Bus Compression

A bus is a channel that several tracks are routed into, and bus compression places one compressor across that combined signal — a drum bus, an instrument group, or the master mix bus. Rather than controlling any single element, gentle bus compression makes the grouped parts respond to one another, so they breathe and move together as a unit. This shared movement is what engineers mean by glue. Typical settings use a low ratio and only a few decibels of gain reduction so the effect is felt more than heard, often with a slower attack to let transients through and a release timed to the track's tempo. Pushing it too far flattens the mix and drains its energy, so restraint is the goal.