Subwoofer phase question

[MusicNBeer]

So I have dual Monolith M10 subwoofers. I get an in-phase relationship with my mains when the phase of the subwoofer is about 180 degrees inverted. The question I have is which is better:
1. Subwoofer phase set to 180 degrees and mains pos/neg hooked normally
2. Subwoofer phase set to 0 degrees and mains pos/neg hooked reverse

Does the phase adjustment on a subwoofer normally change the subwoofer's group delay? Is group delay minimized when phase is set to 0? If so, the time alignment would be best using option #2.

Thanks for any help,
Jim

 

[kyle_neuron]

You’re changing polarity, not phase. That’s an important distinction, as the former doesn’t affect the group delay of the individual speaker, but the resulting relative acoustic phase will affect group delay through the transition region from mains to sub.

As for which is ‘best’, if you’re not playing live instruments, it doesn’t really matter.

 

[MusicNBeer]

You’re changing polarity, not phase. That’s an important distinction, as the former doesn’t affect the group delay of the individual speaker, but the resulting relative acoustic phase will affect group delay through the transition region from mains to sub.

As for which is ‘best’, if you’re not playing live instruments, it doesn’t really matter.

Thanks for the reply, in the case of the Monoliths, it is changing phase because the adjustment is a continuous phase adjustment from 0-180 degrees. It's not just a switch. I assume it's implemented with an all-pass filter.

 

[RobL]

Just need a little clarification. I am using am RME Adi-2 and to simplify things I’m using the balanced outs to the monitors and run the sub off the RCA outs. The RCA’s out 180 deg out of phase from the balanced outs, which I compensate for with the phase adjustment on the SVS app. So what degradation am I actually causing at the LP?

 

[gbrnole]

where is the sub located in your room that has the phase knob turned to 180 - is it located behind the main listening position? if so, this is normal. think of the variable phase knob on the monoliths as being a rudimentary time alignment adjustment. you would get best results using a DSP to calibrate those dual subs but if you have a relatively flat sweep as it stands then consider that a win and enjoy!