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0 pointsastral30312y ago0 comments

A square wave has twice the power of a sine wave of identical amplitude.

This is why distorting the amplifiers (especially digital clipping) is so much worse for speakers than overpowering the speakers. This is a very well known fact in audio circles.

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

Yes, Dell is putting on shitty speakers on their laptops, (what else is new), but VLC should be amplifying the output using level-limiting (hard-limiting), which would effectively bring all the quiet parts to be just as loud as the loud parts, instead of just digitally clipping the output.

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fnordfnordfnord12y ago

>A square wave has twice the power of a sine wave of identical amplitude.

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.

gamache12y ago

Assuming the parent is talking about equal maximum amplitude of the sine and square waves, the square wave RMS voltage will be sqrt(2), or 1.4, times the sine wave RMS voltage. And since power is proportional to voltage squared, the square wave will carry sqrt(2)^2, or 2, times the sine wave power.

lutusp12y ago

Actually, if we look at two half-cycle waveforms, one sine and one square, like this:

http://i.imgur.com/oE5NFZ9.png

(Just the left 1/2 of the graph for this example)

The integral of the sine waveform with a peak value of 1, on the interval 0 x < pi, is :

http://www.wolframalpha.com/input/?i=integrate%28sin%28x%29%...

= 2

The integral of the square wave on the same interval is = pi

So the ratio increase in average voltage at the speaker (comparing the sine to the square) is pi/2 = 1.57. The increase in speaker power is (pi/2)^2 = 2.46.

dpe8212y ago

It also assumes a speaker's reactance is purely resistive. It's not.

fnordfnordfnord12y ago

Derp, thanks to both for the correction.

lutusp12y ago

>> A square wave has twice the power of a sine wave of identical amplitude.

> 1.41 x

Yes, for a voltage of x, but remember that the speaker is a resistance, for which the power varies as x^2/r (Ohm's law: p = e^2/r), So the original claim is correct.

malandrew12y ago

Most metal released these days is digitally clipped. Even classic old 80s "remastered" records are digitally clipping all over the place. The loudness wars has ruined most metal through remasters.

72deluxe12y ago

Ah yes, the death of dynamics in music! One horrendous offender that I own is Paul McCartney's Memory Almost Full. I think he remastered it and rereleased it but there isn't a chance that I'm spending my money on it again! I think the mastering engineer discovered the joys of gain and hard knee in compressors.

KaiserPro12y ago

Its well known if you are over pumping your speakers.

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"

coldtea12y ago

>but VLC should be amplifying the output using level-limiting (hard-limiting), which would effectively bring all the quiet parts to be just as loud as the loud parts, instead of just digitally clipping the output.

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.

astral303OP12y ago

So would compression. The implication is that after you hard limit, you also increase the overall volume, such that the limit threshold of -Xdb is now 0db. Otherwise, there is no point to hard limit.

guard-of-terra12y ago

I actually never seen VLC clip sound that much on volumes > 100%.

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.

j / k navigate · click thread line to collapse

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fnordfnordfnord12y ago

>A square wave has twice the power of a sine wave of identical amplitude.

1.41 x

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

gamache12y ago

lutusp12y ago

Actually, if we look at two half-cycle waveforms, one sine and one square, like this:

http://i.imgur.com/oE5NFZ9.png

(Just the left 1/2 of the graph for this example)

The integral of the sine waveform with a peak value of 1, on the interval 0 x < pi, is :

http://www.wolframalpha.com/input/?i=integrate%28sin%28x%29%...

= 2

The integral of the square wave on the same interval is = pi

So the ratio increase in average voltage at the speaker (comparing the sine to the square) is pi/2 = 1.57. The increase in speaker power is (pi/2)^2 = 2.46.

dpe8212y ago

It also assumes a speaker's reactance is purely resistive. It's not.

fnordfnordfnord12y ago

Derp, thanks to both for the correction.

lutusp12y ago

>> A square wave has twice the power of a sine wave of identical amplitude.

> 1.41 x

Yes, for a voltage of x, but remember that the speaker is a resistance, for which the power varies as x^2/r (Ohm's law: p = e^2/r), So the original claim is correct.

malandrew12y ago

Most metal released these days is digitally clipped. Even classic old 80s "remastered" records are digitally clipping all over the place. The loudness wars has ruined most metal through remasters.

72deluxe12y ago

KaiserPro12y ago

Its well known if you are over pumping your speakers.

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"

coldtea12y ago

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.

astral303OP12y ago

So would compression. The implication is that after you hard limit, you also increase the overall volume, such that the limit threshold of -Xdb is now 0db. Otherwise, there is no point to hard limit.

guard-of-terra12y ago

I actually never seen VLC clip sound that much on volumes > 100%.

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.

j / k navigate · click thread line to collapse