Does a clipping amp damage speakers?

you could look at it like this - say you had a 100w rms speaker and run it with a 100w amp unclipped. then suppose you run the amp so hard into clip that it produced, say 200w of distorted power. let's say that the driver worked for a few mins and then burned the voice coil out. this happens because 200w of thermal power dissipated in the coil was enough to take out the driver. if you took a 2nd amp, say capable of 500w and run this at exactly 200w, if 200w is the power at which the voice coil has reached its limit of temp, then similarly this would burn up at 200w too. the 2nd amp was not clipping but it still killed the driver. so it is power overload that kills speakers, whether the high power came from a clipped amp or not.

cyte wrote: [QUOTE=Conanski] Play a low frequency square wave through a driver with no crossover/filter and the driver will stop moving during the peaks and troughs.

Like what 1 or 2hz? What has that got to do with audio? At any audible frequency the amount of time a driver spends "stationary" with a square wave input signal is inconsequential and even if this does happen it's not going to significantly factor into the stress levels experienced by the driver, no damage will result if the signal is within the power handling capacity of the driver.

Hmmmm! Plenty of assumptions that an Audio program signal is entirely symmetrical.

Unfortunately this isn't the case. Now lets consider the signal with say an asymmetry with more positive half cycle duration than negative.

The current output of the Amplifier moves the coil forward (convention) in the magnet gap. Should this exceed the Xmax value of the 'Speaker being driven then the loss of magnetic field from the poles means a change in the impedance of the coil and a reduced cooling effect. Thus exceeding the 'Speaker's rating and will overheat the coil. In more extreme cases, exceeding Xmech, this will damage the mechanical structure of the 'Speaker.

So when you overdrive your 'Speaker, the Current - this is the component of the Power being applied which actually moves the coil - behaves something like this in this 'Scope pic:

The sinewave signal is the Amplifier Voltage output and the clipped waveform in the center is the Current.

Now should anyone then apply a clipped source signal to this same situation, especially one which is asymmetric, then you can easily see the effect which the current will have on the coil of the 'Speaker.
At the point of destruction when the Amplifier Output was increased in the test result above, the current increased dramatically but unfortunately not for long enough to take a pic of the results before the 'Speaker coil failed completely.
Please note: no I'm not going to deliberately wreck any more 'Speakers to get more results unless that is if someone else wants to provide them FOC for destruction!

So, in answer to the Thread Title: "Does a clipping amp damage speakers?" then yes it certainly can, as does over-driving with an un-clipped signal above their rating in either case.

And to comment on the content of earlier posts in this thread relating to Harmonics, it is the RMS Current applied directly to the coil which is the issue!

Mik

Edit: correction of parameters

Edited by audiomik - 14 May 2012 at 1:57am

Lot of differing 'facts' here! Problem is, who is correct? Is this Bill F experienced enough to provide this statement, or do the people opposing this  out-qualify him?

Edited by GEB - 14 May 2012 at 10:11am

Seems the correct information from what I can gather from those who are not talking out their bottoms is that clipping does not cause damage to speakers, but a clipping amp 'may' deliver too much power into the speaker and cause it to fail, in which case it would happen on a more powerful amp regardless. If it were true guitar speakers would fail left, right and centre. There is not DC present in a clipped signal, people are confusing themselves because of the square tops of the signal, were as DC wouldn't be made up of + & - element components in the first place. And the coil doesn't stand still and effect cooling as no sound would come out of the speaker in the first place if it was still!

Edited by GEB - 14 May 2012 at 10:43am

Conanski wrote: infrasound wrote: Yes, it is DC.  No it's not DC, even with a perfect square wave the signal still flips back and forth between the positive and negative portions of the signal at the same rate(frequency) it would if the source was a perfect sine wave so this is still alternating current. A DC signal into a speaker produces no sound but you can definitely hear a square wave so the speaker is still moving.