Re: PK Sound
Efficiency "Eff" on the JBL T.S.specs is nominal reference efficiency in %, (half space acoustic load).
I think "Eff" is the ratio of acoustic watts to electrical watts, somewhere in the middle or average of of the speaker's response curve.
A speaker like the old D131 is super "efficient" at 8.4%, but largely at upper frequencies where it beams like a flashlight.
The lower in frequency the woofer goes, the less the nominal efficiency.
EV used to use nominal efficiency and what is now generally referred to as sensitivity (1 watt at one meter), the EVX-150A was rated at 4.32% and an average of 98 dB 100-800 Hz.
Obviously, either of those figures would be much lower if the rating was averaged from 30-100 Hz.
As always, comparing efficiency or sensitivity without seeing a frequency response and deciding the range of use to be averaged tells very little.
