How does speaker wattage ratings work?

[Midnite Mick]

I know speakers will often handle more than they're rating as long as the signal integrity is maintained but I am curious about how they come up with power handling numbers. When they actually come up with the ratings do they simply take the sumation of all the drivers or are there other factors involved that are considered.

Thanks,
Mike

[disneyjoe7]

I believe since music is made of various sounds / frequency it's why a 200w speaker may only have 120w woofers. My thinking is overall watt rating is roughly the sum of all drivers in the speaker.

[Flash21]

You are correct that clean power can drive a speaker very hard without damage, but at some point you will reach the excursion limit of the woofers, and may overheat the tweeters even with clean power.

[knownalien]

well, I am driving 600 watts into my fronts which "say" they max out at 250. I listen to music close to reference level.

[unc2701]

It's usually a function of the maximum sine wave intensity that the voice coil can maintain without heating above a certain temperature. In Europe, all the parameters are very well defined & known as the DIN power rating. here, it's "250 watts..ish"

BTW, I'd be shocked if you actually ever fed your speakers 600 watts... plus just 3db off reference puts you at 300 watts.

[knownalien]

well, to be more accurate, my speakers are bi-amped.

one amp can deliver 300 watts into 4 ohms
another amp delivers 300 watts into 4 ohms

knowing all of the ideas about what a wall socket can deliver (20 amps) and that speakers don't sit at 4 ohms all the time, ofcourse it is not 600 watts total, but nonetheless, the power is there.

[Eric Wong]

Speaker power ratings in general are very approximated. There are two basic factors of power handling, thermal power handling (heat) and mechanical power handling (physical cone/dome movement).

There are several variables involved in what a speaker can handle including frequency of signal, duration of signal, dynamic range of the signal etc. Generally the lower the frequency presented to the speaker, the worse the power handling gets, especially true of vented enclosures. Further, tweeters have much worse power handing then woofers do, however most energy in the program material is in the bass anyway. Music by its very nature is also very complex, much more so then test tones. In addition, just because the speaker can handle the power does not mean it is being over driven. There comes a point where the more power inputted to the speaker does not make it get proportionately louder, but instead just turns to heat.

So for us, using test equipment and tones we will find the ultimate failing point of the speaker. Then, we will analyze using test tones that simulate music to see when it gets to the point where the speaker may accept the power but not get any louder as well as longevity tests. Further, we will conduct real world tests using real material and real equipment to evaluate the performance then come up with the power recommendation.

Most of our products actually are recommended by amplifier size rather then "power handling", thus we recommend amplifier sizes between 20-275 watts per channel (an example from our Monitor 70).

[Willow]

Eric, even before noticing that you work for Polk, upon reading your 1 sentence , I thought this guy knows what he is talking about....