Using Car Alternator Noise Filters




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Car stereo systems are an excellent way to enjoy music while driving, but sometimes you may hear some annoying noises caused by the alternator. 

If you experience this, do not worry. Fortunately, there are filters available that can help reduce or eliminate this noise, but how to use them properly? Let’s find out.

To use the noise filter, install it between the battery and the alternator to reduce noise at the source. Alternatively, depending on the type, connect the filter between the head unit and the amplifier.  

Key Takeaways
Car audio noise filters can help eliminate unwanted noise in your car audio system.
Ground loops and alternator whine are common sources of noise in car audio systems.
Noise filters work by using ferrite to absorb high-frequency noise from the audio power wire.
It is important to properly diagnose the source of the noise before installing a noise filter.
Depending on the type, noise filters can be installed in-line with the power or RCA cables to reduce interference.

If you want to learn more about the role of an alternator in a car audio system, check out our comprehensive guide. 

Understanding the Need for a Car Stereo Alternator Noise Filter

When you’re cruising in your car, the last thing you want is an annoying, persistent noise ruining the audio experience. The car stereo should provide a pleasant respite from the engine’s roar, not add to the cacophony.

But due to some inherent characteristics of the car’s electrical system, unwanted noise problems might sneak into your car audio.

when to use alternator noise filter in car audio

One common source of this noise is the alternator, the component that charges your car battery while the engine is running.

It can cause a type of noise known as “alternator whine,” often heard as a whining noise through your car’s speakers when the engine is running.

This can dramatically interfere with the audio output from your head unit, disrupting your listening experience. That’s why you might need an alternator noise filter which can make a great difference between a poor and an excellent stereo experience.

How the Alternator Noise Filter Works

An alternator noise filter connects inline between the alternator and battery, filtering out any unwanted noise in the electrical current. The principle behind this is quite simple.

The filter works to balance the electrical potential within your car’s audio system, thus preventing the transfer of any unwanted electrical noise to your speakers.

The power cable carrying current from the alternator to the battery passes through this filter, which acts as a buffer to stop any noise from infiltrating your car audio system.

Identifying the Need for an Alternator Noise Filter

Common Noise Problems in Car Audio Systems

When it comes to the serenity of our car audio experience, we expect perfection. However, like any electronic system, it’s not always smooth. 

There are several noise problems that can intrude upon your favorite tunes or podcasts. Let’s go through some of the most common ones.

#1. Alternator Whine: Ah, the infamous alternator whine, the primary reason we are talking about alternator noise filters. This unwanted noise is characterized by a whining noise that changes in pitch or volume according to the engine speed.

It’s often heard when the car’s alternator is under a high electrical load, such as when you’re running the headlights, heater, and the car stereo at the same time.

#2. Electrical Interference: Various electronics within your car, from the engine control unit to power accessories, can generate electrical noise. 

This interference can be transferred through your car’s electrical system, causing an annoying buzz or whine in your car audio.

#3. Engine Noise: Lastly, engine noise can directly or indirectly affect your car audio. Indirectly, as the engine operates, it generates electrical noise that can interfere with your car stereo.

Directly, your speakers could potentially pick up and amplify mechanical vibrations from the engine, creating a noticeable sound.

How to Know if You Need an Alternator Noise Filter

Recognizing these noise problems is one thing, but how do you know if an alternator noise filter is the solution you need?

The answer is in careful diagnosis. So let’s dive in and see how to diagnose these noise issues:

#1. Listening for Noise: The first step is the simplest one – use your ears. Turn on the car audio system without any music playing.

Can you hear any whining noise, static, or buzzing coming from the speakers? If yes, then you might need a noise filter.

#2. Checking the Volume: Increase the volume of your car stereo. If the intensity of the noise increases with the volume, the issue might be with the head unit or the speakers themselves.

However, if the noise level stays the same regardless of the volume, you might be dealing with alternator noise.

#3. Observing Engine Speed: Start the engine and observe any changes in the noise. If the noise changes in pitch or intensity with the engine’s RPM, it’s most likely alternator whine.

#4. Inspecting the Ground Connection: A poor ground connection can cause noise problems too. Check the ground wire connection from your car audio system to the car’s chassis. If it’s loose or corroded, you might need to fix the grounding before considering a noise filter.

Exploring Alternator Noise Filter Solutions

Best Alternator Noise Filters on the Market

So, you’ve decided you need an alternator noise filter. Excellent choice! You’re already on your way to a cleaner and clearer car audio experience. But which one should you choose?

With so many options out there, it can feel a bit overwhelming. Don’t worry, though. I have done a homework for you.

Let’s take a look at some top-rated alternator noise filters and their key features:

#1. BOSS Audio Systems Ground Loop Isolator: BOSS has a reputation for high-quality car audio accessories, and this noise isolator is no exception.

It works by breaking the ground loop, effectively eliminating that annoying humming or buzzing sound in your speakers.

#2. Install Bay IBNF50 Noise Filter: Install Bay is another top name in car audio, and their IBN50 noise filter does not disappoint.

It’s designed to remove the alternator whine and can be easily installed inline on the power cable.

When choosing an alternator noise filter, compatibility with your car’s electrical system and the head unit is key.

  • Additionally, take note of the filter’s frequency range—this can impact the audio quality.
  • Lastly, consider its size and mounting options. Some filters can be bulky, so ensure you have a suitable place to install it without interfering with your car’s other components.

DIY Alternator Noise Filter

Now, if you’re like me and love a good DIY project, you might be thinking, “Can I make an alternator noise filter myself?” The answer is absolutely! 

While it’s not for everyone, building your own noise filter can be a rewarding and cost-effective solution. 

Remember, working with your car’s electrical system can be dangerous if you’re not sure what you’re doing. If you’re not confident, it might be best to stick with a pre-made noise filter.

But for those with advanced technical and electrical know-how, a DIY alternator noise filter can be an excellent project. It gives a real sense of satisfaction.

Installing an Alternator Noise Filter

Preparing for Installation

When you’ve decided on a noise filter, you’ll need to get your hands on some essential tools and materials for the installation.

Here’s a list of what you’ll likely need:

#1. Wire Strippers and Cutters: These will come in handy for adjusting the lengths of wires and stripping the ends for connections.

#2. Connectors and Electrical Tape: For making secure connections that stand up to the rigors of a moving vehicle.

#3. A Multimeter: This is an optional but highly recommended tool. It’ll help you diagnose if there’s indeed a noise issue and confirm that your installation was successful.

Safety should always be your number one priority when working on your car’s electrical system.

As an important side note from my personal experience—always disconnect your car’s battery before starting the installation.

It might seem like an inconvenience, especially if you have to reset your radio presets, but trust me, it’s better than the alternative of a potential electrical shock or short circuit.

Step-by-Step Installation Process

Now that we’ve got safety and tools out of the way, let’s get down to business. Here’s a step-by-step guide to installing your alternator noise filter:

#1. Locating the Alternator and Battery Your first step is to locate your car’s alternator and battery.

The alternator is usually found on the front side of the engine, and the battery in most cars is either in the engine compartment or the trunk.

You need to install a noise filter on the power wire between these two.

#2. Identifying the Power and Ground Wires Next, identify the power and ground wires.

The power wire connects the alternator to the battery and is red, while the ground wire is black and connects to the car’s chassis.

#3. Connecting the Noise Filter Once you’ve identified the correct wires, it’s time to connect your noise filter.

It connects inline between the alternator and the battery—hence, you’ll place it on the power cable. However, the exact connection depends on the specific filter type, so always refer to the installation manual.

Also, when making connections, be sure to secure the connections using the connectors and electrical tape.

#4. Securing and Testing the Installation After making the connections, secure the noise filter in a location where it won’t interfere with any moving parts.

Once everything is in place, reconnect your battery and start the car. Listen carefully to your car audio—there should be a noticeable reduction in the alternator whine or other noise issues.

Remember, this is a general guide, and actual installation may vary depending on your specific car and noise filter.

If you’re unsure at any point, don’t hesitate to consult a professional. A small installation fee is a small price for peace of mind and a job well done.

Effectiveness of Alternator Noise Filters

One question you may be asking at this point is – how effective are car stereo alternator noise filters?

From personal experience and numerous others’ testimony, they’re effective, especially when it comes to addressing specific noise problems, but the correct installation is the key.

Limitations of Alternator Noise Filters

But let’s be clear—noise filters aren’t a panacea. If the noise in your car audio is stemming from poor grounding, damaged speakers, or other mechanical faults, a noise filter alone might not be enough to solve your problems.

It’s also worth noting that a poorly designed or incorrectly installed filter might cause more harm than good, such as causing a power drop that can affect your car stereo’s performance.

Potential Interference with Other Components

When installed correctly, a car stereo alternator noise filter should function without interfering with other car components. It primarily connects inline between the alternator and the battery, so it’s rather isolated from other systems.

If you notice any unusual behavior in your vehicle after installing the noise filter, it’s important to check the installation.

Ensure that the filter and its wiring aren’t disrupting any moving parts or causing electrical shorts.

Additional Measures to Reduce Noise

As a car audio enthusiast, I understand that achieving the perfect sound involves more than just installing a noise filter. Here are a few more strategies you can employ to mitigate noise problems further:

#1. Improve Grounding: Poor grounding can be a significant source of noise. Ensure that the ground wire from your head unit and amplifiers is attached to a clean, bare metal part of the car’s chassis.

#2. Upgrade Your Speakers: Stock car speakers aren’t always the best. Consider upgrading to higher-quality speakers for a more enjoyable listening experience.

#3. Invest in Quality Audio Equipment: All elements of your car audio system—the head unit, amplifiers, and cables—contribute to the final sound. 

Investing in high-quality components can improve sound and reduce the likelihood of noise.

#4. Proper Wiring: Make sure your audio cables are kept as far away as possible from power and ground cables to avoid electrical interference.

Remember, achieving perfect car audio isn’t an exact science. It’s part art, and part technical know-how. So, experiment, learn, and never stop striving for that perfect sound.

Cost and Considerations

How Much Does an Alternator Noise Filter Cost?

As with many car-related components, the cost of an alternator noise filter can vary widely based on several factors, including the brand, the features, and the level of noise reduction it offers.

On average, you can expect to shell out anywhere from $10 to $50 for a decent car stereo alternator noise filter.

Installation costs are another factor to consider. If you’re a DIY kind of person like me, and feel comfortable following a step-by-step guide, you can install it yourself.

However, if you’d prefer to leave it to the professionals, you should anticipate additional labor costs. Remember that professional installation can ensure that the filter is set up correctly and functions at its best.

Factors to Consider When Choosing a Noise Filter

Choosing the right noise filter isn’t just about price. Consider these factors:

#1. Compatibility: Make sure the noise filter you choose is compatible with your car’s alternator and your head unit.

#2. Installation: Some filters are easier to install than others. Make sure to pick one that matches your skill level unless you plan to hire a professional.

#3. Noise Reduction Capability: Look at the specifications of the noise filter. Does it effectively reduce the whining noise or other types of noises that are specific to your car’s audio problems?

Maintenance and Replacement

Generally speaking, once an alternator noise filter is installed, it doesn’t require a lot of maintenance. However, it’s a good practice to regularly check it when you perform other routine car checks.

Make sure its connections to the alternator and the battery are secure and that it’s not physically damaged.

As for replacement, an alternator noise filter will typically last a long time. However, if you start noticing the alternator whine creeping back into your audio, it might be time for a replacement.

Read More About Car Audio Alternators

How to Upgrade Alternator for Car Audio?

If you are experiencing issues with your car audio system, upgrading your alternator can be a solution. A high-output alternator can provide the additional power needed to run your system without causing any damage to your battery or other electrical components.

To learn more about how to upgrade your alternator for car audio, check out our detailed guide.

Balancing Car Audio Battery and Alternator

Balancing your car audio battery and alternator is crucial for maintaining a healthy electrical system. A properly balanced system ensures that your battery is charged and your alternator is not overworked.

To achieve this, you may need to upgrade your battery or alternator, or install a battery isolator or capacitor.


As we’ve journeyed through the world of car stereo alternator noise filters, we’ve covered some important ground, and there are some of the key takeaways:

  • Alternator noise filters can significantly improve the audio experience in your car by reducing unwanted noises such as the whining noise caused by your car’s alternator.
  • These filters work by evening out the difference in electrical potential between the alternator and battery, which helps to cut out the pesky alternator whine.
  • There’s a range of noise filters on the market, with options for DIY installation or professional installation.
  • It’s important to consider compatibility, ease of installation, noise reduction capabilities, and brand reputation when choosing a filter.
  • While these filters can be a significant help, they may not be a magic bullet for all noise issues. Other strategies might be needed to fully address noise problems.

Using a car stereo alternator noise filter may seem like a small thing, but as an audio enthusiast myself, I can tell you that the difference it makes is anything but small.

It’s about turning your car into a space where you can truly enjoy your favorite tunes without irritating interference.