Watts up with that?

By definition a resistor consumes the entire load placed across it.

Yes. And it converts it into heat.

Speakers don't so they aren't resistive loads...not anywhere near.

Speakers do consume most of the power that goes into them, they just don't convert most of that power into sound. The power that is not converted into sound is mostly dissipated as heat.

The faulty logic of your statement is addressed further in the final paragraph of this post. First, though, see the plot I previously linked to, of the impedance phase angle vs. frequency for a particular speaker. See any plot of impedance phase angle vs. frequency for any other speaker. While most speakers will not have phase angles that are as close to being resistive as the one I linked to, as I previously stated, "it is rare for a speaker to have phase angles that exceed or even approach 45 degrees across broad parts of the spectrum (although that can occur across narrow ranges of frequencies). Meaning that their impedance is mostly resistive."

You have HUGE winds of wire in a magnet and you think that that is mostly resistive when it is driven?

In the example I linked to, the inductance of the tweeter voice coil is undoubtedly the reason for the rise in impedance phase angle in the upper treble region. As frequency decreases, a given amount of inductance becomes progressively less significant. The crossover network further complicates matters. The bottom line, for a given speaker, is the measured impedance phase angle. How can you claim that the impedance is essentially inductive or capacitive, when the measurements indicate otherwise?

How can an almost pure resistive load be 5%, or even 10% efficient? THAT does not make sense. By definition a resistor consumes the entire load placed across it. Speakers don't so they aren't resistive loads...not anywhere near. Where did the other 90% to 95% go?

I suspect that you'll agree with me that the impedance of an incandescent light bulb is essentially resistive, at least at 60 Hz and other low frequencies. And I suspect that you'll agree that the great majority of the power supplied to it is NOT converted into light, and its efficiency is therefore very low (roughly 10% or so per this Wikipedia writeup). Where do you think the rest of the power supplied to it goes? Ever touched a 100W light bulb that has been on for a few minutes or more?

Regards,
-- Al

Here are the "real" OSHA numbers for continuous noise, not random, like music, exposure. 85 dB levels with music is far from continuous and is more than fine. My "ear" says the Fletcher Munstrom (spelling) flattens out at about 80dB, where the low end seems linear. The human ear is lousy below about 80 dB for linearity of broad spectrum sounds. We hear around 1-4 KHz at 75 dB OK. That's as nature intended. True, you can "flatten" the sound by EQing to 75dB (remember loudness controls), just don't turn it up much with that EQ active!

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9735
TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
|
Duration per day, hours | Sound level dBA slow response
____________________________|_________________________________
|
8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115

And, Go here;
http://www.stereophile.com/content/dynaudio-confidence-c4-loudspeaker-measurements

Most of a speakers "power" is dissipated at the lower frequencies below 200 Hz and more than 4/5th total isn't uncommon. Here, the graph of C4's clearly shows significant phase departures from "zero" that approach +30 to -50 degrees. It isn't near zero till about 200 Hz in this speaker. Since the majority of the load is mostly reactive below 200 Hz this is a terrible "resistive" load per your conclusion. It is NOT a resistive filament. No where near. It does produce a very reactive signature to the majority of the signal power being applied. This is what your amplifier is fighting against. The numbers at the frequency of the power dissipation peaks show that this isn't as bright of an idea as lighting a light bulb.

As far as the jackhammer example, It's amazing that a device that is intended to crush rocks loses just 1 watt to sound. Sound SPL at a given volume has a measurable power in air that is always the same no matter what produces it. 1KHz at 100 dB SPL is ALWAYS the same power level in-air. It doesn't know who it's mommy is. The energy "used" to launch it varies tremendously in wasted effort, true. The SPL of a jackhammer's frequency range is pretty low and at a pretty high 120 dB SPL so it is amazing that it has a 1 watt sound launch energy value. And the actual "sound" efficiency would be the power going in to make the SPL level coming out (here we'd ignore the jackhammers real job and look at it as a noise maker) right?. How much power is going into a jackhammer relative to the lost energy due to the "sound" escaping from the intended process? Most of the energy is going into the rocks, so it's a pretty lousy speaker for making 120 dB of noise...as it should be.

Since the majority of the load is mostly reactive below 200 Hz this is a terrible "resistive" load per your conclusion. It is NOT a resistive filament. No where near. It does produce a very reactive signature to the majority of the signal power being applied.

Rower, the point of contention was whether the 90 or 95% inefficiency of a speaker is mostly the result of power dissipated in the speaker as heat, or is mostly the result of reactive impedance characteristics.

In the severe example you provided, the impedance phase angle only exceeds 45 degrees by a very small amount in a very narrow range of frequencies, between approximately 60 and 70 Hz. Throughout most of the spectrum, including the bass region, its phase angle is much less than 45 degrees. While that kind of impedance characteristic could perhaps be legitimately referred to as "very reactive" in a relative sense, relative to many other speakers, it is not by any means "mostly reactive below 200 Hz." An impedance is not "mostly reactive" unless the phase angle exceeds 45 degrees. And there is no way that the depicted impedance phase angle characteristic, or just about any other reasonably conceivable impedance phase angle characteristic, would account for the major portion of a 90 to 95% inefficiency.

Yes, I certainly agree that the speaker will be a difficult load for many amplifiers to drive, with good sonic results. But that wasn't the issue.

Regards,
-- Al

Al,

I'd like to see the weighted impact of energy distribution across the spectrum to conclude it's a "small" effect. I'm not saying you're wrong, but the laws of physics say the WEIGHTED effects in the frequency range of highest energy can be pretty severe. The lower in frequency you go, the more of the total power that is distributed, and hence, the reactance will really bug an amplifier.

True, the phase angle has to be greater than +/- 45 degrees to me mostly reactive.

True too, where a speaker is mostly resistive the power is tossed as heat. It just seesm to me that 75% of the power is applied across the lower ~200 Hz, where the speaker is most unsettled in impedance. So it isn't necessarilly the "range" of the frequency but the percentage of power supplied AT that frequency. Still, this could be much less than the minds eye thinks looking at the graphs. Stuff can get away from you when we make assumptions (we all know about assumptions).