Convention Paper
Bessel Filters as Loudspeaker Crossovers
AES Convention 72 · Paper 1949 · October 1982
Abstract
Bessel filters are all-pass networks. However, a particular combination of minimum phase group-delay and all-pass group-delay within the filter's passband and overlap range produces an excellent performance both in frequency and time domains. Thus, Bessel filters are highly desirable as loudspeaker crossovers. The lack of dispersion of frequency components in time in the Bessel crossover contributes to an excellent transient response, and the phase match in its overlap region insures small lobing in the overall acoustical radiation pattern. The results of FFT measurements on a fourth-order Bessel crossover and impulse as well as TDS measurements of a complete four-way studio monitor system are presented. A near phase-linear flat magnitude response loudspeaker is accomplished with an excellent subjective sound quality.
