How to Test a Subwoofer With a Multimeter? (5 Easy Steps)

No matter how expensive or cheap your subwoofer is, it will degrade over time. You can easily detect the problem when hearing distorted sound or no bass coming from the woofers. 

Before considering the solution, you need to confirm if the sub has problems. A multimeter will be helpful to help you improve the sound quality in this case. 

How to test a subwoofer with a multimeter? This article will reveal five steps you need to take for this purpose. Let’s see what they are! 

How Does A Subwoofer Work?

A subwoofer is a loudspeaker designed primarily to create low-frequency sound. Any stereo system must have one to get the best sound effect.

Mostly, people like to use a powered subwoofer. If you have a passive one, you have to connect it to an amplifier. 

There are large drivers, also called woofers, in a subwoofer. Those woofers have a plastic or wood cover and look like speakers. They send sound waves to woofers within the audio system, resulting in audible bass frequencies.  

Subwoofers have the best performance when installed in home theaters and car stereo systems. Not all of them feature built-in amps, so you must attach an external amp to some models. 

How To Test A Subwoofer With A Multimeter?

Various signs might indicate whether or not your subwoofer is malfunctioning. These include issues like hearing scraping noises and no bass sound. 

A subwoofer that is broken may not even have a vibrating cone. Moreover, it may have gotten damaged or be in bad shape if it is very shaky. 

If you detect any signs, use a multimeter to check. This tool can help you measure impedance and continuity. You may also use it to examine a blown voice coil. 

There are only five steps to testing your car subwoofer with a multimeter. We will explain each in detail. 

Step 1: Disconnect the power source

Before working with electricity, make sure to disconnect all the power sources. So start by unplugging your subwoofer. 

You need to detach it from the external amp if it’s a passive sub. But if you use the active model, remove it from the car battery. 

Step 2: Remove the subwoofer from the housing 

After plugging in the subwoofer, remove it from your vehicle securely. Depending on the device’s design, sometimes you have to detach the cone from its enclosure to access the wire coil. 

Step 3: Insert the multimeter probes into the terminal

The subwoofer cone has wire coil input terminals, where you need to insert the multimeter probes. They are black and red, matching the colors of the probes. 

In this step, you will connect the probes to the positive and negative terminals of the subwoofer. Ensure to insert them before starting your multimeter. 

Step 4: Adjust the multimeter’s resistance.

Your subwoofer’s resistance tells a lot about the device’s conditions. To measure this figure, turn your multimeter’s dial to the Ohms setting. 

This task is about turning on the multimeter’s power and changing its display setting to ohm. The reading will show up on the digital display immediately. 

The omega symbol (Ω) you see on display is the ohm. Ohms may vary significantly, from 200Ω to 200kΩ. 

Turn your multimeter to the 200Ω limit as it’s the nearest higher range that yields the most accurate results. 

Place the positive and negative leads close together to check if you have adjusted the multimeter correctly.

The multimeter should make a beep sound in its continuity mode. Otherwise, it must show a reading extremely near zero or, better, zero when you adjust it to the Ohm setting. If you get them, move to the next step. 

Step 5: Check the result 

After measuring, you can read the result on the digital display of the multimeter. It should be from 1 to 4. One of the three cases below may happen:

• The reading doesn’t show any resistance or reaction. It means that you have a blown subwoofer or the subwoofer’s voice coil has been damaged. 
• The reading constantly fluctuates, revealing that the subwoofer’s voice coil suffers severe damage. It’s also a sure indicator of a blown subwoofer. 
• The reading is higher than 1Ω and lower than 4Ω. In this case, the voice coil is still working well. So the problem in your car stereo system may arise from elsewhere. 

Conclusion

To use the multimeter to check your subwoofer, you need to disconnect it and set up the multimeter correctly. Then, read the result on the display. It will notify the current situation of the device, especially the voice coils. 

This video will give you a visual explanation of our shared guide. Please check and contact us if you have any questions. 

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