As a result, each filter section has the same group delay. This crossover is recommended over the 2nd order Butterworth type due to its accurate summed frequency response and forward pointing main lobe.
Inverted polarity is required for one of the drivers.
That is, even though the filters have their own characteristic phase responses the phase difference between the two output signals is the same at all frequencies. As a result, each filter section has the same group delay. This crossover is recommended over the 4th order Butterworth due to its superior summed frequency response and lobing characteristics. Both drivers are wired with similar polarity. In general, Linkwitz-Riley crossovers can be constructed in all even orders, that is 2nd, 4th, 6th, 8th order and so on.