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How To Test a Car Subwoofer?

A subwoofer can significantly improve the sound quality of your vehicle’s audio system, making it a must-have device for drivers who enjoy jamming out. But it’s possible to overload a subwoofer, causing it to fail. 

Fortunately, you can test a car subwoofer to ensure it’s working correctly, but how to test it right? Let’s find out.

Here’s how to test a car subwoofer:

  1. Gather the tools required to test a subwoofer.
  2. Disconnect the subwoofer from its power source.
  3. Remove the subwoofer from the vehicle.
  4. Insert the multimeter probes into the wire coil terminals.
  5. Turn on the multimeter to read resistance levels (ohms).

As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.

Tip: When testing, most subwoofers should measure between 2 and 4 ohms, depending on the type.

If you measure a subwoofer with a dual voice coil (DVC), you must test both voice coils separately, connecting the multimeter to both terminals pairs.

When one of the voice coils measures incorrectly, you have to replace the whole subwoofer.

In the article below, I will address the steps you’ll need to take to test a car subwoofer, allowing you to determine the condition of your subwoofer speaker without needing to contact a potentially pricey technician.

Gather the Tools Required To Test a Subwoofer

You’ll need a multimeter with ohm (Ω) readings. One of the best multimeters for subwoofer tests is the AstroAI Digital Multimeter from Amazon.com, as it features a straightforward dial interface that makes it easy to test for ohms. 

AstroAI Digital Multimeter TRMS 6000 Counts Volt Meter Ohmmeter Auto-Ranging Tester; Accurately Measures Voltage Current Resistance Diodes Continuity Duty-Cycle Capacitance Temperature for Automotive

It also has a large backlit screen, making it easy to see readings. This multimeter also features a hanging magnet backing that lets you place the device on a wall or nearby surface, leaving your hands free to connect probes and wires.

You might also need a screwdriver to free the speaker cone if you’re working with an active subwoofer or subwoofer speakers recessed into your car’s paneling.

Disconnect the Subwoofer From Its Power Source

After gathering your supplies, you’ll need to disconnect the subwoofer from its power source.

This process may be as simple as disconnecting the subwoofer from its external amplifier (passive subwoofer) or disconnecting the subwoofer from your car battery (active subwoofer). 

Remove the Subwoofer From the Vehicle

Once the subwoofer is disconnected from its power supply, you can safely remove it from the vehicle.

Depending on the subwoofer’s design, you might need to remove the cone from its casing to access the wire coil.

Insert the Multimeter Probes Into the Wire Coil Terminals

After freeing the subwoofer cone from its casing, it’s time to insert the multimeter probes into the cone’s wire coil input terminals. These are red and black and correspond to the multimeter’s red and black probes.

Match the multimeter probes to their respectively colored terminals on the subwoofer speaker. After ensuring they’re fully inserted, turn on the multimeter.

Turn On the Multimeter To Read Resistance Levels (Ohms)

Switch the dial on the front of your multimeter to ohms and turn on the power. You should immediately see a reading on the digital display screen. 

Depending on your subwoofer, the multimeter should display a reading between 1Ω and 4Ω. If it doesn’t, the subwoofer is likely blown and should be disposed of if the multimeter displays a lower reading. 

If you prefer a visual explanation, check out the video below:

Testing a Car Subwoofer: Active vs. Passive

Before testing a car subwoofer, it’s crucial to determine whether you’re dealing with an active or a passive subwoofer.

After all, you’ll want to ensure that the speaker you’re testing isn’t receiving any electrical power before testing it. Otherwise, you could accidentally electrocute yourself during the testing process.

Passive subwoofers are connected to external amplifiers, making them easier to power down before testing. But active subwoofers (also called powered subwoofers) feature built-in amps, making them trickier to test. 

Before testing an active subwoofer, you’ll need to disconnect the power wire connecting the subwoofer to your car battery. Wear insulated gloves when disconnecting the power wire to prevent electrical shock. 

Because active subwoofers are housed inside cases, you’ll likely need a screwdriver to remove the cone from the device before testing it. 

Fortunately, the testing process for an active subwoofer cone is identical to that of a passive one once you’ve completed these steps.

Do I Need To Test the Car Subwoofer Before Buying It?

You need to test the car subwoofer before buying it. Unscrupulous private sellers may attempt to part with faulty speakers to make a hefty profit. You’ll want to avoid sellers that don’t allow you to test a subwoofer before purchasing or who aren’t willing to test the subwoofer in person with you.

More than likely, these folks are attempting to sell damaged goods.

Fortunately, you don’t need to carry a multimeter to test a car subwoofer. Instead, you can use a 9V battery to get the job done.

How To Test a Car Subwoofer With a Battery

Multimeters are relatively affordable, and typically cost between $10 and $40, but they can be awkward to carry around. Additionally, you may struggle to find a multimeter at your local home improvement or auto repair store.

For that reason, it might be more convenient to test your chosen car subwoofer with a battery. 

Here’s how to test a car subwoofer with a battery:

  • Acquire a brand-new 9V battery.
  • Connect the negative subwoofer speaker wire to the negative terminal of the battery.
  • Touch the positive subwoofer speaker wire to the positive terminal of the battery.
  • Observe the cone’s movement.

Let’s take a moment to explore these steps in greater detail.

Acquire a Brand-New 9V Battery

The first thing you’ll need to do is purchase a brand-new 9V battery.

While you could test your subwoofer with a used battery, it’s far better to use a new one at full power. You can find a rectangular 9V battery at your local grocery store or department store. 

Alternatively, you can order a pack of 9V batteries online. 

Energizer MAX 9V Batteries, Premium Alkaline 9 Volt Batteries (8 Battery Count)

The Energizer MAX from Amazon.com is an affordable option and features easy-to-read terminal indicators.

While this pack contains more batteries than you’ll need to test a subwoofer, you can most likely use the spare batteries to power your home’s smoke detectors or garage door openers for years to come since they can be stored for up to 10 years.

Connect the Negative Subwoofer Speaker Wire to the Negative Terminal of the Battery

Locate the positive and negative terminals on the 9V battery. There should be indicator arrows or symbols on either side of the battery.

Typically, the positive terminal is rounded and smooth, while the negative terminal has a flatter tip that resembles a metal washer component.

Connect the negative subwoofer speaker wire to the battery’s negative terminal by wrapping the exposed end of the wire around the terminal. Set the battery on a flat surface.

Touch the Positive Subwoofer Speaker Wire to the Positive Terminal of the Battery

Touch the exposed end of the positive subwoofer speaker wire to the battery’s positive terminal, keeping your fingers on the insulated wire cover.

Now observe the subwoofer cone’s movement to see if it moves outward or inward.

Observe the Cone’s Movement

After touching the negative speaker wire to the negative terminal, you should notice the cone move outward or inward.

If the cone doesn’t move, the subwoofer is likely blown. Here is an easy-to-follow video guide on how to test a car subwoofer with a 9V battery: 

Conclusion

Now that you’re familiar with the different ways to test a car subwoofer, you’ll be able to purchase high-quality used subwoofer speakers with confidence.

You can also check your current vehicle subwoofers to ensure they’re in tip-top condition.