Audiophilepure

MartinLogan Balanced Force 212 Subwoofer Review

The phase dial is the lower-most one in the photo. This adjusts the phase-angle of the deep bass sound. You have to do this by ear. Play some music with deep bass and turn the dial until it “sounds” the most appealing.

At the bottom are push buttons to play a Tone Sweep (120 Hz to 20 Hz). This lets you find out if you have anything resonant in your listening room so you can fix the problem. I ran this test and found a resonance in the 100 Hz – 120 Hz range. The spectrum below shows the sweep from left to right. I used an accelerometer for this test. There is a large peak in that range. Since it is above the highest crossover (Low-Pass) frequency of 80 Hz, it is not a problem that would be caused by the subwoofer.