Parallel Compression
Definition
A technique in which a heavily compressed version of a signal is blended with the original uncompressed signal. Preserves the natural dynamics and transients of the original while adding the density and sustain of the compressed version.
In Simple Terms
Running a track through a really aggressive compressor, then blending that processed version quietly underneath the original. You keep all the natural dynamics but add power and thickness behind it. Best of both worlds.
In Practice
Parallel compression on a drum bus adds thickness and power without the pumping artifacts that would result from applying the same aggressive settings in series.