I think many of the values discussed here and elsewhere assigned to high efficiency speakers are not accurate. First the entire discussion of what is delivering the improved efficiency is not differentiated- is it drivers or how the driver is used that gets you better efficiency? These two ideas.make a huge difference in performance but are distinctly different methods of achieving improved efficiency with their own costs, benefits and penalties..
Example 1: a lower efficient driver can be made more efficient by placing it on a horn, which complete changes other characteristics/parameters of performance and behavior. An acoustic suspension system or a horn system are very different from each other in many ways having a direct impact on performance.
Example 2: You can build a more efficient driver by lowering the mass of its moving parts. Lowering this mass can cause multiple things to happen, typically increasing ring modes and distortion. Here efficency makes the driver sound worse. Another outcome of lowered mass is poorer low frequency performance.
Example 3 Higher efficiency drivers do not always offer lower power compression. If you use titanium instead of aluminum for your former, the thermal resistance is far higher with titanum than aluminum, so heat can’t escape the lower mass system increasing thermal power compression. Higher efficiency increases thermal power compression in this case. DO you know what your VC former material in the speaker system you buy actually is? Thermal power compression is affected by a long list of factors that are far too detailed and complex to discuss here or ina spec sheet: issues such as VC impendance, VC material, front plate/pole piece proximity to coil, airflow and venting of the magnet system. Looking at a efficiency measurement and assessing quality is like looking at frequency response and assessing sound quality- it really isn’t an indicator of performance in a way that is simple or easy to [universally] understand.
I know poeple really want there to be a simple way of looking at things but this is some deep science. A speaker involves practicaly all the sciences and there is no way to simplfiy it and express that in a spec- unless you are willing to bullshit or tell a helluva convincing marketing story. Most do exactly that, but its a diservice to the thinking person’s aims in a playback system.
If you love the idea of a flea watt amp, you are sorta stuck with high efficiency loudspeakers to have any hope of dynamic range. If you are more open minded and are wiling to look at moderate efficiency speakers in the mid 80s, using the wide array of excellent high power amplifiers available, or active speaker configurations, you can have your low distortion, wide dynamic range AND better bass AND wider dispersion, etc, etc. But you cannot have all that AND super high efficiency.
I think we are back to listening to a speaker with a proposed amplifer and assessing if this combination works for you and addresses the things you care about.
Brad
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