Table of Contents

Intro

In this post, I am going to outline how to fix a high-pitched whining noise in a car stereo. I have had issues with sound quality in my car stereo and I went out to find the answer to resolve my problems.

Please make sure to troubleshoot safely and take all precautions when working with electricity. Always remove the power from the battery to avoid electrical shock while working on the system. 

Issues

The car stereo sounded great after new speakers and amp, but there was a high-pitched whining noise when the car was “on”. It was loud and interfered with the sound quality of the stereo. This can be caused by a few things, but most likely by the interference of the electrical waves from the car’s power systems. There are multiple noises that can be causing an issue. In my case, I was able to drill down my issue to “ground loop noise” and “electromagnetic interference”.

The most common issues that cause a high pitched noise in audio systems are:

  1. Loose Wire Connections 

  2. Ground Loop Noise

  3. Electromagnetic Interference

Let’s now look at some of the ways we can solve this issue.

Solutions

The first step is to figure out which issue you are dealing with, by methodically going through the potential root causes one by one. I would start in this order:

    • Loose wire connection
    • Remove Ground Loop Noise
    • Reduce Electromagnetic Interference
    • Use High-quality RCA cables
    • Use High-quality power cables 

ID the type of noise in the system

    1. Turn the vehicle off, but keep the key turned so that the accessory power is on.
    2. Pause the music that is currently playing. While the music is paused, turn the volume 3/4 of the way up. Again, there is no need to send audio through the speakers at this time.
    3. Cycle through the modes, AUX, Standby, FM, AM, CD, etc., and take note of whether the hum or buzz was present. If it changed based on the input – that could give you insight on what to try to fix. For example, if the noise occurs only on your AUX setting, then it could be your cord (3.5 audio connector) you use to hook up your phone. Replace the cord or use a ground loop filter on it. If the noise is on every input, then you know it’s not based on the input accessories.
    4. If no hum or buzz was present, turn the vehicle ON and repeat steps 1-3 to try to isolate where exactly the hum or buzz noise in your audio system. Does it happen on one input only, or on all inputs?
    5. Rev the engine while keeping the music paused, and just listen to see if the pitch or intensity changes when you rev the engine. If it does, then you can take the below steps to help remediate these issues. There are multiple causes and fixes for electrical issues, these are some common ones.

1. Loose wire connection

Loose wires can cause several problems in-car audio, ranging from minor interference to potentially causing a fire. Loose power cables can be dangerous because of the electric current running through the system. You do not want to have a loose cord in your audio system. There are a few places that you could have loose wires in your system:

A. Amp

B. Battery

C. Head Unit

 

1A. Amp

Check all the wire connections at the amp to ensure a tight connection. There are several types of wires going to your amp. Power wires, RCA wires, and Speaker Wires. They all must be on the correct input on your amp and tightly secured. The ground wire will generally be black, while the power wire will generally be red or white. When properly installed, the ground wire will go from the back of your amp to the chassis of the vehicle.

1A1. Confirm the ground wire (-) from the amp to the vehicle chassis is secure

Locate the ground (-) wire termination point from your amp to your chassis and ensure that it is touching the bare metal securely. Once you trace the ground wire to where it is mounted on your chassis, ensure it is completely touching and is tightened so that it makes direct contact with the bare metal chassis. The installers should have sanded the area where it is mounted so that it is bare metal. Ensure that the wire length is not excessive. The shorter you make the ground wire, the less resistance in the system, and your amp will work better with less resistance.

1B. Battery

Pop the hood and locate your battery. Inspect the + positive terminal post. Ensure all the wires are firmly connected to the Positive post. The negative terminal of your vehicle battery has a wire that terminates on the chassis. This is done generally at the creation of the vehicle. It may be necessary to clean the battery posts with a cleaning agent to ensure a secure connection with the terminal. 

1B1. Confirm the ground (-) wire is securely connected from the negative (-) battery terminal to the vehicle chassis
Ensure it is securely touching against the chassis as well as the battery box. You can find it on the negative terminal of your battery – or if you have a metal box around your battery, the wire will branch off that to your vehicle chassis to ground out.
1B2. Install a Distribution Block

A remedy for an issue with a poor connection to the battery would be installing a high-quality power distribution block. This will ensure a secure fit for all your power accessories in your vehicle.

1B3. Do the “Big 3” Upgrade

The “Big Three” electrical upgrade is an excellent, cost-effective solution that will upgrade your vehicle’s electrical system capacity (ability to handle more power). You will need to buy get and install the parts. This can be done after a car audio system has already been installed to assist with power consumption. Three (3) critical cables in the electrical system are replaced or supplemented with 1/0 or 4 gauge wires: the battery ground to chassis wire, the chassis to engine block wire, and the alternator plus to engine block wire.

1C. Check connections at the Head Unit

Based on your installation ability, you can try to check the wires at the back of the head unit. Make sure they are all securely connected if you are able to. Sometimes the cables get disconnected or jammed when the head unit is installed. There is always a chance of loose wires at the head unit. Try the other steps in this post before you take it into an audio shop. If you do go this route, I highly suggest taking it to a “mom and pops” audio shop vs. a name brand store like Car Toys.

2. Ground Loop Noise

Ground loop is caused by an improper grounding of a negative wire somewhere in your system. This tends to be a popping noise after an interval of time, basically, however long it takes electricity to move throughout your system – then ground out somewhere in the vehicle and make that “pop” noise through your speakers.  There are only a few places that it could be. 

A. Amp

B. Battery

C. Head Unit

2A. Amp: Install a RCA cable filter into your amp

One thing you can do is put a filter on the RCA line to your amp. This is an easy way to reduce noise introduced in your system if you can not organically find and fix the issue. It is important to get but a quality RCA filter to effectively de-noise your RCA line. This places a filter on the audio signal on the RCA’s from your head unit before it hits your amp. I suggest a high-quality isolator like this one. You will need to get 1 RCA cable filter for every 1 RCA channel. One RCA channel consists of a left and right input (white and red wire, mono and stereo, etc).  Generally, car audio setups have 2 channels (4 RCA cables), so you will need (2) RCA cable filters. 

Don’t Forget!

You will need a pair of RCA “patch cables” to get the signal back from the RCA ground filter into your amp.

2B. Battery

Ensure all your wires are secure and fastened so they do not move while driving. Ensure your ground wire from your battery is securely connected as well as all the wire connections at the two battery terminal posts. These can sometimes be secure but not fully flat or touching, which can sometimes cause a short.

2B1. Clean Battery Terminals

Cleaning your battery terminals is an easy way to bring back life to an older battery. Sometimes buildup around the battery terminals decreases the flow of electricity. Cleaning the posts with a brush like this makes this task very easy. It can also be achieved with a can of Pepsi or Coke and a scrubbing brush.

2C. Head Unit:

Based on your setup and installation ability, you can try to check the wires at the back of the head unit as mentioned before, or install a filter at the head unit to limit the noise. You may not be using a AUX line input, to get your music from your phone to your speakers. If you are not, then skip this step. 

2C1. Install an in-line Aux filter:

This places a filter on the audio signal on the AUX cord to your head unit before it hits the RCA’s, then your amp. then the speakers. 

3. Electromagnetic Interference

It is uncommon but likely that your power cables to your amp are bunched together, or run, near your RCA cables. This is a classic no-no because you are introducing interference into an amplified system.

3A. Re-route your Power or RCA cables away from each other

This must be done for the complete length of the car, when possible to avoid any interference from the power cables. If you have not laid the cables yet, then please do not run the RCA and power cables on the same side of the vehicle. The best practice is to separate these two cables to reduce the possibility of interference in the audio system.

If you already have a system in place, now would be a good time to upgrade your RCA’s cables also – before you reroute them.

4. Use high-quality RCA cables 

Cables made with low quality generally don’t have the proper shielding to deflect interference and electric noise as it waves all around you. Investing in high-quality RCA cables ensures proper noise shielding, and increased sound quality in your system.

4A. Install high-quality RCA cables

This is one of those things that you wish you would have done right the first time. If you are still getting interference with your audio signal, then you probably don’t have the appropriate shielding on your RCA cables and will continue to get interference. If your system is already set up, then you will need to re-lay the RCA cables with new ones.

Try the “AUX in-line” and “RCA filters” before you do this step and see if that resolves the issue

5. Use high-quality power cables 

You got your stuff in a kit and someone installed it and it’s buzzing. Well, your power cables *may* be low quality where they could not be sufficiently insulated to not cause interference with your audio system.

5A. Install high-quality power cables

If you have not separated the Power cables from the RCA cables, like put them on separate sides of the car, then you need to do that first. Otherwise, you could get better power cables.

Installation Tip: Match the size (gauge) of the wires that you use for the power (+) and ground (-) wires. Ex: If you use a 4 gauge power (+) wire from your battery to your amp, then you will want to also use a 4 gauge wire to ground your Amp to the car chassis. Never use unequal wire sizes to power your amplifier.

Do not go to Car Toys

I strongly advise against ever getting your car serviced at Car Toys as noted in my Google review of Car Toys, Plano, Texas location. They generally charge by the hour and try to string out the amount of time it takes to do the work, as well as sell you additional items.

Summary

Those are common issues and solutions to car stereo whining noise. Let me know if any of these worked for you or didn’t. As always, glad to help others who might have run into similar problems as me. 

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Kelsey Salman

Solution Engineer, Application Security

A techie, photographer, and drummer – based in Dallas, he can often be found at dog parks and Major League Soccer stadiums around the United States. He is also an avid aquarist and the happiest guy around when the company’s good.