What is your take on high efficient speakers vs. low efficient speakers?

The best performance comes from electrostatic speakers. They are generally mid efficiency speakers but are very amps sensitive and owner sensitive. Otherwise it is 6 of one 1/2 dozen of the other. The best performance I have heard come out of dynamic loudspeakers came from inefficient speakers driven by huge amplifiers. 

All good comments up to now. I'd only add electrical impedance is critical measure of truly efficient speakers.

As owner and modifier of Klipschorns I have had choice to continue with shallow slope crossovers or go to steep slope. Klipschorns nominal impedance with stock shallow slope crossover rated as 8 ohm, with 104db sensitivity,  it would seem to be easy to drive speaker. In reality there are drops down to 3 and 2.7 ohms with steep phase angles, requires fair amount of current. Taking this into account impacted my choice of amps, 45 and 2a3 SET were considered but eliminated due to these severe phase angles which really require amp capable of delivering some current at 4ohms. I settled on custom built 300B monoblocks which have pretty massive power supplies (each have PS equivalent to what one would normally see in stereo 300B). While I may yet try a 2a3, would have to have pretty special power supplies to cope with these phase angles.

So, for me a truly high efficient speaker is one that 45 or 2a3 flea watt amp can drive comfortably, this would be 100+db sensitivity with benign electrical impedance curve. Klipschorn or other 100+ sensitivity with less benign impedance curve something slightly less than truly high efficient.

I think the thing that matters in the end is what sounds best to the listener & how the speaker sounds in the room with the paired electronics. No matter what the opinion is,  the end result is a dice roll.

@mijostyn that is interesting…it’s the polar opposite of my experience 

@larryi wrote:

Thank you for an excellent description of what is most prized about the sound of high efficiency systems, particularly, horn-based systems.

Glad you found it worthwhile.

While good design of such systems will ameliorate midrange "peaky" or "nasal" colorations, such systems do tend to be a bit less smooth in frequency response than better low-efficiency direct radiating speakers. I hesitate to say this because so many people have heard grossly uneven horn and wide range high efficiency driver systems, and do associate such systems with such coloration, but I will say that such problems can be effectively ameliorated in better designs. Still, I can see why such systems will not be to everyone’s taste.

Smoothness, or lack thereof in frequency response can definitely be a factor, I agree. Great horns don’t really sound like horns (if there even is a decided consensus about what horns in general sound like, and with the implicit notion here perhaps that "horn sound" has a more or less distinct character), and the bigger they are even less so, I find. Yet, large and great horns definitely don’t sound like smaller, low efficiency direct speakers either, but are in some respects more reminiscent of very large panel speakers. Indeed I would go so far to claim that some don’t like horn sound just by virtue of it sounding different compared to low. eff. direct radiating speakers, even if the former are devoid of uneven frequency response or colorations in general.

@audiokinesis wrote:

Very often the limiting factor for high-efficiency systems is the on-axis frequency response at high frequencies. And one way to get very high efficiency numbers is to use a horn whose pattern at high frequencies is very narrow, such that all of the high frequency energy is concentrated in a narrow beam, thereby maximizing the on-axis sound pressure. If the same compression driver were used on a wide-pattern horn, the same amount of acoustic energy would come out, but because it’s spread over a wider angle the on-axis PRESSURE would be less.

The EV Constant Directivity horns (HP9040 + DH1A) on my EV main speakers, by virtue of not narrowing the HF response on-axis, should require equalization in its upper band above some 3kHz, at least for their intended cinema use, but surprisingly we’ve only found it necessary and most important to apply some notches and a peak suppression via a Xilica DSP (active config.). This ameliorated a slightly can-ey and mechanical imprinting for a very smooth upper band reproduction. The lack of a need for an EQ gain-boost in the upper octaves I’m guessing may have to do with the limited spacings they’re now used in vs. large auditoriums, with the former providing some boundary gain. What’s your assessment here?

Some horns have coloration, which imo eliminates them from serious contention. At the risk of over-generalizing, I’d be wary of horns which have sharp-edged internal "kinks" and/or sharp edges around the mouth.

The EV horns of mine both have a diffraction slot and sharp edges at the mouth area, and so may set the alarms ringing in many a horn-audiophiles’ head, but they actually sound very smooth after being properly implemented with mentioned DSP filter-actions above.

What’s less discussed or acknowledged even is the importance of horn size and its sonic implications. This is also a factor determined by the compression driver used here, with the very powerful DH1A being more properly loaded with the HP9040 horn compared to the smaller HP940 sibling (which I used previously). The DH1A simply seemed to "shoot through" the smaller HP940, but the sonic outcome also had to do with the horn resonance being placed higher in the upper mids on the HP940 vs. in the lower mids on the HP9040.

In any case a larger horn appears to fold-out the sound much more effectively for a more relaxed imprinting than a smaller horn, while also sounding more fully developed physically. Things being equal a smaller horn sports the more intensely "directed" sound (to many perceived as a horn-sound characteristic?), and the larger ditto has a much larger, even a huge and more relaxed sphere or bubble of sound.

I know horn geometry and diffraction eradication found in newer horns is very important sonically, but you come a long way with blunt, physical size in older more industrial (and still very well developed) designs, I find. Size is less sellable, though, and many don’t like the mere association with pro segment products.

Thanks for your great contributions, Duke.

@johnk --

Well put.