can you blow a speaker from too little power? only smart people please

[Sandtazam 10+ year member]

I don't have time to read all the replies but I'll give my take on the subject.

You can blow a speaker just as easily by under powering it as you can by over powering it. When you under power a speaker, the amplifiers dampening factor looses control of the speaker and allows it to move out of control which in turn will create heat in the voice coils. A woofer with too much power will at least be under the control of the amp but be over driven past its limit of excursion. This can result in bottoming out the voice coil in which case the woofer is still trying to travel beyond its limit. This too will create a heating of the voice coil. Both can be prevented by the proper choice of equipment and correctly setting the gains. Another factor comes into play as well. Power & ground. While many people buy big power wire, they don't always upgrade the ground. In addition, many cars are glued together now. For example, a Ford f-150 can have as much 15 ohms of resistance from the metal behind the seat to the battery. This problem can cause the same effect as under powering a woofer. It can also cause amps to shut down. Especially on a regulated power supply. A regulated amp will try to produce its full rated power no matter what voltage is going into it. Problem is, as it runs out of voltage, it also looses dampening factor. Now you are in effect, under powering your woofer and it's now flying out of control and trying to burn itself up. If you are experiencing what seems to be an underpowered situation, I recommend checking the resistance of your ground location to the battery. Don't rely on scraping the paint. It won't matter if the vehicle is glued together. If there's any part of this I need to elaborate on, let me know. I hope this helps.

 

[hatedonmostly 5,000+ posts]

I don't have time to read all the replies but I'll give my take on the subject. You can blow a speaker just as easily by under powering it as you can by over powering it. When you under power a speaker, the amplifiers dampening factor looses control of the speaker and allows it to move out of control which in turn will create heat in the voice coils. A woofer with too much power will at least be under the control of the amp but be over driven past its limit of excursion. This can result in bottoming out the voice coil in which case the woofer is still trying to travel beyond its limit. This too will create a heating of the voice coil. Both can be prevented by the proper choice of equipment and correctly setting the gains. Another factor comes into play as well. Power & ground. While many people buy big power wire, they don't always upgrade the ground. In addition, many cars are glued together now. For example, a Ford f-150 can have as much 15 ohms of resistance from the metal behind the seat to the battery. This problem can cause the same effect as under powering a woofer. It can also cause amps to shut down. Especially on a regulated power supply. A regulated amp will try to produce its full rated power no matter what voltage is going into it. Problem is, as it runs out of voltage, it also looses dampening factor. Now you are in effect, under powering your woofer and it's now flying out of control and trying to burn itself up. If you are experiencing what seems to be an underpowered situation, I recommend checking the resistance of your ground location to the battery. Don't rely on scraping the paint. It won't matter if the vehicle is glued together. If there's any part of this I need to elaborate on, let me know. I hope this helps.

no

 

[kr15 5,000+ posts]

A long time ago I had a 380rms lanzar 12 on a Fosgate amp getting 250rms, and it blew..the thing was that I had my gain at 100% (total neb shitt) and the speaker got clipped to heLL and it smoked the coil

so I guess Im saying that my take on this is that the speaker needs to be clipped in order to damage it from underpowering

 

[justafifteen 10+ year member]

How does underpowering a speaker cause it to heat up to the point that it'll blow?

 

[hatedonmostly 5,000+ posts]

A long time ago I had a 380rms lanzar 12 on a Fosgate amp getting 250rms, and it blew..the thing was that I had my gain at 100% (total neb shitt) and the speaker got clipped to heLL and it smoked the coil
so I guess Im saying that my take on this is that the speaker needs to be clipped in order to damage it from underpowering

That 250W RMS can produce more power than 250W. The 250W was probably at a clean 1% THD.

Of course it can do more at 10+% THD.....

 

[Vossy 10+ year member]

Soooo, if I could blow a sub from too little power.... what happens if my volumes not up?

FAIL

 

[Sandtazam 10+ year member]

When the dampening is gone, the mass of the speakers moving parts are too much for the amp to control, the speaker is now moving in one direction while the amp is trying to move it the other direction. This generates heat. Enough to make a voice coil destroy itself.

 

[Sandtazam 10+ year member]

Then the problem could be your ground as mentioned before. Also, if the amp is not strong enough to control the mass of the moving parts of the speaker, you're still loosing control of the speaker just at a lower level. Dampening factor is a critical part of making subs do the right thing. You can have an amp rated at a bazillion watts or 10 watts, if it can't control the speakers movement forward and backwards, it'll just destroy the speaker eventually. In most cases when someone looks at a woofer and it's moving to the extreme of its excursion, it's usually because the amp has just let go of the speaker and it's flying out of control.

 

[Sandtazam 10+ year member]

That 250W RMS can produce more power than 250W. The 250W was probably at a clean 1% THD.
Of course it can do more at 10+% THD.....

When you clip the signal, the amp is now trying to hold the speaker in one direction. This can be caused by the signal clipping from the deck, low voltage, poor ground, crap recording and the connection between the driver seat and the volume knob. The last is usually the first problem to look at. Another thing to look at is the fact that distortion usually doesn't penetrate a trunk or a band pass boxes port and therefore is not as obviously noticeable to the listener.

 

[justafifteen 10+ year member]

When the dampening is gone, the mass of the speakers moving parts are too much for the amp to control, the speaker is now moving in one direction while the amp is trying to move it the other direction. This generates heat. Enough to make a voice coil destroy itself.

Doesn't this have to do with the box, not the amp?

 

[t-money 10+ year member]

Sandtazam, cool story bro, Wow, if anyone is trying to learn about car audio, PLEASE DO NOT listen to this guy. I can't believe the things he says. Tell you what bro, if you want credibility please show us where you got that info from, because you are way off lol. And to think you probably think you're correct lol. Please don't help anyone else on this forum, i think you've done enough lol.

 

[AlterEgo99 5,000+ posts]

no

^this

 

[Ge_off_me 5,000+ posts]

^this

This this

 

[helotaxi 5,000+ posts]

The movement of the woofer cone looks EXACTLY like the waveform going in. That's what a loudspeaker is supposed to do.
Take a woofer and attatch a D cell flashlight battery for a second or two and tell me if the cone keeps moving. That is direct current. The top/squared piece of a clipped waveform is direct current and the cone is NOT moving.

Wire 20 D cells in series to get 30V. Then swap the polarity on that battery pack 40-200 times a second and tell me that the cone stops moving. A square wave is still AC. An ideal speaker with zero mass and infinite BL with zero inductance might be able to reproduce a square wave as it appears but a real speaker in the real world can't come close. A low voltage, low frequency square wave might have the cone stop moving at the peaks as the low power does not create the force needed to move the cone to a limit. That's not what we're talking about here. With a high voltage signal, you're going to have cone movement as long as the voltage is applied until you hit a mechanical limit. Hook a driver up to a 30-40V DC source and tell me that it doesn't hit a limit.

The power of the signal determines the amount of force moving the cone which determines the level of excursion. The reason that a speaker approximates the signal fed to it is that the force and thus acceleration are progressive as the waveform builds and then decreases. The motion of the cone lags the signal as well based on the inductance and cone inertia. Once the input waveform is not approximately sinusoidal the cone movement no longer looks like the wave form. Think about it, the cone cannot move instantly from one excursion limit to another which is exactly what it would have to do to match a square wave. Additionally, the inductance of the coil also smooths out the hard corners. The result is that the cone movement still approximates a sinusoid unless a mechanical limit is reached.

 

[iLL Ridge 10+ year member]

Good breakdown on that tip.