# overpower speaker or subwoofer



## djloui (Nov 10, 2014)

I have always been told that its better to drive more power to speakers than driving less power to them. However, i dont know how much power is acceptable to overpower a speaker. For example, I have 6 inch 135 RMS subwoofer. Will it kill the sub if I power it at 280 RMS?


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## 86eldel68-deactivated (Nov 30, 2010)

djloui said:


> ... I have 6 inch 135 RMS subwoofer. Will it kill the sub if I power it at 280 RMS?


If it's already powered (active), you don't want or need to power it with a separate amp.

If it's not powered (passive), using a too-powerful amp could damage the driver by pushing it past its mechanical limits.

(Side note: A subwoofer with a 6" driver isn't much of a subwoofer.  )


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## djloui (Nov 10, 2014)

Thank You. What about a cabinet speaker? My cab speaker is rated at 350 RMS and a peak of 500. Will it blow if I power it around 450 RMS since the peak is 500?


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## 86eldel68-deactivated (Nov 30, 2010)

If the speaker is rated 350W RMS, IMO pushing 450W RMS through it steady-state will cause damage.


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## Talley (Dec 8, 2010)

My ultras are rated max 300w RMS and I hurt one of the woofers driving it with 125w. My new XPA-7 now delivers 520w and I've had it cranked with no loss yet. Not saying this is good but it will let you know if I see trouble.


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## NBPk402 (Feb 21, 2012)

If you drive your amps into clipping you can fry speakers even if they are rated for more power than you have (the amp can't keep control of the speaker and the piston can come out of its cylinder). If you have more power than the speakers are rated for you can also fry them if you run them continuously over the rated power by heating up the voice coils. If you are careful to not clip, and not run continuously over the rated continuous power levels recommended by the manufacturer you are safe.


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## tonyvdb (Sep 5, 2007)

Playing alot of test tones or bass heavy music at moderate to loud levels can also fry the voice coil in speakers due to distortion and heat.


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## willis7469 (Jan 31, 2014)

ellisr63 said:


> If you drive your amps into clipping you can fry speakers even if they are rated for more power than you have (the amp can't keep control of the speaker and the piston can come out of its cylinder). If you have more power than the speakers are rated for you can also fry them if you run them continuously over the rated power by heating up the voice coils. If you are careful to not clip, and not run continuously over the rated continuous power levels recommended by the manufacturer you are safe.



This is pretty much the short version. 
The problem with OP's question is that the answer involves so much more than 500,000wRMS with a 2w speaker. I always feel like his questions are a test...


Sent from my iPhone using Tapatalk


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## DqMcClain (Sep 16, 2015)

Yeah, this is an interesting question. 

Under-powering a speaker is at least as dangerous as over-powering it, partially because over-powering is much easier to avoid. When you under-power a speaker (i.e. drive it with an amp rated for significantly less power than the speaker) it is very easy to drive the amplifier to the point of clipping. In mid- and hi-frequency speakers, the distortion can be audible... and then the listener knows to back the level off. But with low-frequency drivers it takes a lot more distortion before the problem becomes apparent... and at that point, the clipped signal is being delivered to the driver for extended periods. This is especially hazardous because the clipped signal will build up heat in the VC much faster than the original signal, and you can wind up cooking the coil without ever hearing anything wrong. 

Over-powering a speaker almost requires malicious intent. First you have to provide an amp that has an RMS rating above the Peak rating of the driver, and then you have to drive the system hard. The distortion is equally inaudible if you're at or near Xmax for the driver. Things don't get really ugly until you hit Xmech, which is the point where the motor is physically hitting its limits. (i.e. the coil former is bouncing off the back the the magnet assembly) Hitting Xmech by over-driving a speaker is extremely obvious by its sound... but unfortunately it also results in irreversible damage very rapidly, often in terms of seconds or less. That said, operating at or beyond Xmax will eventually result in damage and is to be avoided. This damage could be thermal, or mechanical (ripping suspension, glue joints, cone parts, etc). It depends on the situation. 

As a general rule, if you've got an amp with an RMS rating that is between the RMS and Peak ratings of the driver you should be OK as long as you don't push things past reasonable listening levels. In the OP's case, a driver with a 135W RMS (which usually means a 270W Peak) powered by a 280W RMS amplifier is only a little on the high side of good. Just don't open than amp all the way up and spend your days listening to EDM and you should be fine.


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## lcaillo (May 2, 2006)

djloui said:


> I have always been told that its better to drive more power to speakers than driving less power to them. However, i dont know how much power is acceptable to overpower a speaker. For example, I have 6 inch 135 RMS subwoofer. Will it kill the sub if I power it at 280 RMS?


The absolute answer is yes. The answer in practice is probably not unless you either over equalize or consistently drive it really hard. RMS is an average, and most power at those levels will be peaks. It really depends on the content and how you listen.

In general, the idea that underpowering is worse than overpowering is overstated, particularly with woofers. It is more of a problem with tweeters, where heat dissipation is less effective.


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