Building an ultimate low power class A amplifier – my way

Distortion
At several watt levels, this amplifier has only very low H2 + H3 and all higher order harmonics are some 30 dB down. Low distortion is maintained up to the clipping level.
I can see that you are using coherent averaging. I am sure that you know that this method makes FFT plots look better than they really are, regarding noise floor. It still measures (THD and THD+N numbers) properly, however an inexperienced reader may be fascinated by the low noise floor, which is both false regarding noise density and mains spuriae.
 
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Yes, I know and that’s why amplifier's noise floor was measured by the proper method (post #4). I implore anyone to point out an amplifier with lower output noise. Noise floor is about 25 nV/rtHz.
Not to mention that considerable part of measured noise is not form the amplifier output, rather by EMI incursion into non professional level measurement gear.
Coherent averaging was used to reveal low high order distortion harmonics. Check post #423. 🙂
 
TTA004B/TTC004B - What characteristic(s) makes these better devices than some others?


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Did you measure the THD on the real amp?
Of course.

Is Lateral Mosfet actually better than BJT?
I’m sure you know that there is no general answer to that, rather it depends on application and design.
For this specific design, lateral MOSFETs were superior to BJTs. The same design, only with a CFP output was actually built, listened to and measured.