Good speakers less efficient?

Thank you all for your responses. I now have a better high level understanding of the design issues and tradoffs.

My experience has been that high efficiency speakers are more likely to compress than low efficiency speakers...even at modest SPL levels. A low efficiency speaker often remains more balanced at various SPL levels whereas a high efficiency design often sounds balanced only within a much narrower SPL range.

I don't know why this is....but it is certainly my general observation...perhaps Duke can explain? (I am referring to regular box speakers here)

dipolar radiators have efficiencies in the 85 to 88db range.

i happen to prefer this type of speaker. depending upon the room and the impedance curve, they can pose a challenge fot a tube amplifier.

if one prefers this design to other designs... well, draw your own conclusion.

Sharorne,

My experience with tonal balance shifting as the volume level changes has generally been the opposite of yours, though I don't doubt your observation. My experience with high efficiency speakers has mostly been with horn systems (though usually with a direct-radiator prosound-type woofer).

I have generally attributed tonal balance shift to differing power compression characteristics of the different drivers. Relatively few drivers give a full 3 dB increase in loudness for a doubling of input power - usually it's more like 2.6-2.8 dB. If the woofer compresses more than the tweeter, then the tonal balance will shift towards the tweeter's end of the spectrum at high volume levels. If the tweeter compresses more, then the tonal balance will shift towards the woofer's end of the spectrum at high volume levels.

I recall a couple of years ago listening to a very well known and generally well respected three-way, which sounded recessed and distant at low volume levels, well balanced at medium to borderline high volume levels, and decidedly forward at high volume levels. I think that the midrange (which was an especially high-tech unit) had less power compression than the woofer and tweeter, so the speaker had been "voiced" to sound balanced in the medium to borderline-high volume range. At higher volume levels the midrange left the woofer and tweeter in the dust, and at lower volume levels it withdrew into the background (okay I'm exaggerating a bit with my imagery here, but to my ears that was the trend).

Getting back to your observation, this is just speculation on my part but it's possible that very high efficiency conventional tweeters use ultrathin voice coil wire that heats up quite easily and rapidly, so that in practice such tweeters have more thermal compression than their medium efficiency cousins.

There can be other mechanisms at play, such as the ear's level-dependent perception of certain types of distortion, that may be dominant in some situations. This would tend to shift the perceived tonal balance upward as the volume level increased.

I don't think I've given an satisfactory answer (at least I'm not satisfied with it). I think there's quite a bit more to be known on the subject than what I now know.

Duke

That's a good point Bartok.

Most mid-range to large models from manufacturers such as Merlin, Altec, Klipsch, Zu, Avantgarde, Cain and Cain, Silverline, Acoustic Zen, Gallo, Wharfdale, Coincident, Tannoy, Fostex, Oris, Duevel, Green Mountain Audio, Maxxhorn, Devore, etc. really do suck most amps dry.

Thanks.