Signs of a blown subwoofer
Once in a while you might find that your sub doesn’t sound the same. It starts malfunctioning and you are left at a loss wondering what happened to the sweet bass that you had gotten used to. When this happens, it is very likely that your subwoofer is blown. Why and how does this happen and most importantly, what can you do?
What causes subwoofers to blow?
Subwoofers get blown when they either receive excessive power or too much of a distorted signal.
Excessive power
Excessive power is the reason why many subwoofers get blown in most cases. While listening to your sounds in a high volume can seem exciting and more appealing, please bear in mind that a sub can only handle so much. If you force it to operate beyond its limits, you creating too much pressure that ultimately results in damage.
While subwoofers are specially built with the ability to handle even more power than their indicated RMS (root mean square) popularly known as continuous power handling, it is paramount that you ensure that the sound is clear and without distortion when you crank up the volume.
NB: knowing the RMS wattage of your sub is important as it makes sure that you give your sub just the right amount of power, continuously.
Distorted signal
More often than not, we find ourselves turning up distorted signals in a bid to improve it which is really bad for your subwoofer. It is made worse by the fact that sometimes we cannot identify a distorted signal until it is so high that it has already caused damage.
How can you tell that your subwoofers are blown?
You can find out if your subwoofer is blown by;
Listening to the sound
One of the key signs of a blown sub is poor sound quality. If you notice any cracks in the sound, it’s time to do an audio test.
First, reduce the sound to a low volume and commence audio playback. Increase the volume and bass slowly, all the while paying extra attention to the sound. If it is distorted, you subwoofer is partially blown subwoofer and if there is no sound at all, it is definitely completely blown.
NB: If the subwoofer is receiving its signal via a cable, check the cable first, before drawing any conclusions.
Physical inspection
Test the movement of your subwoofer by first removing the cover so you can access the cone of your subwoofer’s speaker and then carefully examine it for damage. Use both hands to press the sides of the cone.
Remember not to use too much force. If it moves more than usual or does not move at all, you without a doubt have a blown sub. If it moves just right, listen to any scratching sounds it may be producing which could indicate that it is damaged.
Voltage
Use a multimeter to measure the amount of voltage, resistance, and current. This helps you determine if there is a lack of electrical resistance, which ultimately indicated a damaged coil.
Note that if the reading has trouble staying in one place, then the cone of your sub is most likely blown.
How to Measure the Electrical Resistance of Your Subwoofer
First, disconnect the subwoofer from its power source, and the audio input from the subwoofer.
If your subwoofer is not powered by an external amplifier or receiver, then you will need to remove it from its enclosure.
Connect the two probes to the multimeter, and turn the multimeter on to measure ohms (Ω). Insert the red probe into the positive lead and the black probe into the negative lead.
The multimeter will then measure the amount of resistance. You will need to round this off to the nearest whole number to get the accurate resistance.
Can you fix a blown subwoofer?
In some cases, it is possible to fix your blown subwoofer, while in other cases, you decide to just go on and buy a new one.
I advise that you to first disconnect your sub from your home theatre system as leaving it there may cause more damage to your other devices, hence leading to a much bigger and more stressful issue.
Secondly, get your sub inspected by a professional who will be in a better place to inform you on the extent of the damage. If you aren’t satisfied with his/her findings, getting another expert opinion couldn’t hurt.
If not too much time has gone by since you purchased your subwoofer, check to see if its warranty is still valid. If it is, then you are in luck. Just be sure to check the validity of the warranty before you disassemble the sub.
FAQs
Do subwoofers have fuses? Where are they located?
Yes, they do. Subwoofers fuses are mostly located in-line with the subwoofer wires, within the speaker enclosure. If there is an amp dedicated to the subwoofer, the fuse could be located there. In-line fuses can have different appearances.
What does the term mean clipping in a subwoofer mean?
Clipping is a type of sound distortion that occurs due to an audio waveform being clipped by the amplifier.
How/why does clipping occur?
When clipping occurs, it is an indication that the amp is being overworked by a subwoofer or other speakers to such an extent that it just can’t provide enough.
What is the best Hz for a subwoofer?
The recommended crossover frequency and the THX standard is 80Hz.
For On-wall or Tiny ‘satellite’ speakers: 150-200 Hz, for Mid-size center, surround, bookshelf: 80-100 Hz and for large center, surround and bookshelf: 60-80 Hz.
What does recone of a subwoofer mean?
Recone refers to complete rebuild of a subwoofer or speaker. Sometimes removing the already worn out parts is the way to go when you have an old troublesome sub.
Conclusion
A blown subwoofer can cause untold stress especially when it is barely new. It can also prove costly to repair or replace.
I am optimistic that this article has left you better informed on what to do, or not do to avoid blowing your sub, and what to do when you are unfortunate enough to experience this problem.
Check my list of top subwoofers for ideas on what to purchase in case you decide buy a new subwoofer instead of repairing the blown subwoofer.
