Empress Effects ECM-519 compressor - Manual (Page 7)

Controls at a Glance
bypass: Use to engage/bypass the unit. It will illuminate when the
compressor is in the signal chain. It is true bypass and will pass
signal when bypassed even if the unit is powered off.
ratio: Determines the compression ratio for signals above the threshold.
3:1 - Gentle and transparent.
6:1 - More aggressive compression.
12:1 - Limiting.
Note the threshold raises slightly with higher ratios so that the
output volume is more constant when switching ratios at typical
gain reduction settings. This makes comparing the effect of different
ratios more accurate.
input: Controls the level of the signal entering the compressor.
The unit has a fixed threshold so higher input settings will result
in increased amounts compression.
mix: Blend between wet(compressed) signal and dry(uncompressesed)
signal. Counter clockwise is dry, clockwise is wet.
attack: Controls the time constant which affects how quickly
gain reduction acts after the signal has exceeded the threshold.
(50us - 50ms) *
release: Controls the time constant which affects how quickly the
gain reduction decreases after the signal drops below the threshold.
(50ms-1s) *
*The attack and release controls are not used when the compressor is in
auto mode. Switch to manual mode for control over attack and release.
output: Controls the overall output level leaving the compressor.