What exactly does max RMS power limit of a speaker tell us?

[anphex]

Hey guys,

today I've been wondering what the max RMS power of a speaker actually means.
All sources I found say something along that it's the "maximum safe volume" to run a speaker, but no data really.
Safe in terms of what? Of not melting the internals? Of not damaging the membranes mechanically? Or is it saying something like "X watt @ 10% THD"?
Are max RMS power and THD related at all?

What do I make of this spec line? Does it tell me that this speaker can get really loud? Does it tell me it can handle lot's of power without starting to burn even if it's playing at 200 % THD?

 

[tomtoo]

Hey guys,

today I've been wondering what the max RMS power of a speaker actually means.
All sources I found say something along that it's the "maximum safe volume" to run a speaker, but no data really.
Safe in terms of what? Of not melting the internals? Of not damaging the membranes mechanically? Or is it saying something like "X watt @ 10% THD"?
Are max RMS power and THD related at all?

What do I make of this spec line? Does it tell me that this speaker can get really loud? Does it tell me it can handle lot's of power without starting to burn even if it's playing at 200 % THD?

It tells you only not to give it not more longer time if you not like to roast the coil. No rms powerhandling is not related to thd of a speaker. It says the speaker can handel it in thermal and mechanical sense.

 

[BDWoody]

Does it tell me that this speaker can get really loud?

How loud it can get is a combination of speaker sensitivity and power handling capability.

Maximum wattage tells you what that manufacturer recommends as the upper limit to feed it. As far as I know, there is no standard for exactly what it means, so it's more of a general guideline so people don't blow up their speakers with too much wattage.

Is it max continuous? Max burst? At what frequency or frequencies was it tested? If they don't specify, it's hard to know exactly what it means.

 

[anphex]

In Germany we have a standard for this, as for pretty much all big and little, necessary and unnecessary things.
It is called DIN EN 60268-5, 300 h-Test but I couldn't find anything about this unless I buy some nifty 200 € E-Paper.

 

[DVDdoug]

It probably means you can use an amplifier that RMS rating without burning-out the speaker.

A speaker that's rated for 100W is supposed to be safe with normal program material that's hitting 100W on it's peaks so it's safe with a 100W amplifier as long as the amp isn't over-driven into distortion. When you drive an amplifier into clipping only the peaks are clipped so the total/average/RMS power continues to go up, and clipping generates harmonics which means more energy into the tweeter. ...The paper I linked to below says a guitar speaker should be rated for twice the amplifier's power since guitar amplifiers are routinely driven into distortion.

As far as I know it doesn't tell you anything about speaker distortion.

Speaker power ratings are complicated and almost nobody follows any rules. Amplifier manufacturers lie a bit too, so maybe it works-out...

Music and program material is also complex and you might have peaks that are 10 times the RMS or average and there is more energy in the low-mid range than in the higher frequencies so the tweeter in a "100W" speaker can't handle 100W. It's likely that the woofer (or midrange) can't handle constant 100W test-tones either. (It's the RMS or average that burns-out a speaker.)

This page links to an old JBL PDF about speaker ratings.

 

[somebodyelse]

In Germany we have a standard for this, as for pretty much all big and little, necessary and unnecessary things.
It is called DIN EN 60268-5, 300 h-Test but I couldn't find anything about this unless I buy some nifty 200 € E-Paper.

Not just Germany for this one, hence the EN part, and there's a matching IEC standard, but at a price as you say. How many are following it is another question.

 

[Ron Texas]

It probably tells you nothing because there is no standard for that specification.