A subwoofer is a critical component in any car audio system. It is a speaker dedicated to producing low-end frequencies, also known as the bass. Having a subwoofer in your car will add depth/realism to the music and make your experience a lot more pleasant.
What Does It Mean By A Blown Subwoofer?
If you have any experience with the subs, you’ll know that their performance starts to deteriorate after some time, and you don’t get the same level of thumping Bass as you did before. Not only that, but you also feel distortion in the sound.
It usually happens when a subwoofer has blown.
But how can you tell that your Sub is blown and doesn’t have any other issue?
How to Tell if A Subwoofer is Blown
The easiest way to tell if a speaker/sub is blown is by checking stiffness of speaker cone. If it’s too stiff to press with your fingers, then it’s likely blown. Another sign of such speakers is the distortion if volume level is high. Lastly, use a multimeter to check its resistance.
Below are some of the common ways you can detect a blown subwoofer.
1. Physical Inspection
Most of the times, you can detect a blown sub simply through physical inspection. If it’s damaged from the inside, there will be some cracks on it.
Place a hand on each side of the sub, and use your fingers to press down the cone to see if you hear anything or if it moves.
If it’s stiff and doesn’t press even after applying some force, then the voice coils are frozen inside, meaning the sub is blown.
A regular subwoofer has little suspension, which allows the cone to come back up when you press it down.
But if it moves easily and more than usual, it indicates that the spider and surround suspensions are worn out.
The same is the case if you hear any crack or noise when pressing it down.
2. Listen to Music
Simply listening to music can reveal many things about your car audio system.
Keep your music at a base level, and increase it slowly. If you hear any distortion while the volume is increasing, there’s some fault in the sub.
This distortion can also be a result if the subwoofer is overpowered. So make sure to check that as well before going any further.
Similarly, if you aren’t getting the bass you used to, even at a higher volume, the subwoofer is likely to be malfunctioning.
3. Touch the Subwoofer
A subwoofer is a specialized speaker, and like any other speaker, it converts electric energy into sound energy by vibrating its cone.
You can easily feel this vibration by placing your hands on a functioning sub. Likewise, feeling no vibration from your sub whatsoever is a good indicator that it is blown.
However, it can also happen if your amp is weaker and a wire is damaged. So make sure to check those as well before drawing any conclusion.
4. Use a Multimeter
This is perhaps the easiest and quickest way to detect a blown sub. Because now you get help from a multimeter.
Also called multitester, this tool helps you know (among other things) the resistance of a subwoofer. Lack of any resistance will mean the coil is damaged.
Before doing anything else, you’ll have to disconnect input and power sources from the subwoofer.
After this, set the multimeter to Test Ohms, and connect its probes to the negative and positive terminals.
If the Ohm reading you see on this multimeter is very close to what the sub was rated at, then it’s fine.
But if it’s off the mark by a good margin in either way or is fluctuation heavily, then the subwoofer is blown.
What Causes Subwoofers To Blow?
So far, we have discussed different methods to detect blown subs and what causes them to blow in the first place.
1. Overpowering Your Subs
One of the common reasons for subs to blow is overpowering. It gives us extra volume when we supply too much power to the subwoofer. But this extra volume not only distorts sound but damages the subwoofer in the long run as well.
When the sub is overpowered, it tries to move the voice coil and cone further than they were designed for. It tears off the spider and cone and causes the voice coil to crash into the magnet’s backplate.
2. Underpowering Your Subs
Underpowering is the exact opposite of overpowering. Here you don’t give the sub enough power to produce a detailed sound.
It’s not inherently bad but will result in a clipped signal when we increase the volume. A clipped signal occurs when the volume of a source signal exceeds the electronic capability of a circuit.
Because it squares (clips) the peaks and troughs of the voltage waveform, the cone moves quickly (almost infinitely fast), tearing in that process.
Similarly, it makes the coil to be still all the way forward or backwards. This results in the voice coil to get heated and lose its shape.
Frequently Asked Questions
How do you know if you have a blown subwoofer?
The most basic test you can do is physically inspecting the subwoofer. Place your fingers on the cone and apply some force. If it moves inwards slightly and comes back as soon as you release the force, then the sub is good. On the other hand, if the cone is too stiff or moves too easily, then the subwoofer is probably damaged from inside.
How do you test a car subwoofer to see if it works?
Take a 9V battery and connect its positive and negative leads to the subwoofer terminals. If the cone pops in or out, it means the subwoofer is working.
What does a blown sub smell like?
A blown subwoofer smells like just any other burnt electronic equipment.
How long should a subwoofer last?
With proper maintenance, a well-built car subwoofer should last more than 5 years.