How Do You Tell if a Home Theater Subwoofer Is Blown?

Written by Jonah Matthes
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Subwoofers give home theaters an amazing sound. There’s nothing quite like the addition of a subwoofer or two to lift your home theater experience, but what happens when a subwoofer starts malfunctioning? Is it ruined forever? Could it possibly be fixed?

How can you tell if your home theater subwoofer is blown? Subwoofers are blown when they either receive too much power or too much of a distorted signal. You can find out if your subwoofer is blown by listening to the sound, reviewing the movement of the woofer, and using a multimeter to find out if the coil is blown.

Test the sound at a low volume to listen for whether your sub has been blown. If it is distorted, you have a partially blown subwoofer, and if there is no sound at all, it is completely blown. If the subwoofer is receiving its signal via a cable, then check the cable before rushing to conclusions.

To test the movement of your woofer, you’ll want to remove the cover to reach the cone. With two hands, carefully move the cone to assess the damage.

  • If it does not move at all, it is definitely damaged.
  • If it is extra wobbly, this is also a sign of damage.
  • If you hear scratching sounds, you definitely have a blown sub.
  • You can also use a multimeter to test for a blown coil. A multimeter measures the amount of voltage, resistance, and current, and you can determine if there is a lack of electrical resistance.

When you are experiencing any of these signs, then it's likely that your subwoofer is blown. But you’ll want to, first, completely assess the situation. You need to understand the severity of damage that exists, and then you can decide what you need to do next.

What Happens When a Subwoofer Blows?

You are simply enjoying your home theater system, and all of the sudden, something happens with your low-end sound. Maybe it gets very soft or starts to sound distorted. Maybe there’s no sound coming from the low-end at all, or it starts to sound very strange and extra loud. Whatever is making you think that your subwoofer is blown, it can be devastating, because subwoofers are a key component in home theater systems.

When a subwoofer has been damaged, or blown to some degree, one of two things has happened: it’s either received too much power or too much signal. Clipped signals are the culprit of many damaged subwoofers, as well as putting too much pressure on your subwoofer with too much power.

Clipped or Distorted Signals

When you turn up a signal that is distorted to hear it better, you can easily damage your subwoofer. Clipped or distorted signals are absolutely terrible for your subwoofer. In some cases, you may not even know that your signal is distorted until the levels are so high that it begins to distort and cause damage.

Too Much Power

In many cases, a subwoofer is blown is due to too much power. Even though a lot of volume can be exciting and enjoyable, a subwoofer can only handle so much. It can be forced into operating beyond its limits, thus creating too much pressure that results in damage.

Even though subwoofers are intelligently created to withstand even more power than their specified RMS (root mean square) ratings, also known as continuous power handling, it is important to make sure the sound is clear and distortion-free at extra high volumes. If you don’t already, you want to know your subwoofer RMS wattage to ensure that you are giving the right amount of power to your subwoofer(s) on a continuous basis.

Different Ways to Test if a Subwoofer is Blown

When you suspect that a subwoofer in your home theater has been blown, it’s important to fully assess the woofer to determine the total amount of damage that has taken place. It may have been damaged in more than one area, and it’s important to understand the different types of damage that commonly take place when a subwoofer is blown in your home theater. Below are the three main ways to test if a subwoofer is blown.

  • Test the sound. Is it clipping, distorted, etc?
  • Test the movement of the cone.
  • Use a multimeter to test electrical resistance.

Read further to learn exactly how to perform these tests without further damaging the possibly defective subwoofer.

Test the Sound

The sound that you are getting from your subwoofer is a great indicator in the amount of damage that has been done. The major sounds that you’ll hear during a fully blown or partially blown subwoofer are:

  • No sound at all - This means that your subwoofer has likely been completely blown. Be sure to test the cable and audio source. Make sure these are working properly before jumping to conclusions.
  • Partial sound with distortion - When you hear a weak, distorted sound coming from your subwoofer, at any volume, you probably have a partially blown subwoofer on your hands.

Test the Cone

How Do You Tell if a Home Theater Subwoofer Is Blown - Speaker Cone

Accessing a subwoofer cone is an easy way to identify damage. Subwoofer cones are built with a suspension system that allows them to fluidly move, and by using your hands, you can easily identify when the cone is off. When you use two hands, ever-so-carefully, and lightly press on the subwoofer cone, you might experience:

  • No movement - When a cone is locked in place, it is an indicator that damage has occurred.
  • A wobbly cone - When the cone unsteadily moves around, its suspension system has been greatly compromised.
  • Scratching sounds - If the cone is making scratchy noises while you move it with your hands, then damage has occurred. It needs to be removed from your home theater system, before causing damage to any other equipment.

Use a Multimeter

How Do You Tell If a Subwoofer is Blown - Use a Multimeter

A multimeter is a great tool to have on hand, and this tool will be able to tell you if a subwoofer has any damage to its coil. When you use this device, you’ll want to check for electrical resistance (also known as ohms, symbol = Ω). If there is zero electrical resistance, you have damaged your coil, or if the reading does not stay in place, you may have a damaged coil. Here is a standard, easy to use multimeter that you should probably keep around the house.

Hare are the steps to measure the electrical resistance or ohms of a subwoofer:

  1. Disconnect the subwoofer from its power source, if it has one.
  2. Disconnect the audio input from the subwoofer.
  3. Unless your subwoofer is powered by an external amplifier or receiver, then you will need to remove the sub from its enclosure.
  4. Connect the two probes to the multimeter. And turn the multimeter on to measure ohms (Ω)
  5. Insert the red probe into the positive lead and the black probe into the negative lead.
  6. The multimeter should then measure the amount of resistance. You will usually need to round up to the nearest whole number for the correct resistance.

What to Do if You Know Your Subwoofer Is Blown

While damaging a subwoofer is an extremely stressful event, it’s best to take action on the situation, once you know that you have, in fact, damaged it.

First, you’ll want to remove your subwoofer from your working home theater system. If you keep it in place, it may end up causing damage to your other equipment, which can create an even bigger problem. Because of this, it’s best to remove it completely.

Second, you may want to get an expert opinion on the state of your subwoofer. If the subwoofer is relatively new, it could possibly be covered under warranty. Check this BEFORE disassembling the subwoofer! It is good to test it yourself, but it is even better to get multiple people to assess the damage. Whether this means calling up your extremely tech savvy friend or taking it to the Geek Squad at Best Buy, why not get a second and third opinion?

Lastly, review how you want to proceed without your subwoofer. Are you in a good place to buy a new one? Could you live without it, currently? Have you considered trying to fix it? Most times, buying a new subwoofer is the route to go, but there may be another route for you. Make sure to review all of your options to find out what’s best for you.

Here is one of our articles on protecting home theater equipment. This could possibly help prevent this type of issue in the future.

Related Questions

Can you fix a blown subwoofer?

Yes, there are ways to fix a blown subwoofer, but it is not something to be taken lightly. You’ll need to detach and separate parts of the subwoofer, which requires precision and skill. The act of fixing the area of the subwoofer that has been damaged is also very challenging. If you want to try to fix your blown subwoofer, it’s best to get it in the hands of a seasoned professional that has the tools and knowledge to perform the tasks at hand. I would not suggest attempting to fix a subwoofer unless you actually know what you are doing.

What are good options for purchasing a new subwoofer?

One of the best things about buying a new subwoofer is that there are likely much better options on the market than your current one. It can be an exciting time for you, even though it is sad that your blown subwoofer’s life is over. There are great options everywhere and for every budget. Polk Audio has a few highly rated, budget-friendly options on Amazon, its PWS10 10-Inch Powered Subwoofer and its PSW505 12-Inch Powered Subwoofer. At a slightly higher price, the Bic Acoustech PL-200 II Subwoofer is another great choice. And at a cool $500, you can upgrade to the SVS SB-100 Subwoofer with a 12-inch Driver, 300-Watts RMS & a Sealed Cabinet. The choice is yours, but whatever your specifications are, there is a match for you.

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About Me

Hi! I’m Jonah. I grew up addicted to different electronics. I began working for an Audio/Video installation company years ago and realized my passion for Home Theaters! The Home Theater DIY is a place for me to share my different findings and experiences about home theaters and home electronics. For more information, check out my about me page!

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