The Phase screen allows you to adjust the phase of the subwoofer from 0–180° in increments of 1° and also allows you to invert the polarity of the phase.
The Phase control is entirely dependent on numerous factors including the size and configuration of your listening environment, the placement of the unit, and seating arrangement. Due to the way bass sound waves develop in different rooms there is no rule of thumb for setting phase. For instance, if your room has a peak at the subwoofer crossover area, you may wish to set the phase so the actual acoustic outputs of the subwoofer and main speakers are out of phase. Experiment and try different settings and be patient.
If you are using the subwoofer to augment other MartinLogan products, we suggest starting with the phase set at 90° (with Inverted polarity turned on).
In a system where phase and polarity are properly set, the main speakers and subwoofer should work together and sound as if there is more total bass in the system. If your main speakers and subwoofers are out of phase their sound waves will cancel each other and total bass output in the system will sound decreased. Again, experiment and listen for the smoothest bass without any prominent or absent notes.