Crossover Q Setting - please can someone explain this to me

[matengawhat]

Straight from the instruction manual - not tried fiddling yet as like to know what it does first - "The X-Over Q setting controls the slope of the trace beyond the cut off frequency, in dB/octave. The aim is to make a ‘mirror image’ match with the slope of the high-pass filter – a steep cut-off of the high-pass filter from the sound processor/receiver should be matched by a steep cut-off of the low-pass filter from Logo. Similarly, if the sound processor/receiver provides a more gradual cut-off, the X-Over Q setting should have a lower value."

How do you know what the slope of the high pass filter is?

 

[Tom Moreno]

The Q is part of any equaliser or filter circuit. In an equaliser circuit there are three functions; frequency, gain, and Q. The frequency obviously selects the frequency that is being effected, the gain is how much that frequency is being increased or decreased, and the Q determines how wide a frequency range around the centre frequency is being affected. When this is in a filter the Q reflects the amount of slope. This would be in measurements of -3dB per octave, -6dB per octave, -9dB per octave, or more. This is because filter circuits normally do not cut off the frequency range below the filter frequency in an all or nothing manner, this would sound very unnatural. Normally the Q setting would be something in the nature of -6dB per octave, but if I were you I would probably leave it at manufacturer's default setting as it would be rare to tweak this deeply.