Car Stereo Making Whining Noise: how do I stop it?

Your car stereo is a constant companion while traveling about. A car stereo making whining noise means you have to turn your radio off or live with annoyance. The sound of screeching on your drive to work is no way to start the day. If this sounds like your situation, you need a solution to this problem, and it is easier than you think.

Car stereo making whining noise

A common occurrence in aftermarket car stereo systems, whining most often comes from an improperly grounded wire. There are many wires to check where you may be getting the whining, eliminating the most obvious, first, may save some time. The key is understanding the whine is caused by a poor earth or an alternator. This will help you understand what is necessary to fix it.

What is alternator whine?

Alternator whine is caused by a difference in voltage (electrical potential) between two connection points. The voltage disparity can be due to an improperly grounded alternator, radio, or stereo component. Stereo whine can be caused by an amplifier picking up on a high-frequency noise and amplifying it. This noise usually comes from your alternator or a wire nearby your amp RCA cables. Troubleshooting your car stereo and its components is how you will find the problem.

Why does it make this noise?

Several things can cause a car stereo to make a whining noise. The most common culprit is electrical feedback from the alternator of your car. A loose wire from any of your stereos components and associated wiring can be the culprit, too. That would include:

  • Alternator ground wire
  • Amplifier ground wire
  • A bad stereo head unit
  • Crossovers connectors
  • Equalizer ground wire
  • Speaker ground wires

How to stop the whining noise

The first step is to isolate the problem. Check the earth/ ground wire to your stereo first, then all other wires associated with the car sound system. This includes the alternator ground, the connection between the alternator and battery, and speaker wires. If after doing this you still have a whine, check all of the other components’ connectors.

car amplifier in boot of car with red rca cables and a blue light
Checking the connections are tight on your amp is an important step in troubleshooting interference noise

Troubleshooting bad ground wires is the no-cost, low-cost method of finding the whine in the stereo. If this procedure fails to cancel the whine, you need to test each component separately with a multimeter.

Using a digital multimeter, you can test the voltage from each component to check that they are all reading the same voltage. If you do not own one, purchasing your own multimeter will be much cheaper than taking your car to a technician. Just think of the fun you will have chasing wires!

Testing your Car Stereo Components

Set the multimeter to 12 volt DC and put the +ve terminal to the power lead and the -ve terminal to the earth connection. Do this for each component of your car stereo. If there is a disparity of over half a volt, you need to tighten or relocate the ground wire.

This means the ground wires of all of your stereo components. Using a multimeter is the most effective way to find any voltage disparities and eliminate the whine.

If none of the above measures eliminate the problem, you can install an audio noise filter on the power leads between the battery and stereo head unit. This should get rid of the whining noise, but it is important that you test the rest of the audio components.

If, after installing the audio noise filter the whining is still present, it is most likely a high-frequency noise traveling along the RCA cables to your amp. Installing a line filter on the RCA cable will remove this noise. If after doing all of the above, you still do not have a solution, you need to check your radio head unit to see if it is the culprit.

two black rca cables with gold ends
Fitting a line filter on the RCA cables between the head unit and amp can remove unwanted noise.

The head unit is tested by disconnecting the RCA cables from your amplifier. You will then need to insert a muting plug. This RCA plug has connectors shorted together and will allow you to eliminate noise from crossovers and equalizers. After doing the above, start your car, and if the noise is still there, you have a bad head unit. If the noise is gone, then you have a problem with a component upstream from the amplifier.

Check your Antenna

An overlooked component of your stereo, the antenna can also be a weak link in your car’s stereo system. While checking all of the other components of your system, make sure your antenna is tight and grounded properly.

Eliminate the Whining

A great car stereo is just mediocre if it whines. No one likes a whiner, and finding the cause of car stereo feedback is imperative to your enjoyment. Taking your car to a professional for repair is always an option. However, knowing how your car stereo works and how to fix it is gratifying. Removing the whine from your car stereo is more time-consuming than costly. Doing the job yourself will save money, and when it is fixed, you can say I did this!

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