Parallel compression, sometimes called New York compression, is a mixing technique that combines an unprocessed (dry) signal with a duplicate that has been heavily compressed. The compressed signal brings up quieter details, while the dry signal preserves transient integrity and natural dynamics. This creates a fuller, more energetic sound without the pumping artefacts of traditional compression.
It is commonly applied to drums, vocals, and full mixes to add density and punch. Engineers often control the balance between compressed and uncompressed signals using a fader or blend knob, tailoring the intensity to suit the material.