−40−30−20−100+10THRESHOLD11.523461020∞COMPRESSION40010040101ATTACKdB/MSEC4K1K40010010RELEASEdB/SEC−20−100+10+20OUTPUT GAINPOWERSTEREOCOUPLERAUTOINPUTOUTPUTGAINCHANGESYSTEMBYPASSSLAVEBELOWABOVEAUTOATTACK/RELEASECOMPRESSOR/LIMITERMETER12−20−15−10−50+5+10DECIBELS
The audio path, and what comes outThe side-chain, and the gain reductionA compressor turns the loud parts down. Its detector watches a copy of the input; above the threshold, the VCA (voltage-controlled amplifier) turns the sound down by the ratio. Attack and release set how fast; output gain (make-up) lifts it all back. Watch runs at 1/4 speed.The lesson in the lab: The compressor in Live, where you set one by ear.