One of the most frustrating things that can happen to a car speaker is for it to blow out. Blown car speakers are very difficult to repair, and the sound quality that they produce will be greatly reduced. In many cases, you'll be able to recognize whether a speaker is blown by listening almost immediately. Tweeter car speakers and other types can also have problems with wiring, power levels and more. Each of these can result in a similar sound to the stereo system, but not actually mean that the speaker is blown. Therefore, it's important to check and be sure that the speaker is blown before you resort to buying a new one.
Step 1 - Listen to the Speaker
If you worry that a speaker in your car stereo system may be blown, listen to it carefully. Stop the car so that you don't have any other noises to distract you. If a speaker is completely blown, it will likely not produce any sound and may just make a soft hissing or ringing sound instead. This should be relatively easy to identify. A partially blown speaker, on the other hand, may produce somewhat normal sounds at lower volumes, but will likely become more and more distorted the louder that the system is designed to go. Therefore, you should listen to the speaker at a range of different volumes to determine if the distortion remains constant or if it seems to worsen.
Step 2 - Check by Touch
Many larger speakers, like woofers and subwoofers, will actually vibrate when they are actively creating sound. Turn the volume of your speaker system up and place your hand against the front padding of the speaker. If you feel any vibration, the speaker is creating sound. However, if you do not, it's likely that your larger speaker is not working properly. This test will not work as well for softer or smaller speaker sets.
Step 3 - Isolate the Speaker in Question
Use the fader system controls on the head unit of your car stereo to help isolate the single speaker or couple of speakers that you think may be blown. If you can focus the sound in one portion of the car, you'll be able to tell better if the speaker in question is not working properly. The sound will almost fade out or will fade out entirely when you focus the sound from that speaker.
If you have additional problems with a car speaker and you're unsure if it's blown out or not, disconnect the battery and examine the wiring. If the problem seems to be with a single speaker, look to make sure that speaker is still wired to the amp and the head unit properly. If you have any other questions about how to diagnose this problem or are unsure of where to proceed, take the speakers and car to an audio professional at a store in your area.