Re: Settings Gain and other settings on AMP.
Infrasonic (subsonic) should be set to just below Fb (tuning frequency of box), bass eq shouldn't be used but it can be in some situations, phase should be 0° to begin with and after setup, it can be tweaked to preference.
Gain should be set with an oscilloscope, a DD-1 or a Digital Multimeter. It should be set with the head unit volume at its max undistorted level and if that's not known, head unit should be set at ~45% if mids/highs are powered through it and at ~80% if they are externally amplified.
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