lonemountain...

Scroll to about 5:50 and onwards on this Levinson demo...These are about 100db/1W/1M pro audio style of speakers. The demo is at @110+ db. This is the type of speaker that starts to laugh at all the Harbeths, panels, etc. No orchestra ever came home full tilt with the latter type of ’speakers with challenges", in comparison. But...for "Female Vocals" @ 65db (nap time)?? Ok, sure, anything and everything works for that stuff...comes down to your listening preferences.

@lonemountain wrote:

Asking the question "What is efficient enough?" brings up mutiple challenges. the first being hardly anyone listens much over 90dB SPL!

Brad,

As you’re no doubt aware of, comparing lower efficiency speakers with true high eff. dittos isn’t an apples to apples scenario. It doesn’t only come down to how loud one enjoys playing the stereo, but rather and not least how a given volume is reproduced - i.e.: the very nature of the sound. Many aspects come into play here, like speaker principle/driver types, directivity pattern, headroom (or lack thereof), cone area and overall physical size, specific design choices, etc., and these aspects can be a product of or otherwise relate to a given sensitivity, which again has sonic implications. Choosing high eff. speakers can’t help but reflect on these interdependencies, and thus speaking of and preferring high eff. speakers doesn’t really revolve around a numeric sensitivity value in itself - certainly not as an isolated parameter and choice alone. That should be pretty obvious by now, I’d say.

I was at AXPONA this weekend and in our room we are demong ATC. I meassuredIf the SPL when things got "loud" : it was around 92dB SPL. If the 1w/1m spec of a passive was 90dB, it would require less than 2 watts to get that speaker to play at 92dB 1M. If it was 86dB 1w/1M it would require 4 watts to get it to 92dB at 1M! 92dB SPL is very loud for many of us, most audiophiles wouldnt even want it at 90-92dB SPL in their living room or listening room.

That’s a very crude outline of what’s actually required power-wise. Many low eff. speakers at actual listening distance will be closer to their limits or lacking noticeable headroom at 90-95dB’s than one imagines, and moreover you have to factor in the girth of passive crossovers and their varying degrees of load-strain on the amplifiers; a 100W amp may be brought to its knees with a passively configured speaker long before those 100 watts are actually converted into an SPL that truly reflects the theoretical outcome at the listening position in relation to the rated(!) speaker sensitivity. Seems to me you’ve become a bit spoiled dealing with active speakers mostly, as well as drive units that are anything but representative of the general range of hifi speaker drivers ;)

It appears in reading this thread that most would agree that above 90dB 1w/1M is efficient and 86dB 1w/1M is "not efficient". We need 2 watts to get our 86dB speaker to 89dB SPL, which is indistinguishable from 90dB to most of us. This 2W instead of 1W is really a critical issue and one that drives a purchase?

While, all things being equal, a 85 vs. 91dB sensitivity difference isn’t trivial, the latter isn’t high efficiency by any means, period, irrespective of the general gist around here. Relative to 85dB sensitivity it’s certainly a higher number, but that’s just about as far as it goes. Keep wandering in the low to moderate efficiency spectrum however may make for a more convenient outset to discuss low vs. "high" efficiency, as it appears to keep the speaker principles within a more manageable and homogenized sameness, and thus a numeric sensitivity value varying 5-7dB’s is mostly what it comes down to here, not that it can’t be a deciding factor with regard to amplifier choice, a sense of headroom and max. SPL.

Comparing low efficiency speakers with true high efficiency dittos (>97dB, or thereabouts) is another matter though. Here high eff. mostly involves horns, compression drivers and larger diameter woofers, as well as larger enclosure sizes, and this has sonic implications for a variety of reasons, as I implied above.

My point is that very very few of us listen at 92dB SPL. The argument for an "above 90dB 1w/1M speaker" is not a relevant argument as no one even wants to listen that loud. 90% of our listening is WAY under 90dB SPL. If this is true, why is 90dB+ 1w/1M efficiency such a important spec that we all need to pay attention to it?

So, what you’re saying is that people buying high sensitivity speakers effectively and essentially has an excess of efficiency that isn’t of any use, unless very low powered amps are sought? When this speaker segment may often be referred to as having excellent dynamic capabilities, sense of power, scale, ease, etc., do you think that only pertains to SPL’s above ~90dB’s? And even if it does (in peaks), isn’t that relevant to some of us? And what about these traits (and others) specifically - are you going to tell me they aren’t partly related to higher sensitivity, with all that entails?

I meassuredIf the SPL when things got "loud" : it was around 92dB SPL. If the 1w/1m spec of a passive was 90dB, it would require less than 2 watts to get that speaker to play at 92dB 1M.

? Only if your listening distance is 1 meter....SPL drops by 6 db, every doubling of listening distance. If your listening distance is 13 ft, a 90db (1meter) sensitive speaker will produce 78 db avg at your listening position (13ft) with 1 Watt of power.

Headroom and the variables that play into it is a debated topic and it will tend to dictate higher powered amps. Higher powered high fidelity amps could get expensive.

P.S.

Take a SPL meter with you to nightclubs, concerts, discotheques, etc. When you’re really enjoying the beat (having fun), take the SPL meter out and you will often note that it is higher than 90 db and a lot more...Or just go watch an orchestra. You’d be surprised at what your db meter reads.

Asking the question "What is efficient enough?" brings up mutiple challenges.  the first being hardly anyone listens much over 90dB SPL!   

I was at AXPONA this weekend and in our room we are demong ATC.  I meassuredIf  the SPL when things got "loud" : it was around 92dB SPL.  If the 1w/1m spec of a passive was 90dB, it would require less than 2 watts to get that speaker to play at 92dB 1M.  If it was 86dB 1w/1M it would require 4 watts to get it to 92dB at 1M!  92dB SPL is very loud for many of us, most audiophiles wouldnt even want it at 90-92dB SPL in their living room or listening room. 

It appears in reading this thread that most would agree that above 90dB 1w/1M is efficient and 86dB 1w/1M is "not efficient". We need 2 watts to get our 86dB speaker to 89dB SPL, which is indistinguishable from 90dB to most of us.  This 2W instead of 1W is really a critical issue and one that drives a purchase?   

My point is that very very few of us listen at 92dB SPL. The argument for an "above 90dB 1w/1M speaker" is not a relevant argument as no one even wants to listen that loud.  90% of our listening is WAY under 90dB SPL.  If this is true, why is 90dB+ 1w/1M efficiency such a important spec that we all need to pay attention to it?

Brad     

@lonemountain Brad, you make an interesting point. While most folk would consider your example as efficient, the other variable, which could effect how an amp interacts with this speaker is how the load the speaker presents varies across it’s frequency spectrum. For example, I know of a very good metal box speaker that has specs similar to what you post ( not quite as good, about 89db vs.90db), but this speaker drops down to less than 1 ohm in the bass regions between 35hz and 55hz. Therefore, I’m not so sure I personally would consider this speaker as an efficient speaker, or easy to drive.

@daveyf

One of my points is that this very issue of "what amp is enough?" is based around very fuzzy poorly defined/poorly understood info about speaker efficiency, Would you call a 90dB SPL 1w/1m speaker efficient or not?

Brad

@daveyf +1

Mike

@lonemountain Brad, I think one of my points is that the free choice of speakers and amplifiers are connected. IOW, a highly inefficient speaker is going to severely limit your amp choice, and conversely a very low powered amp ( or an amp with minimal current drive capability) will also be a non-starter with a speaker that cannot be properly driven by said amp. Therefore, picking out either one of these designs invariably leads one down a path, that may or may not be where one wants to go.

Is the entire "speaker efficiency" conversation motivated by passions and opinions about the free choice of amplifiers -not speakers ? 

Brad 

Its very important to some so much so that they house giants. Its also of very little importance to some so much so that they house giant amplifiers. If you don't want high power it would be important to you.

Dear @phusis  : " Indeed sufficient headroom is a prime takeaway here (regarding both speakers and amps) - that is, it’s that it actually matters, and far more than people seem to realize. "

Normally audiophiles do not cares enough about " headroom " eve3n some of them not even know what it means in electronics and especially when we are talking of speaker/amp combinations.

As  a fact I learned through my first hand audio experiences when I owned thr Classé DR3-VHC This amp is a pure Class A design with a power of " only " 25 watts but in its times was only one of the few amps that handled with aplomb the Apogee Scintilla that gone even lower than 1 ohm impedance and with not high efficiency but around  79db at 3m. but ( if I remember the Classé came with 7db on headroom and from here its VHC denomination: very high current. ).

R.

@phusis

My argument is that this efficiency as it relates to speaker performance is a complex issue, much more than a simple number. You forget I am engaged with dealers and end users who ask these questions (and similar ones) quite often. The desire to reduce a complex issue down to a simple one is very attractive when the subject is complex. THAT is my point, not that there aren’t times when facts are facts.

Since you own DH1A, I can use a historical reference: I bet you remember many people arguing the advantage of 1.3 inch throat driver/horns (EV) vs 2 inch driver/horns (JBL) and vice versa. That discussion was often reduced to focus on one attribute (throat diameter) when really it was a far more complex issue than that, depending on what you were trying to accomplish.

Brad

Well, D.Wilson ( paw, unfortunatelly. ) was not so stupid and " deaf " as his national manager and he used only Krell/Spectral amplifiers with the Watt/WAMM speakers to monitoring all his great Wilson Audio recordings.

"

The manual suggests that direct-coupled Futterman and similar tubed amplifiers are inappropriate, but gives the OK for other tube models when used on their 4 ohm tap. I have to disagree. A 1 ohm load severely limits the output power from a tube amplifier. For example, a 100W output (17dBW, 8 ohm) into a 4 ohm load will typically fall to 7dBW, or 10W in level terms, when faced with 1 ohm. Simply, this means that the amplifier will clip 10dB earlier if a strong musical signal appears at 2kHz, which is not unlikely, since this frequency is well in the main music power band.

Let us also assume a typical case where the tube output impedance and cable loop are limited to 0.4 ohms. Overall there is a loss of 0.8dB over the whole range, but at the 2kHz minimum impedance the loss increases to nearly 3dB, this inducing a dip in acoustic frequency response of 2.2dB which may well alter the sound of the speaker.........................................................Last and by no means least, there is the matter of that awkward load impedance, and the corresponding, almost unforgivable dip to 0.33 ohms noted on the review pair.......................................................Depending on the amplifier used, there was also a touch of hardness on, or edge in, the upper midrange which was ameliorated by using the Goldmund Mimesis 3 power amplifier and one or two of the other high-current amplifier types such as the Krell. This mid-treble problem was rather amplifier-dependent (due to the impedance characteristic...."

Btw, we have to remember that that 1 0hm and 0.32 ohm at those frequencies is not a discrete impedance value but part of the speaker impedance curve and  the adjacent frequencies and developed harmonics are " touched " too.

Stupid people are all over the world and just fine with me.

R.

Over the years I have found that lower power amps (35-45 wpc) always sound better to my ears. That makes low efficiency speakers (83-87db) a non starter for me

@rauliruegas wrote:

Well , that large size is not exactly typically " because depends on the kind of drivers other than horns and an example are my ADS speakers that yes are " large size " but the size is due that the speakers can goes down to 16hz through two 14" acoustic suspension woofers but today I have the ADS from around 100 hz and up and the soft domes ( silk ) acoustic suspension 2" for the mid-range and 1" for the tweeter ( one a top the other:nearest as it can be. ) needs a very small " box space " due to its very high gauss magnets ( are not vented and non-ferrofluid. ) around 24k in the tweeters and 18K in the mid range, both drivers made it in Germany for ADS and its efficiency is 95db ( almost a horn . ). Unfortunatelly the drivers manufacturer just does not exist any more.

True 95dB sensitivity is certainly quite efficient compared to the general norm of speakers (that are closer to a typical 85dB’s, making for a ~10dB difference here), and in conjunction with your ADS L-2030 speakers extending as low as they do with dual 14" woofers per cab there’s no escaping the implications specified by one Mr. Hofmann and the following larger size.

My efficiency context is higher, and once horn-loading becomes necessary/preferred, not least when you want them to act like horns in their entire frequency span, up to very large size is unavoidable. In my setup context I’ve not yet fully exploited the efficiency factor (save for the midrange/tweeter horn); if I wanted at least ~105dB sensitivity top to bottom (i.e.: 20Hz-ish on up) it would require non-truncated front loaded horn subs and similar type horns for mid bass (but with the fewest and low degree horn path bends) or star quad 15" direct radiators, which is a significant upgrade size-wise below ~500Hz easily by a factor of 2 compared to what I have now. Having said that my corner mounted tapped horns subs takes further advantage of significant boundary gain (1/8 space), and so the least efficient driver section is the midbass bins sitting at ~98dB’s (hardly slouches, also considering they’re high-passed).

Trying to make some sense of the madness one could ask whether an efficiency that high is really necessary in a home environment. Obviously that’s up for each to assess and decide, but to me at least it isn’t about bonkers SPL’s; it’s about maxing out the sonic potential of horns and aiding the best integration, also with direct radiating sections. Ease of load of the amps, not least with active config., is another boon. Indeed sufficient headroom is a prime takeaway here (regarding both speakers and amps) - that is, it’s that it actually matters, and far more than people seem to realize.

What keeps most audiophiles (who’re already inclined towards high eff.) from venturing into very high efficiency and directivity control in the entire audio band - with all that entails - is mostly about large size becoming an obstacle, be that aesthetically or practically. However it’s also about a particular mindset, because it requires of one to acquire pro segment, DIY or vintage gear when such large designs are hardly available domestically, not least at less than astronomical prices. It’s a radicality of approach few (but perhaps more and more) are willing to pursue.

Kudos on your setup, btw.

@deep_333 wrote:

Generally, high efficiency speakers have sounded unrealistic. What do the masses think of and come to conclusions when they’re thinking high efficiency? There it is, it can be attributed largely to bad actors like Klipsch, who’re all over the place and generally made plenty of flawed speakers with a couple of exceptions perhaps. It also seems like any other jester will come up with some horn speaker whilst tinkering in his garage, bring it to shows, etc and they’ve sounded stupid.

Nevertheless, when you buy a high efficiency speaker from guys who really know what they are doing, they seem to sound truthful. ...

I agree.

@lonemountain wrote:

Very good point and great example that there is more to know about a speaker than a 1w/1m spec. Could a 86dB 1w/1m speaker with a very flat impenace curve outperform a 91db 1w/1m speaker with a wildy changing impedance curve? Yes.

That’s not really saying anything about the argument of high efficiency, in fact it goes without saying. Your effort to isolate a high sensitivity rating as a singular, non-determinant factor in no other context than itself is just trying to serve an argument against it, and not seeing it for what it can do in the greater scheme of things. Come on :)

Btw, I remember listened 4-5 times in the past the original Wilson Watt and this is a fantastic true monitor not high efficiency as a horn but measured 91db and this Watt has a problem for any amplifier ( tubes forbidden with ) at 1khz its impedance surve measures 1ohm and near 2khz 0.32 ohm . IN those times the preffered amps for it were Krell and Spectral.

This is mostly incorrect.

At the time this speaker was made, the national sales manager of Wilson was using Atma-Sphere OTLs in his home system. The Watt was an easy load for any tube amp (David designed his speakers using ARC amps and often showed with them; my first exposure to Wilson was at the ARC factory).

That 1 (or 2) Ohm load was at about 2KHz where there wasn't a lot of energy. The tweeter had a resonance problem and so there was a 2KHz trap that presented the amp with a low impedance, thus knocking out the resonance pretty well. This worked great with tube amps! Not so much solid state, as solid state amps would often make more power into a lower impedance rather than less.

@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..  

@daveyf This makes more sense. Your original post seemed to suggest your dissatisfaction with speakers not efficient enough for “your” tube amp vs speakers that are inefficient way below the average speaker.

I’ve demoed many good/great speakers at brick n mortar and audio shows, but very few subjectively “resonated” with me. That’s why I thought it a good thing that the OP found such a speaker.  Unfortunately, the speaker requires significant power. Maybe a tube pre + SS amp might work out economically and sonically.  Good luck with your search.

@rauliruegas

Very good point and great example that there is more to know about a speaker than a 1w/1m spec. Could a 86dB 1w/1m speaker with a very flat impenace curve  outperform a 91db 1w/1m speaker with a wildy changing impedance curve? Yes.

Brad

Dear  @daveyf  : I think that in many ways the speaker impedance curve and phase is way more important than efficiency.

Almost no speaker manufacturer ( if not all of them. ) gives to the owners that speaker measured characterisatics and normally only gives the speaker " nominal " impedance.

With out those 2 characteristics how any speaker owner could mate in a " decent " way the amp for his speakers audio system?

The Watt had pretty decent efficiency at 91 db but those very low impedances happens  in a very usual frequency range where MUSIC comes.

That's why several audio system owners are not satisfied with the speaker or amp or boths.

R.

Dear @lonemountain  " most bad decisions in audio are made based on bad info or lack of info.  There is a lot of misleading info posted on forums "

yes, but in the forums are many very good information ( not bad information ) where we can learn. I learned in this thread with several of the posts of gentlemans that have higher knowledge level in the specific regards that me and one of them is @phusis  and other like them.

Btw, I remember listened 4-5 times in the past the original Wilson Watt and this is a fantastic true monitor not high efficiency as a horn but measured 91db and this Watt has a problem for any amplifier ( tubes forbidden with ) at 1khz its impedance surve measures 1ohm and near 2khz 0.32 ohm . IN those times the preffered amps for it were Krell and Spectral.

As a fact David Wilson made it all his Wilson Audio LP Recordings using in the studio the Watts and at Wilson place the WAMMs. I own all those fantastic recordings that are impressive: microphones by Sennheiser ( recordings in the late 80's ), Recorder by John Curl, cables by Bruce Brisson. We have to remember that DW before started in the speaker design was a recording engineer for several years.

R.

Dear @ghasley : You say that prefers no negative feedback and maybe because you have a deep misunderstood on feedback amp issue but some of us can learn about in this link coming for a truly expert engineering:

whitepaper (sotaturntables.com)

He was designer in Analog Devices Inc: "

Several years? I was with ADI- designing a wide variety of ICs for almost forty years and was most fortunate to become an ADI Fellow and Senior Fellow.

I am not a free-lance engineer. I retired from ADI a few years ago and I design audio (and other gear) for fun and for free, "

Sometimes post in Agon and is a gentlemans that we have to listen and read him. But as always are other people that just never learned due to their own or audio sale agenda,  especially in electronics items.

R.

Moreover, the claim that high efficiency is necessarily and always bound to be attained "with a price," sonically speaking, is a fallacy.

Generally, high efficiency speakers have sounded unrealistic. What do the masses think of and come to conclusions when they’re thinking high efficiency? There it is, it can be attributed largely to bad actors like Klipsch, who’re all over the place and generally made plenty of flawed speakers with a couple of exceptions perhaps. It also seems like any other jester will come up with some horn speaker whilst tinkering in his garage, bring it to shows, etc and they’ve sounded stupid.

Nevertheless, when you buy a high efficiency speaker from guys who really know what they are doing, they seem to sound truthful. ...

Chat with legendary loudspeaker engineer Laurie Fincham ...

Mike

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.

@phusis I think the power handling might also be part of the difference in price. My speakers also use a set of field coil powered 15" units, hand made by Classic Audio Loudspeakers that seem well north of the $4k of the 1602s.

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.

Horns were used in the old days because tube amplifier power has always been expensive so you had to get the most out of the power you had. The use of controls on these older speakers clearly places them in the Power Paradigm.

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 :)

FWIW I'm one of the few that see a direct line between what we measure and what we hear. I'm of the opinion that the implications of what the measurements are telling us are not well understood so people still trot out the old saw of our ears being able to hear things we can't measure. So I'm of the same camp as Daniel vonRecklinghausen.

@rauliruegas 

it’s true - I am ATC USA and do not want to hide that.   Previously I’ve worked for EV (their rep out of Chicago including OEM)and JBL (in charge of cinema and installed sound in the USA)and now ATC ( I’m the importer for both pro and hi fi for the entire US).  I have the privilege of being able to ask an engineer who does driver design for living what’s what.  My goal is as much for me as for my customer: the more you know the better, as most bad decisions in audio are made based on bad info or lack of info.  There is a lot of misleading info posted on forums - this is what motivates me to post, to represent a different perspective, to represent what I know to be true.

Brad

@lonemountain  : Now I understand why for you is important but not so important the speaker efficiency issue. I visit your virtual system and seems to me that you are an audio distributor od low efficiency ATC speakers.

@phusis  "  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.."

Well , that large size is not exactly typically " because depends on the kind of drivers other than horns and an example are my ADS speakers that yes are " large size " but the size is due that the speakers can goes down to 16hz through two 14" acoustic suspension woofers but today I have the ADS from around 100 hz and up and the soft domes ( silk ) acoustic suspension 2" for the mid-range and 1" for the tweeter ( one a top the other:nearest as it can be. ) needs a very small  " box space " due to its very high gauss magnets ( are not vented and non-ferrofluid. ) around 24k in the tweeters and 18K in the mid range, both drivers made it in Germany for ADS and its efficiency is 95db ( almost a horn . ). Unfortunatelly the drivers manufacturer just does not exist any more.

R.

Dear @lonemountain : Yes, today TAD speakers are not exactly high efficiency at 90db and are expensive but its sound quality level performance is excellent.

In the past Exclusive in Japan ( Pioneer ) had the 98db big  2401 Twin model obviously all TAD drivers and in Japan in those early 80's its retail japan price was 1,200,000 Yens and a direct competence to JBL and other USA speakers or from England as the Vitavox.

TAD today monitors for home audio are in the 85db efficiency and excellent performers too.

R.

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      

@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.

@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:

... 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 :)

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

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

R. 

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.

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

Mike

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.

@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.

@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

@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

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

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.

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 :)

@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. 

 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 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.

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. 

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

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).

@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.