What makes for high sensativity drivers?

I'm getting a pair of old ceramic Altec 416s reconed with GPA kits at a local JBL authorized dealer and the owner tore off the bad cones and copper coils to inspect the baskets before proceeding...

Anyway, after inspecting the burnt coils and cones of the old Altecs I got to thinking about how I enjoy drivers with high effeciency (sensativity) ratings.

What designs make for high effeciency?

1. Small VC gaps?
2. Strong motors?
3. few windings of the VC?
4. Flat wire coils?
5. Light weight cone?
6. High compliance spiders and surrounds?

Thx....

A lot like asking what is necessary for good health. Only maybe a hundred or more nutrients, exercise, and a zillion more.

A speaker is a system, and changing many parameters influences sensitivity. Also, sensitivity across what band?

If you change one part of a design the others are affected. You always seem to want black and white answers in a 64 million color world...