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.