How To Fix a Blown Subwoofer

By Richard Pryn •  Updated: 02/11/22 •  8 min read

Maybe you were enjoying music a bit too much and now your once amazing subwoofer speaker is now broken, and you are sitting in silence, thinking about the amount of money that you will need to spend on repairing it or buying a new one.

Fortunately, you can repair a blown subwoofer yourself, but you will need some tools and expertise that the average person may not have if you feel you are up to it, this is a guide on how to fix a blown subwoofer.

But before we get into that, we will talk about what causes a subwoofer to blow as well as ways that you can prevent it from happening again so that you don’t have to get your toolkit out again any time soon.

How To Fix a Blown Subwoofer

What Causes A Subwoofer To Blow?

There are multiple different things that can cause a subwoofer speaker to blow which include having the volume too high over a prolonged period which can overpower the subwoofer itself or the clipped signals.

We will cover the most common causes so that we can get down to business and repair them.

Overpowering a subwoofer speaker is one of the most common ways that they get blown out and is caused by their peak power being sustained for too long.

When too much power is being sent to the driver which is the speaker that makes the low-frequency sounds, it generates more heat than the subwoofer can handle which then builds up in the voice coil.

The voice coil refers to the part of the subwoofer that is made of magnets that are used to attract and repel which makes the diaphragm move, thus producing sound.

Having the voice coil overheat will cause the glue to soften which deforms it and results in complete damage. If the voice coil reaches this amount of damage, it will not work as intended and can scrape on the sides of the gap as it is no longer glued in place.

Luckily for you, this can make a rattling or buzzing sound that you can listen to for a hint as to what has caused the blowout.

The voice coil may also be too damaged to even rattle around and instead will halt any playback from playing which is another common side effect of blowing out a subwoofer.

Having overpowered clipped signals is another way that you can overpower the subwoofer and cause problems. This occurs when the clipped signals experience a big increase in the power that they deliver to the subwoofer’s drivers.

Finally, we will get into the mechanical and wire failures that can cause a subwoofer to blow.

Sometimes what is known as the cone and the spider which is the black mesh part that vibrates as the music plays can be stretched to their limit which can tear the suspension and pull out the voice coil in the process.

With the voice coil resting in the wrong place outside the magnetic field, it can cause overheating and damage.

Other mechanical issues that may sound small but can cause a lot of issues can include the glue or screws coming loose or the voice coil gap having bits of debris interfering with the movement.

Sometimes the wire of the subwoofer that connects the negative and positive leads can break or fail that then stops the flow of the current, leaving the subwoofer with no power.

How To Tell A Subwoofer Has Blown

Sometimes it is not as obvious as not being able to hear any playback, and if you suspect that your subwoofer is blown, there are lots of different ways that you can check.

The first thing to do is probably fairly obvious but is to listen to the music that is coming out of the speaker. As mentioned earlier, if you hear buzzing or rattling noises as the music plays then it is most likely the voice coil that has been damaged.

You can also listen out for the bass and if it sounds weak or distorted when you increase the volume then it’s another sign that you have blown the speaker.

The next thing you can try is to get a bit more hands-on with the speaker. Be gentle as you do this to prevent any further damage and press on the cone, if the cone wobbles, then it is likely due to the spider being loose.

But if it hardly moves then a jammed voice coil is the culprit. Hearing any noises such as scratching as you press the cone can be a symptom of the voice coil being distorted from thermal damage.

If you are still not satisfied with the diagnosis, then you can open up the subwoofer and take out the driver carefully. This allows you to get a good look at the voice coil, if it looks burned or discolored then you have a blown coil.

How To Fix It

How To Fix a Blown Subwoofer

The first step to fixing a blown subwoofer is finding out what caused it.

If you are one of the unfortunate ones and have experienced an issue with the voice coil or a broken spider, you will have to go through a full coning process which requires you to buy a cone, coil, lead wires, gasket, dust cap, adhesives, and surround which can end up costing you more than simply buying a new subwoofer.

The full coning process is a very time-consuming one because you have to be very delicate to prevent damaging the cone kit as you are installing it. Therefore, it is recommended by many people to leave this job to a professional.

It may be easier to repair it if the damage is only on the magnet assembly and has left everything intact, but this will still require you to take them apart and demagnetize and re-magnetize them again.

If you have read through this section and are still set on repairing the subwoofer yourself then you should keep reading to find out how.

The tools you will need are a soldering iron, screwdriver, air compressor, multimeter, glue, and a flat-edged knife.

To replace the voice coil, you will have to get yourself a new one first which can be found on the internet or at a relevant store, but make sure that you get the correct one for your model.

The next step is to use the air compressor to get rid of any dust and debris in the area so that they don’t interfere with the coil.

Take out the speaker surround by using the knife to gently separate it.

Take all of the adhesives off with your fingers and take extra care not to damage anything. After this, take the speaker cone and the voice coil out of the subwoofer, cut the terminal wires in order to do this.

Next, carefully fix the new voice coils into place and apply enough glue to the cone side and back where the old speaker was and leave to dry for 24 hours.

Keep making sure that there is no dirt because this will cause damage later down the line and you will have to go through this process all over again.

Take the terminal wires on the new voice coil and reattach them to the end of the old terminal. This is where the soldering iron comes in to make it as secure as possible but do not do this if you are not confident with the tool because you can cause an electrical fire or burn yourself if you’re not careful.

Use the soldering iron to fuse anything else that is loose so that any vibration sounds are stopped. Then put the cone back onto the frame with glue and stand for 24 hours.

Believe it or not, this is the simple way to repair a blown subwoofer so keep this in mind when you are faced with repairing yours as it may not be so straightforward and may be a different problem or multiple.

In most cases, it’s worth buying a new subwoofer because if you buy a new one, it will be better designed to cope with more power and will also save you money in most cases.

As well as this, since repairing a subwoofer takes a lot of care and precision, there are chances that it can go wrong, and more damage is caused so why not save yourself the stress and get a new and improved one that will last you a lot longer instead.

Final Thoughts

If you do not want to go through the pain of having to repair your subwoofer again or have just bought a new one, and you’re scared the same thing might happen, there are ways that you can prevent the subwoofer from blowing again.

An interesting tip that has been proven to work is to place the speaker in a corner of the room because it boosts the output, making the playback sound louder but sometimes at the price of quality.

You can also try shutting the doors in the room to keep noises out and the music from the speaker in.

However, sometimes you just have to accept that subwoofers get worn out and lose the sound volume and quality that they used to have and therefore will need to be replaced.

Richard Pryn

Hey there. I am an award winning composer for movie trailers, including Bladerunner 2049, Diablo II, WandaVision, and loads more. I am the founder of The Trailer Music School where my aim is to teach everything I know about music composition, production, and generally being a functional human being. I podcast, blog, vlog and jog (sometimes). I also love coffee, nachos and self-improvement. I live with my wife, three kids and numerous pets. I am also known by my pseudonym, Richard Schrieber (it’s a long story).

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