Editing Audio crossover (section)

==Overview==
[[File:Linkwitz vs Butterworth.svg|thumb|410px|right|Comparison of the magnitude response of 2 [[Pole (complex analysis)|pole]] Butterworth and Linkwitz-Riley crossover filters. The summed output of the Butterworth filters has a +3dB peak at the crossover frequency.]]

The definition of an ideal audio crossover changes relative to the task and audio application at hand. If the separate bands are to be mixed back together again (as in multiband processing), then the ideal audio crossover would split the incoming audio signal into separate bands that do not overlap or interact and which result in an output signal unchanged in [[Frequency response |frequency]], relative levels, and [[phase response]]. This ideal performance can only be approximated. How to implement the best approximation is a matter of lively debate. On the other hand, if the audio crossover separates the audio bands in a loudspeaker, there is no requirement for mathematically ideal characteristics within the crossover itself, as the frequency and phase response of the loudspeaker drivers within their mountings will eclipse the results. Satisfactory output of the complete system comprising the audio crossover ''and'' the loudspeaker drivers in their enclosure(s) is the design goal. Such a goal is often achieved using non-ideal, asymmetric crossover filter characteristics.<ref name="Hughes" />

Many different crossover types are used in audio, but they generally belong to one of the following classes.