Vortex Media VTX 1000 - Manual (Page 73)

The ceiling loudspeakers may not be able to reproduce low frequency energy. Since the subwoofer handles
that job, we will remove low frequency energy from the ceiling loudspeakers via a Linkwitz-Riley high pass
filter has been assigned to Outputs 1 and 2. The cutoff frequency is 250 Hertz, meaning that below that
frequency, the signal will be attenuated at a rate of 12 dB / octave.
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