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<blockquote data-quote="Immacomputer" data-source="post: 3294264" data-attributes="member: 570419">Whenever you have an input signal that is slightly distorted, you have harmonics of that signal&#039;s frequency. The ratio of the total harmonic signal strength compared to the original signal strength is your THD. Anything below ~5% and you won&#039;t be able to hear the difference unless you have really good ears. In amps, the difference between 1% and .01% is not as huge as it appears. Your speakers will usually distort the signal more than 10% anyways.Here are some pictures from a spectrum analyzer and o-scope that show you what I&#039;m talking about.First is the clean 50hz sine wave. This signal is undistorted.Scope shot (amplitude vs time graph):<img src="http://i15.tinypic.com/46y6kah.png" alt="" class="fr-fic fr-dii fr-draggable " style="" />Spectrum shot (this shows the power vs frequency graph):<img src="http://i13.tinypic.com/4tfuxdv.png" alt="" class="fr-fic fr-dii fr-draggable " style="" />Now here is the clipped 50hz sine wave and its spectrum graph:<img src="http://i17.tinypic.com/4d1oaow.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /><img src="http://i9.tinypic.com/4p1udmq.png" alt="" class="fr-fic fr-dii fr-draggable " style="" />All those extra bars in the spectrum represent power from the harmonics. It&#039;s the ratio of the summation of the power from these signals compared to the power of the original signal that gives you the total harmonic distortion. This graph also shows why clipping a signal introduces more power than it&#039;s clean counterpart. That extra power is what can blow the speaker, not the waveform.</blockquote>

[QUOTE="Immacomputer, post: 3294264, member: 570419"] Whenever you have an input signal that is slightly distorted, you have harmonics of that signal's frequency. The ratio of the total harmonic signal strength compared to the original signal strength is your THD. Anything below ~5% and you won't be able to hear the difference unless you have really good ears. In amps, the difference between 1% and .01% is not as huge as it appears. Your speakers will usually distort the signal more than 10% anyways. Here are some pictures from a spectrum analyzer and o-scope that show you what I'm talking about. First is the clean 50hz sine wave. This signal is undistorted. Scope shot (amplitude vs time graph): [IMG]http://i15.tinypic.com/46y6kah.png[/IMG] Spectrum shot (this shows the power vs frequency graph): [IMG]http://i13.tinypic.com/4tfuxdv.png[/IMG] Now here is the clipped 50hz sine wave and its spectrum graph: [IMG]http://i17.tinypic.com/4d1oaow.png[/IMG] [IMG]http://i9.tinypic.com/4p1udmq.png[/IMG] All those extra bars in the spectrum represent power from the harmonics. It's the ratio of the summation of the power from these signals compared to the power of the original signal that gives you the total harmonic distortion. This graph also shows why clipping a signal introduces more power than it's clean counterpart. That extra power is what can blow the speaker, not the waveform. [/QUOTE]

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