Installing VLC Media Player voids your speaker warranty

I would suggest VLC disables this feature for new installs and move it to an easily discoverable preference.

Or if they really care enough to allow their users to boost the volume levels of quiet movies to replace the gain multiplication with a proper dynamic range compressor activated when the volume goes above 100%.

Of course, Dell could include analogue filtering circuitry to filter out the excess power in inaudible frequencies if they wanted to.

But it's not just the total AC power that matters, it's also the power density that matters. So for example a sine has a very high power density (in fact if you do the math, the power density for a pure sine is infinite). This is turn means, that whatever resonances the system has, that overlap with the frequency of the sine, they will get excited and can resonate toward mechanical breakdown (damaged speaker). A low power density signal, like noise, where the total output power is spread over the whole spectrum (or the spectral response of the system in question) and below the maximum rated power of the speaker is much less likely to do damage.

Now we have to look at clipping. Analog clipping is not just some random noise, it's in fact a harmonic distortion. And as such it can redistribute the power in the spectrum. And digital clipping actually causes an integer overflow, which in fact adds further power to the signal.

But it goes further: The output of a DAC is a voltage. A voltage by itself does not carry power, you need an amplifier to do that. So the first step after the DAC and after the reconstruction filter (which also acts as a DC block) is a transimpedance amplifier that turns the voltage into a power signal; what this means is, that for a signal of a certain power that's going into a certain load it gives rise to a specific RMS voltage on the load terminals. In audio the reference power level is usually 0dB(m), i.e. 1mW – on the typical load impedance of 1kOhm this corresponds to a RMS voltage of 1V at the load (and higher voltage at higher impedance, lower voltage on lower impedance loads).

In a perfect amplifier the impedance is independent from the input signal and its output load. In a real amplifier though the impedance can vary depending on the signal and the output load. And the impedance usually also depends on the frequency of the signal.The effect is, that an amplifier introduces further harmonic distortions, if the signal puts too much power onto its input. If this happens in the preamplifier stage this can drive an output stage outside the specifications of the connected loads.

You see, because distortion happens mostly if you drive an amplifier close to it's maximum capabilities the usual approach is to design the amplifier some comfortable margin to the needs for the connected load; typically you use a margin around 6dB, so for a 6W load you'd choose a 12W amplifier, so that no matter what input signal the amp gets, the total harmonic distortion stays within safe limits. To protect the load you then choose the amplification factor so, that for a reference power input signal the output power is lower than or equal to the power for which the load is rated.

Now say, you're a cheapskate engineer, maybe with little analogue electronic design experience. So you see your speakers have a maximum rating of 6W. So you do a parametric search and come up with amplifier ICs from the usual suspects (Maxim, TI, ST); they're rated a 5W, 10W, 15W...; obviously cannot drive those 6W speakers at maximum power (it will badly distort), but 10W should do the trick, right?

Well, now, because you forgot the total harmonic distortion: Which means that if you raise the input signal power by 6dB (i.e. double the power) the output of an amplifier may rise well over 6dB. So lets say you had first a signal output power of 2.5W for a -6dB(FS) signal, then you raise it to 0dB(FS) (which would be your volume slider in the control applet at 100%), theoretically the output signal should now be 5W. But because of the underrated amplifier the output distorts and the actual power going into the load rises well above their maximum 6W rating.

TL:DR; Dell did mess up their amplifier design, but not by overrating the amplifier, but by underrating it. If they had chosen a properly rated with margin (so that THD stays low) amplifier and chosen the gain so that a 0dB(m) line signal would have produced 6W output power (about 15dB gain) the speakers would have been safe.

Have you heard about this problem in any other laptop before?

It's so completely impractical for a hobbyist project to own every possible piece of hardware, or at least a huge majority of it. Yet it's nothing for a Fortune 500 company to do the same.

Really slants the playing field away from independent software developers.

I'm no expert but maybe it's actually possible to create speaker that doesn't go bad.

(I could code the protection into the sound driver in half a day probably)

The easiest way to solve this is use stronger materials for the speaker construction. This does, yes, affect the quality of the sound, which is already somewhere between catastrophic and abysmal on a laptop. The frequency response is likely to be worse, on a set of speakers that already has a frequency response that makes them quite useless for music.

You can also do it in electronics, as measuring the power delivered to speakers is not exactly rocket science. The response time wouldn't be great, but it's continuously shredding the speakers with square signals that damages them, not a couple of pulses every once in a while. You can also detect heavy slopes. You can even detect heavy slopes in software.

But no, seriously, this is a problem that can be solved. The mere fact that a lot of manufacturers manage to come up with speakers that don't break should be a testimony to this. I have (granted, desktop) speakers that have gone through a decade of heavy metal, grindcore and fucking SIDs and MODs, on bad ALSA drivers that I could barely get to work for years. They're fine. This is just Dell selling cheap shit.

You shouldn't be able to blow up your speakers if your amp, speakers and limiters are setup correctly.

After all, if you're busting out £20k on a set of decent speakers, you don't want to burn them out because your idiot producer "turned it up to 11"

Maybe if your speakers are very quiet and crappy and you have to get every control to 100% (hardware, system, vlc) in order to hear anything - maybe in this case it will.

Hard clipping is very noticeable for the listener so not many people will set it to the maximum if they have choice.

Anyway, you can protect from this either in hardware or in the driver.

1.41 x

>Playing metal at full volume is not as damaging as playing anything intensely digitally clipped at full volume.

The output of the amplifier really ought to be bandwidth limited either as a natural consequence of the components used or explicitly with a filter. It is silly to spend power on things that can't be heard.

That's compression, not hard-limiting. Hard limiting would leave the quiet parts quiet relative to the loud parts. It would only crush them if they were not enough dynamics in the first place.

I don't know of any widely used definition of "clipping", nor any definition that fits the context of this discussion, that allows for a signal's peak value not to be reduced. It's called clipping because the extreme values look to have been clipped away, as if by scissors. The parts that have been clipped away contain energy, don't they? So won't the clipped signal will carry less energy than the original?

When you take a sine wave of peak value 1 and clip it, what you get is not a square wave with a peak value of 1. Rather, you get a peak-truncated sine wave in which values in excess of the clipping threshold V are replaced with the clipping threshold. There's less power in this clipped sine wave than in the original because min(V, |sin t|) <= |sin t| for all t.

They are still terrible speakers, though. I almost laughed when showing a friend Star Wars for the first time; it doesn't even come close to doing the soundtrack justice.

External DVD Drive, play one of my DVDs on the Mac, audio is perfectly fine.

Play the same DVD on my Asus UX31, cannot hear the people talking, use VLC player to up the audio to 125% and its fine.

IMHO everyone who is saying "this should be fixed by software" is doing it wrong. How much would it cost to write, test, debug, etc. the appropriate firmware/drivers? And it would still be subject to "warranty is void because you didn't use the right software". That cost could buy a lot of capacitors... and then if the values were chosen correctly, whatever the software does, it would not be able to put more power through the speaker than designed.