Group delay in low frequencies

Just as a reminder, group-delay due to the loudspeaker in a box is limited to about 0.15 * alignement order / frequency, which is also equivalent to (0.15 * order) periods.

Ie for a standard 4th order bass-reflex with a standard B4 at 30Hz, max group-delay is about 20ms.

So if you measure group delay of 60, 70ms or more, this is due to the room modes not to the loudspeaker itself !

Considering that a group-delay of 1 period (1 cycle) is non audible in low frequencies, we can consider that both 4th or 6th orders alignement should not be audible in any case.

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