Learn How to Test Subwoofer With Multimeter – Other Methods Explained!

The audio and sound quality are vital to achieving a full feeling when listening to music. Many people enjoy upgrading their sound systems with better speakers and subwoofers to improve the quality of the low-end frequencies. Suppose you are experiencing any problems with your subwoofer, such as distortion or a lack of bass. In that case, you can test a subwoofer with a multimeter.

No matter how expensive your subwoofer is, it will eventually produce worse sound quality if it is not maintained correctly. This guide will learn more things about a subwoofer and multimeter. We will also show you how to test a subwoofer with multimeter and interpret the results.

What Is A Subwoofer?

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A subwoofer is a loudspeaker designed to produce low-pitched audio frequencies known as bass. Larger speakers, called woofers, typically reproduce these frequencies, often found in home theater and car audio systems.

The frequency range for a standard subwoofer is 20-200 HZ. THX-certified subwoofers’ frequency is lower than 80 Hz and below 100 HZ for a professional live sound subwoofer.

While most sound systems include a built-in subwoofer, you may also choose to purchase an external subwoofer. External subwoofers are typically placed in the corner of a room to take advantage of the room’s acoustics and create a deeper, more powerful bass sound.

How does a subwoofer work?

A subwoofer works by reproducing the low-pitched audio frequencies from a high-powered amplifier. The sound waves from the subwoofer are then sent to the woofers in the sound system, which creates the bass frequencies that we hear.

Most subwoofers have a built-in amplifier, but some do not. If your subwoofer does not have a built-in amplifier, you need to use an external amplifier to power it.

Woofer vs. Subwoofer

A woofer is a loudspeaker designed to produce mid- and high-pitched audio frequencies. We can usually find woofers in sound systems that include a subwoofer.

A subwoofer is a loudspeaker designed to produce low-pitched audio frequencies, also known as bass. We can usually find subwoofers in the home theater and car audio systems.

A woofer is a specialized speaker, while a subwoofer is a type of woofer specialized in covering a narrower range of frequency. Also, the subwoofer’s enclosure structure came from wood or plastic, designed to minimize standing waves and resonance, which helps improve the low-frequency response.

Since subwoofers focus on a narrower spectrum, they can produce a fuller sound that a regular woofer can’t achieve.

Signs of Blown Subwoofer

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If you are unsure if you have a blown subwoofer or experiencing any other issues, some signs indicate that you have a blown subwoofer.

The most common sign is distorted sound. Several issues may cause it, such as a blown speaker, a problem with the amplifier, or a wiring issue. Sometimes, you won’t notice the distortion in its sound when turned at low volume, but when you crank it up, the sound quality begins to distort. The distortion continuously increases as you also raise the volume.

Other signs that you have a blown subwoofer may include:

📢Lack of bass response

When the subwoofer lacks bass response, it can signify that it is blown. It means that you do not hear the full spectrum of low-end frequencies. It can be due to a blown speaker, a problem with the amplifier, or a wiring issue.

📢No sound coming from the subwoofer

If you do not hear any sound from the subwoofer, then it is likely that the speaker is blown. Even if the subwoofer is safe and sound, sometimes you won’t hear any sound even if you turn the volume to maximum.

It may be due to a damaged audio carrying cable, so you need to check if the audio signals transmit it to the subwoofer. When the subwoofer still receives the audio signals but is not producing any sound or bass, it’s likely that the speaker is blown.

📢Smoke or excessive heat

If you see smoke or excessive heat coming from the subwoofer, it is an indication that it is blown. The smoke is a sign that the internal components of the subwoofer are burning, and the excessive heat is an indication that it is not working correctly.

If you are experiencing any of these signs, it is best to take your subwoofer to a professional for repair.

Why do subwoofers blow?

Speakers and subwoofers are likely to blow if they are getting too much power above their RMS power or if you keep them on for too long.

If the subwoofer is receiving too much power, it will receive too much-distorted signal, making the speaker blow. This issue may also damage the amplifier, and it can cause the subwoofer to overheat.

If you keep the subwoofer on for too long, it will eventually overheat and blow the speaker. The prolonged use of the subwoofer will cause the amplifier to work harder than it is supposed to and will eventually blow the speaker.

Another reason why a subwoofer may blow is due to “clipping.” If the automobile audio amplifier receives too much signal, clippings happen. It also occurs when the audio signal voltage reaches the peak limit of the amplifier, which destroys the waveform.

What is a Multimeter?

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A multimeter is an electronic device used to measure a circuit’s electrical properties. It can measure voltage, current, and resistance. You can use it for almost everything from simple testing such as measuring battery voltage to fault detection and other complex diagnostics.

You can also use multimeters to test a wide range of electrical components, including:

  • Batteries
  • Cables
  • Switches
  • Capacitors
  • Transistors
  • Diodes

You can also use multimeters to test a wide range of electronic devices, including:

  • LCD monitors
  • PCs
  • Printers
  • Copiers

More advanced features from multimeters can check all of the following values:

🔈Frequency (Hz)

The number of times a wave repeats in 1 second. It is produced by measuring the time taken for a waveform to go from one peak (or trough) to the next.


It is the alignment of two signals with each other. When two waves are in-phase, they will be at their maximum simultaneously. When two waves are out-of-phase, they will be inverted with each other.

🔈Inductance (H)

Measured in henries (H), Inductance is the degree to which an electric current is delayed in an electric circuit.

🔈Resistance (ohms)

Measured in ohms (Ω), Resistance is the degree to which a material opposes the flow of electric current.

🔈Temperature (°C/°F)

It measures the average kinetic energy of the atoms or molecules in a substance. It is measured in degrees Celsius (°C) or Fahrenheit (°F).


Measured in decibels (dB), it is a unit used to measure the intensity of a sound.

🔈Duty cycle

The ratio of the time a signal is on to the total time it is applied. It is measured in percent (%).

🔈Capacity (farads)

Measured in farads (F), Capacity measures the amount of electric charge that we can store in a capacitor.

🔈Conductance (Siemens)

Measured in Siemens (S), Conductance is the ability of a material to allow an electric current to flow through it.

🔈DC (direct current) voltage and amperage

DC voltage and amperage are the steady flow of electricity in one direction. It is measured in volts (V) and amps (A).

🔈AC (alternating current) voltage and amperage

This type of electrical current periodically reverses direction. It is measured in volts (V) and amps (A).

Different Types of Multimeter

There are a few different types of multimeters that you can use to test your subwoofer with a multimeter.

Digital multimeter – This is the most common type of multimeter. It is a handheld device that has a digital display. It can measure electrical values like the current, voltage, resistance, capacitance, impedance, diode, etc. These multimeters are pretty small in size.

There are three types of digital multimeters:

  • Auto-ranging multimeter
  • Clamp digital multimeter
  • Fluke multimeter

Analog multimeter – This is an older style of a multimeter. It is a large handheld device that uses an analog display to measure electrical properties. You can calculate constrained electrical values like the voltage, current, and resistance.

How to Test Subwoofer With Multimeter

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Now that you know a bit about multimeters let’s go over how to use one to test a subwoofer. Follow the steps below to successfully test your subwoofer with a multimeter and identify the resistance.

  1. Completely turn off the subwoofer and unplug it from the power source.
  2. Disconnect the speaker wires from the subwoofer.
  3. Connect one probe of the multimeter to the red wire and one probe to the black wire.
  4. Turn on the multimeter and select the “resistance” setting.
  5. The multimeter will display the resistance reading. Compare this reading to the subwoofer’s specifications. If the resistance is not within the manufacturer’s recommended range, you may need to replace the subwoofer.
  6. If you don’t have a multimeter, you can also test the resistance of a subwoofer with a continuity tester.

Suppose you’re having trouble testing the resistance of your subwoofer. In that case, there may be something wrong with the wiring or the connections. Consult a professional to help you troubleshoot and fix the issue.

Since a subwoofer has an audio output, you can test it through different ways:

  • cones testing
  • coils testing
  • sound testing
  • no amplifier testing

🔊Test the cones

Subwoofers have colid cones attached to the suspension system, making the sub produce a strong bass. The structure of the cones enables them to move forward and back, capturing and swirling plenty of air and producing the sub-low frequencies. It is essential to check the cones for any physical damage and measure how they move.

However, the cone’s movement must not be random. The appropriate mechanics for the cones should be illustrative, with extra upper loops that keep the voice coil centered in the gap after the primary loop. So, you’ll need to find a way to suspend the cones without activating them.

You can test the cones by measuring the resistance between the two pins on the back of the subwoofer. If there is low resistance, the cones are in good condition. If there is high resistance, the cones are likely damaged and need to be replaced.

Here are the steps to test the cones:

1. Turn off your subwoofer and disconnect it from any power source.

2. Remove the screws that hold the cone and take off the subwoofer grill.

3. Check the cone. If you notice some minor bends, scratches, and tears, you need to replace the cone.

4. Analyze the cone’s movement. Place your hands on the side of the subwoofer, and touch the cone with your palms. Slightly press the cone to see if it moves. If you feel some rigidity or looseness, the suspension is most likely stretched or broken down.

5. Listen to the movement of the cone. Bring the cone closer to your ears, and gently press it again with your hands. The suspension is most likely broken if you hear any scraping or rustling sounds.

🔊Test the coil

The voice coil is the coiled wire responsible for converting the electrical current into magnetic force. It is responsible for the cone’s movement and, ultimately, the production of sound. So, it’s essential to test the coils for any physical damage and measure how much they are moving.

Here are the steps to test the coils:

1. Turn off your subwoofer and unplug it from any power source.

2. Remove the screws that hold the cone and take off the subwoofer grill. Detached the back and the side panels. Make sure you don’t cut any wires in this process.

3. Examine the rear portion of the cone and look for the coil attached to the positive and negative terminals.

4. Unscrew these terminals. Don’t remove the cone and the coil.

5. Test the coils by measuring the resistance between the two pins on the back of the subwoofer. Then, analyze the results. If the resistance is above 1.0 Ohm, the coil produces enough power. However, if it is less, the coil might be damaged and need to be replaced.

🔊Test the sound

Now that you have tested the cones and coil, it is time to test the sound. Testing the sound output is one of the most common ways to determine if a subwoofer is working appropriately or not. 

Here are the steps to test the sound:

1. Link your subwoofer to the power and audio source, then switch it on. Place the volume at a moderate level.

2. Play music on the audio source.

3. Keep your ear near the subwoofer and listen carefully for any popping or rattling sounds. Try increasing and decreasing the volume. If you hear any abnormal noise, the sound is weak, or there’s no music, the subwoofer is likely damaged and blown.

4. Switch on the composition with a specific rhythm and check the bass. If it is too low, the subwoofer is not producing enough bass. If it is too high, the subwoofer is producing too much bass. When the subwoofer’s response also has gaps and is uneven, the cone is probably is not fixed accurately with the suspension.

What is an Amplifier?

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An amplifier, or amp, is a device that increases the power of a signal. It is used to improve the voltage or current of a signal. It allows you to drive a speaker with more power and produce a louder sound.

There are two types of amplifiers:

Class A amplifier – This amplifier is very inefficient, but it has a very low distortion rate.

Class AB amplifier – This amplifier is more efficient than the Class A amplifier, but it has a higher distortion rate.

Test Subwoofer without AMP

As we discussed above, the easiest way to check your subwoofer is through the sound test. An amplifier helps the process since the louder sound can hear all distortions and problems much better.

However, if you’re just testing to see if your subwoofer is blown, you can test it without the amp. Here’s how:

1. Prepare the materials needed. You will need the multimeter, a wire, and a 9V battery.

2. Connect the subwoofer with the battery. Take the wire and connect the positive end of the 9V battery to the coil’s positive terminal. Then, connect the negative end of the 9V battery to the coil’s negative terminal.

3. Once you connect the battery, see if the subwoofer’s cone is increasing or not. If it rises as soon as you join the battery, it means the coil is good, and the subwoofer is working. If it doesn’t increase, then the subwoofer might be blown out.

4. To confirm if the subwoofer has blown out, use the multimeter and follow the steps above. Again, if the reading indicates above 1 ohm, the subwoofer is blown.

Frequently Asked Questions

Q: What makes a speaker a subwoofer?

A: A speaker is called a subwoofer when it produces sounds lower than 150 Hertz. This type of speaker is used to reproduce the low-pitched bass frequencies in music.

Q: Why are subwoofers important?

A: Subwoofers are vital because they provide the missing bass frequencies in most stereo systems. They can also improve the system’s sound quality by providing a fuller range of sound.

Q: Why is my subwoofer not working?

A: There are many reasons why a subwoofer might not be working. The most common problems are a blown speaker, a disconnected wire, or an incorrect wiring configuration. You can test a subwoofer with a multimeter and use the methods described in this article to detect more problems.

Q: What should I do if my subwoofer is blown?

A: In my case, I brought it to a technician to have it repaired. But if you want a new model, you can purchase a new one. Be sure to check the specifications of the new subwoofer to make sure it is compatible with your stereo system.

Q: Why do I need an amplifier to have a sub?

A: You don’t need an amplifier to have a subwoofer, but an amplifier will help you get the most out of your sub. The amplifier will increase the power and volume of the signal going to the subwoofer, which will result in a louder and fuller sound.

Q: What are the main parts of the multimeter?

A: The multimeter has three main parts: the meter or display, the selector switch, and the ports. The display shows the readings from the test probes, while the selector switch allows you to choose the type of measurement you want to make. The ports are where you plug in the test probes.

Q: Besides using it for subwoofers, what else can I use a multimeter for?

A: You can use a multimeter for various tasks, including measuring voltage, current, and resistance. You can also use it to test batteries, fuses, and light bulbs. Be sure to read the instructions that come with your multimeter so you can learn how to use it correctly.

Final Thoughts

I understand that it can be such a heartbreak when you’re listening to music and your subwoofer stops working. Subwoofers are an essential part of any sound system, and it’s important to know how to test a subwoofer with a multimeter to check if they’re not working. There may be plenty of reasons why your subwoofer isn’t correctly working, and one common reason is blown subwoofer.

Test your subwoofer with a multimeter because is a great way to troubleshoot any problems you might be having. By following the steps in this article, you can quickly and easily find out if your subwoofer is blown or working properly. Be sure to use the information in this article to help you get the most out of your subwoofer. Enjoy!

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