Hearing a buzzing sound from your car stereo speaker can be really annoying. You may hear the buzzing only when playing music really loudly or when the music has a lot of bass. You may hear the buzzing at all times. Determining the source of the problem is really important though. The problem can be with your speakers, forcing you to replace them, or the problem could be with other components in the car stereo system.
Check the Speakers
The first step to determine whether the problem is with the speakers is to expose them. Most speakers come with a metal sheath covering. Removing this covering will expose the speaker cones for inspection. When the cones are exposed, you can check each of them by running your fingers along them. Try looking for rips and/or tears in the cones. Even the smallest of rips and tears can cause a buzzing sound in a car stereo speaker as speaker cones are really delicate.
If you find that there are absolutely no rips and tears along your speaker cones, put back all the coverings of the speakers. You will have to look for the problem in another car stereo component. The problem could be with the sound source (the head unit). Trying out the speakers on a different audio source can help you determine the problem.
Check the Audio Source
Before you start checking the audio source by running the speakers on a different head unit, you have to disconnect the current head unit completely. First, disconnect all the cables that are connecting your speakers to the head unit. These can either be RCA cables or red and black cables that go into those black and red pull tabs at the back of speakers. Disconnecting them is a very easy job.
Once you have disconnected all the cables, get another stereo unit for testing. You can ask a friend to borrow their stereo unit for this process. Once you have a borrowed stereo unit, plug all the previously disconnected cables into this stereo unit. This is the only way you will be able to determine whether the buzzing problem of your car stereo speaker is actually a problem in the speakers or the head unit. Make sure the borrowed head unit has a similar ohm rating and wattage.
Once you have connected the borrowed head unit, run the speakers. Go to as much volume as you normally would. If the buzzing stops, it will mean that the problem is with your head unit and it will need to be serviced. If the buzzing persists, it will mean that the problem is with your speakers. If there were no visible rips in the speaker cones, it could be a problem with the coils. In that case, you will need to service the speakers.