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
Phusis, I would bet there are a host of SS amps that would handily out perform any SET amp. Any small class A Pass amp for sure. JC1's definitely and most probably all of Atma-Sphere's amps. Like trying to race a 911 in a VW Bug.
@atmasphere --

I have. The Classic Audio Loudspeakers are **easily** in the same league. If I had to compare, the CAL is a bit smoother, owing to a better interface between the throat and horn, resulting in far less artifact. The field coil compression driver is also a higher performance bit of kit.

I would expect no less of the T3’s, or CAL speakers overall. The DD67000’s are great speakers, and somewhat better than their smaller K2 S9900 sibling than I initially thought, but there’s a shred of "splashy-ness" to their midrange than when not there lends a smoother imprinting, as you point to with the CAL’s. What are the T3’s sold for - close to $100k? Re: mentioned "better interface" it reminds of what Simon Mears told me of the importance of the coupling between the compression driver exit and the throat of the horn it’s mounted to; transition, transition, transition - as he put it.

@mijostyn --

Phusis, I would bet there are a host of SS amps that would handily out perform any SET amp. Any small class A Pass amp for sure. JC1’s definitely and most probably all of Atma-Sphere’s amps. Like trying to race a 911 in a VW Bug.

"Outperform;" per your ears or more from a theoretical perspective? And in what context of speakers? SET’s, great ones at that, are dependent on very high efficiency speakers (and not too heavy an overall load) to perform their best, at least from my chair. Paired properly as such I find the combo is magical, or just rather natural and uninhibited sounding. I suspect most haven’t really auditioned them in the context I refer to, and if they have the speakers here (typically all-horns) may been so far from their usual sonic menu that an assessment would veer closer to their imprinting, and not the amp(s). Myself I certainly can’t complain using a variety of SS-based amps in my set-up, but I wager a substantial aspect of this rests in it being a fully active configuration.
@phusis, yes, my set up is fully active but you could never use SET amps in my system. I really require big amps. I was talking in the context of very efficient speakers. SET amps are very romantic and if that is what you like then by all means but a class A SS amp particularly a Pass or Curl design is going to be more accurate, have more control over the woofer and still have a little of the romance. I would also rather buy records than $1000 tubes.
Costs for high-eff drivers are greater, Size high- eff designs are larger can cost more to build ship take up more room at dealers and distributors. And I will also add that buyers don't want changes. And they have been told for decades that all horns are problematic and they bought the line that small is better. Face it would you buy a toaster that was better than others but was larger and looked not like a toaster? We are simple tools and want to blend in and conform with others not to stand out.
What are the T3’s sold for - close to $100k? Re: mentioned "better interface" it reminds of what Simon Mears told me of the importance of the coupling between the compression driver exit and the throat of the horn it’s mounted to; transition, transition, transition - as he put it.
@phusis As I understand it, my speakers are currently about $33,000/pair. Mr. Mears is correct. The coupling was optimized on a computer and the result is very smooth and seamless. People often comment on hearing T3s (and T1s) that the speakers sound more like ESLs in that they are so fast and seamless. IOW no ’horn artifact’ at all.


Regarding the SETs, IMO/IME their main advantage is that as the power is reduced, the distortion decreases linearly to unmeasurable. This is important because (to trot out an old expression) it really is all about that first watt. But just so you know, this character is not unique to SETs, although it is rare in push-pull amplifiers. But you can imagine since I’m writing this that I know of a few amps which share this important characteristic. But one **disadvantage** of SETs is that their primary distortion product is the 2nd harmonic, as well as low power and troubles making bandwidth due to the output transformer.


Now we all know that the 2nd harmonic is innocuous in that the ear is insensitive to it (and because the ear converts all forms of distortion into tonality, it assigns the quality of ’warmth’ and ’bloom’ to this one). However, the ear assigns this same quality to the 3rd harmonic as well, but there is an important distinction. Circuits that have a 2nd harmonic as their primary distortion product mathematically have what is known as a ’quadratic non-linearity’. Its not so important to know the math, but if you feel like working it out what you will see is that harmonic orders above the 2nd decrease rather slowly as compared to a circuit that has a ’cubic non-linearity’ (produces the 3rd as the primary distortion component). An amplifier that has this quality has its distortion decreasing much faster as the order of the harmonic is increased! This is important since the ear uses higher ordered harmonics to sense sound pressure (and assigns the quality of harshness and brightness to them). IOW, an amplifier with a cubic non-linearity will sound more detailed (because distortion masks low level detail) and **smoother** because the higher ordered harmonics are at a lower level.

In terms of circuit design an amplifier with this characteristic must be fully differential and balanced from input to output. In this way even orders are cancelled with each stage in the amp (instead of being compounded), leaving the 3rd as the primary distortion component, at about 1/10th what you would get with a single-ended circuit, assuming that neither employs any feedback.

Now if you mix single-ended and push-pull, you wind up with a prominent 5th harmonic in addition to a 2nd and a 3rd (put another way an amp like this has **both** cubic and quadratic non-linearities). This is why many people prefer SETs, but those same people find that if they hear an amp with similar concepts (triode, class A, zero feedback) executed fully differential, that it has all the desirable properties of SETs without a downside. BTW this difference is easy to hear (its not subtle) and of course its also easy to measure.