Group and phase delay requirements for loudspeaker systems

The question of true requirements regarding phase shift tolerance in audio systems is reopened. No need for phase delay linearity can be justified for music signals. The actual requirement is a tolerance of 2 ms for group delay through the parallel channels (woofer and squawker) of a speaker. Simulated drum tone experiments are reported to verify this well known number, 2 ms. Group delay in the highly desirable 3rd order Butterworth crossover network is found to be identical in high and low pass channels. Phase shift in transducers causes the phase troubles in speaker systems. An idealized two way speaker combines the response of the transducers into the crossover network and solves all of the phase shift related problems in a two way speaker.