How to tell if a subwoofer is blown

How to tell if a subwoofer is blown?

Subwoofers are surely a significant part of the car sound system. There are no other components that can do the magic for an amazing sound. But what to do if a subwoofer starts distorting or cracking the sound? How to tell if the subwoofer is blown? Why do subwoofers blow? How to fix it?

If you notice a sudden change in your car’s sound or stop functioning properly, there is a chance that you might have a blown sub. 

So it’s important to look for other signs of a blown subwoofer, or you should perform some diagnosis to be sure.

Signs of a blown subwoofer

So how to tell if your subwoofer is blown or not? What are the signs of a blown subwoofer?

Subwoofer blowing is a common thing. Subwoofers can blow for multiple reasons, like receiving excessive power from the amplifier or getting too many distorting signals. Too much power forces the coil to get separate from the cone.

How to tell if a subwoofer is blown

There are few simple tests you can do – to check the signs of a blown subwoofer – if it is blown or not. 

Step 1: Check the sound at low volume

When you check – you should check the sound quality carefully. First, start with a lower volume and lower base – then slowly increase the volume and bass at a decent level. The result can be different depending on the amount of the damage:

  • The worst-case scenario could be if there is no sound at all. That’s a clear sign that the subwoofer is entirely blown. Make sure you check the power is on, the audio source is working, and the wires. 
  • In the case of a partially blown subwoofer, you will notice a weaker or distorted sound. 
  • And if the sound is like scratching, it means the subwoofer’s cone got damaged; replacement is the only solution. 

Step 2: Check the subwoofer cone

In this step, you need to check the subwoofer cone by pushing with your fingers. Unscrew the cover of the subwoofer and remove it so that you can have access to the cone – now have a closer look. 

Then by using both hands, gently press the cone from both sides. Please don’t put too much pressure; you don’t want to damage it by pushing too hard! 

How to tell if a subwoofer is blown
How to tell if a subwoofer is blown?

Subwoofers are usually designed to move the cone spontaneously by using a suspension system. While you press the cone, you should look out the following signs: 

  • If there is no movement at all, it means the subwoofer has blown.
  • If the cone movement is quite unsteady, it means the suspension system is not working as it requires. 

Step 3: Test the voice coil using a multimeter

In step 3, you will need to check the voice coil using a multimeter. The voice coil generates the force in a subwoofer cone. 

A multimeter is a tool with positive and negative terminals to intent force by the reaction of a magnetic field. 

When it comes to testing the subwoofer coil, the Multimeter comes in handy to track the force. It means you can check if the voice coil is still generating force or not. 

How to tell if a subwoofer is blown
How to tell if a subwoofer is blown?

While using this device, you will check the electrical resistance (which is known as ohms Ω) by using the positive and negative terminals. 

To obtain the resistance value, follow these steps:

  • Disconnect the power
  • Turn off the subwoofer
  • Disconnect the wires from the subwoofer 
  • Remove the subwoofer from the car door
  • Connect the multimeter probes to the voice coil terminals
  • Turn on the Multimeter
  • Now read the meter

The results could be – 

  • If there is no resistance at all, it means the voice coils are damaged.
  • If you notice any sudden shifting, it means the voice coils are damaged.
  • If the resistance is more than 1.0 Ω (ohm), then the subwoofer voice coils are completely ok.

Causes of a blown subwoofer

There are two main reasons behind a blown subwoofer:

Excessive power supply

Too much power supply is the most significant cause of a blown subwoofer. Normally, the amplifier supplies excessive power to the subwoofer, which leads to its maximum limit. This can occur because of mismatched electrical resistance, for instance. 

While listening to music at a high volume, we create too much pressure, and the sub operates outside its limits ending in blowing it. 

So make sure you know the RMS wattage of your sub (the maximum limit your subwoofer can handle) before you blast the car music up and drive like there’s nothing left to lose.

Luckily, the latest subwoofers can handle more power than the certain RMS (Room mean square). Better not to exceed the indicated RMS limit.

Distorted signal

Like excessive power, too little power can cause damage to subwoofers too. If the subwoofer gets too low power from the amplifier, it can create distorted signals. 

And if you turn the volume up to get a clear sound – that might go wrong. Distorted signals are too bad for subwoofers.

To cut down the risk, you will need to understand how the distorted signal sounds, and you need to identify it as fast as possible.  

Use an amplifier that matches your subwoofer’s RMS to ensure that your sub is continuously getting an accurate amount of power. 

How to fix a blown subwoofer?

Most of the subwoofers come with a warranty. If your blown one is still new, there might be a chance that the warranty still covers it; you need to check the validity first before you attempt to fix it. There is a chance – you might get a replacement.

The bright side of a blown subwoofer is – some people take this as an opportunity to upgrade the subwoofer or speakers or even the whole car audio system. 

Some people upgrade from 2 way to 3 way or 4 way speakers for better sound. Check out the post on the difference between 2 way, 3 way and 4 way speakers.

How to fix a blown subwoofer
How to fix a blown subwoofer

If this is not the right time to upgrade, you can still fix the older one. Fixing a blown subwoofer is quite easy; in some cases, you don’t need to hire a technician; you can do it yourself.

Here is the guideline on how to fix a blown subwoofer DIY:

Remove the subwoofer

First, you need to remove the blown subwoofer from your car audio system as soon as you notice it blew. 

Because if you don’t then it may cause more damage to the other equipment too. Try not to mess up; remove it in the first place.

Voice Coil

If the voice coil is stuck, it might be a cause for the distorted signal. Try to use a round object like a flashlight or something similar to push the voice coil back into place. 

Now it’s time to give it a try; try at gentle volume. 

Broken foam surround

To repair a broken foam surround, you need to separate the gasket and cut the sub’s damaged portion. For the rest of the residue part, use rubbing alcohol gently. 

Now install the new foam surround.  

Repair a tear

Take a paper towel, apply speaker dust cap glue, and coat the hole properly. Try to be calmer while repairing to make sure you have a dexterous job.

Repair cone and coil

Gently remove the coil and the spider from the sub. 

To repair a paper subwoofer cone – the best way is to cover the damaged area with elastic glue and patch it with thin paper on both sides.

Stiffer cones are usually made of plastic or aluminum so that you can use thick carbon or even foam patches on the damaged area from both sides. 

You can use rubber cement glue too.

Video Credit – eHow

Final words

Driving a car with no audio or a blown subwoofer causes untold stress, especially if you have a new sound system.

We all know, “prevention is better than cure.” To learn more about your sound system, read the manuals before you use it. 

Make sure you know the RMS (Room mean square) of your subwoofer as well as the power source your amplifier produces.

Still, you have us on your side; this article can help you know how to tell if a subwoofer is blown, signs of a blown subwoofer, causes of a blown subwoofer, and how to fix a blown subwoofer. 

If you have any questions or comments or suggestions, please do let us know by commenting below. Let us know your thoughts on this. 

About Brenda Smith

Brenda Smith is an Audio consultant and part-time automotive content writer. She has an Audio engineering degree from a reputed university of Tampa, Florida. Being a great audio enthusiast, she works with her audio consultation startup and writing automotive content as a part-time writer.

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