What makes a High Efficiency Speaker

Speaker efficiency or sensitivity refers to ability to produce a certain sound pressure level with a certain input signal at a certain distance, typically measured in #dB/1watt signal/1 meter distance. A high eff speaker would typically be considered 90 dB or above, but that is a subjective interpretation. In other words, with a 1 watt input signal, that speaker would produce 90dB measured at 1 meter distance from the driver.

Others will probably chime in on the difference between efficiency and sensitivity (there is one, its pretty technical, and the terms are often used interchangably, even if not entirely accurately).

Duke- you have said it all. Thanks for taking the time to put it all together so clearly for all of us. That is one posts that should be put into an FAQ. Anyone from Audigon listening/monitoring?

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.

Very interesting. Great thread, one and all. Thank you for taking the time to provide all of this info. To this I would only add that having never heard the Zu speakers, if they sound good, then they are good, regardless of how they measure or how much hype or creative "accounting" their marketing department uses. And if they are only 97 dB thats still a pretty darn efficient loudspeaker and should be capable of being driven by small SET amps. To quote Duke "What Zu has done is build a speaker whose perceived bass extension is much better than I ever would have thought possible in that box size and efficiency combination." And that is quite an accomplishment, in my (technically ignorant, but interested) opinion.