Subwoofer Phase Setup

[MKGus]

Hey Everyone,

I have a question about subwoofer phase that I am having trouble researching, partly because I'm not even sure what to google search. Ha! I know if I explain it here people will understand my issue:

Basically I'm getting my subwoofer signal (stereo subs) right after the amplifier for the speakers with a speaker-level to line-level device and running the signal via RCAs to the amplifier for each subwoofer. The speaker wire I pull the signal from continues on thru a high-pass filter and then to a crossover and then to the 2-way speakers. I believe the high pass filter introduces a 90 degree phase shift (please correct me if I'm wrong), and my subwoofers only have the option for 0 or 180 degree phase shift.

Is there a device which can control the phase of the signal for the subwoofers so I can get everything in phase. Furthermore, how do I even verify the amount of phase shift of each component so that I can make the right corrections?

 

[MKGus]

The roll-off on the high pass is 12 dB which means it is 2nd order (I believe). Does that introduce a 90 or 180 degree phase shift? If it is 180, what does that mean for the polarity of the subs relative to the mids? If it is 90, I don't see a simple solution.