What is the benefit of low efficiency speakers?

I think Xiekitchen is finally beginning to touch on the substance of the issue.

I believe that the vast majority of speaker designers don't WANT their speakers to have low sensitivity, they choose the drivers for OTHER characteristics. Remember when 'air-suspension' speakers were introduced (in the '50s? by Acoustic Research?)? The goal was good bass response from small enclosures. One way they did that was too decrease the stiffness of the cone's double suspension so that cone travel could increase. Increased travel required more space between the voicecoil and the magnet structure. Increasing the gap reduced sensitivity. So for better bass from a smaller box, we get lower sensitivity. The other drivers (MR, tweeter) have to be of approximately the same sensitivity, so now we have speakers with typical sensitivities of less than 90dB/2.83v./1M instead of 95 - 105dB sensitivity.

BTW, there's a difference between the terms sensitivity and efficiency, but for this discussion, the terms are interchangeable.

Upper, the easy answer to your revised question is that there's no easy answer and there are LOTS of variables.

1. Designs that use multiple identical drivers (such as the Epiphanys) wire them in parallel or a combination of series and parallel to get a high-enough impedance so that the system is driveable. I BELIEVE* the best sounding method of wiring is parallel, but that produces the lowest impedance, and that result may be too low to drive. My Kindel PLS-As, designed in the mid-'80s, have 16 1"-dome tweeters of 16 ohms impedance wired in parallel. Including a resistive network, the PLS-A's impedance dips to about 2 ohms in the trebles.

2. A designer's favorite driver may be available in a 'wrong' impedance. Eg, a designer may want to use woofer A and tweeter C, each of which has a nominal impedance of 8 ohms, but the MR driver he/she wants to use happens to be a 4-ohm unit. If it's sensitive enough, a series resistor could be added, but if it's not, I don't know what the designer could do...beside pick a different driver

Some of us surely have lots more knowledge of this, and maybe lots of us will learn something from your questions.

* If someone KNOWS different, pls correct me.
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