How important is the efficiency of a speaker to you?

@rauliruegas While the speakers in my OP were indeed not the same as the ones in my example with the Parasounds, the speakers in the OP were in the same category ( and actually the same maker) as the ones in my example. I suspect that the Parasounds ( like most amps, and as Atmasphere pointed out above) would not be working at their best with such a load.

@daveyf  : As many others including what posted that gentleman ceratinly did not read yet te JC 1+ review that between other things states:

" 

The JC 1+'s shielded input- and driver-stage circuit boards use an FR408 substrate, a substance that was developed for ultra-high-speed applications in supercomputers and aerospace.

• As in the JC 1, the JC 1+ input stage uses hand-matched pairs (footnote 2) of Toshiba 2SJ74 P-channel and 2SK170 N-channel J-FETs. Parasound and, I believe, Ayre Acoustics have invested heavily to secure an ample stock of these no-longer-manufactured, low-noise J-FETs. While the JC 1 driver was a single-stage circuit, for the JC 1+, John Curl designed a two-stage, cascode driver that would have some of the favorable attributes of vacuum tubes.

• As the number of high-performance loudspeakers with impedances that drop below 2 ohms is on the increase, Curl increased the number of Sanken NPN and PNP bipolar output transistors from 18 to 24. The output-stage circuit boards are now mounted vertically rather than horizontally, which should result in more effective heat dissipation. To deal with the increased current, the copper traces on the amplifier's main circuit board and the output-stage circuit boards are twice as thick as on the JC 1.

• The peak output current is specified as 180A, supplied by Nichicon Gold Tune capacitors, two more than the JC 1. Richard Schram says that although the Gold Tune capacitors were discontinued years ago, Nichicon continues to manufacture them exclusively for Parasound. "

Peak current : 180A. So what are you talking about? J.Curl does not makes that kind of mistakes.

R.

@rauliruegas   I suggest since you are such a big fan of the Parasound JC1+'s sound that you go out and immediately buy a pair, if you haven't already...That's what I am talking about...;0)

Dear @daveyf  : I know and listened sevral times in different home top room/systems the original JC 1 and the JC 1+ too.

But, I don't need to buy it because my Levinson 20.6 monoblocks was and till today it's the J.Curl Statement Design. Yes better than the JC 1+ and better that many today $$$$ SS monobloks and guess what: the 20,6 are pure Class A and doubles its power down to 0.5 ohms. It's a true beauty of design and it's a learning electronics for any SS amps designers.

That's what I'm talking about.

R.

@rauliruegas   Presumably by now you have replaced the caps in those ML 20.6's?? Yes?

 I suggest since you are such a big fan of the Parasound JC1+'s sound that you go out and immediately buy a pair, if you haven't already...That's what I am talking about...;0)

@daveyf :)

Distortion vs frequency is a better measure of how musical the amp might be. It must not rise in the audio band else higher ordered harmonics can become more audible than THD values (usually measured at a pretty low frequency) would suggest. You can see this is a problem with the JC1. This is caused by a low Gain Bandwidth Product value, where the feedback ceases to be supported at a certain frequency and so decreases, initially at 6dB/octave. Distortion thus rises on a complementary curve. This is a very important reason why do many solid state amps of the past have sounded bright and harsh- its literally what has kept tubes in business the last 6 decades.

Dear @daveyf   .: You are rigth and I was lucky enough to found out all the power supply, protection circuit, input electrical circuit electrolithics at its original values through the best of the best caps: Vishay.

When I did it ( less than 2 years ago ) and I listened again what I listened was and is nothing less than stunnig for say the least. I bougth my 20.6 second hand and I did it to been paired with a pair of 20.5s that I owned too in a bi-amp configuration and latter on that I learned I sold the 20.5s

" The amplifier performed beautifully, showing maximum distortion of 0.42% THD + N at 20 kHz. This distortion level would not be audible on music and is comparable to published ratings for high - quality tube amps driving standard loads; here, we were using one-fourth of the amplifier's minimum rated load! "

 but in that 20's monoblocks review ( not the 20.6 that are even better ) that  THD does noit changes even at 1 ohm where the 20's  shoiwed 800 watts. Even those reviewers made this experiment with the monobloks:

"" An enthusiastic reviewer might call a beefy amplifier an "arc welder" as an exaggerated compliment to its ruggedness and current -handling capacity. However, no one would really expect an amplifier to actually melt steel. Almost no one, that is, except this reviewing team. We say this amplifier is an arc welder and back up this statement with a photograph (Fig. B1) of two 0.05 -inch steel plates welded together by a pair of Mark Levinson No. 20s. Arc welding is accomplished by creating an electric arc that melts metal. The molten sections of the items to be joined flow together and are then allowed to cool. In practice, the power source is connected to the two pieces to be joined and to a flux - coated welding rod. The arc is struck by momentarily shorting the rod to the work pieces. The flux is vaporized, forming an ionic conducting path for the arc and cleaning the metal. The arc stabilizes at about 100 amperes and 30 V (creating temperatures of 3,000° F), depending on the thickness of the metal and welding rod. If this sounds like the world's worst amplifier load, you're right! Coauthor Clark summoned Paul Grzebik to carry out the task. Paul has the reputation, in Detroit's technical community, for a willingness to try anything once, from building a parade float to scaling a TV transmitting tower. He readily agreed to our assignment. Clark drove both No. 20 amps with a 1 -kHz square wave to full output into a series resistor mixing network that combined both amplifier Fig. B1-Results of the arc -welding experiment. outputs in parallel to obtain the high current needed. After experimentation (and several blown line fuses), approximately 1 ohm was found to deliver the maximum current for starting and sustaining the arc. Wearing a mask and gloves (the intense blue light from the arc can burn the unprotected retina, while molten metal can splatter on the hands), Grzebik began welding. The arc turned out to be a fairly effective plasma tweeter, creating strong 1 - kHz square -wave sound radiation that required wearing ear protectors as well. Grzebik completed a small weld and, impressed, pronounced it satisfactory. After the welding, the No. 20s, still only lukewarm, were again put on the test bench. Distortion tests verified that no change in their performance had resulted from this extraordinary exercise. What's the point? With this test, Clark verified his confidence in the exceptional output capability and comprehensive protection built into these amplifiers. A few other amps might be able to weld steel without destroying themselves, but the No. 20s were certain to survive the experiment. One note: Don't attempt this feat yourself unless you are an accomplished welder, have the proper equipment, and are using amplifiers with extraordinary protection circuitry and output stages that can handle current extremes. Injury to yourself and destruction of lesser amplifiers may result. Don't expect manufacturers to repair your damaged amp under warranty, either! "

So,  we don't have to care on what  that tube manufacturer posted because it does not happens exactly as that. The very old 20's proved that and that design comes from 1986.

As always, there are designers and designers and J.Curl is really good . Remember the Vendetta Research phono stage? came from J.Curl and several other electronics designs as the Parasound and the like.

R.

@atmasphere   :0)

@rauliruegas  If you are happy with owning an arc welding machine, more power. Personally, I prefer to listen to music, and as such I generally prefer the lower powered amps, most particularly of the tube variety. I am in 100% agreement with what @atmasphere stated above. 

If a speaker requires an amp/ arc welder up front to drive it, then IMO, there is a problem with the speaker design. YMMV.

If a speaker requires an amp/ arc welder up front to drive it, then IMO, there is a problem with the speaker design. YMMV.

Exactly! Such speakers border on criminal as there simply aren't amps that sound like music that can drive them nor would they be all that musical due to thermal compression.

I look at it this way- if you can't drive it well with 100 Watts (in most rooms), its a problem. That is because the ear hears sound pressure on a logarithmic scale. So to get twice as loud (perceptually) that you can get with 100 Watt, you need 10x more- and 1000 Watt amps that sound like music don't seem to exist although class D is getting close with amps that can make 600 Watts or so.

The problem (again) is getting enough Gain Bandwidth Product in the design such that it can support the gain of the amp along with the feedback it has (together, known as 'loop gain'). If not, and this applies to almost all amplifiers ever made prior to about 2000 or so, you get distortion rising with frequency with its attendant unpleasantness- this is a good portion of the reason feedback has gotten a bad rap in high end audio. 

Its not feedback's fault so much as poor execution of feedback.

Plus a 1000 Watt amp would not be able to make up for the thermal compression that would be present- as I mentioned before, as you try to turn it up to get around the problem, it just gets worse. 

This has been discussed ad nauseum here on Audiogon. Low impedances can lower sensitivity which can make amps work harder to produce power and increase amp distortions. The degree to which the amp distorts due to this depends on the stoutness of the amp. The greater the loudspeakers sensitivity the more likely it will be a more open gateway to what distortions are still presented by upstream components, including but not limited from the amp. What is often less discussed is that varying impedances can strain amps too, and is more likely to present difficult phase angles to the amp as well. It is far easier to present and maintain a steady impedance by lowering the impedance of loudspeaker than visa versa. Electro-mechanical components are much more difficult to make perform well than purely electrical components. The variance between loudspeakers is typically much greater than between decently designed amps. This might suggest that more leaway be given to loudpspeakers than amps. As has previously (and wisely) suggested here; speakers designers have to choose what paramters and associated compromises combine to best meet ultimate design goals. Some if not most of the best measuring loudpseakers have lower impedances, and ergo lower sensitivity. There are a bountiful number of well designed amps that can handle such loads with minimal consequence.

Dear @daveyf  : First than all I'm a MUSIC lover and each single week at least I ttend to enjoy Live MUSIC and this " attitude " I have it for the last 25+ years.

I hate to listen the system Hardware and my room/system is builded through several years around nothing less than MUSIC but to enjoy MUSIC in my home we all need some kind of source/hardware.

I used tube electronics over 10+ years till I learned.

My ADS L2030 " old " speakers has 95db efficiency, no there is no single design problem with:

Vintage Holy Grail ADS L2030 High Fidelity Stereo Speakers and ADS C2000 Control Photo #1889387 - Aussie Audio Mart

The other gentleman ixs totally wrong, maybe he need to talk with J.Curl about that design or learn in other way about that specific design. I really don't care on his post that only shows high ignorance in tha specific regards amps.

R.

@rauliruegas Which other gentleman are you referring to? I don’t think anyone on this thread is totally wrong…except maybe you, lol😁.

just kidding..😎

@daveyf  : Yes, maybe me.

@unsound   " speakers designers have to choose what paramters and associated compromises combine to best meet ultimate design goals. Some if not most of the best measuring loudpseakers have lower impedances, and ergo lower sensitivity. There are a bountiful number of well designed amps that can handle such loads with minimal consequence. "

In total agreement with you.

R.

Again

Speaker sensitivty alone is not an indicator of quality or sonic virtue in loudspeakers.  I can think of other values that might be related to sonic virtue, such as widely varying impedance (in a passive design), high distortion, limited dispersion, inconsistent dispersion across the audio band, etc, etc.  High efficiency is simply an engineering choice made, not an evolution.

Brad       

@rauliruegas I think we need to be more clear as to what we are discussing when it comes to lower sensitivity. There is little question that a lot of great speakers are in the less efficient camp, meaning that they are not in the 100db/w mode, but closer to 85db/w etc., These very same speakers may drop down into the 3-4 ohm load in the bass, which might present a more challenging load to some amp designs, but like pointed out, with a sufficiently beefy power supply, will still work fine. These are not really the speakers that I am talking about here ( not sure about others), instead the designs that are on the market ( or have been on the market) that drop down to 1 ohm or less, and as such, are now presenting a very difficult load to the upstream amp. There are not too many speakers that this applies to, but you might be surprised by how many it does. Plus, many of these designs are from well known ( and respected) manufacturer’s, like the ones in my OP.

@lonemountain   While I would agree that sensitivity alone is not a indicator of quality or sonic virtue in loudspeakers, it certainly is an indicator as to what one can expect as to choosing an amp that will work well with said speakers. As such, the number and type of amps that will work is now significantly diminished, and as pointed out above by atmasphere, said amp will almost certainly NOT be working at its best. It also pretty much removes certain types of amp designs...mostly in the tubed genre.

@lonemountain wrote:

When you say that efficiency is not the most important aspect of performance ...

I wrote it’s "not the only" important aspect. These last ~15 years I’ve avoided low efficiency speakers as anything I’d consider buying (with the exception of seriously considering at one point larger and active ATC models, in particular the SCM150ASL Pro’s (and ultimately the SCM300’s, had economy allowed)), but efficiency as a standalone parameter isn’t as much the true indicator vs. what it leads to design- and size-wise, and so it’s really the other way ’round: the designs I prefer are mostly horn-based and large, and therefore, in effect, high to very high efficiency as well. It’s not that I can’t enjoy the sound of many a low. eff. design, quite to the contrary, but I’m simply pursuing a different route with different strengths sonically compared to what smaller, more inefficient and passively configured speakers can deliver.

I disagree that efficiency is the "preferred route" in achieving lower distortion, improved dynamics or increased bass. There are so many other avenues to these features.

Fair enough, but coming down to it we’ll have to disagree on this one. Yes, there are other avenues and areas of importance here that can make a low eff. package sound indeed very good in named areas, but when higher efficiency enters the "equation" to boot (again, not as the only parameter as anything worth considering) the significance in performance - to my ears and sensibilities - is not trivial.

ATC is a notable exception here, to an extend, in that their engineering prowess in driver development and overall execution is on another level compared to most lower eff. speaker manufacturers (and thus, and this needs to be stressed, they’re hardly representative of the low eff. segment of speakers). Active config. only adds to this advantage. The SCM150 and SCM300ASL Pro’s - that I’ve auditioned quite a few times - are excellent speakers in their own right that I could easily live with, and yet a large horn-based system (not least actively configured) does something else both dynamically, with regard to ease(!), scale, presence, immersively, viscerally and bass delivery that you’ll have to experience to fully understand and appreciate.

I did not say that low eff. designs avoid the limitations of poor efficiency simply by adding more power. There may not be limitations of lower efficiency designs, depending on your goals. Or there could be limitations of a high efficiency design.

Different contexts will have things in variables, yes, but getting a true bearing on a more complete wallop and significance of uninhibited dynamics, low distortion imprinting and smooth, effortless bass prowess at more than moderate SPL’s and shorter listening distances will require setting a different benchmark; to some these very aspects aren’t main priorities, let alone secondary, but to others they’re quite another connoisseur matter and will necessitate measures that goes beyond smaller, passively driven and low efficiency speakers.

I think the whole array of solutions are far more complex than high or low efficiency "spec" on a spec sheet. Whether something is 92dB 1w/1m in a loudspeaker gives you zero information about quality when compared to a 86dB 1w/1m spec.. You only know the designer chose to chase efficiency (probably for more than one reason). Intended application is everything..

Chasing efficiency in itself would seem crude, but let’s make it actual high efficiency to begin with if we really want to refer to it as such; my understanding of high efficiency, all along, has been a sensitivity from 95-100dB’s on up. Few designs really accomplish that, and if you intend to have a fairly uniform and controlled directivity pattern at the vital crossover(s), not least crossing low enough to avoid the central midrange while maintaining sensitivity all the way down low to the 20-30Hz region, then you’ll have yourself a large sized package that can really show its mettle with the parameters referred to earlier.

Some lower efficiency designs can achieve lower distortion in the driver, or can extend low frequency of that driver or both. Or your lower effieciency design may improve cooling and power handling without extending voice coil length. I guess to me its like horsepower tells you zero about the performance of a car. There are so many different options available to a skilled designer that focusing only on a high efficiency design is not wise, again, depending on your goals. I favor lower distortion myself, I want to hear more of the fine details, the reverb tails, the room sound, etc. If I can have lower distortion that reveals more of that fine detail in exchange for a larger power amp, I’m in. That’s the trade off I am talking about. And I’ll stick to my guns on this one, you cannot have it all.

And this is where we are ultimately disagreeing. Within the design differences inherently at play here I do believe we can more or less have it all; care taken with a specific design is not limited to low efficiency dittos, and if you’re willing to go the distance and let size and physics have its say, it means upping the potential of such designs even further. No, I wouldn’t cram speakers that large in small rooms, but contrary to common belief they can be implemented excellently in moderately sized listening spaces - not least actively.

@daveyf  you also have to consider that tube amps with high sensitivity speakers also limit many tube systems because of noise and hiss which you can't hear as well with low sensitivity speakers. Not all tube equipment is quiet, just like not all high powered amps sound bad.

@daveyf

You are right about the amp issues regarding hi vs lo efficiency designs, well said. Yes, a low efficiency design might require more power.  But these issues are truely complex and trying to make a blanket statement that some performance related feature is always good or always bad doesnt really work in audio. People long for universal truths, but in audio, the truth is conditional.

Brad

Gents, I think we can summon up the above posts with this: It is extremely important to acquire a speaker that has a good synergy with the amp that powers it.

@invalid   You bring up a great point. The signal to noise ratio is a factor with most gear. Tube gear is likely to be noisier than ss gear. The question is how important is the tube noise through the more efficient speaker to the listener. I'm not so sure that it off-sets the overall performance to such an extent as to rule out certain speakers?

Dear @daveyf  : It seems to me that if you put together some vali with facts and knowledge levels on speakers it looks as some way or the other we need something that just does not exist and we are looking in a transducer that makes all to be posible: there is no single or"  surrounded " perfect speakers/transducer and never will.

In the other side some of those gentlemans with good speaker knowledge levels have not the same good knowledge levels about amps/electronics and this fact makes everything more complicated to really have a good conclusion.

Example: even its inherent importance of speaker impedance phase no one name it and this is something to take care when we are choosing an amp we need to know the speaker impedance measures/curve and its phase down there.

Topic per sé is endless..

R.

The amount of solid state amps that sound good with high sensitivity speakers is also limited, that's why a lot of people choose set amps with these types of speakers.

Example: even its inherent importance of speaker impedance phase no one name it and this is something to take care when we are choosing an amp

@rauliruegas Actually this has been brought up in this thread.

@daveyf  : Trouble ( if any ) with the whole subject  that is confirmed through the thread posts is that each one of us have our each kind of target for home MUSIC reproduction and even several of us just do not have targets about.

In my opinion and before to look for efficiency/amps and the like is to be very specific the kind of MUSIC/sound each one of us want it I think that this is the main and critical factor to decide the: MUSIC reproduction sources, transducers, electronics, room treatment, cables and the like even our seat position and the kind of chair to listen sessions.

R.

@atmasphere wrote:

I look at it this way- if you can’t drive it well with 100 Watts (in most rooms), its a problem.

+1

... and 1000 Watt amps that sound like music don’t seem to exist although class D is getting close with amps that can make 600 Watts or so.

Whether or not there’s a generality to your claim above, I can’t say, but I was surprised to learn that a 600W class A/B power amp from MC² Audio was perhaps even more "musical" sounding than a 30W class A ditto from Belles (which was a great amp) - that is, driving a 111dB horn/compression driver combo connected directly to their terminals (i.e.: actively, sans passive crossovers). Nothing sterile, tonally lean, mechanical or bright sounding about the Brit, I can tell you that, or whatever you’re implying about high power amps sonics. To boot its inherent noise level (in fully differential balanced mode) is slightly lower than the Belles (unbalanced), even with a 32dB vs. 26dB gain. I feared it would have been the other way ’round.

Btw. it’s 8 ohm EV DH1A drivers (that can also be had in 16 ohm versions), but without the intervention of passive crossovers, added to +110dB sensitivity and the amp being limited to run the load from ~600Hz on up, it’s a piece-of-cake job for an amp if ever there was one. Show me an amp running a 16 ohm load, full-range and looking into a passive crossover that will be running in cruise mode the same way. Not going to happen.

It’s not that I need that much power in my setup (also falling in line with the first quoted part of yours above), but I wanted to use the same amps in my 3-way active system from top to bottom, and ended up "replicating" the one used on the subs to begin with - one that turned out to be great sounding full-range as well (which I expected, given their reputation). As they say: if it sounds great, it sounds great.

@invalid wrote:

The amount of solid state amps that sound good with high sensitivity speakers is also limited, that’s why a lot of people choose set amps with these types of speakers.

Another generality, indeed this one is a myth that has gone on forever. From my experience it holds little to no bearing (I can imagine it would have been an issue back in the very early days when SS amps likely sounded like crap, or certainly worse than today), but you’re certainly allowed to take fuller advantage of a low wattage SET design when driving very high efficiency speakers, and such a combo can indeed sound fantastic. The inherent noise level of such amps sees some filtration through passive crossovers. Actively, another matter, and it’s also why I prefer SS amps in that constellation.

@phusis  It is not a myth, it has to do with the low output impedance of solid state amps.

@invalid --

That's not to say it can't be great match sonically. 

@phusis  It is not a myth, it has to do with the low output impedance of solid state amps.

Flea watt SET tubes produce a lousy loose wet noodle bass, sounds like a sloppy fart. It's not a myth. But, guys who listen to Diana Krall @60db may not know any better. When the bar is set so low, loose fart SETs might indeed sound spectacular for such guys.

Nothing sterile, tonally lean, mechanical or bright sounding about the Brit, I can tell you that, or whatever you’re implying about high power amps sonics.

@phusis The issue is that most amps made using feedback, which includes high power solid state amps, is that the output transistors usually limit the design's Gain Bandwidth Product, resulting in a loss of feedback at high frequencies (depending on how much loop gain is asked of the design). The result is distortion rising with frequency, which seems to be more audible than the actual distortion spectra created by the amp. Class D offers a way around this problem.

Another generality, indeed this one is a myth that has gone on forever.

The issue here is that a lot of higher efficiency speakers are designed for amps with a higher output impedance. Such amps try to make constant power rather than constant voltage; this is not a myth. The Power Paradigm is what was around before MacIntosh and EV started promoting higher feedback in the mid 1950s so as to cause their amps to behave as a Voltage source, allowing plug and play. You might want to read this article for more information.

Flea watt SET tubes produce a lousy loose wet noodle bass, sounds like a sloppy fart. It's not a myth.

@deep_333 You might want to read the article at the link above as well. This is not a myth; its a matter of whether the speaker designer meant for the speaker to be driven by an amp of high output impedance. If so, the bass will not be as described (although SETs in general do tend to have less impact on account of phase shift above their cutoff frequency, which tends to be quite high due to their output transformers).

Can we say then that efficiency in speakers is not the #1 goal?  That the idea that dynamic range is improved or noise floor is changed due to speaker efficiency alone is simply not true?  While there may be examples that support this idea, there are far too many exceptions to make this speaker efficiency issue a universal need?

Brad

Efficiency is not important to me in that good quality full range efficient speakers are large and bulky. Large and bulky is the last thing I need. My goal has been to downsize. Otherwise, some of my favorite speakers sound wise are very large, very bulky, very expensive and very efficient. Think large horns for example. Wonderful stuff done right but not where I am going practically. There is a very practical reason why most speakers sold are smaller and correspondingly less efficient. They too can sound very good especially with modern advances in amplification and most people have limited room and don’t want to have to deal with large heavy and bulky speakers. Some do though and more power to them.

PS: Would love to have a pair of Klipshorns, at least in theory. 

@atmasphere well said as usual

@lonemountain everything in the hifi hobby requires evaluating a set of tradeoffs. What "this" you may be willing to trade off for "that" is a personal decision but make no mistake, we each must make a decision of what we are willing to give up in order to get what we value most (and will miss the least).

For me, I prefer no negative feedback and appreciate the delicacy, dynamics, tone and texture that many find in single ended amplification and the speakers that showcase that. YMMV but to describe "limp noodle" as your definition of a given topology leads me to believe you haven't likely heard it done properly.

Many can find what they are after but being open minded helps.

 That the idea that dynamic range is improved or noise floor is changed due to speaker efficiency alone is simply not true?  

@lonemountain  In a word, No. The physics of how voice coils work is the problem.

While there may be examples that support this idea, there are far too many exceptions to make this speaker efficiency issue a universal need?

There really aren't that many exceptions! ESLs are the only speaker that might not be all that efficient but do not suffer thermal compression because they do not use voice coils.

There are attempts to get around the thermal compression problem with lower efficiency speakers, such as vented pole pieces and the like. The incentive is high because lower efficiency speakers are a lot cheaper to make.

For me, I prefer no negative feedback and appreciate the delicacy, dynamics, tone and texture that many find in single ended amplification and the speakers that showcase that.

@ghasley Many amplifiers have troubles with how their feedback is applied (I can explain what the issues are if you're interested). If you get to hear an amp were its done properly, you might have occasion to rethink this.

@atmasphere wrote:

The issue is that most amps made using feedback, which includes high power solid state amps, is that the output transistors usually limit the design's Gain Bandwidth Product, resulting in a loss of feedback at high frequencies (depending on how much loop gain is asked of the design). The result is distortion rising with frequency, which seems to be more audible than the actual distortion spectra created by the amp. Class D offers a way around this problem.

Dependency and "seems to be" - as a technical observation I don't see how it holds an absolute correlation with regard the sonic outcome of SS amps in each and every case and high efficiency speaker combination, and to which degree? Relevance, magnitude and context (in my case also: active configuration) is obviously very important.

The issue here is that a lot of higher efficiency speakers are designed for amps with a higher output impedance.

Wouldn't the design of high efficiency drivers reflect more than a limited range of amp designs of their day? It borders on an anachronistic view, I find, holding that high eff. speakers of more modern/recent years (going back decades, really) should bring about the most favorable sonic outcome with tube amps predominantly. Myself I would be careful not to link local preferences of high eff. speaker designs combined with tube amps as anything that has a strict relation to or foundation in a technical explanation. Mostly preference is just preference (i.e.: highly subjective), but I'm sure many would jump to the gun, so speak, with a technical reference to validate their perceived findings in this regard.  

Such amps try to make constant power rather than constant voltage; this is not a myth.

My context of debunking that myth was in relation to the compatibility of high efficiency speakers and SS amps, sonically speaking. 

The Power Paradigm is what was around before MacIntosh and EV started promoting higher feedback in the mid 1950s so as to cause their amps to behave as a Voltage source, allowing plug and play. You might want to read this article for more information.

Interesting, and informative article. 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:

Any audiophile will agree that the most valuable thing they have with respect to their audio system is their own hearing. 

Dependency and "seems to be" - as a technical observation I don't see how it holds an absolute correlation with regard the sonic outcome of SS amps in each and every case and high efficiency speaker combination, and to which degree?

@phusis Rising distortion with frequency can cause an amp to sound harsh and bright. A typical example would be if the distortion begins to rise at 1KHz which is quite common; the 7th harmonic is at the upper end of the Fletcher Munson curve, so due to the extra sensitivity of the ear at this frequency, the fact that the ear uses higher orders to sense sound pressure, and the emphasis added by the rise in distortion, you get brightness and harshness. As you know, harmonics are what the ear uses to distinguish the difference between a trumpet and a clarinet; if harmonics are added with emphasis in this manner it causes instruments to sound harsher and brighter. The degree to which this occurs has nothing to do with the speaker and everything to do with at what frequency the distortion begins to rise (the point where the loop gain exceeds the GBP).

Wouldn't the design of high efficiency drivers reflect more than a limited range of amp designs of their day?

For vintage speakers, no. For speakers made since the Voltage rules were adapted, yes. But you'll find, if you look, that most producers of higher efficiency speakers tend to use tube amps. At any rate the kind of amp used has nothing to do with the phenomena of thermal compression. 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.

Interesting, and informative article. 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:

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

Amazing how complex and convoluted this discussion is.  I don't think there's a good answer here.

Except, having a Quality tube or solid state amplifier with plenty of power is undisputably a good thing. Yes there are speakers that can run off of 10 W of tube power.  Although this confuses the hell out of me.

Sensitivity of speakers is really confusing to me except that more sensitive speakers can be played with low power tube amplifiers and there may be some value in pursuing this because there are plenty of really good tube amplifiers running off of low wattage this can be a good thing. And we all know tube amplifiers are better than solid-state.

It's also good to buy a dog rather than a cat because the cat could care less about you.

It is extremely important to acquire a speaker that has a good synergy with the amp that powers it.

Tube gear is likely to be noisier than ss gear

@daveyf agreed. However, one can get the speaker first then get the matching amp subsequently - this has been my current strategy.

I have 2 speaker types.

Efficiency doesn’t matter - I purchased a full range herculean braced full range medium sensitivity speaker from a AXPONA demo that "resonated" with me. For this audio chain, I’m interested in transparency and dropping the noise floor.  I use highly regarded SS electronics

Efficiency matters - I wanted a "neutral", affordable, reasonable sized, speaker that can handle flea watt amps and other low powered tube amps. Purchased a 100db speaker specifically to explore tube amps including flea watt. I didn’t think much about synergy as I plan to experiment hearing different tube amps starting with the 300B, and the manufacturer confirmed I can also try a 45 tube amp.

Good luck with your speaker search

@kennyc The only thing that I think also needs to be added, or considered, when one goes and just buys a speaker that is requiring a monster amp upstream, is this…. That particular amp will most likely ( I can think of maybe one tube amp that might work, and it too is very expensive) be a very expensive ss high powered amp.The problem is that many of these very inefficient speaker designs, which can sound excellent, are also typically very pricey by themselves. So, not only is one now digging deep to just buy the speaker, but also one has to consider the potential for in many cases doubling the cost to acquire the amp,unless of course we are talking about Parasound’s…@rauliruegas

@atmasphere 

Im going to depart with your thinking when you say things like

"There are attempts to get around the thermal compression problem with lower efficiency speakers, such as vented pole pieces and the like. The incentive is high because lower efficiency speakers are a lot cheaper to make."

This is simply not true.  As mentioned before and elsewhere, lower efficiency drivers may sacrifice some efficiency to gain other features that improve performance such as lower distortion, better linearity, better low frequency extension etc.   The idea that lower efficiency is always done as a cost saving excercise is clearly not true.   

Brad

@lonemountain You are inferring something I did not say with this statement:   

The idea that lower efficiency is always done as a cost saving excercise is clearly not true.   

I don't need to repeat myself here. But 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.

What I said when you quoted me is correct.

Dear @phusis  and friends:  we have to remember that atmasphere is a tube electronics and from several " vintage " years his flag ship argument to hit class A and AB solid state amps always is that: harsness/brigthness " but with out real facts. His article is only bla bla bla as always in that regards.

If he can proves what is his solid state agenda then that comes here and shows at least 10 SS top/high power amps tha showed what he said in the last 10 years with measures of those amps and what the reviewers said it about. Here one example  and the other is my very old 20.6 monoblocks  where just does not happens his bla, bla, bla,:

Halcro dm58 monoblock power amplifier | Stereophile.com

R.

Loudspeaker power handling vs. Efficiency. Magnetic flux modulation compression see here.😎

Mike

In my experience low sensitivity speakers not just make unpleasant compression but also mask microdynamics and texture. It is so obvious that producing low sensitivity drivers is much cheaper. Weak magnets are cheaper, heavier diaphragms are cheaper, rubber suspension are cheaper. But you pay for marketing, and a beautiful box that was lacquered dozens of times.

Dear @alexberger  : Yes you are rigth and I can see your Altec Lansing drivers, that  EMT, the Tamura and the like. Congratulations.

R. 

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