How To Fix Alternator Whine In Speakers

Norvan Martin
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Noise in your car’s audio system can have many different causes, but the alternator is a common culprit. Car alternator noise or alternator wine is a whining sound produced by the alternator’s sound getting into the head unit via the power cables. However, this is not always the source of unwanted noise. We’ll show you how to differentiate alternator whine from other noises in your stereo system.

We’ll also show you how to eliminate the noise if your alternator is the cause.

If you are having trouble with alternator noise, you can fix the problem by eliminating any grounding issues, installing a noise filter between the alternator and the battery, or installing an inline noise filter in the head unit power cable.

Read on to learn more about these processes and how to differentiate alternator wine from other noises in your car audio system.

Before you go ahead, keep in mind that there are other reasons for car engine noise through your speaker other than alternator wine. Please check out this article to learn more.

How to Recognize Alternator Whine

The alternator whine is fairly easy to recognize. As the name implies, it is a high-pitched whining or buzzing noise. This noise is often heard through the car’s speakers, increasing in pitch and volume as you accelerate your car. 

Alternator whine also increases in intensity when you increase the electrical load of your car, such as when you switch on your AC. If the noise persists even after you turn down the volume of your car stereo or switch off all electrical devices, it’s probably an alternator whine.

You can try the following steps to get rid of an alternator whine in your car stereo:

Step 1: Check Your Car’s Ground Connections

A faulty ground connection is often the cause of the alternator whine. Make sure that your car’s ground connection is clean and properly secured. Clean and tighten the connection if it is loose or corroded. You can also run a replacement jumper from the negative terminal of your battery to clean the metal. 

Step 2: Check For Improper Wiring

If grounding does not eliminate the whine, check your connections for poor wiring. This includes connections that can lead to interference. It is always a good idea to use shielded cables to reduce the chances of electrical interference.

Step 3: Use an Alternator Noise Filter

A noise filter can help eliminate the interference caused by the alternator. The filter is installed in line with the power supply cable. You can purchase a noise filter, or you can build one yourself—more on this in the FAQs section.

Step 4: Use a Ground Loop Isolator

This device can help eliminate the ground loop causing the alternator to whine. It is installed in line with the audio cables. 

If these do not solve your noise problem, you might have to upgrade your voltage regulator or alternator if they are faulty or worn out.


What Causes Alternator Whine?

Knowing the source of a problem will help you properly diagnose the cause of the problem and fix it completely.

An alternator has many moving parts that spin together without issue under proper conditions. A faulty alternator generates noise from interference in the electrical connections and from faulty moving parts. 

Car alternator wine

The whine can sometimes be caused by radio frequency interference from other electronic devices. This can be fixed quickly by switching off the source of interference or getting away from the source if it’s outside your car.

Here are three other causes of alternator whine, all involving the alternator’s electrical connections. 

  1. Worn or Improper Grounding: All cars are grounded to ensure the electrical components work together correctly. This is usually achieved by attaching a jumper to clean metal in the trunk. Sometimes, the jumper corrodes or is displaced by external forces. This can create a “floating ground”, which can cause the whining noise.
  2. Faulty Alternator or Voltage Regulator: A faulty or worn-out voltage regulator or alternator can generate electrical noise. This can be picked up by the car stereo system, leading to whining sounds. Also, an inadequate power supply to the car stereo can have a similar effect.
  3. Bad Connections and Poor Quality Wiring: Electrical noise can leak into the car stereo system if the car has poor wiring or wiring that is improperly shielded. Running the power and signal cables alongside each other can also cause noise due to the electrical inductance phenomenon.  

Top 3 Best Alternator Noise Filters

  • PAC SNI-1/3.5 3.5-mm Ground Loop Isolator: This compact filter reduces alternator noise and other electrical interference that your car’s stereo system can pick up. It’s easy to install and works with many car audio systems.
  • Mpow Ground Loop Noise Isolator: This is a popular alternator noise filter. It works with many car audio systems and is easy to install. It comes with a 3.5mm audio cable for additional connectivity.
  • BOSS Audio B25N Ground Loop Isolator: This ground loop isolator is also designed to work with most car stereo systems and is easy to install. The compact design makes it easy to fit into many vehicles.

FAQs

What is an Alternator Noise Filter, and How Do I Use It?

An alternator noise filter is an electrical device that can reduce or eliminate the noise generated by an alternator. This device works by filtering out the high-frequency noise generated by the alternator using a capacitor or inductor to block the noise signals without impeding the passage of the desired signal. 

You need to identify the noise source before installing the filter. The installation is done in line with the power cable powering the speakers and is done as close to the source of the noise as possible. Ensure that the power is disconnected before commencing installation. 

How To Create a DIY Alternator Noise Filter?

You will need the following materials:

  • A toroidal (or bead-shaped) ferrite core 
  • Capacitors (preferably 0.1-0.47 μF)
  • Insulated copper wire (around 18-22 AWG)
  • Soldering iron and solder
  • Heat shrink tubing
  • Wire cutters/strippers
  • Multimeter (optional)

These are the steps to follow to make your alternator noise filter:

  1. Choose a suitable ferrite core. Here’s a rule of thumb: use bead-shaped cores for low-frequency noise and toroidal cores for high-frequency noise
  2. Wind the insulated copper wire around the core, leaving enough for the input and output leads
  3. Solder one end of the wire to the capacitor and the other end to the other side of the core
  4. Repeat the above step for the other side of the core using a different capacitor
  5. Cover and insulate the connections with shrink-tubing
  6. Test the filter using a multimeter or by installing it in your stereo system 

How to Install an Alternator Noise Filter?

Locate the noise source and find a suitable place to install the noise filter. Disconnect the negative power cable from the battery to prevent electrical shock or damage to your setup. Install the filter in line with the power cable and secure it with any appropriate means. Reconnect the power cable and test to see if the noise has been eliminated.

How to Install a Noise Filter Between the Alternator and the Battery?

This is slightly more complicated than installing the filter in line with the power cable. Disconnect the negative battery cable from the battery to prevent electrical shock or damage to your setup.

Locate the power cable running between the battery and the alternator. Cut it at a convenient location, leaving space to install the filter. Expose the wire by stripping the ends of the power cable. Connect one of the power cables to the “input” side of the filter. Connect the other end of the cable to the “output”. Secure the filter in place and reconnect the power cable to the battery. Test the system to ensure that the noise has been eliminated. 

How to Get Rid of Static Noise in Car Speakers?

Improper connections usually cause static noise. Ensure your vehicle is properly grounded and the connections are protected against interference. Please check out our complete guide on how to stop static in speakers to learn more.

Conclusion

Alternator whine can be a nuisance but it can be eliminated if the cause is known. To find a solution, you need to find the source. Then you can easily take the proper measures to eliminate the noise. 

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin