Originally Posted by Nodscene
I don't want to get too far off topic as this thread is going in a different direction than what I am asking (although it was mentioned). I'll try to keep this short but from my limited experience ages ago and from a friend with a fair amount of knowledge (at least as far as I was concerned), I/we always found that speakers (almost exclusively the tweeters mind you) were mostly blown from underpowered amps rather than too much power. There more than a few occasions where an inexpensive amp (Yamaha and the like) would blow some speakers when cranked for a long period of time but would have zero issue with PA amps (Hafler exc). So we are talking about a Yamaha with 150 watts give or take vs a 500 watt Hafler or 800w PV and the only time a speaker would blow was with the former and this is with relatively the same speakers power handling ability of 100-200 watts or so. Of course I never blew anything myself as I actually listened for any distortion but was always able to get better volume out of the same set of speakers using more headroom from a higher powered amp. I'm not saying you can throw unlimited clean power into any speaker but within reason that was the result. As it's been mentioned that clipping an amp won't necessarily blow a speaker then I'm curious about my experience.
I have actually answered this question above.
It has to do with different types of Wattage deliveries: AC vs. DC; when an amplifier is in a clipped state, both delivery methods are present; but the speaker rating only depicts it's tolerance to one of them.
I will add a little more:
Let's, for the purpose of answering your question, assume that all Watts are the same, and that the only difference is the nature of the Watts development, from a 'current' delivery standpoint. Musical Watts, are intended to be derived from pure, alternating currents, not direct current; for what I believe should be obvious reasons, to most AVS readers.
Now musical waveforms are intrinsically dynamic, which is to say, varying in amplitude, which is commonly measured in Volts. These variances occur due to changes in the opposition to 'current' flow, which we have learned mathematically, to be based on frequency. This form of opposition is known as impedance (because it varies). If the resistance varies then so must the 'current' and therefore the Wattage, due to Wattage = 'current' x 'current' x a sampled resistance, within an AC signal (IxIxR).
: Musical AC Wattage is in a continual state of change, throughout each waveform, and related harmonics. To gain an idea of the typical range of AC Wattage output, we use a method known as root, mean and squared (RMS), to determine such (much more on the later on). This method requires that multiple samples be taken, at different degrees/Amplitudes, then that each sampled be squared, then summed, then divided by the number of different sample points, which provides the mean, then calculate the root of the mean, which concludes the final step in RMS Wattage estimation
: Non-musical DC Wattage is not in a continual state of change, it is essentially constant. The reason being, direct current is deliver via 0Hz, and therefore zero variance in resistances, regardless of time. There is no RMS value for DC, just M or mean. One can very easily add a series of samples, take the sum and divide it by the number of samples, and the result would be the average or mean of the Voltage.
Therefore, they're not electrically similar in the way in which they're produced, calculated or applied. A speakers RMS Wattage rating is based on AC, not DC input Wattage. DC power is constant, not ranging, it's applied at 100% - for 100% of the time. The presence of greater durations of direct current delivery (minimal, to no variance), more quickly brings a drivers voice coil to it's thermal limits, than the delivery of ranging alternating currents. In this regard, a Watt is Watt, and the speaker simply has a different tolerance predicated on how it's delivered: higher for pure AC, lower for mixed current, lowest for pure DC deliveries.
In your examples, the differences are most probably rooted in the presences / occurrences of 'current' that has been delivered in a more direct fashion, which is to say, some amplifiers were probably clipping more than others.
With regards to your tweeter comment: Tweeters simply have smaller gauge voice coils and less cooling potential than that of larger drivers, as such, it's common to see them come undone or 'cook' first, in systems that are being driven heavily into clip, or in systems with a severe, over powered, mismatch, between the amp and speaker system; typically by a factor of no less than 2:1. As a rule of thumb, one should minimally match the RMS Values of their speakers to the max power value of an amplifiers, when high output is the intended application, or much of the amplifiers rated power is likely to be demanded (more on this later as well).