Loudspeaker Blow-Out: Why It Happens & How To Avoid/Fix It


It’s an awful feeling to find out a speaker that once performed amazingly well has been blown and rendered unusable. To understand the reasons behind speaker blow-out and the potential fixes will help us to comprehend the occurrence of blow-out and what to do about it.

How do loudspeakers blow-out and how do we avoid and/or fix it? Speakers generally blow-out when too much electrical power is applied. They also blow-out from physical damage or ageing/deterioration. Avoid blow-out by keeping speakers at safe listening levels and in safe locations. Replacing the blown parts is typically the only solution to fix blown speakers.

In this article, we’ll answer the following questions:


What Is Speaker Blow-Out

Speaker blow-out is an umbrella term that refers to a speaker that doesn’t work as designed or doesn’t work at all. Speakers affected by blow-out are known as blown or blown-out speakers.

Blown speakers can have any of the following symptoms:

  • High levels of audible distortion.
  • Limited frequency response (especially in multi-driver designs).
  • Low levels of sound.
  • Intermittent sound.
  • High noise levels.
  • No sound.
  • Will not turn on (active speakers).

Note that these symptoms do not necessarily mean a speaker is blown but are commonly associated with speaker blow-out. For more information on identifying a blown speaker, skip ahead to the section How To Avoid Speaker Blow-Out.


How Do Speakers Get Blown-Out?

Speaker blow-out most typically happens when the speaker experiences too much signal for too long.

The audio signals that driver speakers are alternative currents with amplitudes measured in AC voltage.

The voice coil of the speaker is designed to be part of the circuit that passes the audio signal. The direction and amplitude of the electrical current are translated into speaker movement that produces sound. A byproduct of this electrical current is the dissipation of heat from the voice coil.

With that primer, let’s get into the 3 ways in which speakers will experience blow-out:

  • Burned/melted voice coils.
  • Torn or stretched cones/suspensions.
  • Blown fuses or loose wires.

Before we discuss each of these blow-out types in detail, let’s have a look at a simplified and labelled cross-sectional diagram of a moving-coil speaker driver:

Cross-Sectional Diagram Of A Speaker Driver

Though the magnetic structure and the basket/housing and overall enclosure may get damaged, it is the voice coil, cone, suspension (spider and surround), and dome that are most likely to get “burned-out.”

Burned/Melted Voice Coils

Heat is generally dissipated by the conductive element of the speaker driver.

However, if the amplitude of the audio signal is too high, the driver may not be able to rid of the heat effectively. This can lead to the burning and/or melting of the conductive element. In moving-coil speaker drivers (which are by far the most common), this element is the voice coil.

Too much heat will effectively melt the coil into a single mass or even weld the coil to the magnet. This renders the speaker incapable of accurately reproducing the audio signal or producing sound at all in the worst cases.

Torn Or Stretched Cone/Suspension

Speaker drivers can sometimes get torn or stretched when a high-level audio signal is applied. The speaker driver will have a limited range of motion and may stretch or tear if pushed too far.

That being said, overloading a speaker with a high-amplitude signal is unlikely to stretch or tear the cone/suspension of the driver.

Rather, the first thing to happen will be audible distortion as the driver reaches its limits of motion and begins to act non-linearly. The aforementioned melting/burning of the voice coil would likely happen before the driver would get stretched or torn.

However, the speaker could certainly get damaged due to physical trauma. Foreign objects and particles could potential tear and/or stretch the speaker. This why many speakers are designed with protective grilles/meshes.

To learn more about speaker grilles and meshed, check out my article Why Do Some Speakers Have Grilles/Mesh & Others Don’t?

Any tearing or over-stretching of the spider suspension within the speaker driver will rid of the restriction of the voice coil movement in the X and Y-axes. The loose voice coil will begin bumping and/or sticking to the magnetic structure and housing of the driver. This type of blow out leads to significant audible distortion.

Ageing/Deterioration

The material of older speakers may degrade to a point where it causes severe degradation to the speaker performance.

We see this often with the foam-type surrounds and suspensions of older speaker models but it can happen with other materials that suffer erosion due to normal wear-and-tear.

Blown Fuse Or Loose Wires

Some active loudspeaker and studio monitors will have electrical fuses as a way to protect from speaker blow-out. However, if these fuses blow, the speaker cannot be powered on and may seem blown-out.

Replacing this fuse could being the speaker back to life while maintaining the protection from high-amplitude audio signals.

Loose wires can also lead to speaker burn-out in the form of distortion, crackling and popping.

To learn more about loudspeaker crackle and loose wires, check out my article What Causes Speakers To Pop And Crackle, And How To Fix It.


How To Identify A Blown Speaker

As previously mentioned, blown speakers may have any of the following symptoms:

  • High levels of audible distortion.
  • Limited frequency response (especially in multi-driver designs).
  • Low levels of sound.
  • Intermittent sound.
  • High noise levels.
  • No sound.
  • Will not turn on (active speakers).

Observing any of these symptoms may mean the speaker is blown.

Use the following points as a guide for identifying a blown speaker:

  • Listen for distortion at low and moderate levels.
  • Listen for reduced frequency response in the low, mid and high-frequency bands.
  • Listen for rattling, popping and cracking.
  • Test for power.
  • 9V battery test.
  • Test for infinite impedance.

Let’s discuss each with a bit more detail, shall we?

Distortion At Moderate Levels

Listen for distortion in the speaker.

It is normal for speakers to distort when their amplifiers are overloaded but if significant distortion is occurring at reasonable listening levels, it could very well mean that the speaker is blown in one way or another.

To learn more about speaker distortion, check out my article Why Do Speakers Distort At High Sound/Audio Levels?

Reduced Frequency Response

Many speakers are designed with multiple drivers and a crossover network the effectively parses out the appropriate frequency bands to those drivers.

If any driver gets blown in a multi-driver speaker, the frequency response of that speaker will be severely altered.

  • If the tweeter is blown, the high-end will be either distorted or non-existent.
  • If the woofer is blown, the mid-range will be either distorted or non-existent.
  • If the subwoofer is blown, the low-end will be either distorted or non-existent.

Rattling, Popping & Cracking

Rattling popping and crackling could be a sign of multiple issues in the speaker:

  • Blow-out due to torn suspension/cone material.
  • Blow-out due to partially melted/burned voice coil.
  • Interrupted current due to poor connection (loose wires) between the speaker and amp.
  • Other loose components such as the grille/mesh.
  • Distortion in the audio signal.

Therefore, rattling, popping and crackling may be a sign of speaker blow-out though not necessarily.

To learn more about speaker burn-out in the form of popping and crackling, check out my article What Causes Speakers To Pop And Crackle, And How To Fix It.

No Power

If the speaker is active but will not turn on, it could be a sign that its electrical components and/or amplifier are fried. This can be considered blow-out.

Hopefully the speaker has a fuse that will protect it from damage. If so, replacing the fuse may allow the active speaker to be turned on once again.

Of course, we must ensure that we’re actually sending proper power to the speaker before assuming the speaker is burned-out or not.

Test With A 9-Volt Battery

We can test whether a speaker is functioning or not by attaching its electrical leads directly to a DC source.

Carefully take the speaker apart and connect one lead wire to one terminal of the 9V battery. Then take the other lead wire and touch it to the other battery terminal. The speaker should produce a popping sound and be pushed outward or inward (depending on which terminals were attached to which leads).

If the lead wires are held on the terminals, the speaker should stay pushed inward or outward. Just tapping the second lead wire should cause a quick pop as the speaker driver moves and returns to rest position. Switching the lead wire and terminal connections should cause speaker movement in the opposite direction.

If no noise of speaker movement happens during the battery connection, the speaker is blown and either the conductor (voice coil) or the suspension must be replaced.

Test For Infinite Impedance

Another test can be conducted by measuring the impedance across the conductive voice coil with a multi-meter. If the impedance is much higher than the rated impedance of the speaker (typically a nominal value of 2, 4, 8 or 16-ohms), it likely means that the speaker has been blown.


How To Avoid Speaker Blow-Out

Avoiding speaker blow-out begins with the purchase and/or selection of a speaker for a particular playback system.

Cheap speakers are often made with less-durable material that will be more easily damaged by regular wear-and-tear and overloading.

Older vintage speaker, like other highly sought after vintage audio equipment, can sound incredible. However, some materials in older speaker may require replacement due to corrosion and disintegration as a result of their ageing.

Perhaps more important than the speaker material is the matching of the speaker to a proper amplifier.

This is largely taken care of with active speakers. More care must be taken with passive speakers to connect them to appropriate amplifiers.

Again, sending too much signal to a speaker can blow it out. This can easily happen if the speaker and amp are mismatched.

We intuitively know that an amp with a higher output than the speaker can handle can blow it the speaker out. However, a weaker amplifier can also cause damage when turned up to the point of extreme distortion even if the speaker is rated to be able to handle more than the amp’s “max output.”

Of course, that is not to say that the speaker and amp must be perfectly matched every time. Rather, it is to say that the speaker should only be driver at safe signal amplitudes.

So keeping a safe listening volume is one way to avoid speaker blow-out.

Yet another way to avoid blow-out is to keep the speakers protected. This is more so for the speakers that live life on the road (guitar cabinets, PA speakers, etc.).

Keeping the grilles/mesh on the speakers is a good idea. Handling the speakers with care is another great idea if speaker longevity is a concern.


How To Fix Speaker Blow-Out

So the question stands. What should we do to fix a blown-out speaker?

First things first, if you believe your speaker is blown, test it as soon as possible. If you know for a fact that it’s blown, do not apply any more audio signals to it. You’ll be risking further damage.

Next, I should state that there are some instances where replacing the speaker entirely is the best option. If replacing the entire speaker is cheaper and less complicated than ordering replacement parts and performing the repair, then it’s better to just replace the speaker.

This could be the case with cheap speaker. It is also the case when the speaker has been completely blown beyond simple repair.

That being said, blown-out speakers can often be repaired. Let’s have a look at how.

Replacing The Surround

The surround is the suspension piece that connects the cone/diaphragm of the driver to the housing/enclosure of the speaker.

This component suffers a lot of mechanical stress throughout the life of the speaker and is often the first component to disintegrate due to normal wear-and-tear.

If the surround has come apart, the repair is relatively easy. Get yourself a repair kit and a replacement surround. Speaker surrounds, unlike the more specific components, are more universal and are available in various common sizes.

Re-Coning

If the cone/diaphragm and/or spider is torn or stretched or the voice coil is burned/melted, the speaker will not be repaired so simply. A re-coning is in order.

Re-coning refers to the replacement of all the moving parts that constitute the speaker cone assembly, including the voice coil and suspension (spider and surround).

Cut out the cone, coil, coil former and spider assemblies of the blown speaker; remove any adhesive remains and burned materials, and install the replacement cone assembly.

Look for re-coning kits and replacement parts. Note that many lower-end speakers will not be worth re-coning and many will not even have the replacement parts necessary for a proper re-coning.

Note that, because the speaker driver works along with its enclosure, a matched driver is required to properly re-cone the blown speaker. Even a driver with better specifications, on paper, may sound worse than the original when put into the same enclosure.

Blown Fuse Or Loose Wires

Though perhaps not true blow-out, loose wires and blown fuses must be fixed in order for the speaker to perform properly.

Replacing a fuse, if the speaker has one, is fairly simple. Remove the burned fuse from the fuse box and replace it with a fresh one. Many active speakers and monitors come with an extra fuse located in a pocket near the power socket. Perhaps you’ll be required to order in a replacement fuse.

Fixing loose wires could mean replacing the connection cable between the speaker drivers and their crossover network and/or amplifier. Re-soldering the connections may also be required.

Take the speaker apart carefully and re-solder if necessary.


Related Questions

Why do speakers distort at high levels? There are two main reasons as to why a loudspeaker would distort at high levels. The most common is that the audio source, itself, is distorted. However, speakers can also distort if their drivers are pushed to the extremes of their designed motion, in which case they behave non-linearly and produce distorted sound.

For more information, check out my article Why Do Speakers Distort At High Sound/Audio Levels?

What causes speakers to pop and crackle and how do we fix it? Speaker popping and crackling is caused by interrupted electrical current (audio signals) or, in other words, a loose or dirty connection. To fix crackling and popping, troubleshoot the connective wires to find the problem area and secure the connection and/or replace the cable.

To learn more about speaker burn-out in the form of popping and crackling, check out my article What Causes Speakers To Pop And Crackle, And How To Fix It.

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