Getting to grips with strange sounds from your stereo

It really caught me by surprise, because it was not a plain disc skip in which a scratched disc or broken CD head is usually the cause. After turning it off and back on again, it worked fine. But two days later, it finally died completely while I was driving on a rugged road with a lot of bumps.

The next day, I had my car audio checked out, and the outcome was really interesting. The problem was not a broken power cable or blown fuses from simple wear and tear like I had thought, but rather a shorted integrated circuit (IC). I don't know what exactly caused the zapped IC, but a short circuit could always be the culprit, since the head unit requires lots of power and will draw a heavy current that can sometimes break the circuit.

Other common symptoms are unclear bass reproductions from woofers or odd noises from dome tweeters. The unclear bass might be caused by an old rubber surround, and it tells you it's time to change to a new one, or to a new speaker set.

A strange noise from a dome tweeter, particularly when the volume is turned up, indicates a malfunction of the driver's voice coil. This is because the voice coil is attached to a diaphragm that is then positioned inside a magnetic airspace created by the fixed structure of the driver's motor system. This motion of the driver's moving system is what creates the sound we hear. Using the speakers for a long time wears them out or burns out the voice coils.

For both symptoms, I suggest that instead of fixing them, changing the entire speaker system would be your best bet.

If the sound system appears to be working incorrectly - either with a drop in system voltage associated with excessive current draw or with strange sounds - you must first turn off the system and look for possible causes. These could include severe loads drawing substantial amounts of current from the electrical system, an electrical surge or electromagnetic distortion. Electrical surges are very serious, though.

To deal with the problem, you probably need a large capacitor, placed in parallel with the amplifier. The purpose of having the capacitor is to provide a sort of reserve power source from which the amplifier can rapidly draw power when it needs it (such as during deep bass notes) and to stabilise the voltage level at the amplifier.

Certainly, it is important to take note of any strange car-audio sound that can tell you what is wrong with the system, so that you can rectify it in a timely manner. If the system is still under warranty, you might at least be able to change to a new one. Apart from this, it helps you avoid more serious problems in the future.

By Wijit Boonchoo

Ultimate in Luxury

The Luxury LS 460 is a wonderfully comfaortable car fitted with all mod cons, althoough not necessarily the most fun vehicle to drive.