How to Check Subwoofer Ohms with Multimeter (Complete Guide)

A movie night with a distorted subwoofer is a disaster. It is no longer a secret that adding a subwoofer to your sound system provides you with the best audio experience.

After all, low frequencies like deep bass can only be achieved with subs, which improves the overall audio quality. However, it is important to note that the ability of subwoofers to produce low-frequency sound reduces over time or gets damaged due to overuse.

You might wonder why the 2 or 4-ohm subwoofer you purchased a couple of years ago currently produces low or no quality sub-bass. The good news is that you are in the right place.

A multimeter is one of the easiest ways to check your subwoofer’s health by checking its ohms.

To check subwoofer ohms with a multimeter, you should: disconnect the subs from their power source; remove all audio inputs and power cables; connect the multimeter probes to the voice coil terminal; and set the multimeter’s resistance to ohms.

In this article, we will explore the topic and provide you with an in-depth answer on how to check subwoofer ohms with a multimeter.

How to Check Subwoofer Ohms with Multimeter


What is Ohms in a Subwoofer?

If you don’t already know, you might wonder what all the fuss is about Ohms. I would too.
Ohms is the standard unit used to measure a speaker’s or subwoofer’s impedance.

This begs the question, “What is impedance?” The impedance of a subwoofer defines its resistance to the flow of electricity.

A subwoofer with more ohms has a higher resistance, whereas subs with fewer ohms offer less resistance to the flow of electric current.

Impedance in subwoofers indicates the amount of power a subwoofer can hold and how much of it can be transformed into sound.

Subwoofers with a lower impedance require less electricity to work. However, this comes at a cost, as the sound quality will be poorer.

On the other hand, subs with a higher impedance require more electricity to work but produce better sound quality.

Why Check Subwoofer Ohms?

After explaining what ohms are, it is important to know why you should check your subwoofer ohms. This provides context before proceeding to how to test subwoofer with multimeter.

A subwoofer is crucial to your overall audio experience because it has a great impact on your system’s sound quality. As a result, it is important to check its health.

When you start getting distorted sounds, you should check if your subwoofer is blown. Furthermore, any decline in the quality of your subwoofer is another reason to check its ohms reading.

Checking or testing your subwoofer’s ohms provides some basic information about it and its health. This provides you with valuable knowledge on what is wrong with it and how it can be fixed.

What is a Multimeter?

A multimeter is an electronic device used to test resistance, current, and voltage. This makes the device one of the simplest ways to check subwoofers’ ohms.

The ohms reading will help determine if the sub is blown and provide an answer to the sub’s unresponsiveness, distortion in sound, or malfunction.

How to Check Subwoofers Ohms with Multimeter

We already explained what ohms are and why it is important to check subwoofer ohms. This provides insight into the subwoofer’s health.

Using a multimeter is the simplest way to determine if a subwoofer is in good condition by testing its resistance, or ohms. The steps you need to follow will be highlighted in the succeeding paragraphs. Let’s delve into it.

Disconnect the Sub from Power Source

This is the first step to testing the subwoofer with a multimeter. This step requires you to turn off the subwoofer or disconnect it from its power source. You might also need to remove it from its external amplifier.

Disconnecting the sub from its power source or external amplifier will give you the correct and proper measurement. This is required to get the proper diagnosis.

Remove Audio Inputs and other Cables

After disconnecting the sub, removing all audio inputs and power cables is the next step in testing the subwoofer with a multimeter. Remove and untangle all cords and wiring to free the subwoofer.

Remove the Sub from its Enclosure

The next step is to remove the sub from its enclosure. You need the subwoofer freed from its housing to properly have access to the voice coil for testing.

Removing the sub from its enclosure varies depending on the design, type, or brand. It is important to pay attention to the subwoofer’s design or type as you disassemble it.

Irrespective of the subwoofer type, gaining access to the voice coil is important. Hence, you should disassemble the sub to gain access to it.

Connect the Multimeter Probes to the Voice Coil Terminal

The succeeding step after gaining access to the voice coil is connecting your multimeter to it. This stage requires you to connect the multimeter probes to the voice coil.

The multimeter probes are in red and black colors, which signifies positive and negative; likewise, the subwoofer’s wire or voice coil input terminal.

So, you should match the colors between the multimeter probes and the sub’s voice or wire coil. You should also make sure that the multimeter probes are completely inserted and secured.

Turn the Multimeter on and Set its Resistance to Ohms

Once the multimeter is securely connected to the subwoofer voice coil terminal, you should proceed to turn it on. After powering the multimeter, change the front-dial setting to ohms. The standard unit is represented by the omega symbol (Ω).

Immediately after changing the measurement to ohms, you should get a reading on your multimeter. The reading represents your subwoofer’s resistance, which is represented by ohms.

You should ensure that the multimeter is set to the 200-Ohm limit by manually turning it. This is due to the fact that it is the closest higher range that produces the most accurate readings.

Understanding the Multimeter Readings

Having multimeter readings in ohms is useless if they cannot be interpreted. Depending on your sub’s condition, you can have different readings.

Examples of readings and their interpretations include:

Multimeter reading showing no resistance: If your multimeter reading shows no resistance, it means that the subwoofer is blown or its voice coils are damaged.

Constantly shifting reading: This reading signifies the voice coil’s complete damage. It is also an indicator that the voice coil is blown.

Readings between 1 and 4: This is a good reading. It signifies that your coils are in good condition, and you should look for the problem somewhere else.

Final Thoughts

A sound system with a malfunctioning subwoofer is no good. There are different reasons why you might want to test your subwoofer.

The most common are decline in quality, malfunctioning, and distortion in sound. In order to understand your subwoofer’s health, it is important to test or check its health, which a multimeter can help you achieve.

To test subwoofer with multimeter is an easy process, which we highlighted above in the article’s body. The multimeter reading will save you time and effort and help you determine what is wrong with your sub.

The multimeter reading will provide insight into your subwoofer’s health. It will show if the sub is really blown, its voice coils are damaged, or it is in fact in good health.

This makes testing your subwoofer with a multimeter important when you are unsure whether your sub is blown, damaged, or not.

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