Speaker sensitivity vs SQ


My first thread at AG.

Millercarbon continues to bleat on about the benefits of high sensitivity speakers in not requiring big amplifier watts.
After all, it's true big amplifiers cost big money.  If there were no other factors, he would of course be quite right.

So there must be other factors.  Why don't all speaker manufacturers build exclusively high sensitivity speakers?
In a simple world it ought to be a no-brainer for them to maximise their sales revenue by appealing to a wider market.

But many don't.  And in their specs most are prepared to over-estimate the sensitivity of their speakers, by up to 3-4dB in many cases, in order to encourage purchasers.  Why do they do it?

There must be a problem.  The one that comes to mind is sound quality.  It may be that high sensitivity speakers have inherently poorer sound quality than low sensitivity speakers.  It may be they are more difficult to engineer for high SQ.  There may be aspects of SQ they don't do well.

So what is it please?

C85b9041 52a0 4fa7 ac78 d902149a2d82clearthinker
Great sounding speakers come in all sensitivities, it is all about design goals. And a designer may feel that certain drivers give them the sound they are looking for and those drivers may not be all that efficient. And some companies may feel that exclusivity is more profitable than wide appeal. 
  ,  Sensitivity depend of moving mass cone and magnet performance.  To achieve good bass and  we have to use  very big enclosure  .or use active bass with build in amp.  we can use unexpansive class D amp  to drive bass section and use external 
high quality low power amp to drive all above low frequency region.     Some company included me follow this way 
Sure, there are good designs from many different topologies. But after owning over 30 high end speakers I have to say (at least for me) that the better ones have always been easier to drive and not requiring an arc welder of an amp. As in most things, simpler is usually better. Give me a pair of horns and a low-medium powered tube amp for sound that just grabs you and pulls you in.

Oz



You can find great sounding speakers at any efficiency level.

I also advise avoiding low sensitivity speakers for a few reasons.

1. less power needed
2. less power makes it much easier to try tubes
3. lower power amp, tube or ss: smaller, less weight, less heat, greater flexibility of placement
4. less cost gives more money for the speakers, the most important determinant of SQ.
5. less money in the future when making changes.
6. less money leaves more to spend on content!

When you hear an inefficient speaker and fall in love, you are doomed! 

Post removed 
I have 92db sensitive Ref 3a de Capos run with a 4 watt Decware Mini Torii.
No trouble driving them to good levels and the sound is amazing
I agree with Oz, Elliot and MC, I will always opt for higher efficiency speakers.
There are categories of speakers which sound different from each other:

A. horns
B. omnis, open baffles
C. electrostatics 
   Maggie’s (perhaps need own category)
D. “regular” box speakers (perhaps wide dispersion go under B)

How many people in 2020 are going to choose anything other than their preferred category no matter what sensitivity?
Lower sensitivity can produce more bass with a smaller enclosure but need power.
Higher ones for same amount of bass require larger cabinets but less power.
Higher efficiency could have better dynamic contrasts and a greater sense of liveiness, and offer better sound at low levels, but this is general.
Depends on matching on your musical tastes. In truth you can have great designs from both worlds.
G

Chasing flavors of distortion aka cone breakup or the focused constructive and destructive interference of a horn does not move accurate reproduction forward. Nothing wrong with picking baskin Robbins flavor #426 if that is your thing...

pistonic motion cuts 3db off sensitivity, ain’t no free lunch
Also the box flopping around also adds to output, just not in time with the note played ....
So building a dead box.... cuts output..,,

shall we go on ?

the big baffle can be thought of as a 2D horn ....


Also don’t confuse low sensitivity with a poorly engineered load ( bizarre phase angles, super low impedence, etc... 

or a bunch of series / parallel connections....
Great video relating to the topic!  Check it out.

https://m.youtube.com/watch?v=PEcFkSQMc8g
Encouraging to see at least some get it. Not surprised at all to see the O P does not.

Maybe because it helps to want to understand? People who want to understand tend to say things like so and so says. People who want to argue, instead of says which is neutral and true they say things like bleats which is insulting and demeaning. This may be from learning by bad example or could be they resort to insults because they don’t have an argument. Either way it’s an insult not an argument.

Others here are in love with tech talk. There’s definitely a place for that but I prefer whenever possible to stick with good solid practical advice. It may be at times hard to understand why it works but it does in fact work and therefore is practical. Useful. All these useless pie in the sky fantasy questions the OP is asking, "why?" Can be argued endlessly.

My advice is simple: exclude from consideration speakers less than 92dB sensitivity.

Don’t read into that facts not in evidence. Not saying buy high sensitivity. Not saying they all sound great. Not saying low sensitivity speakers sound worse. Not saying there is any correlation at all between sensitivity and sound quality. Not saying anything other than exactly what I already said: building a really good high end system is hard enough already. Don’t make it harder than it has to be.
So the story usually goes like this.

Back when tube-based amplification was the only option, and most tube amps were really low powered, designing speakers with high sensitivity was the only way to go--there was simply no alternative if you wanted to reproduce voice or music.

With the advent of transistors, and then ever "cheaper" watts, designers started creating lower sensitivity speakers.  Think Thiel, Apogee, and a bunch of others.  It's reasonable to assume that they had specific design goals that led them in this direction, and that it wasn't the result of a lack of effort on their part.

The renaissance of tube amplification has seen a similar movement among suitable speakers, so nowadays there are plenty of options for everybody.  Of course, it's preposterous to rule out all speakers under a certain sensitivity.

Another major factor here is impedance; speaker sensitivity doesn't exist in some kind of electro-acoustic vacuum.  A certain well-known brand makes speakers with 86dB sensitivity but about an average 12 ohm impedance.  Go figure.

The long and the short is: find the speaker first that most pleases you, then find the right amp to drive it.  This advice has already been repeated many times over on this forum.
So there must be other factors. Why don't all speaker manufacturers build exclusively high sensitivity speakers?
@clearthinker  Cost, in a nutshell. High efficiency drivers are much more expensive due to a greater degree of precision required to precisely place the voice coil in a narrower gap, plus a more powerful magnet system.
b_limo1, great video, have seen it once before. Interesting perspective.

tomic601, When you say "don't confuse low sensitivity with poorly engineered load". I feel they are closely related. And I believe this is John DeVore's point in the video. I know of a high end speaker that is rated at 90db at nominal 8 Ohms (2.83v at 1 meter), have listened to it many times at a friends place. But when you look at the measurements of that speaker it has dips in the impedance down below 3 Ohms as low as 2.6. The speaker maker is only telling us a partial truth with their specs. It is only a 90db speaker for some of the frequencies and in effect a much harder to drive speaker to pull out all the audible sound well. Which I believe plays into the issue pointed out on the video of 1W per meter vs 2.83v per meter can be deceiving. With this particular speaker, you need an amp that doubles down on power when you halve the impedance to sound right. In other words it needs an amp designed for low efficiency speakers.  
I own Mission Cyrus 781 speakers sensitivity rated 90.5 db...

I drive them with my Sansui AU 7700 rated 8 ohm 55 watts....

No problem....I can make deaf my neighbours.... They sound  very refine and bass powerful...



😊
+1 newres, well said. 

Speaker manufacturers ask for 10s of thousands of dollars,  play fast and loose with sensitivity numbers, and (usually) don’t publish any impedance graphs. Mostly we’re left to hoping that JA has tested the speaker and published results 

Hate car analogies, but here goes.
How much? $80k
Horse power? Don’t know
Torque? Hmmm, good question 
weight? Not sure...  
I'd go with mahgister.

AR 18s speakers (88dB) driven by a Rotel RA-414 amplifier (35W) can rock the place with 50-60 people whole night long and like that every weekend for years.

How much easier to drive you need them to be? I am sure there are armchair theories, but in real-use practice that is all one may need.

Skipping humongous speakers (Moabs anyone?) leaves more space to cram another few people in the room.
I agree that speaker manufacturers don't, but should, publish their impedance graphs.

However, I also believe that there are a plethora of amplifiers that can power most, except for the ridiculously low impedance speakers, and they sell for reasonable prices nowadays, particularly if purchasing used.

Thiel speakers and other hard to drive speakers are still as popular as ever.  Thiel owners seem to find amps that make them sing and they love their speakers.
There is an inevitable tradeoff relationship between box size, bass extension, and efficiency. And it’s a fairly brutal relationship.

If you keep the same bass response, every 3 dB increase in efficiency calls for a DOUBLING of box size.

So compared with a 1/2 cubic foot 85 dB mini-monitor that goes down to 40 Hz, a 97 dB efficient speaker with the same bass response would be SIXTEEN times the size (four doublings of box volume), or EIGHT cubic feet.

Now imo there are definitely some qualitative advantages to that higher efficiency, but in my experience the market for eight cubic foot speakers is rather limited.

Anyway my guess is that the higher costs and the box size penalties attached to high efficiency are the primary reason why low efficiency speakers dominate the marketplace.

Duke


@ clearthinker
An excellent first post. As you can see by Duke’s response above you are correct, there are other factors that are impacted by and to be considered when evaluating a speaker’s efficiency.

MC’s response to your thread is somewhat puzzling, you do seem to "get it".
Encouraging to see at least some get it. Not surprised at all to see the O P does not.
There is an inevitable tradeoff relationship between box size, bass extension, and efficiency. And it’s a fairly brutal relationship.
This observation nail the question with the beginning of an answer...


With active speakers and DSP box size and bass extension are being challenged in interesting ways. Look at the Develiat Phantoms down in subwoofer range with appossing drivers and a lot of watts. 
I am amazed at how many small manufacturers there are out there. Do they all support themselves as a business or is it hobbyists making themselves look bigger than they are?
I have owned all manner of speakers--conventional sealed box, bass reflex box speakers, electrostatics, planar magnetics, etc., and all types of speakers, with varying efficiencies, can deliver decent sound.  But, over time I have gravitated toward high efficiency speakers because they can be utilized with my favorite amplifiers (most of which are low-powered tube amps) and because they tend to deliver superior dynamics.  I know there are theoretical reasons for this--low power being delivered to the driver for any given volume level means less heating of the voice coil (heating causes an increase in resistance that then reduces the ability to deliver more power, in other words the driver output does not increase linearly with increase power (i.e., dynamic compression)--but, whether or not this is true, I tend to find higher efficiency speakers more dynamic sounding).

I currently own a system with twin 12" woofers in an Onken cabinet, midrange supplied by a compression driver/horn combination, and highs delivered by a bullet tweeter.  Horn systems like this tend to be large in size, which is why the industry went away from these systems, particularly when stereo required installing two speakers (and HT requiring even more speakers).  I don't think it was sound quality that killed horn-based system.
@b_limo,

Thanks for sharing the video. Ever since I traded my 92db efficiency speakers for 96db efficiency speakers, I have been living on easy street. Another advantage is the compatibility with flea watts amps to pure class A. 
Like always this thread is another illustration of the Groucho Marx law:

«To each his own, because all things and needs differ especially us in front of a mirror»
@lalitk 
Ever since I traded my 92db efficiency speakers for 96db efficiency speakers, I have been living on easy street.
And your speakers are on the larger side perhaps partly as a result of the increased efficiency and larger driver?  And I would die to have them, they are just beautiful.

The SoundLab ESL's are considered by some to be one of the best sounding line of loudspeakers available. They are also notoriously insensitive, and a very demanding load for a power amplifier They are also extremely transparent, and about as good at reproducing instrumental and vocal timbres as any speaker I have heard..

Then there is the Altec Voice-Of-The-Theater loudspeaker (A7), a very sensitive and easy-to-drive speaker. I lived with a pair for six months, and consider it to be as colored a loudspeaker as I have ever heard. Intolerably, comically colored. It's akin to a video monitor with it's color temperature WAY off, and its contrast control turned to max. Nasty, ugly sound, like chewing foil.

If you compare the two, and prefer the A7 because it is more sensitive/easier to drive than is a SoundLab, we'll have to agree to disagree. That's like preferring a smaller house to a larger one because it's cheaper to heat and cool.

Of course, it all depends on one's priorities in reproduced music. If dynamics is your No.1, high efficiency is for you. I myself am not willing to give up transparency and/or natural timbre reproduction to get dynamics. Are dynamics and transparency/lack-of-coloration mutually exclusive? I haven't heard everything (including the Tektons), but from what I have, I find the two inextricably related.

Thank you @jetter. I am now spoiled, probably never going to buy another multi-driver speaker. Beautiful, effortless sound! 
Of course, it all depends on one’s priorities in reproduced music. If dynamics is your No.1, high efficiency is for you. I myself am not willing to give up transparency and/or natural timbre reproduction to get dynamics. Are dynamics and transparency/lack-of-coloration mutually exclusive? I haven’t heard everything (including the Tektons), but from what I have, I find the two inextricably related.
Interesting...

My speakers Mission being less sensitive are better at timbre than dynamic... I will never exhange natural timbre perception for dynamic tough....For sure the 2 qualities cannot be separated on good speakers...My tannoy were good on the 2 front on equal measure...Alas! Too big for my room and needs i sold my 2 pairs ....


@djones51 --

With active speakers and DSP box size and bass extension are being challenged in interesting ways. Look at the Develiat Phantoms down in subwoofer range with appossing drivers and a lot of watts.

The Phantom's to me are more an interesting development in what can be achieved from a very small sized speaker package than what's entirely successful in itself against speakers of larger volume; they may impress (some people) in the context of being very compact, but against larger sized main speakers and subs come off like they're working hard to sound bigger than they are. Going further into the high eff. realm with a comparison here only exacerbates this impression, which is to say: challenging physics in regards to size only gets you so far.

Quite a few other interesting active designs (like the Genelec "One's") have immerged challenging their passive iterations (if they exist as such as well) to come out victorious and at a favorable price, and that's something to cherish. These however are usually compact designs for smaller to moderate spaces, and don't escape the limitations of physics imposed on them. Fortunately active configuration can had with large, eff. speakers as a solution of separate components, but this does require some tech understanding (that can be learned) with DSP's and setting up cross-overs, if they aren't pre-configured. 

@audiokinesis --

Now imo there are definitely some qualitative advantages to that higher efficiency, but in my experience the market for eight cubic foot speakers is rather limited.

Anyway my guess is that the higher costs and the box size penalties attached to high efficiency are the primary reason why low efficiency speakers dominate the marketplace.

What's particularly interesting with high eff. larger speakers, to me, is that simplicity can be maintained when incorporating horns or waveguides fitted to compression drivers, and thus avoid some of the complexity issues that face low(er) eff. larger speaker designs. A 2-way high eff. design can be had with fairly large woofer/mids crossed to a horn/waveguide with very nice power response in the XO-region, though needing subs augmentation. I use such a configuration myself, now awaiting new horns from ~700Hz on up with a mouth area of some 2 x 3 feet for controlled directivity, if needed, down to 500Hz for a smoother transition to the dual 15" drivers below; coherency is paramount, and in conjunction with high eff. and sheer size is an intoxicating trait. 

Fortunately it's up to each individual to pursue the advantages afforded through high eff. and size, even if it isn't popular, and it mayn't be expensive. 
I don't know how to quote posts, but in reading this, I hope all have read what Tomic601 has posted above.  It answers a lot of why some top designers have lower sensitivity speakers, but are still very easy to drive, even with lower powered tube amps.  

Vandersteen and Theil are time and phase correct and due to what Tomic said about pistonic drivers, speakers like Vandersteen's will be lower sensitivity.  
Post removed 
there is plenty of money in a $50k plus speaker for fine drivers with best available energy in the gap Ralph, actually make that $15 k for Vandersteen Quattro, throw in built in subs w 11 bands of EQ and an easy to drive load

One reason why Thiels don’t sound like Vandersteens, before the Mafia attack, I own both. BOTH. and Panels that store energy, electrostatics that sound like transformers....etc...

its a brutal truth, move the accuracy ball forward or flavorize. Just know what your religion is...ha.

enjoy the music....


nwres I could have said one designer at least gives you lower distortion with lower sensitivty as a byproduct AND an easy load. Since 1977.
do give some thought to the amp and speaker designer engineering an easy load and then further optimizing the amp for that load....just 5 parts in the signal path...

and for the measurement camp, both measured by JA

and for the flat earth science denial sect, he loved the sound.
@lalitk,
Agree many worthwhile advantages to higher efficiency/sensitivity speakers. It does seem that to design and build this type of speaker requires a certain degree of effort, thought and implementation. Well worth it in my opinion. To be able to utilize a high quality but lower power amplifier (With simpler circuit/signal pathway)  is a very good option to have.
Charles
@phusis wrote:

"What’s particularly interesting with high eff. larger speakers, to me, is that simplicity can be maintained when incorporating horns or waveguides fitted to compression drivers, and thus avoid some of the complexity issues that face low(er) eff. larger speaker designs. A 2-way high eff. design can be had with fairly large woofer/mids crossed to a horn/waveguide with very nice power response in the XO-region, though needing subs augmentation. I use such a configuration myself, now awaiting new horns from ~700Hz on up with a mouth area of some 2 x 3 feet for controlled directivity if needed, down to 500Hz for a smoother transition to the dual 15" drivers below."

This is almost exactly what I’m working on, and had hoped to introduce in 2020 but... stuff happened that year...

Anyway I designed a large-format Oblate Spheroid waveguide using Earl Geddes’ equations, like you targeting a 700 Hz crossover to twin 15" midwoofers. That 700 Hz figure is consistent with the findings of David Griesinger which Geddes subscribes to, and is very close to the 800 Hz crossover that Greg Timbers uses in the JBL M2. Imo the ability to cover the spectrum from there on up with a single driver is a major advantage over more "conventional" approaches, in addition to the other advantages of large drivers and high efficiency.

And of course the way around the bass extension/box size/efficiency tradeoff relationship is to hand off the bottom couple of octaves or so to subwoofers.

I’m rather surprised by how similar our approaches are. I knew we were barking up trees in the same forest, but didn’t realize it was the same tree!

Duke
Speaker sensitivity has little or nothing to do with sound quality. High or low sensitivity speakers are merely two different paths to same destination. Matched with the proper amplifier, either have the capability to produce satisfying sound quality. Of course, some will do this better than others but there are many variables much more important than a speaker's sensitivity.
Duke - IF you can say, are you 3D printing the waveguide ?

best to you in 2021

Jim
bdp24,

I agree with you about the relative merits of Soundlab electrostatic speakers vs. the Altec Voice of the Theater speaker.  The Altec tonal coloration is way too unnatural for my taste as well.  At one time I considered buying Soundlab speakers.  But, while most of the commercially available compression driver systems suffer from too much tonal issues for my taste, I've heard many custom systems that sound very good; I ended up with such a system.

I feel the same way about many other high efficiency speaker types, such as full range single driver systems.  I ultimately don't like their tonal balance and rough frequency response (notable exceptions are Charney Audio and certain Voxativ models).

I like some systems that use "fullrange" drivers as wide range drivers in multi-way systems.  In some, a woofer supplements the fullrange driver, in others, a tweeter is added on top.  An example is the Soundkaos Model 42 (fullrange driver plus a Raal ribbon tweeer on top).  My favorite system utilizes an old Jensen M10 fieldcoil driver (13" fullrange driver) in an open back cabinet (open baffle) operating full range, but with a first order high pass crossover to a tweeter supplementing the single driver (the system I heard had a Jensen RP 302 tweeter, but, I am told that a Western Electric fieldcoil 597 driver is better).


Pa speakers are much more sensitive than hifi speakers, but produce more ditstortion and do not have the same frequency range. To compensate they require active filtering and subwoofers. Making a sensitive speaker isn't that complicated: a woofer with a stiffer suspension (= less lower frequency) and a compression horn tweeter (= more distortion). A pa speaker with the sensitivity of an average  hifi speaker would require a truck full of amplifiers to achieve the same decibels. That's why in sound reinforcement only the max db level of a speaker is most  important. for each 3 db more, the amplifier power has to be doubled!
@larryi,

You may wanna add Tannoy Canterbury Prestige GR speaker to your list of speakers that has exemplified themselves in achieving excellent tonal balance from a single driver.

The Canterbury’s sports a 15-inch dual concentric single chassis driver that incorporates two separate drive units, integrated into one. If you like, you can further read about the merits of dual concentric driver on Tannoy website. Here I wanted to express briefly, the frequency response from 15” driver is pretty flat throughout the entire audible frequency range. The Canterbury’s are excellent speakers capable of delivering very detailed, integrated, dynamic and warm sound. I also dig their traditional look with exquisite birch plywood cabinetry and champagne gold metalwork :-)
@tomic601 asked:  

"are you 3D printing the waveguide?"  

No. I looked into it and concluded that was impractical. The piece is 22" in diameter.

Duke
Aside from your personal likes dislikes in speakers the main advantage of Highly efficient speakers (> 95 dB  with 1 watt at 1 meter) is the greater dynamics that can be achieved.  Doubling the power of your amplifier will only give you a 3Db gain in SPL.  Lets take a look at the power requirements for a couple of speakers,  Setting the max SPL at 116 Db. the B&W 603 S2 is rated at 88.5 DB @ 1 watt input.  To produce 116 Db you will need a 1Kw amp.  My old Altec A7-500's are rated at 103 Db at 1 watt and can Produce 116 dB with a little over 16 watts.  To my ear this is why some speakers sound muted/sluggish on rim shots and other sounds that require fast response.
disclaimer the math is approximant but close. My personal system uses a set of speakers that are rated at 84dB at 1 watt and my power amp is rated at 1Kw RMS and tests to 1.1 Kw/channel both channels operating..   I can only say that switching from a MC2100 to the larger amp was like cleaning a dirty windshild and bass is tight as a drum pun intended.
I have yet to hear the OB speakers Danny Richie offers in his various GR Research kits, but they are pretty darn sensitive (mid-to-high 90's) and are reportedly very transparent, natural at timbre reproduction, and dynamic as well. As soon as social interaction is again possible, I plan on inviting myself over to the Portland home of the Audiogoner who owns the NX-Otica (I think), which he pairs with the Rythmik/GRR OB/Dipole Sub, which I too built.