Connecting a subwoofer amplifier to a subwoofer is only the first step in setting up your car audio system's subs for the best performance. Tuning the amp is also essential. Amplifiers are tuned by setting three separate controls--the amplifier's gain, crossover frequency and bass boost. These can all be set for proper subwoofer performance by using your ears and a musical sample.
Place your CD into your car receiver and select a track with a strong bass presence. You can use other sources--for example, if your receiver works with an MP3 player, you can choose a track from that. Start playing the music, and set the receiver's volume to a moderate level.
Turn the sub amp's gain control to "0"--all the way to the left. The gain control will be a small knob on the end panel of the amplifier. Actual position depends on the brand and model of amplifier. Gradually turn up the gain, listening for the subwoofer to respond. As the volume of the sub increases, continue turning the gain up until the subwoofer sound is slightly distorted. Gradually turn down the gain until the distortion disappears.
Set the amplifier's crossover frequency to 100 Hz. This control will also be a small knob on the end panel. While listening to your music, turn the crossover slightly to the left, lowering the frequency. This will decrease the amount of high-frequency information the sub receives, tightening the bass response of the sub. Turn until you hear only distinct bass tones from the subwoofer.
Set the bass boost to "0." Bass boost increases the power of the bass output. Gradually turn the bass boost up until the bass matches your listening taste.