Power rating for speakers

[worf]

What's the difference between 25w-150w and 50w-150w? Looking to get my first pair of high end speakers. When I see the specs, I see that they are rated from 25 - 150 and others models are rated from 50 - 150. What does this mean? Would mean if I played the music at a low level (say 10W) for a speaker thats rated 50-150w, I'd be damaging the speaker?
Thanks

 

[no. 5]

Would mean if I played the music at a low level (say 10W) for a speaker thats rated 50-150w, I'd be damaging the speaker?

Absolutely not. You cannot damage a speaker by giving it "too little" power, if that was true, speakers would be damaged by sitting in the store room. If a low power amplifier damages a speaker, it is not because insufficient power was sent to the speaker, when an amplifier clips, it sends a lot more power to the speaker it's connected to, largely in the form of high frequency harmonics that can fry the tweeter.

The power ratings for speakers can pretty much be ignored, there is a maximum amount of power a speaker can take before its thermal and/or mechanical limits are exceeded, but the numbers attached by the manufacturer usually give next to no information about that.

And for what it's worth, ten watts into a speaker with 90dB/watt/meter sensitivity will produce 100dB SPL, and that's not exactly soft background levels.

 

[BoB/335]

I disagree! You can NOT just ignore power ratings on a speaker.

The minimum rating of a speaker is to show how efficient a speaker is meaning even a lwo watt amp will power the speaker to an enjoyable listening level. The max level should be self explanatory.

A speaker can certainly be damaged by an underpowered amp. A speaker will blow when an amp goes into clipping. Pushing a low powered amp to volumes the amp is not capable of getting to without adding distortion will clip an amp. It's probably easier for the common consumer to damge a speaker using too little power than using too much power.

Using your 25-150 watt example. A 25 watt amp will power those speakers. If you are having a party and want to really crank up your system that 25 watt amp will blow those speakers long before a 100 watt amp will because the distortion that the 25 watt amp will be introducing into those speakers will certainly be clipping at that volume. Don't get me wrong either. A 200 watt amp will also power those speakers really well even though the amp is rated for more than the speakers. If you really push that amp into clipping (which should be pretty darn loud) you will still damge the speakers because of the clipped signal being sent to the speakers. Typically a speaker should handle twice the RMS rating of a speaker with no problems so long as you don't clip the amp.

It seems most 100 watt 7.1 receivers are in the $500 price range and should be a great match for either speaker in your example.

 

[no. 5]

You can NOT just ignore power ratings on a speaker.

I'm not so sure, after all, how are the numbers arrived at?

For example, the maximum wattage, would exceeding it put the drivers past their mechanical excursion limits? Woofer, midrange and tweeter drivers will have different limits, so then the spectra of the signal used would be useful to know. But that information is not provided.

Or is the max wattage the thermal limit? There again, each driver will have a different limit, and time then becomes a factor; if 100 watts of pink noise for 500 ms will melt the voice coils, how much music would it take? After all, the temporal and spectral makeup of music is very different than pink noise, and is even different between styles of music.

I completely agree that a speaker's power handling should not be thought of as irrelevant, but there are more details that need to be known, and the "25 - 120 watts" rating that is usually provided is not enough.

The minimum rating of a speaker is to show how efficient a speaker is meaning even a lwo watt amp will power the speaker to an enjoyable listening level.

Doesn't the sensitivity rating provide a better metric for that?

A speaker can certainly be damaged by an underpowered amp. A speaker will blow when an amp goes into clipping. Pushing a low powered amp to volumes the amp is not capable of getting to without adding distortion will clip an amp.

Absolutely! But clipping 1dB off the peaks won't hurt anything, the clipping must produce enough energy to do damage. For example, a seven watt SET amplifier driven into extreme clipping will produce fourteen watts, that's not enough power to damage a tweeter that can take twenty, much less a woofer or midrange.

 

[lsiberian]

What's the difference between 25w-150w and 50w-150w? Looking to get my first pair of high end speakers. When I see the specs, I see that they are rated from 25 - 150 and others models are rated from 50 - 150. What does this mean? Would mean if I played the music at a low level (say 10W) for a speaker thats rated 50-150w, I'd be damaging the speaker?
Thanks

I will say this once. Go listen to as many speakers as you can. Don't focus on any specs. Just use your ears. Find the best sounding speakers you can. Try them on movies and music. Find the speakers that disappear the most. IOTW the speaker reproduces the sound accurately enough for you that you don't notice the speaker. Once you find the speakers then you can deal with the power ratings and etc.

 

[annunaki]

Multiple threads have been started on this topic and loads of misinformation is always spread. Do a search and read those threads. There is usually some good info in them.

Many factors come into play when it comes to power ratings and not enough info is usally given to make the manufacturer rating relevant.

Speakers fail for two reasons, period:

1. Too much power over a factor of time (thermal)

2. Too much power causing the woofer/tweeter to exceed it's mechanical limits (mechanical)

Never is a speaker blown by too little power.

Never is a speaker blown by clipping (distortion) in and of itself, but rather the factors attributed to it (increased power output from odd order harmonic information [again more power output])

 

[jostenmeat]

What's the difference between 25w-150w and 50w-150w? Looking to get my first pair of high end speakers. When I see the specs, I see that they are rated from 25 - 150 and others models are rated from 50 - 150. What does this mean? Would mean if I played the music at a low level (say 10W) for a speaker thats rated 50-150w, I'd be damaging the speaker?
Thanks

hi worf, there is a very good audioholics article about power handling. I find it too technical at times, but there are some interesting points to pick up nonetheless.

Loudspeakers & Power Ratings: What's the Deal Part I?

however, yes, no worries about 10w into a 200w speaker.