Is Phase and polarity the same thing?

It's not even that complicated.
6db filter preserves phase.
12db filter inverts phase.
On my 1.6 maggies, the x-over has both 6 and 12 db/octave elements....can't for my worthless life remember hi or low is which, but as a result, the HF part of the panel is hooked up out of phase with the LF part of the panel.

I believe this is what Eldartford meant?

Magfan, I was trying to keep this simple as the primary concern was phase versus polarity. Yes, most speakers don't just have no phase shifting at all in their crossovers. Perhaps I should have limited what I said to single driver speakers.

Eldartford, again I know this but was trying to keep it simple and again there are no such complications with a single driver. As I said before, I had dealt with different manufacturers how to deal with the onset wave at the microphone and from the drivers. I had a pair of Tannoys long ago and like JBL they treat the onset wave as a withdrawal of the drivers. I always reversed the speaker leads for better sound.

Magfan...
6dB..... 90 degrees (not zero)
12 dB...180 degrees
18 dB...270 degrees
24 dB...360 degrees (which is like zero)

Eldartford, silly question, than.
If 6db / 12db are 90degrees apart, how could you get the drivers back to phase in the Magnepan 1.6, which I have confirmed does use 'one of each' in its x-over? Seems they'd be 90degrees out?

Also, with most if not all modern rock, absolute phase is strictly of academic interest, since no effort is made to preserve or even identify phase. On some recordings in the past, my absolute phase switch made a difference, on most recordings, not.

Magfan...I rebuilt my MG1.6 crossovers, so I am familiar with them. The low pass (woofer) is 12dB and the high pass is 6 dB. The break frequencies are quite different (I can't remember the exact numbers).

The phase of the passed signal changes over the range of frequencies from below to above the break frequency, with the total change being as I cited. It is not a fixed phase shift. I suspect that there is a frequency between the MG 1.6 high and low break frequencies where the phase difference is closer to 180 degrees than zero, and that's why the tweeter is hooked up "backwards". Physical spacing of the drivers are also a factor. When both drivers are generating sound you want them to be in phase or they will tend to cancel and there will be a sharp notch in the overall frequency response. As a matter of fact, the best way to determine the crossover frequency is to reverse the polarity of one driver and look for that sharp notch.