Connect a subwoofer between the stereo and the system's tweeters. Most subwoofers have a number of input and output ports to facilitate integrating the subwoofer into the signal chain.
Installing a subwoofer in a car or stereo system is a simple process. Locate the output of the stereo amplifier, which should be split into left and right channels. Using speaker wire, component cables or 1/4-inch cables, attach the subwoofer to the stereo amplifier. Match the left stereo output with the left input on the subwoofer and vice versa. Then, connect the subwoofer's output jacks to the inputs of the tweeters, or the smaller speakers meant to cover the middle and high portions of the frequency spectrum. Again, ascertain that the subwoofer's left and right output jacks are connected to the appropriate speaker. Provide power to the amplifier, subwoofer and tweeters to complete the system.
After installing the subwoofer in the signal chain, change the subwoofer settings to obtain a clearer sound. Common subwoofer settings include speaker volume and crossover frequency. The crossover frequency is the point at which the signal is split between the subwoofer and the tweeters. For instance, setting the crossover frequency at 150 hertz allows all signal below 150 hertz to play through the subwoofer, while all signals above 150 hertz play only though the tweeters. The appropriate crossover frequency varies considerably between listening environments, but most audio systems utilize crossover frequencies in the 60 to 180 hertz range.