What makes a High Efficiency Speaker

Great discussion. But note that an eight ohm speaker that is 1% efficient in converting electical energy into mechanical energy will output a sound pressure level of 94db. Boy are we waisting a lot of energy!!!

Not really, Etby. If the speaker only needs 1 watt to output 94db, the you are 'wasting' 0.9 watts per hour! The parasitic losses on your microwave are about 5w/h.
And at 84db, the loss is 0.09w/h. Don't sweat it!

Great discussion on HIGH efficiency but WHAT MAKES A SPEAKER Efficient? PARTS PARTS PARTS!! Excellent Design, low weight material for cone and suspension, Excellent magnets, proper wiring and design. Oh and Size of the speaker makes a difference also, generally larger drivers are more expensive as the weight requires better design and parts to keep efficiency. Everything has exceptions however.

Horns have become very popular as a high efficiency design but any design can have a high efficiency rating, however the more speakers you have in a design the more energy that is wasted from crossovers and additional components, this one of the reasons why single driver systems have continued in popularity.

Lot's of talk about dB/watt vs dB/volt, but let's not forget that this spec is measured at a particular distance, one meter I think. SPL decreases with distance from the source, and different speakers distribute their sound differently. In particular, sound from a planar or line source speaker system falls off much less than sound from a point source. For example, with my Maggies, I can walk from the far end of my room right up to put my ear to the speaker and hear almost no change in SPL. Maybe I'll do that with my RS meter and post numeric results. Someone else can do a PS speaker. Bottom line is that for two speakers with the same sensitivity or efficiency spec, one planar and one point source, from a normal listening distance the planar will sound louder.

Eldartford- Is that because of the much larger radiating area? If so, then the low efficiency/sensitivity specs for planars may be deceptive. Not that that would necessarily change their appetite for lots of current, but amp matching might be a little easier than some of us have suppossed.