sound and operation of PSP Impressor. Depending on the sidechain filter settings, the filter also allows the compressor to be used as a de-esser or to reduce the pumping effects of heavy bass drums and the like.