Speaker wire polarity can be identified by connecting the wires from the speaker to a 9-volt battery and seeing what speaker goes out and in. The speaker that goes out first and then back in is the one that will have the proper polarity.
When the speaker cone goes in first and out afterward, the polarity of the wires is switched. The wires should be adjusted to make the positive one, which is normally red in color, attach to the positive side of the battery. The black-colored speaker wire should then be connected to the negative side of the battery. Before doing the test to make sure that the polarity of the speaker wire is correct, it is important that the tester make sure that the battery is a fully charged one. A brand new battery that has come directly out of the packaging will work best to test the polarity. The front of the speaker should also be removed to ensure that the tester is able to see the cone of the speaker because this is the part that should be moving in and out. Removing the front of the speaker usually only involves disconnecting several clips around the outside of the speaker.