How much power can a speaker handle?

[davmol]

I have a pair of Wharfedale Linton 85th - specs below:

Sensitivity (2.83v @1m)	90dB
Recommended Amplifier Power	25-200W
Peak SPL	110dB
Nominal Impedance	6Ω
Minimum Impedance	3.5Ω

Currently driving them with Fosi V3 Monoblocks (48v 10amp split between the two), via a WiiM Ultra with 2volts output on RCA at 25dB gain:

• Gain : XLR/¼” TRS: 20dB ; RCA: 25dB, 31dB;
• Terminal Impedance : 2-8Ω
• Rated Power Output : 48V/5A--240W@4Ω ; 32V/5A --100W@4Ω

I can also drive via TRS from a Topping D50III with 5v output.

My question is could my speakers be damaged by these amps if driven at max or near max output, given that I think it was tested at 240w at 1% THD? I realise these speakers are 6ohm but dip to 3.5ohm and I assume Wharfedale is recommending a max of 200W output at nominal 6ohm, which these Fosi amps I think are not capable of producing (I assume then could be driven to clipping it turned up to high?)

To be clear, I would not intentionally drive the speakers at max output but I am interested in safe maximums. Also, I'm not looking at what is comfortable or what levels I listen at, I'm just interested in the theoretical maximum amp output that these speakers could handle, ideally given at the standard 4 or 8ohm with 1% THD, so that I can easily compare to manufacture specs if shopping for amps in future (I am happy with the sound of the Fosi's, but might like some audio jewellery in future )

Thanks!

 

[dfuller]

They could be, but let's note that one speaker at 100w is going to be putting out somewhere around 110dB. You're going to run into other limits before power.

 

[ryanosaur]

If you were to crank a test tone and run it continuously, you could quite possibly damage your Speakers fairly quickly.
Remember that music is not a continuous signal. That said, depending on how robust the actual Drivers are (many variables there) and how the XO network is constructed, it would still be feasible that you could overdrive your Speakers depending on how hard and long you push it.
Of course it will sound like cr@p as you hit distortion before you burn out a coil most likely.

 

[DVDdoug]

It's a bit "fuzzy"...

A 200W speaker is supposed to be safe with an amplifier hitting 200W on the program peaks. So, yes you could burn-out the speaker with a 240W amplifier which is not pushed to it's maximum.

I assume Wharfedale is recommending a max of 200W output at nominal 6ohm,

Right. It should be safe if the 6-Ohm calculated power is less than 200W, even though the actual power is higher.

But it's the short-term average power that blows speakers, not the peaks. And different program material is different so its a statistical estimate. i.e. You can generally burn-out a 200W speaker with constant 200W test tones and the tweeter can't handle as much power as the woofer.

Or, if up push an amplifier into clipping the average power goes-up even though the peaks are clipped limited so that's another way to burn-out a speaker.

There's a myth that pushing a lower power amplifier into clipping is worse than a higher-power amplifier because clipping creates harmonics that go to the tweeter but that's just a myth and you can burn-out a speaker either way.

I don't trust that speaker manufacturer's are following any standards but there is an old JBL paper about speaker power ratings called spkpwfaq.pdf.

...I don't trust amplifier specs either, although I believe the Fosi has been independently tested, and they are usually fudging the other way which is less dangerous to the speakers.

 

[voodooless]

Or, if up push an amplifier into clipping the average power goes-up even though the peaks are clipped limited so that's another way to burn-out a speaker.

It’s way worse than that. If you high-pass that clipped audio, you’ll see that the tweeter will get much, much more power than normal.

Therefore you can basically fry any hifi speaker with any amp. In anything, a lower powered amp might be more dangerous if driven into clipping, because it simply happens at a lower volume and people don’t expect this to happen already.

So no, this is not a myth.

 

[Chris A]

My question is could my speakers be damaged by these amps if driven at max or near max output...

Perhaps you might also think about what's occurring to the sound quality output of your loudspeakers (transient effects). Have you ever seen loudspeaker driver voice coil wire? It's thinner wire than what you see in a bread toaster. If you think about what happens when you push 100W through that wire--how rapidly it gets red hot, that's what's happening to your loudspeaker drivers when you start to get anywhere close to the rated power output of the amplifier. Like a 100W incandescent light bulb.

What does that do to their acoustic output? See the enclosed, below.

You might now see why higher sensitivity loudspeakers are preferred if you're going to play them anywhere near that loud--even just in the music peaks on very dynamic music tracks.

Chris

 

[DVDdoug]

Therefore you can basically fry any hifi speaker with any amp.

Like I said, you can burn-out a speaker either way.

With an under-powered amp you are likely to hear distortion and turn it down. With a higher power amp that stays clean you might keep turning it up!

It’s way worse than that. If you high-pass that clipped audio, you’ll see that the tweeter will get much, much more power than normal.

Yes but most of the clipping comes from the lower frequencies and strongest harmonics are in the mid-range. If you clip the heck out of a normal audio signal, you'll normally perceive a loss of high frequencies as the lower frequencies dominate. But sure, it's a relative loss and you'll get more sound out of the tweeter and you can fry it.

You can try that in Audacity - Open a song and Amplify by 20dB (you'll have to "allow clipping"). Then export as a regular WAV file so it it will be clipped at 0B. It will sound "dull" or "muffled" (and of course distorted) when you play it. (Don't forget to turn down the playback volume. )

From the harmonics alone you can only get 50% distortion... A sine wave clipped to a square wave at the same peak is only double the power (+3dB).

 

[JeremyFife]

The other part of the question is: under what circumstances will you be putting out full power, how likely is that?

It would be too loud for me to enjoy. Drunken behaviour, or inquisitive children used to be possible but not really an issue now.

 

[xanalog]

Speakers don't like steady state signals...
...but what they like less is distorted (steady state) signals, which make the total (heat equivalent) RMS value a speaker sees much higher.
No Bueno!

 

[Penelinfi]

The other thing to consider is that you might actually blow up the Fosi first if they cannot dissipate heat properly running at over 200W output