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How To Tell if a Home Theater Subwoofer Is Blown?

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? How can you tell if a subwoofer is blown and if it can possibly be fixed?

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.

In this guide, we’ll explore the signs of a blown home theater subwoofer, from sound issues to physical inspections, and how to diagnose these problems using a multimeter. Additionally, we’ll cover steps to take if your subwoofer is indeed blown, including repair options and considerations for purchasing a new one.

Key Takeaways

  • Common Causes of Damage: A subwoofer may be blown due to a blown fuse, a damaged voice coil, or exposure to too high bass levels, which can lead to mechanical breakdown.
  • DIY Testing Method: Gently press the subwoofer’s cone to assess movement and listen for unusual noises, indicating damage. Additionally, using a multimeter to measure electrical resistance can help identify a damaged voice coil.
  • Response to a Blown Subwoofer: If your sub is blown, disconnect it from your system to prevent further damage, consider seeking a professional assessment, and explore options for repair or replacement.

What Happens To a Subwoofer When It Blows?

While enjoying your home theater system, you suddenly notice an issue with the low-end sound. It might become faint, distorted, overly loud, or completely silent, suggesting a potential problem with your subwoofer. In most cases, this can be concerning, as subwoofers are crucial for a complete home theatre experience.

Damaged or blown subs are frequently caused by one of two issues: either it has been overloaded with excessive power or received a clipped signal. Both overdriving the subwoofer with too much power and exposing it to clipped signals are common reasons for damage.

Clipped or Distorted Signals

Turning up a distorted signal to hear it better can easily harm your subwoofer. Clipped or distorted signals are particularly damaging. Sometimes, you may not realize the signal is distorted until it’s loud enough to cause noticeable distortion and damage.

Too Much Power

Often, a subwoofer blows due to excessive power. While high volume can be thrilling, there’s a limit to what a subwoofer can handle. Pushing it beyond its capacity creates excessive pressure, leading to damage.

Subwoofers are designed to handle more power than their RMS (root mean square) or continuous power handling ratings suggest. However, it’s crucial to ensure that the sound remains clear and free of distortion at very high volumes.

Different Ways How To Tell If a Subwoofer Is Blown

When you suspect that a subwoofer has been blown, the easiest way to confirm is to fully assess the woofer.

It may have been damaged in more than one area, and it’s important to understand these common damages are crucial for assessing a blown subwoofer in your home theater. Here are the three main methods 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 of 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 Subfoower For Blown Cone

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

Checking the subwoofer cone is a straightforward method to detect damage. Subwoofer cones have a suspension system for smooth movement. Gently pressing the cone with your hands can reveal issues, such as:

  • 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 To Check For Damaged Coil

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

A multimeter is a great tool to have on hand, and using this tool is the easiest way to tell 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 (on Amazon) that you should probably keep around the house.

Here is a short video and the steps to measure the electrical resistance or ohms of a subwoofer:

How To Test A Subwoofer With A Multimeter
  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. 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.

Check If A Subwoofer Fuse Is Blown

To check if a subwoofer’s fuse is blown, you will have to locate the fuse holder, usually on the back of the subwoofer. Remove the fuse and look for a broken filament or a cloudy appearance, both of which suggest a blown fuse.

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 damaged it.

Firstly, remove the subwoofer from your home theater system to prevent further damage to other components. It’s essential to disconnect it as soon as you identify the issue.

Second, you may want to get an expert opinion on the state of your subwoofer. If the subwoofer is relatively new, it could be covered under warranty. Check this BEFORE disassembling the subwoofer!

On the other hand, while self-assessment is useful, getting a second or third opinion from a tech-savvy friend or a professional service like Geek Squad can offer a more accurate diagnosis.

Lastly, review how you want to proceed without your subwoofer. Are you in a good place to buy a new one? 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 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 remember 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.

Can High Bass And Touching a Subwoofer Damage It?

You might want to avoid high bass levels, especially in car audio, as they can damage a subwoofer (or speakers) by pushing it beyond its limits, leading to overheating, mechanical failure, or distortion.

Touching a subwoofer cone can potentially damage it, especially if pressure is applied unevenly or forcefully. While light, careful touches usually don’t cause harm, I advise it’s best to avoid touching the cone to maintain its integrity and performance.

What are good options for purchasing a new subwoofer?

There are great options everywhere and for every budget. Top brands like Polk Audio have a few highly rated, budget-friendly options on Amazon, its PWS10 10-Inch Powered Subwoofer (on Amazon) and its PSW505 12-Inch Powered Subwoofer (on Amazon).

At a slightly higher price, the Bic Acoustech PL-200 II Subwoofer (on Amazon) is another great choice. And at ~ $500, you can upgrade to the SVS SB-100 Subwoofer with a 12-inch Driver, 300-Watts RMS & a Sealed Cabinet (on Amazon). You might also want to explore what is the best cables for subwoofers. The choice is yours, but whatever your specifications are, there is a match for you.