Do you have a question about the JBL SP-150 and is the answer not in the manual?
Bass output varies with position. For more bass output, place the subwoofer near a wall boundary.
Connect the audio/video receiver or processor's subwoofer output to the JBL Subwoofer's line level input.
Connect the audio/video receiver's Left/Right main channel outputs to the JBL L/R Speaker Level Inputs.
Choose to have your subwoofer turn on automatically or manually when it senses an incoming signal.
Match the subwoofer's phase to the output of the bass driver in relation to other speakers for best perceived bass.
Manually control crossover frequency (50-150Hz) and adjust volume for a balanced sound with main speakers.