Why subwoofers blow: slam, bang, pop, and sizzle
Too much power or distortion damages subwoofers

An exploded view of the parts of a speaker. This particular example is the woofer from a set of Focal component speakers. (click the image to enlarge)
In a perfect world: the music sounds great
The sine wave below represents a signal that an amplifier sends to a subwoofer as a variation in voltage over time. The vertical axis represents voltage, the horizontal axis represents time. In AC (alternating current) signals, like music, the voltage swings between positive and negative values. Point A represents the point in time when the amplifier is telling the sub's voice coil and cone to be as far forward, toward the front, as that particular voltage (+V1) tells them to be. Point B is where –V1 voltage positions them toward the rear. Traveling back and forth rapidly, the cone pushes air and makes sound — and it's musical.

Overpowering your subwoofer – Slam and Bang
First we'll cover what happens when you give your subwoofer too much power. It's great to turn it up, but that extra volume starts to distort the music. Not only does it sound bad, but it can damage your speakers and subs, especially if you do this all the time.
Slam: The incoming signal tells the cone to move too far forward
Let's say that points A and B (and +V1 and –V1) are the maximum ratings of our subwoofer. If we increase the volume of the signal, the higher voltage (+V2) now tries to move the cone even further toward the front (C). The signal is still a clean signal, but now it is trying to move the cone and voice coil much further than they were designed to go, tearing the cone, spider, and surround apart, destroying the subwoofer.

Bang: The signal tells the coil to move too far backward
On the other side of things, when the signal (-V2) tells the voice coil to move too far toward the rear (D), the voice coil crashes into the back plate of the magnet assembly, cracking the coil and its former (the tube it coils around), and probably jamming it in the voice coil gap.
Underpowering your subwoofer — Pop and Sizzle
Underpowering a subwoofer isn’t inherently bad for the sub. Not giving it enough power just means that the music will sound weak and lack detail.
The danger is when that power is coming from an amplifier that's being overworked and sending out a clipped signal. The clipped signal tries to make the sub do things it's not designed to do, which leads to it tearing itself apart or overheating and burning out.
First, what’s a clipped signal?
Clipping a signal, or squaring its waveform, occurs when the volume of a source signal exceeds the electronic capability of a circuit. Let's say our amplifier can't play a signal more powerful than what voltage V1 can produce. If we tried to increase the volume at the source, the amplifier wouldn't produce more voltage, it would distort the signal, eventually into the form of a square wave.

Pop: A clipped signal tries to move the cone too quickly
You will notice that the sides of the clipped signal are vertical. That means that the signal will try to move the sub's cone from all the way forward (point E) to all the way to the rear (F) in zero amount of time, travelling at the speed of infinity. Nothing travels that fast, and the sub either tears itself apart trying, or the flapping cone wobbles just enough to jam the coil in the magnet's voice coil gap, killing the sub.
Sizzle: A clipped signal also tells the voice coil to hold still and heat up
The other parts of a square wave, the top and bottom, are horizontal lines that represent the times the signal is telling the cone to stay all the way forward or all the way back. Current flowing through a stationary coil only heats up the coil, which doesn't even benefit from a cooling breeze due to movement. The coil usually burns through one or more of its windings, or heats up enough to deform its shape so that it jams in the magnet's voice coil gap.
There's another, more complex reason voice coils burn when subjected to over-driven, clipped signals. A square wave carries twice the RMS power of a sine wave of the same amplitude (height). So not only is the signal telling the voice coil to pop into a position and sizzle, it's doing it with almost twice the power of the sub's maximum capacity. Usually, it's the glue holding the coil wire to the former that first melts under all the heat, and the coil crashes in its gap.
Distortion is the sub killer
Low power and low volume will not hurt a sub – but distortion will. A clipped signal is a sub's worst enemy. It isn't loudness that destroys an under-powered sub, it's trying to get bass volume by turning up a distorting signal that does it.
Subs are made to withstand a lot more than their specified RMS ratings, so giving them a little more than their highest RMS rating is safe, as long as it's clean and distortion-free.
How to not blow your subwoofer — match the RMS power ratings
Ignore all "peak" and "maximum" wattage ratings, and use only RMS ratings. They may be harder to find, but RMS ratings are the only power ratings you should use. To safely drive a subwoofer, use an amplifier that can give it no less than 75% and no more than 150% of its highest RMS power rating.
It's also crucial you set the amplifier's gain correctly. If you don't know how, you can check out Tuning Your Subs or Using Test Tones to Set Amplifier Gain for some helpful tips. And remember, if you want to run two or more subs, you've got to supply enough power for each and every one of them.

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James from Jacksonville
Posted on 12/3/2018I am brand new to the subwoofer in home audio. Reading this great article I came across the following sentence.."To safely drive a subwoofer, use an amplifier that can give it no less than 75%..." I just bought a Sub woofer that has a RMS of 300 watts and my AV receiver is only 100 watt RMS and at the most might go as far as 1/4 the volumn. I just booked it up and at low volumn with gain set all the way down it made some sporadic loud scratchy (?) sounds. So I shut it down waited, checked all the knobs and switches. Again it did the same after being on for a few minutes. I am using it in a 2.1.1 for mostly music. I have a few questions... Is this normal? And did I buy to much sub for my receiver? It's being used in a 16 X 14 bedroom and the wife does not like classic rock. I'm not even sure how I can test this sub if I can't drive it to the minimum 75% RMS. Any and all suggestions are welcome. I would not want to damage a new sub by not knowing the proper so and use. Thank you
Buck Pomerantz from Crutchfield on 12/4/2018James, The 75-150% rule of thumb about amp power applies more to world of matching car audio components than it does to home theater systems. It's okay to drive your sub with much less power than its rating - after all, you can always turn the volume down without hurting anything. Scratchy noises are something else, though. Without knowing precisely what gear you're referring to, we can't help you with advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you.Darren Davies from Cardiff
Posted on 11/26/2018Hello I'm having an issue.... AVR Denon 7200wa Sub : Velodyne digital drive 10 popping sound from the driver when a punchy bass note is happening. Mostly when the AVR volume is in the low region -55db The sub volume is at 34 AVR sub level is 0 Seems like I'm over amping a weak signal sub gain is 10 O'clock, If I set it closer to 12O'clock the sub seems to click into standby even though it still works (auto on is disabled) I raise the AVR sub level to +4 and the popping goes away when using most sources, but then switch to a TV show that has a lower level than a movie and the popping can come back. What I'm hoping for here is recommended settings, as I'm never quite sure if I'm under powering the sub but still overworking the AVR or vice versa I'm so tired of trial and error and still not feeling good about what I'm doing thanks in advance even if you can't help :) Darren
Buck Pomerantz from Crutchfield on 11/27/2018Darren, If you bought any of your gear from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number is on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.Chris arnold from Vermontville
Posted on 11/4/2018The subs are crackling. And i know that they are not broken its almost as if its getting full single frequencies low and high making it "clip" iv also bi amped and bi wired i have a marantz an pioneer more or less just explored the possibilities. Well i had it working perfect then took it appart and never went back to gether the same way. The subs i checked they work. The amp a dayton spa 1000 . Fuse didnt blow and all wires are ... seemingly funtional.. got any ideas ?
Buck Pomerantz from Crutchfield on 11/7/2018Chris, If you bought any of your gear from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number is on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.Graham from Loveland
Posted on 10/19/2018Hello, 12" pioneer sub being powered by Xpr520 2channel amp. Amp keeps going into preotect mode. System will play, but when driving, amp will switch between protect and normal, cutting the sub in and out. Worked fine 2 weeks ago, just literally started one night. Checked all the connections and fuses, have an in-line and it's fine. RCA are fine as far as I know, ground is clean, remote wire secure. Was going to try changing my speaker wires. Was thinking either my sub was blown of my amp is just toast. Checked my cone and rest of sub, seems fine, less than 2 years old. Amp is newer than that. Any tips would be much appreciated.
Buck Pomerantz from Crutchfield on 10/22/2018Graham, It sounds like you have a DVC 4-ohm sub wired as a 2-ohm load connected to a bridged 2-channel amp that can't handle a 2-ohm load. If that is the case, the best you can do with your gear is to wire them together like this.Allen from Anderson
Posted on 10/3/2018I have 2 skar ma 8s in a ported box and they're powered by a skar sk 1500 the speakers r rated 400rms the amp is rated 1800 rms at 1 ohm I have the wired 1 ohm parallel but the amp is clipping like the speakers need more should I get a higher wattage amp
Buck Pomerantz from Crutchfield on 10/4/2018Allen, That amp is already powerful enough to blow those subs to pieces. Sounds like the amp gain hasn't been set correctly. Check out this article for help with that.Richard
Posted on 6/15/2018Can i run a 500 watt rms 2 ohm mono amp to push a 600 watt rms 2 ohm dvc sub
Buck Pomerantz from Crutchfield on 6/18/2018Richard, The only safe way to hook that gear together is like this diagramManuel Santana from Springfield
Posted on 6/7/2018Hello again, I have a pair of 10 inch dvc planet audio anarchys that are 750 watt rms each so 1500 rms total and 1500 max for each sub but you would want run at rms power an not much more if im right. The subs sound good but my first pair i fried the coils and im not sure quite how yet. They where hooked up to a planet audio anarchy 4000 amp wired parallel. The new anarchy subs i got are under warranty claim so i do not want to have any problem so i wired them in parallel/series for a 4 ohm independence but this seems to not be nearly enough power for what i want or had at 1 ohm. I can tune to make sure i dont over power but im not quite sure what number i should have the sub sonic filter tuned at and i dont quite under stand whay clipping is ether. Sorry for all the questions and tje lomg message but i was also wondering which works better in a rectangle slot stye ported box for stuffing. Polyfill or egg crate style foam pad and if it will decrease or increase sound.
Buck Pomerantz from Crutchfield on 6/9/2018Manuel, Clipping occurs when you turn the volume up so loud the amplified signals distort, possibly damaging the subwoofers. For bass notes, clipping sounds like a grinding or crunching instead of clean, mellow bass tones. For voices, clipping sound like the singer's voice has become hoarse or scratchy. Polyfill is only used in an enclosure that is too small for the sub in order to make it behave like a larger enclosure.
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