First, put the volume control on the host all in the center position, then turn the volume up to 80%, and turn off the power amplifier volume gain to a minimum.The electronic divider input gain, and then increase the electronic divider output gain until the speaker appears distorted sound, and then back to some. At this point, the gain has been set and then tuned.
First turn off the treble in the front and rear channels, listen to subwoofer, adjust the frequency, so that subwoofer can be natural operation, and no mechanical noise and subwoofer. Adjust the ratio of the frequency, the rear channel volume is small, and then test the subwoofer phase, in the small volume to change the subwoofer phase 180 degrees. Positive and negative reverse or adjust the electronic divider 0 degrees - 180 degrees switch to see which phase volume is relatively large, that is the correct phase. When all the phase and frequency range are set and then carefully adjusted. General subwoofer crossover set is about 80-100Hz, and Qualcomm part of the treble tone crossover is about 60 - 90HZ.