How to Tell if a Subwoofer Is Blown?

4 Signs of a Blown Subwoofer:

Before we go further, let’s have a look at the signs of a blown subwoofer:

• Low sound or no sound at all
• Distortion in sound frequency
• Blown voice coil
• No speaker movement

1. Low Sound or No Sound at All:

The main result you will notice of a blown subwoofer is low sound or no sound at all coming from it. The speaker may have an issue if the subwoofer’s sound is noticeably low, distorted, or nonexistent. Additionally, if the sound is fuzzy, this could also indicate that the speaker has blown.

2. Distortion in Sound Frequency:

Because subwoofers are very low-frequency speakers, they are more likely to blow than other speakers. When this happens, you may notice that the sounds coming from your system have changed and become distorted ⁽¹⁾ or muffled.

3. Blown Voice Coil:

If you notice any unusual performance from your subwoofer, it could mean your subwoofer’s voice coil has been damaged. You start hearing the rattling sound created by the broken wires inside the voice coil, which causes them to vibrate in an uncontrolled way. You may also notice that your sub has suddenly become quieter than usual.

Subwoofer Blown Voice Coil Symptoms:

• The subwoofer stops producing sound or may have distorted, muffled, or scratching sounds.
• The voice coil rubs against the magnet, causing a rattling noise from the speaker.
• The coil may be visibly damaged, with tears in the wire or dents in the speaker cone.
• There is no bass response, regardless of how high you turn up the volume.
• The subwoofer produces a popping or crackling sound.
• There is a burning smell coming from the subwoofer.

4. Speaker Movement:

A malfunctioned speaker cone can also be a reason behind a blown subwoofer. You will notice that your speaker’s cone is moving in and out rapidly in response to the sound waves it’s producing. In the engineering world, we call this movement an excursion caused by a change in air pressure around the speaker.

4 Ways How to Tell if a Subwoofer Is Blown?

Above were the signs of a blown subwoofer. Now, you can investigate yourself to confirm if you have a blown subwoofer or partially blown subwoofer by performing four different ways.

1. Physical Inspection:

If you want to ensure your subwoofer has been blown out, you must inspect it physically to determine the cause of the issue. Below are the steps to check it physically:

• First of all, power off and unplug your subwoofer.
• If the subwoofer is in an enclosure, take it out. You must unscrew the subwoofer’s holdings and gently pull it out toward you for removal. However, you need to remove the grille (if present) on the front of the speaker by unscrewing its holdings too. Inspect the woofer cone and surround for any burn marks, tears, or other signs of physical damage.
• Now, check the voice coil by gently moving it back and forth to ensure it is not rubbing against the magnet. If you notice any problems with either component, your subwoofer will likely be blown-out.
• If you cannot identify a physical problem, you may be able to determine if your subwoofer is completely blown out by testing it with an ohmmeter.

2. Test the Car Subwoofer:

If you have a blown subwoofer, there are several steps you can take to test the sub. The most used ways to try it are given below:

2.1 Knowing the Resistance Through Multimeter:

• You will have to connect a multimeter in series with the subwoofer’s voice coil. Also, set the multimeter in Ohms (Ω) to measure the resistance.
• Once connected, it will show the figures on display. Note down that reading of resistance. If it is within a range of 2-8 ohms, then your subwoofer is not blown, and you can use it without any worries.
• However, if the resistance reading is 0 ohms or higher than 8 ohms, then your subwoofer has blown and needs to be replaced.

It is essential to ensure you have connected the multimeter correctly in series (positive terminal with positive and negative to negative terminal) with the voice coil, as an incorrect connection might give you wrong readings. Make sure you check the resistance range of your sub before testing it with a multimeter to ensure an accurate result.

2.2 Without Using a Multimeter:

You can also check if your subwoofer is blown without using a multimeter. There are two ways to determine. One way is to connect a 9V battery to the subwoofer. If you hear any sound coming out of the subwoofer after a proper connection, it means your subwoofer is working fine. The second way to ensure a not blown subwoofer is to check it through the car amp or any traditional amp (suited to the subwoofer’s power). Slowly increase the volume on the amp and check the bass effect. If you get a fine and loud bass, that means your sub is working fine.

3. Check The Cone Movement Through Touching:

You can also detect the sub’s problem by checking the subwoofer cone movement with your fingers. The best way to do this is by physically touching the cone and observing any instability in its direction by gently pushing it. If it moves too freely or too loosely, then chances are that it has been damaged and needs to be replaced.

However, if the cone feels stable and has no excessive movement, the subwoofer is likely still in working condition. It is important to note that when checking the speaker cone, you should use very light pressure, as too much force can cause further damage.

4. Check the Audio Quality By Listening to the Music:

Another way to detect the problem is by determining the sound quality. To perform the task, follow these steps:

• First, ensure you haven’t set your system’s volume too loud. If it is, it can mask any damage or distortion to the subwoofer.
• Next, listen to some music on your system. As you do this, pay close attention to how the bass sounds coming from the subwoofer. Is it loud and clear, or does it sound tinny and distorted?
• To confirm, try playing some lower-frequency music. This will give you a better idea of how the subwoofer is performing. Is it able to accurately reproduce these lower frequencies, or is it struggling to keep up?

Why Do Subwoofers Blow?

Many reasons can cause a subwoofer to blow. Some of them are given below:

• Overheating
• Overpowering
• Underpowering
• Poor Wiring
• Mechanical Damage
• Too Much Distortion in Signal (Distorted signal)

Overheating:

The leading cause for a subwoofer to blow is exposure to an excessive amount of heat. Overheating can happen in several ways:

• Playing too loud for too long.
• Using an amplifier that is too powerful.
• Leaving it out in direct sunlight.

When a subwoofer overheats, its internal components can become damaged, leading to the system’s failure and even an explosion of the speaker itself. It is essential to ensure that your subwoofer is not exposed to constant heat, as this can cause irreparable damage.

Overpowering:

Subwoofers are designed to handle a specific wattage at a given volume. Pushing the subs beyond their limits can cause the internal components to overheat and eventually fail. Overpowering your subwoofer with too much wattage is one of the most common reasons for failure. When this happens, the coil, which is the moving part of the speaker, can get too hot and melt or burn. This can cause permanent damage to your subwoofer and render it unusable. Therefore, it is crucial to provide a sufficient amount of power.

Underpowering:

When a subwoofer is underpowered, it will be exposed to higher levels of power than it can handle. This can also cause the voice coil to heat up faster than it should and eventually burn out, resulting in the subwoofer blowing. If too much power is sent through the sub, it can also put an unnecessary strain on the components, resulting in poor performance and eventual breakdown.

The best way to avoid this is to use an amplifier that can adequately provide the power needed for a subwoofer, allowing it to perform optimally. In addition, correctly setting the crossover and level controls on your receiver or amplifier will help protect a subwoofer from power issues.

Poor Wiring:

Poor wiring can cause a subwoofer to blow in several ways. First, if the speaker wire is too thin for the amplifier connected to it, too much current may flow through the wire, causing it to overheat and eventually burn up. 

Also, if you don’t have a correct ground connection between the amp & sub, the subwoofer will receive too much power, causing it to overheat or blow.

Finally, if the speaker wire is wired in reverse polarity between the amp and subwoofer, this can cause a short circuit that could blow the subwoofer’s internal components. Therefore, proper wiring of all components is essential to avoid dangerous situations.

Mechanical Damage:

Subwoofers can blow due to mechanical damage, a physical force or impact that damages the subwoofer’s components. This includes improper handling, dropping it, continuous power handling, or pushing it too hard against an external object like a wall or table.

The physical shock from these events can cause speaker diaphragms to tear, voice coils to short out, or other components like resistors, capacitors, and transformers to break. In some cases, the damage can be so severe that the subwoofer’s amplifier may also blow out.

Too Much Distortion in Signal (Distorted Signal):

It is essential to know that too much distorted or clipped signals can cause subwoofers to blow (distorted sound). Distortion occurs when there is an extreme increase or decrease in sound pressure – which causes the sound to become distorted, resulting in a buzzing or humming noise. You can also fix subwoofer distortion by following some simple methods.