Group delay in subwoofers

I understand the phenomenon of group delay when subwoofers are connected to a preamp and that they need to be placed approximately 8 ft closer to the listener than the mains.  Is this also the case when connecting a sub through the speaker level inputs from an amplifier or is group delay much less of an issue in this configuration?

Um, um, um, it is complicated.

By themselves, a large woofer driver does not have any group delay other than the position of the motor relative to the other motors.


DSP processing like you find in a lot of advanced subs can add up to a couple of milliseconds worth of delay. This affects the slope and phase matching as it hands off to the main speakers. On the other hand, if both your top and low are going through DSP, the difference is negligible.


Thanks for the comments.  I had a feeling that it wasn't quite as simple as I had hoped.

JC: Group delay for subs isn't as important as the proper phase/amplitute matching through the crossover, room acoustics and EQ.

That's where you should focus your time and energy.
Thanks, Erik.  I absolutely agree and would need to buy a processor to do it the right way.
Rythmik Audio subs come with a plate amp that includes a continuously-variable phase control. The control allows time-aligning woofers to speakers without physically moving either. The Rythmik PEQ model plate amps also provide both low level connection (on RCA jacks) and high/speaker level (on binding posts).