ABSTRACT
To the best of my knowledge, the only practical design of this sort of crossover that has been published was by Harry Baggen, in a famous article in Elektor in 1987 [4]. It was a three-way crossover based on fourth-order Linkwitz-Riley filters. Since the highpass outputs were derived by subtraction, using the time-delay concept, only two Linkwitz-Riley filters were required, to some extent making up for the extra cost of the subtractors and the second-order allpass filters used to create the delays. This crossover may be over twenty years old, but its conceptual significance is such that it is still being actively discussed today.
