Midas PRO SERIES Owner's Manual page 390

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Appendix A: Application Notes
Lo pass filter (LPF)
The LPF attenuates (not boosts) all frequencies above a certain level (cut-off
frequency), while allowing all those below it to pass through. The harshness or
smoothness with which the sound is removed beyond this point is determined by the
dB/octave, with 6dB being the most common. The LPF is generally used to reduce
noise in quiet passages or to take the fizz off any source with excessively high
frequencies, but may also produce a sound effect by manipulation of the controls.
The low pass filters of the PRO Series have gain roll off after the corner frequency,
which is variable.
PRO Series Live Audio Systems
Operator Manual