How important is the efficiency of a speaker to you?

Again: efficiency is just ONE aspect out of many that has to be addressed in high performance loudspeaker design.  High performance drive units are so much more complicated than "how loud they are", with so many more aspects to them than efficiency alone.  Would you judge a car's track performance on miles per gallon?   

For an alternative dicussion about drivers from a man who is highly respected everywhere in the world for driver design, try this.  Billy explains much better than I:

.ATCWhitepaper.pdf (transaudiogroup.com)  .   

Brad

@atmasphere wrote:

... you’ll find, if you look, that most producers of higher efficiency speakers tend to use tube amps.

Being few of these designs are vintage, or so I suspect, it hardly reflects a strict need for a particular driver-amp type adherence. My guess is many like for horn-based designs to be "toned down" a bit (tubes generally would seem to do just that) so to likely please a former habitual exposition to less dynamically/transiently capable direct radiating and lower efficiency designs. As you no doubt know, listening to a high eff. compression driver/horn combo, not least large format iterations, is quite another animal compared to a dome tweeter and 4-6" coned midrange/woofer; the sheer energy and unforced presence the former is capable of (which is usually felt even at low to moderate SPL’s) can be an overwhelming experience to the "uninitiated," which isn’t to say it’s unnatural sounding - quite to the contrary, to my mind. I find a great horn-based system is simply relaxed, full sounding and dynamically uninhibited. Once you tap into these traits smaller and less efficient designs simply sound malnourished and restricted by comparison.

At any rate the kind of amp used has nothing to do with the phenomena of thermal compression.

Agreed.

My speakers were designed for amps of higher output impedance, but owing to level controls for the mids and highs (which are there even on vintage designs to allow the speaker to be adjusted to the Voltage response of the amplifier) they work fine with my class D amps.

This. My setup context is having the most elaborate "tone controls" at my disposal, i.e.: a digital crossover, which is configurable from the listening position on the fly. Even so - and knowing the sound of my amps over other, passive speakers - nothing indicates any compensation is needed to counterbalance a bright-ish character. What's more: my speakers, despite their design having a few years on its back, is more pro-sector (cinema) than vintage, and so are likely more compatible with SS amps. 

What are you trying say here? If we didn’t have ears, its unlikely that we would be playing around with audio equipment :)

(your reply to below quote)

"Offering technical insight it must also come to acknowledge that what is advocated here can as well be counteracted perceptively, if nothing else by the myriad intricacies of a context"

I merely implied that context is paramount, and moreover suggested that what you advocate design-wise could as well end up being refuted (i.e.: the ears being the most important and last "judge" of things), not necessarily to say some people wouldn’t like the sound of your amps, but that they may prefer a speaker-amp combo that goes contrary to what you recommend :)

@lonemountain wrote:

Again: efficiency is just ONE aspect out of many that has to be addressed in high performance loudspeaker design.

But who's claiming high efficiency is the only or single most important parameter worth pursuing to best achieve earlier named sonic attributes? From my chair it seems high efficiency is struggling to be recognized as a worthwhile factor at all; those of use trying to break through with the importance of high efficiency (which, it goes without saying, isn't implying that other parameters aren't important) are oftentimes met the default response that it simply isn't, which in some cases borders on being willfully ignorant, if you ask me. 

Moreover, the claim that high efficiency is necessarily and always bound to be attained "with a price," sonically speaking, is a fallacy. Typically it comes down to (the need for) large size and a different speaker principle (i.e.: horns), and these aren't deficits in themselves but merely what's required of a high efficiency design (what some may regard as a "scruffy" looking woofer for a front loaded horn sub or mid bass is actually the proper driver for the purpose with its lighter cone and all, and moreover the horn reduces or even eradicates mechanical noise and acts as a low pass filter). What rubs many the wrong way however is large size, and this is the real price to pay. 

@atmasphere wrote

... it may interest you to know that high efficiency drivers, in particular woofers can be 10x more expensive than drivers of similar bandwidth and power handling that are not efficient. As an example the TAD 1602s (15", 97dB, Fs 22Hz) are typically $4000.00 each. Put a field coil into the mix and the driver gets even more expensive.

You’re referring to a boutique element of high efficiency drivers that aren’t representative of this segment. Low eff. drivers have their expensive iterations as well, and when you count in the typically larger size of high eff. drivers, bigger voice coils and more magnet material, not least from the more widely accessible pro sector, their pricing compared to low eff. "hi-fi" dittos is actually very fair. Most of these very expensive high eff. drivers are vintage designs of limited production, btw., and it’s not that the production tolerances here are somehow magically "tighter" to reflect and account for the higher pricing.

Tidbit: just going by specs the EV woofers of my main speakers share the 97dB and 22Hz Fs TAD numbers of yours (Fs 21Hz, "broken in"), and I’m guessing they’d have retailed for about 1/10 of $4,000.

I suspect the $4,000 price claimed is not real- likely seen by atmasphere  somewhere on the resale market because the product is long discontinued.   That price is not representative of what it really sold for back when it was made or what current drivers sell for that replaced it from TAD.  I know the distributor in the US.

 TAD DOES make expensive drivers, they are Japanese (Pioneer) but are used mostly in their own speakers or OEM in horn loaded systems.  Very good drivers for sure.  TAD was a good low distortion driver used regularly by George Ausperger in his large all horn designs which were quite popular in recording studios years ago.  Today, TAD is still used by folks that build these all horn loaded systems that echo those Asperger designs.  I hate the way they sound- high distortion and just loud.  Lower fidelity by today's standards.  They are common for hip hop where SPL matters on client playback.  Mixing still done on lower distortion direct radiators (we sold TImbaland ATC 100s for this exact purpose).

Many studios still have these TAD or JBL loaded horn systems in the wall- they do look cool and are part of the studio "vibe".  They were always used for the band to hear playback at higher SPL in the best possible fidelity (which is very low compared to modern hi fi or studio speakers).  SPL = excitement.  The trend now in studios is direct radiators, such as ATC, that favor low distortion so you can mix faster, worry less about translation and hear more details.  

It is interesting that the TAD 1602 drivers had very little test data or info available.   It does say the 1602"S" was a special version of it with shorter voice coil for lower distortion.  You would have read about that same short coil idea in the white paper from Billy Woodman I posted.   All the ATC studio and hi fi drivers use short coil long gap topologies for reduced harmonic distortion.

This is precisely what I am saying that efficiency is but one part of the picture as today short coil, venting, narrow gaps with precise coil fitment, flat wire coils, the right former material, etc is way more important when amps are relatively cheap.  These types of drivers are impossible to build by machine.  Hand made drivers is the way to get it done and everyone in the industry used to build their own: KEF, B+W, JBL, on and on.  Now, hardly anyone does this anymore as it's way too expensive, difficult to train people and environmentally challenging.  A small company cannot afford to build their own.  ATC is the last of the breed in the UK.  Everyone else has left and gone to China.

Brad