How To Troubleshoot Car Amplifiers

You are driving down the road listening to some sweet Yanni tunes when all of a sudden his awesomeness is disturbed by scratchy pops and hisses! Well this simply will not do. Now, the problem could be a couple of things but for the sake of this article, we need to find out if the amplifier is to blame.

The amplifier in your car stereo system performs a basic function. It takes whatever signal your stereo unit is putting out, be it a radio signal or a CD or whatever you are playing and boosts the signal going out to your speakers. There are usually two major problems that effect power amps, so I've split the troubleshooting up accordingly.  Once you've completed the steps in this article, if you decide that your stereo system needs to be upgraded or replaced, I highly recommend checking out Secrets of a Professional Installer - you'll pick up some great tips that will help you switch out your system quickly and efficiently.

The power problems might require the use of a voltmeter. You can find these at your local Radio Shack or electronics shop. Be careful working around you car's power, it can jolt you good.

  • Power Problems -- If your amp is not powering up or is in some sort of standby mode, check these things first.
    1. Check your amplifier's grounds. Number one on the list is to make sure your amp's ground wire is attached tightly to bare, rust-free metal in your car somewhere, probably the chassis. If the ground does not look good, then detach it, clean the area and the ground wire with a metal brush and secure it again. Any of your amplifier's problems could stem from improper grounding.
    2. Check the power going to your amp. Use a voltmeter to see what kind of juice you've got coming into your amp. It has to be at least 13 volts. If it isn't, then you've got yourself a low battery or a bad power cable. There also could be a problem in your amp's power supply. A great test is to hook up your amp in another car and check the voltage. If you've got power going into the amp, but it is not powering up, then the amp's power supply is fried. While you are at it, check the inline fuse. Make sure the fuse is good and if it is, make sure it is the right amp rating.
    3. Check your gains/input sensitivity. Gain input controls allow you to match the output voltage from your head unit to your amp and then on to your speaker. If your gain inputs are set too high, your amp might just shut down on you. It basically overheats if it is up too high, and will automatically shut off. Another symptom of this problem is if your volume seems to get lower. You want to match as closely as possible the gain of your head unit and all other components in the system. Check out all the components' specifications for their optimal levels.
    4. Check your speaker's impedance. Impedance is basically how much current flows with a specified voltage across resistors, capacitors, inductors, etc. It is measured in ohms. Make sure your amp and speakers are working in the same impedance range. If not, you could be screwing both of them up royally and the amp will go into "protect" mode. Use a voltmeter set to ohms and see what it says.
  • Sound Problems -- If you are experiencing sound problems, check out these things in addition to the above.
    1. Use a different set of car stereo speakers. Hook up a speaker that you know works well to your amp. If you still have a bunch of noise, it's the amp.
    2. Use different cables. Remove the RCA cables that are attaching the head unit to your amp, and replace them with ones that you know work. If there are still problems, then you know it's the amp. If not, replace the cables.
    3. If you have a power antenna, listen closely when you turn the radio on. If you hear an audible pop from the speaker, then the antenna might be interfering with the amplifier. Check all the wires leading to and from both and make sure they are intact and not crossed.
    4. Again, make sure your grounds are all good. This could cause all sorts of different problems.

 

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