Editing Audio crossover (section)

====Derived====
Derived crossovers include active crossovers in which one of the crossover responses is derived from the other through the use of a differential amplifier.<ref name="Chalupa1986" /><ref name="Elliot2017" /> For example, the difference between the input signal and the output of the high-pass section is a low-pass response. Thus, when a differential amplifier is used to extract this difference, its output constitutes the low-pass filter section.  The main advantage of derived filters is that they produce no phase difference between the high-pass and low-pass sections at any frequency.<ref name="Bohn" /> The disadvantages are either:
# that the high-pass and low-pass sections often have different levels of attenuation in their [[stopband]]s, i.e., their slopes are asymmetrical,<ref name="Bohn" /> or
# that the response of one or both sections peaks near the crossover frequency,<ref name="Elliot2017" /><ref name="Crawford1972" /> or both. 

In the case of (1), above, the usual situation is that the derived low-pass response attenuates at a much slower rate than the fixed response. This requires the speaker to which it is directed to continue to respond to signals deep into the stopband where its physical characteristics may not be ideal. In the case of (2), above, both speakers are required to operate at higher volume levels as the signal nears the crossover points. This uses more amplifier power and may drive the speaker cones into nonlinearity.