Boss LMB-3 Owner's Manual page 9

ABOUT THE LIMITER'S ACTION
The LMB-3's limiter will function differently depending upon how you set the Ratio and
Threshold Levels. The RATIO and THRESHOLD knobs work as described below.
RATIO : The compression ratio for the input signal is called Ratio. For instance,
when the Ratio is set to "2:1", an input signal that is 6 dB louder than the
Threshold Level will be compressed to one half, or 3 dB When it is set to
" :1", any input signal above the Threshold Level will be compressed to
the Threshold Level, then output.
THRESHOLD : The Threshold Level is the level at which compression starts to work.
When the input signal has reached the Threshold Level, the signal will be
compressed at the compression ratio set with "RATIO", then output.
When the input signal is lower than the Threshold Level, it will be output
without compression.
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