Driver efficiency vs. overall speaker efficiency

Okay, so "efficiency" deals ONLY with how much volume a speaker can put out? And has nothing to do with the quality of sound reproduced?

I'm learning here... ;-)

When it comes to speakers, "efficiency" is the % of electrical energy that the transducer converts into sound pressure -- the rest being converted into heat, etc...i.e., lost to our ears.

Sometimes this word is used by manufacturers to underline how loud their speakers/drivers can go when fed with a reasonable amount of W (i.e. energy). It sounds "marketing" to me...

Plus you have other manufacturers sporting interesting performance levels, to quote Trelja

who use drivers of 88 db/2.83 V sensitivity and then claim the speakers are 94 db/2.83 V sensitive

...
Would that be 94db @1M, both speakers fed a 1kHz sine wave, the mic on axis, 2ms gate / or is it that they have two drivers in parallel for each pass band / or?

You are correct about the definition of efficiency, Gregm. The term we are actually discussing in this thread is sensitivity, but I didn't want to interject it until you so wisely brought up what efficiency actually is.

My perspective is that the box should add maybe a couple dB to the sensitivity of a driver. And, that is the best you can do, using a driver such as a Lowther. When you begin adding crossover components, the senstitivity goes down, and the impedance curve begins to dance around, both of which make the speaker more difficult to drive. Think of crossover components as speed bumps for your amplifier.

Trelja...What if the "box" includes a passive radiator? Of course the PR draws its power from the driver, but I think it does the electrical-to-acoustic conversion more efficiently (because cone excurion is less) than if the audio all came from the driver cone.

I am talking about SPL. Audio quality is another matter.