Subwoofer Blown Voice Coil Symptoms

Major Subwoofer Blown Voice Coil Symptoms:

Here are some of the most common reasons that can cause your subwoofer to work inappropriately:

1. Distorted or Fuzzy Sound:

When a subwoofer’s voice coil is blown, it will produce a fuzzy or distorted sound. An interruption in the electrical current causes this supplied to the voice coil and woofer cone, which results in an imbalance of power within the speaker. The resulting sound may include high-pitched distortion, muffled tones, clicks, or pops. In some cases, it may not produce any sound at all.

2. Reduced Volume:

When the voice coil on a subwoofer is damaged, it can no longer move air to produce sound. As a result, your subwoofer’s volume (loss of sound) will be reduced significantly. Furthermore, you may notice the sound distortion, as I’ve mentioned above. Basically, if you experience a sudden reduction in volume or strange noises coming from your subwoofer, then there’s a good chance that its voice coil has been blown.

3. Overheating:

When you play music on a subwoofer whose coil has been blown, it can cause the car subwoofer to overheat, resulting in other parts being damaged too. Overheating is one of the most common signs of a blown voice coil, as the wounded part loses its ability to dissipate heat. Avoid playing music for an extended period of time to prevent the heating effect.

4. Burning Smell:

If you don’t fix the overheating effect, your speaker’s coil may meltdown, resulting in a burning smell from your subwoofer. This usually occurs when you send too much power or play the subwoofer for many hours without rest, resulting in an odor similar to burning plastic or rubber. Excessively high volume levels and amplifiers with faulty circuitry can both cause this issue.

5. Scratchy or Rattling Sound:

Just like the subwoofer distortion, a scratchy or rattling sound also indicates a blown voice coil. Not only it produces a rattling sound, but you can also notice some other unpleasant sounds from your blown subwoofer. The most common cause of this damage is extended use at high volume levels, which puts additional strain on the voice coils causing them to fail eventually.

6. Sound at All:

A sub with a blown speaker’s coil will produce no sound at all, even when all other components function correctly. As we all know, a voice coil converts electrical energy into mechanical energy (sound waves). A broken or burned-out voice coil means that this critical function fails to occur, and thus, no sound is produced as a result. In some cases, you can also hear a faint humming noise.

7. Cone Movement Issues:

If you inspect the subwoofer after removing it from its mounting position, you will notice some speaker cone movement issues after gently pushing it with your thumb. The problem in the blown speaker cone movement can cause the subwoofer not to produce sound.

8. Low or No Bass:

Just like the sound, you may also face low or even no bass output if you play the music through your blown subwoofer voice coil. This occurs because when the voice coil shorts out due to over-excursion or thermal overload, it disrupts the power flow from the amplifier to the speaker cone, resulting in weak bass output.

9. Smoky or Burnt Appearance:

This is the easiest way to determine if the subwoofer voice coil has been blown. You’ll see a smoky or burnt appearance when you visually inspect the speaker’s voice coil. When driven beyond its intended power limits, the heat generated from the speaker’s voice coil causes parts of the winding to expand and produce smoke, resulting in a burned smell.

What Causes a Blown Speaker or Subwoofer Voice Coil?

Several factors may lead to a blown subwoofer voice coil:

1. Overpowering or Underpowering:

Both properties can cause a blown voice coil. When you overpower a subwoofer (sending excessive power to it), it can cause an overheating effect, which results in a molten voice coil. On the other hand, when you underpower a subwoofer (the speaker is driven with too little power), the amplifier will start clipping. And in a result, distorted signals will be sent to the subwoofer.

2. Improper Wiring:

When you wire a speaker in such a way that it cannot handle the electrical current being emitted, you may create some severe blowing problems for your subwoofer—improper wiring results in mismatch impedance which will lead to an electrical overload. This overload causes arcing or sparking, which heats up and melts the wiring insulation, creating shorts within the system and leading to the failure of the voice coil.

3. Playing Distorted Audio:

When you play a song that has some distorted audio signals in it, your voice coil is prone to be overdriven. The result is an increased heat buildup in the coil and surrounding area that will melt down the coil.

4. Playing Subs at High Level for Extended Time:

The most common mistake many audiophiles make is running the music at high volumes for many hours. Too much current is drawn from the amplifier and sent to the subwoofer’s voice coil in the whole process, causing an excessive amount of heat in the voice coil area. As a result, you will damage the suspension and even melt down pieces of the subwoofer, including the coil.

5. Environmental Factors:

That’s my favorite part! I’ve noticed that environmental factors, such as exposure to extreme temperatures or humidity, can also negatively affect the subwoofer’s components. It may cause the materials in speakers or subwoofers to degrade over time, leading to a blown voice coil.

6. Amplifier Clipping:

When you push an amp beyond its power limit, it can start to clip the sound waves. This means that the sound output becomes distorted and more potent than intended. When this distortion exceeds the limits of a subwoofer’s voice coil, designed to handle only a certain amount of power, it can cause overheating and damage & eventually blow out the voice coil completely.

Excessive clipping from an amplifier will thus cause significant damage or destruction to any connected subwoofers, as their voice coils are not built to withstand such extreme pressures.

7. Age:

The combination of heat and mechanical stress present during everyday use will eventually take its toll on any subwoofer, no matter how well-built it is. As the voice coil wears out, it gradually becomes weaker until it breaks completely. This results in a blown subwoofer with no sound coming from the speaker.

4. Methods to Test a Blown Subwoofer Voice Coil:

Here are some of the common methods that I use to test a subwoofer, especially when it blows:

1. Visually Inspect:

Follow the below steps to determine whether the coil is blown or not:

1. Check the outer speaker cone of the subwoofer for any signs of damage, such as cracking, tears, or warping. This could be an indicator that there’s a problem with the voice coil inside.
2. Unplug the subwoofer from its power source and then remove it from your audio system so that you can access the back of the unit.
3. Gently remove the subwoofer’s speaker grill to expose the inner components of the subwoofer, including the voice coil.
4. Check around and inside the voice coil for any signs of cracking, discoloration, or other damage that could indicate a problem. 
5. Look for signs of burning or charring around the voice coil, which could indicate that it has been overworked and blown out.
6. Carefully inspect the edges of the voice coil for fraying or other physical damage. You likely have a blown voice coil, if there’s any evidence.

2. Test Through Multimeter:

Follow the below points to check the ohm of your subwoofer through multimer:

• Gather the necessary equipment: a multimeter, affected subwoofer, and wires.
• Disconnect the subwoofer from any power source before beginning your testing procedure.
• Unscrew the bolts that hold the woofer in place and remove the sub from its enclosure.
• Carefully inspect the voice coil for signs of physical damage that may indicate a blown coil. If there is no visible damage, move on to step five.
• Set your multimeter to the “ohms” setting and place one end of the leads onto each terminal of the speaker cone.
• Check your readings: the voice coil works correctly if the readings are within normal range. If there is no reading or a very low reading, the voice coil has been blown and needs to be replaced.
• Once you have identified if your subwoofer’s voice coil has been blown, use caution when handling the subwoofer and reconnect it to its power source.

3. Listening Test:

You can also test your subwoofer without a multimeter:

1. Power up the subwoofer and start playing some music with a deep bassline.
2. Listen carefully to the sound coming from the voice coil and compare it with a reference sound you are familiar with.
3. If you hear any rattling or distortion, then this is a sign that your voice coil might be blown.
4. If there is no distortion, your voice coil may function correctly.

4. Cone Pushing Test:

You can also perform a subwoofer pushing test to determine if the subwoofer is blown or not:

1. Place your hand firmly on the outside edge of the speaker cone and press it in towards the center slowly and evenly.
2. Release the subwoofer cone and repeat the pushing step a few times, making sure to keep your hand as close to the edge of the cone as possible.
3. Listen carefully for any rubbing or resistance sounds – these could indicate a damaged voice coil or magnet structure.

2 Methods to Fix Blown Subwoofer Voice Coil:

Here are some of my favorite methods to fix the blown voice coil:

1. Recone:

I follow this method mostly to unfreeze my subwoofer. To recone a sub, follow the below steps:

1. Begin by disassembling the subwoofer and removing the damaged parts. You will need to know what type of voice coil, cone, spider, and surround you need for your speaker model when shopping for a recone kit.
2. Install the new parts according to the instructions in the recone kit or that come with your speaker. Ensure everything is connected correctly and secured before moving to the next step.
3. Once you’ve installed all the parts, you can begin soldering the connections. Be sure to use a quality soldering iron and solder appropriately sized for your application.
4. After connecting all components, test the subwoofer to ensure it works correctly. If everything sounds good, reassemble the speaker and enjoy!

2. Voice Coil Replacement:

You can repair or replace the voice coil to start hearing the sound again from your subwoofer. Follow the below steps:

1. Disconnect the subwoofer from power and remove it from its mounting enclosure.
2. Gently remove the speaker’s cone not to damage other components like the magnet or spider.
3. If necessary, remove the dust cap, being careful not to cause additional damage to the speaker or voice coil.
4. Unscrew the screws holding the coil and carefully pull it out.
5. Once you have removed the old voice coil, use a multimeter to test for continuity between its four leads. If there is none, you know the coil needs replacing.
6. Now install the new coil, aligning it correctly with the spider and magnet.
7. Reattach the dust cap, cone, and screws in their original positions.
8. Once everything is secure, re-mount the subwoofer and plug it back into power before testing its sound quality.