Is the most efficient speaker the best speaker?

Timlub,

The 84 to 90 dB drivers would NOT be pro drivers. More typical of brands like Scanspeak, Morel, etc. Mentioned "pro" to illustrate higher sensitivity drivers in a separately listed category.

You're right about the gain for 4 ohm. Wasn't being specific.

Been looking at drivers lately.

Let's say we want 30-40 Hz capable woofer. Generalizations. Argue about speaker specs, excursion, quality and range in another thread. If you don't believe me, look at the pro drivers at Parts Express.

At 84 dB W/m, that will probably require a 6.5 to 8 inch driver in a 1 to 1.5 cu ft box. Double up the drivers (half the impedance) and the box size and you get another 6 dB.

At 90 dB W/m, that would be a 10 to 12" in a 3 cu ft box.

At 96 dB W/m, that's 15 or 18" in a 6 cu ft box.

Okay, active subs have made the bass aspect less critical but then, you have to balance control and different kinds of distortion and there's compromises either way.