Speakers will always have two connection terminals, positive and negative, and a wire attached to each terminal. However, when connecting your speakers, it's very easy to forget which wire goes to which connection. When wiring speakers, it's very important that the polarity is respected at both ends of the wiring; where they plug in at the audio system and where they're connected at the speakers. If the polarity on one or a few speakers should be reversed from the system's polarity, it would create a phase difference where the sound from the speakers connected one way would cancel out the sound from speakers connected the other way, an effect more noticeable at lower frequencies. There are fortunately a number of ways to determine the difference between positive and negative when dealing with speaker wires.
