Clipping, Power and Voice Coil Damage
 

There are basically two ways to damage a speaker:

1. Exceeding mechanical limits.
2. Exceeding average max power delivery to the voicecoil.

Clipping, that is maxing out an amps voltage ouput, can not in itself damage a speaker. Unless of course it exceeds rule 2, but that obviously breaks the rules regardless of the shape of the waveform.

Prove me wrong.

If you want to get really technical, hitting a speaker with a sledgehammer will count as pushing it past its' mechanical limits, so I think you have this argument in the bag. ;)

screwdrivers and surrounds are my hell

I wonder why we used to get so many blown 100w tweeters when guys used 30w/ch. amps?

Could someone delve into this a little more for those like me? The semi-newbs...
In normal (or abnormal) operation, what would create the situation wherein the mechanical limitations of a speaker are surpassed, and the average max power delivery to the voicecoil(s) is (are) exceeded?

I guess it would be cool if what Kev said, could be dumbed down a little. If I understand the concept, I'll be better equipped to add some thought to the post...

the argument for the square waveforms blowing speakers has to do with the fact that the speaker builds up heat in the voice coil. the square waveform doesn't allow the speaker to cool itself as it normally should.

I could be wrong here, cuz I haven't done anything with electronics for a while. But, as far as I know, the coil in a speaker, is essentially the same as any coil you could find in an electrical circuit (electronically speaking). And, as long as you get a sinewave going throught it, it acts a bit like a resistance, with is resistive value fluctuating with the frequency of the applied AC voltage. Now, if it were DC voltage, with a resistance and a coil, the circuit would then get a certain "charge" time where the current is slightly ahead of time on the voltage (or the other way around). But, after a given amount of time, with plain DC, both catch up to one another and you get max voltage and max current at the same time. Now, with a sine wave, both are always fluctuating, but throw in a square wave, and the one out of phase has time to catch up and reach a higher point in power, and therefor, the coil become hotter even if the voltage itself is not necessarily higher.

Now, those with superior knowledge and or better memories, please, correct my statement as I'm sure there are a few things wrong here.

Simple, they were not 100w tweeters. I know there is a sticker on the back that says so, but this is a recommended maximum amplifier power. It takes into account the fact that a music program will be used. If you actually drove 100 watts into it there would be smoke in short order.

Consider this, a tweeter does not move enough to take advantage of voice coil cooling through air flow. So for argument sake the input could be DC current and it wouldn't make a difference as long as the average power was the same (for comparison). How much DC current could said tweeter handle? Not very much.

Moving on to a clipped signal. When a sine wave is clipped, higher frequency harmonics appear in the signal that were not in the recorded program. So the power in the upper frequencies goes up. Remembering the fragile nature of a tweeter, it is unlikely to survive long. Rule number two broken again and the shape of the waveform was only a symptom, not the cause. Otherwise severely distorted guitar recordings would kill a lot of tweeters, even at low volume.

I've been down the slipped screw driver road and only use robertson now:)

OK,OK I concede I may have been a bit narrow minded lol.

What I'm proposing is that a clipped music signal does not damage speakers. That only exceeding it's power limit or mechanical excursion limit can damage it under normal usage. Normal means barring sledge hammers and screw drivers. ;)
Clipped refers to that crunching sound that happens when you push your system too far. It's a type of distortion that occurs when the output voltage can't go high enough to track the input signal (due to power supply limitations). When viewing the signal as a plot of voltage vs time it appears that the tops of the sine waves are cut off, or "clipped". This effect gives electric guitar its characteristic sound. As long as the power level is within reason a distorted guitar recording will not damage any speaker.

Shamelessly stolen photo: