fatate- The phase knob/switch takes care of *distance* within approx plus/minus 1/2 a wavelength of the crossover freq. (80 Hz for example, 13.75 ft/wavelength, so a 180 deg phase switch would adjust for about 6.667 ft of placement variation between the speakers and sub. That's why I prefer variable phase knobs: you can adjust exactly. ) All the phase knob/switch does is to move the peak of the waveform forward or backward in time so that it can overlap that of the mains where they crossover. (Not really "forward" in time, but hopefully you get the idea.)

SoP- I guess Velodyne figure out they needed them after yours was built. If you don't have the problem, then nothing to worry about.