Why did my speakers blow?

Annie Amen By Annie Amen, 12th Jan 2011 | Follow this author | RSS Feed
Posted in Wikinut>Guides>Technology>Car Audio

An explanation of distortion, what causes blown speakers and how to prevent them. Written by an industry professional with 10 years experience in the mobile electronics world.

Why did my speakers blow?

Why did my speakers blow? I hear this all the time from customers.  There’s a big misconception when it comes to understanding why speakers blow.  Many people think that too much power damages speakers.  And that’s true to an extent, but I’d say 95% of the time it happens because of the exact opposite.  Sometimes my customers dreamily reminisce about the system their friend had and how loud they played it and they describe to me that it was “So loud, the speakers couldn’t handle it”.  And really that is not the case at all!

So why do speakers blow?  Speakers are easily damaged from a LACK of power.  Distortion happens when you run out of power.  The speaker starts breaking up and you hear fuzzy and garbled sounds, sometimes crackling and gritty noises.  This is actually the sound of the amplifier clipping.  Whether it’s the amp built into the radio or it’s a separate amp that you’ve powered up with a thick power wire coming from the battery, you will run into the point where the amp runs out of power and starts clipping.  That is when you start to hear distortion.  And over time, distortion will cause the voice coil in the speaker to heat up and break apart and shortly thereafter, it stops making contact completely and thus you have blown speakers.

So how do you prevent this from happening?  It’s all about the power.  If you like it loud, you need the power to back it up.  You need the right amplifier and you need to supply it with the proper power wire.

But what if you have a 1600 watt amplifier and a 1200 watt subwoofer and you still manage to damage your subwoofer?  This can happen due to a number of reasons, and I see it happen often enough that I feel I need to explain this.

Typically when a customer comes into my store and relays this dilemma to me, I immediately ask them if they know the RMS rating of the amplifier and the subwoofer.  They usually repeat to me what they originally told me: they have a 1600 watt amp and a 1200 watt subwoofer.  So I ask to see this 1600 watt amp and this 1200 watt subwoofer and I can quickly see that these are the numbers largely plastered on the equipment.  They are not the true power rating, but simply a peak power rating which is the number that grabs everyone’s attention.

After closer inspection, I see the amplifier has two 25 amp fuses and there is 8 gauge wire ran to it.  If this amp was really capable of 1600 watts, it would need a much larger gauge wire like 2 or 0 gauge.  However, with two 25 amp fuses, I can tell right away this amp is really only putting out about 350 watts RMS.  And the subwoofer?  After looking the model # up on the internet we find it’s rated at 600 watts RMS.  So what does all this mean?

We are under powering the subwoofer and pushing the amp into clipping which is distorting and damaging the speaker.  If we really wanted to use the 600 watt subwoofer, we would need to supply it with an amplifier pushing out about 600 watts RMS.  And that’s not the only problem here.  To really pull that amount of current, you need to use 4 gauge wire.  You could get away with 8 gauge, but 8 gauge is only capable of pulling so much current, about 500 watts safely.  At some point, you will end up starving the amp for power.  That means you’re not getting your full 600 watts out of your amp, which means you’re once again, under powering your subwoofer and running the risk of damaging it.

So here are the key factors to keep in mind so you can avoid damaging your speakers:

1) Always check the RMS rating of your speakers and make sure it matches or is close to the RMS rating of your amplifier.  Don’t pay attention to peak power ratings, they are very misleading.  Companies use this number to grab your attention and sell you on their product.

2) Always make sure you are running the proper gauge power and ground wire based on the RMS rating of the amplifier.  If you don’t trust the rating on the amplifier, check the fuses on the amp and use an amps to wattage calculator to determine the true output.

3) Never play your car stereo speakers with distortion.  Remember, distortion is what damages speakers.


Amplifier, Blown Speakers, Clipping, Distortion, Peak, Rms, Speakers, Subwoofer, Watts

Meet the author

author avatar Annie Amen
As an entrepreneur and dedicated student of life, I feel I may have inspiring insights, tips and tricks that can help others practically and spiritually.

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author avatar Russell
15th Nov 2011 (#)

Hi I know this was posted a ling time ago but I have a question I have a Renault 5 gt and two 12" subwoofers it has a built in amp which says 1600 watts I will find out the rms later I was wondering what type of car battery will I need ?

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author avatar Paul
15th Dec 2012 (#)

This information is incorrect. Speakers do not blow because of clipping. Clipping does happen when an amp is pushed past its clean limits, but it does not blow speakers. A clipped signal "clips" the tops and bottoms off of a signal curve resulting in square waves, resulting in a distorted sound. This does not heat up the voice coils to the point of failure however. If this were true, then every highly over driven, distortion filled guitar cabinet would be toast. What really causes speakers to blow is when the coils are pushed passed their maximum excursion limits or X-max. The wattage rating of a speaker is basically its thermal limit, A speaker can and will blow way before you get to that wattage. If there is to much low frequency being delivered to that speaker.

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