Subwoofer Making Noise Without Input – 7 Ways to Fix

Understanding the Reasons Behind the Hum Noise:

Before we go to the solutions, knowing the reasons behind the subwoofer’s hum noise is essential. This way, you can easily spot & fix the problem in no time. The five most common issues that lead to the subwoofer making a humming noise without input:

1. Ground-Loop:

Ground loops are the most common reasons that can cause a humming sound without input. When your audio setup faces a ground loop ⁽¹⁾, you hear the humming effect, as it causes the electrical current to travel through your audio cables. These currents interact with the subwoofer’s power supply and amplifier, creating interference that you experience as an awful noise.

The most common cause of ground loops is connecting the subwoofer to different pieces of audio equipment using unshielded or poorly shielded RCA cables. In simple words, a ground loop can occur if the two pieces of audio equipment are plugged into various switch outlets.

2. Sub’s Analogue Nature:

As you know, subwoofers reproduce low-frequency sounds and use analog signals rather than digital ones. Simply, it means the signal is sent continuously without any gaps between the data packets. Since the signal does not pause or stop for any reason, it generates vibrations which can cause subwoofer hum. You can quickly hear the humming when you place the subwoofer near objects that can pick up and amplify sound, such as walls or furniture, making it even more noticeable.

In addition, you don’t securely attach the speaker wire to the subwoofer, this can also cause humming noises. Poorly installed wiring may allow an electrical current to leak out of the wire due to a loose subwoofer connection, resulting in a subwoofer hum.

3. Head-Unit:

Connecting a subwoofer to a faulty head unit can also cause subwoofers to make a buzzing noise. A defective head unit may not be able to power the subwoofer correctly, resulting in an audible hum from the speaker. Additionally, if the head unit is not sending enough power to the subwoofer, it may also cause a buzzing noise. However, there are two things to consider in a defective head unit given below:

Capacitors Gone Bad: When these capacitors become faulty or damaged, they can cause various problems in your sound system (also the car audio system), one of which is a buzzing noise from your subwoofer.

Power Supply Gone Bad: The lack of power means they do not get enough electrical current and cannot produce sound at total volume. This limitation makes them prone to having a humming or buzzing noise. This noise is generally low and continuous, like a humming in the background.

4. Poorly Installed Subwoofer:

Poorly installed subwoofers can also make the subwoofer create an awful noise. The improperly connected power cables can cause electrical field interference around the speaker itself. The vibrations from this interference can create a low-frequency hum that is audible through the stereo system speakers.

Additionally, when you install a subwoofer incorrectly, the subwoofer’s vibration can create a humming noise without even input. This is because these vibrations cause air to pass through the subwoofer and make a low-frequency hum that affects nearby speakers. Lastly, any loose screws or wires around the speaker can lead to electrical arcing, producing a humming noise.

5. Wrong RCA Connection:

When connecting a subwoofer to an audio amplifier, securing the subwoofer’s connection with the right RCA cables is essential. The subwoofer will produce a loud humming if the RCA connections are incorrect.

How to Know the Exact Cause Behind Subwoofer Humming?

If you have a buzzing noise coming from your subwoofer without any input, it could be caused by any number of issues that I mentioned above. To narrow down precisely what is causing the problem, you will need to troubleshoot and determine the exact cause. Here are some steps you can take to help identify the cause of the hum:

• Check your connections: You first should ensure that you have the correct audio & power cable connections. You must also consider no bare wires are showing up. If any connections have come loose, reconnect them & see if the hum is present or not.
• Check the voltage on the subwoofer: You can use a multimeter to measure the output from the wall outlet (Ensure you follow the safety precautions ⁽²⁾) or power supply. You must ensure the reading is within the correct range for the subwoofer.
• Check the ground connections: If your subwoofer has a ground pin, connect it properly and securely to a metal object like a wall outlet or power supply.
• Test your audio source: Try connecting the audio source to another sound system, like a stereo receiver or amplifier, and see if the hum persists. If it does, then the source of the buzz is likely the audio source itself.

7 Ways to Fix the Subwoofer Making Noise Without Input:

1. Use an Audio Isolation Transformer:

An audio isolation transformer is a device that can prevent any electrical interference from interfering with the sound signal. This interference can come from other devices connected to the same power source or EMI (electromagnetic interference signals).

An audio isolation transformer will intercept and block this unwanted noise so that only the desired sound signal passes through it. Additionally, an audio isolation transformer can help to improve the overall clarity and quality of the sound, as it eliminates any noise that could otherwise disrupt the signal.

2. Separate Your Cables:

When you accidentally or unknowingly bind two cables together, it creates an electrical current that can interfere with the audio signal and cause buzzing. Separating your cables can prevent EMI interference and reduce or eliminate the subwoofer hum. It’s essential to keep in mind that simply untangling your audio cables may not be enough.

It’s necessary to keep your cables as far from each other and any other electrical equipment as possible. This will help reduce or eliminate the EMI interference that can cause subwoofer hum. Additionally, you should make sure your cables are securely fastened and sealed in place to prevent them from touching each other or anything else that could cause interference.

3. Use a Different Outlet:

Especially in home theater systems, I’ve fixed the humming noise just by changing the power outlet. The type of outlet used will depend on the subwoofer’s specific model and voltage requirements. If your subwoofer needs 120 volts, connect it to an outlet that supplies 120 volts. If it requires 240 volts, use an outlet that provides this voltage.

In addition to the type of outlet used, its location is also essential. Also, ensure you plug the subwoofers into separate switch outlets from other electrical devices and appliances, such as microwaves or refrigerators, that can cause interference.

4. Reverse the Polarity:

You can also fix the subwoofer’s noise just by reversing the polarity. When you reverse a power plug’s orientation, it changes the direction of the flow of electrons, affecting the speakers, which rely on the flow of electricity through their wiring to produce low frequencies.

In simple words, having a power plug or connection orientation to the battery in incorrect polarity can cause the subwoofer to make a buzzing noise due to an imbalance of the electricity flow. The direction of electrical discharge is reversed by reversing the plug, restoring balance, and neutralizing the noise.

In some cases, simply flipping the plug can bring relief from that annoying buzz. However, if this does not work, check the wiring for any issues and ensure it is properly connected. (Use a proper ac circuit)

5. Replace Capacitors in Head Unit:

Replacing the capacitors with higher-quality ones or increasing their capacitance can improve the power supply and eliminate the buzzing noise. The higher-quality capacitors can provide better filtering while dissipating more heat, thus providing a cleaner and more stable power source for the subwoofer. Additionally, they are less prone to failure than lower-grade capacitors.

6. Unclog the Ports:

Unclogging the ports of a subwoofer is an easy and effective way to reduce the buzzing sounds coming from the speaker. When dust, dirt, and other debris build up inside the ports, it can cause airflow turbulence, creating vibrations that are heard as a buzzing noise. Cleaning out these ports with a vacuum or soft brush can reduce the amount of turbulence and restore standard sound quality.

7. Use the High-Quality RCAs:

High-quality RCAs are a great way to help eliminate or reduce the subwoofer hum. This is because higher-quality cables provide better insulation for the electric current, helping reduce interference and ensuring that your sound comes out clear and clean without subwoofer hum. Higher-quality RCAs will also help minimize potential power losses due to poor-quality cables. Using the proper wires and connectors ensures that your subwoofer will produce a crisp, clear sound without any buzzing or humming background noise.