Driver efficiency vs. overall speaker efficiency

Satch...Efficiency is stated as dB per VOLT (not current). Of course the current will be more with a 4 ohm load, but that's the power amp's problem.

Satch:

I'm not an expert,so allow me to quote my source:

http://www.northcreekmusic.com

If you link through to the page that describes their rhythm speaker,in the fine print,it talks about an mtm set-up and its effects.(It's the paragraph labeled "Sensitivity and Impedance".)

No free lunch.

High-efficiency speakers-

Are they just going to give more sound-per watt, or will they also communiate more texture (micro-dynamics?) of the sound, along with the extra dB?

Here we go again. One thing we modern folk oft do is to use the WRONG terminology. 'Efficiency' is different than 'sensitivity'. Speaker-system efficiency normally is measured 1 meter from the speaker/driver when driven with exactly 1 watt of power measured into the speaker's rated impedance. IOW, a '4-ohm' speaker system's output is measured while being driven by TWO volts into 4 ohms (which equals ONE WATT). Decades ago, with the increasing popularity of solidstate amps*, the audio industry started publishing sensitivity ratings, and not all of them do it correctly.

Sensitivity is measured with a signal created by driving an 8-Ohm load resistor with 2.83 volts. That does happen to be 1 watt into 8 ohms, but it's not 1 watt into 6 or 4 or 3 or 2 ohms. The correct way to state this is 'sensitivity at 1M using 2.83v. into 8 Ohms' or something like that. And BTW, it's not PER meter, it's at 1 meter.

*--Solidstate amplifiers are constant-voltage devices and not constant-current devices are as most tubed amps. That is, because a SS amp's output impedance is so low, it will maintain its output voltage into decreasing loads until it reaches its maximum current output. A tubed amp generally will NOT increase its current output much as the load impedance decreases.
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