No bass

Hi! I have the JBL S2-1224 12" 275 rms subwoofer paired with the JBL GX-A3001 amplifier. I had the subwoofer set at 4 ohms and the gain at 50%. Good base and it hit hard. Then I learned about clipping and that you should set the voltage from the amplifier to the subwoofer. I calculated the...