My Speakers Have No Bass

I have installed a new set of speakers and there is no bass. Have I done something wrong?

One of the most common causes of lack of bass from speakers is out of phase wiring. This occurs when the positive and negative wires are connected incorrectly. The positive and negative wire connection at the source must be the same at the speaker connection.
Check the connections for consistency first.
Another clue to this fault is that the bass will sound louder outside the vehicle than inside.

Most speakers will have a positive (+) sign and/or a negative (—) sign on the terminal, with some featuring a red mark for positive and/or a black mark for negative. If in doubt, there is a relatively simple way to check the phase of the wiring. Using a 1.5V or AA battery, hold the positive and negative wires connected to your speaker on the relative terminals of the battery. If in phase, both speaker cones will move outward, but if one is out of phase the cone will move inward. Both speakers must move in the same direction when tested.