Critical subwoofer tip


I assume that everyone already knows the importance of phase matching a sub to the main speakers but it’s a little more complicated than simple 90 degrees or 180. The B&W sub that I have has four choices. In every case there has been a definite correct position that can be non standard. My current setup shined at 270 degrees vs the std positions. It’s completely obvious and the other choices would not have been satisfying. 
From my lengthy experience I would want a subwoofer with several phase choices. I personally don’t see how one could seamlessly integrate the mains and the sub without this flexibility. No one asked but i thought this info might be useful to anyone purchasing a subwoofer. YMMV
4425
Good thread on a tough, often debated topic.  MC correct about ability to sense phase of say 20hz and 40ft wavelength using his numbers but two points.  First, thats the extreme case. For most folks xo is up say at 60hz.  So that means a wavelength of 13 ft  for room length.  At 80hz then 10ft is the length. That's real world and pertinent at the top of the sub's range.  Run in phase then, if overlapping some with mains, will produce a peak or boom (best not to use node here)  that will be corrected if the phase is rotated.  At 180 degrees it's a notch and we aren't bothered as much by missing freq.  So yeah, while MC seems theoretically correct at the lowest frequencies, in a modest room at a typical xo point, it could matter.  The OP didn't mention his room size.  The bigger, perhaps the more phase indeed matters.

Second, and this is a question that pertains to rotating the phase, but if a first harmonic is above the sub xo, say 120hz and is therefore played by the mains' low drivers, does our perception treat it as inferior to an in-phase harmonic?  This has prob been addresses ad nauseum in the speaker builder's threads for mid to tweeter crossover design.

Prob over my head now so I'll just sit back, spin some music and see what the group thinks.
Unlike millercarbon, I can switch the phasing of my sub and HEAR! the difference. If there was even an ounce of truth in his erroneous, chaotic statement, I could never hear a difference when I switch the phasing! 

Just an incredibly asinine statement that is SO easily proven incorrect!
Phase match is critically important for me when it comes to my Dual SVS SB16 ultra is like day and night 
The effects of adjusting phase can be easily measured from the listening position.
The effects of adjusting phase can be easily measured from the listening position.