Express Paper
Perception of Time Distortions Caused by Loudspeaker Crossover Filters
AES Convention 154 · Paper 103 · May 2023
Abstract
Loudspeakers are often designed with multiple drivers, each optimized to operate within a defined frequency range. Loudspeaker crossovers are banks of filters which produce the target electrical transfer functions from a full range input signal. These filters can be realised with passive components, or with active electronics using analogue or digital methods. Digital active crossovers introduce a further dimension of design freedom with FIR (Finite Impulse Response) filters, which enable the design of arbitrary (minimum, linear, or zero) phase filters. Minimum phase filters introduce group delay, and therefore a non-linear phase response. Linear phase FIR filters as the name implies, have a linear phase response, but must by definition also have a symmetric impulse response. It remains unclear whether distortion of the phase response in minimum phase filters, or “pre-ringing” of the impulse response in linear phase filters is the more audibly significant effect. This study investigated the audibility of these time domain effects, but found no statistically significant difference in impairment in the case of monophonic headphone playback.
