Did Amir Change Your Mind About Anything?

@mahgister Actually, I just read a bunch of van Mannen for fun. Luckily I have both a BSEE and MSEE in information theory and signal analysis, thus feel somewhat competent to comment a bit (though I prefer a much more reserved approach to science and engineering). A key point he mentions is that sinusoidal signal sweeps don't fully characterize the frequency response of, say, an amplifier, because of some theoretical requirements. Linearity is one of those requirements and there are all kinds of nonlinear things going on in real systems. Indeed, the effects of nonlinear transfer functions can be quite interesting and require very interesting mathematical tools. But, really, it's what we call distortion.

So, if an amplifier designer is trying to create a great amplifier, what should she do? She could test using sinusoids and try to reduce distortion and noise in her design or she could do....what...exactly? van Mannen has concerns about feedback topologies as well, but still, other than trading-off options, she still will want to test using the best tools she has in an effort to reduce noise and distortion.

Thanks for you interest...

For sure you know better than me to analyse what he want to do...

bUt human hearings is sensible to some harmonics positively and not to some others so much positively  for example...  The tonal perception is heavily influenced by harmonics , Van Maanen explain in his paper how the fact that human hearing is time dependant help him to design in a better set of trade-off his own circuits..

I read it because of these application from the Oppenheim and Magnasco experiments revealing after 60 years of investigation that human herings cannot be reduced to spectral analysis alone  nor to any linear Fourier inspired theory ... van Maanen used that in his design trade off and you are best equipped than me to understand HOW PRECISELY he did it...

i used his articles as contradiction of the claim by Amir that linear measures of gear are enough... Amplifier must stay in linear control but the direction toward a better sound is possible only if we understood the non linear way hearing perceive sounds..

Reducing noise and and controlling distortion not only reducing them is always a goal ...  But it is half of the task ... The other half of the  task is designing  circuits more susceptible to please and inform the human hearings who do not work as a Fourier engine at all... The Fourier engine must serve hearings not reduce hearings to its mere linear workings in a time independant way... Ears perceived real physical invariants in the real world and analyse them non linearly in a time dependant way, no fourier approach can explain it ..¯ Van Maanen is conscious of that and use it as inspiration for his  complex design... Why did he call his design "TIME COHERENCY " ? you know enough about electronics to connect the dots better than me here  ... 😊

One thing is sure Van Maanen nor Magnasco and Oppenheim will mock people trusting their hearing acquired biases and training as deluded... They are in science first  not first  in marketing of gear or marketing of tools...

Thanks very much for your interests ...

@mahgister Actually, I just read a bunch of van Mannen for fun. Luckily I have both a BSEE and MSEE in information theory and signal analysis, thus feel somewhat competent to comment a bit (though I prefer a much more reserved approach to science and engineering). A key point he mentions is that sinusoidal signal sweeps don’t fully characterize the frequency response of, say, an amplifier, because of some theoretical requirements. Linearity is one of those requirements and there are all kinds of nonlinear things going on in real systems. Indeed, the effects of nonlinear transfer functions can be quite interesting and require very interesting mathematical tools. But, really, it’s what we call distortion.

So, if an amplifier designer is trying to create a great amplifier, what should she do? She could test using sinusoids and try to reduce distortion and noise in her design or she could do....what...exactly? van Mannen has concerns about feedback topologies as well, but still, other than trading-off options, she still will want to test using the best tools she has in an effort to reduce noise and distortion.

Amir is a great messenger of science! Thank you very much Amir!

I forgot to say that you missed a point about Van Maanen...

A key point he mentions is that sinusoidal signal sweeps don’t fully characterize the frequency response of, say, an amplifier, because of some theoretical requirements.

He said as a physicist that a sinusoidal continuous signal dont act on the circuits of amplifier as a Sudden variable  dynamic burst of music , then as you said the frequency response of a circuit cannot be predicted adequately under this kind of linear continuous signals... He then designed his circuits in a way for them to be able to reacted and be more linearly predictable under REAL MUSICAL BURST...

Correct me if i am wrong... it is what i remember...

@mahgister Fair enough. Having also worked on studies of human subjects in later careers in technology, I can assure you that subject reports are clouded by an enormous range of biases, expectations, timing effects, etc. Amir goes into the problem of performing even simple tests to distinguish systems and how challenging it is, so I have strong doubts about the subjectivist-style claims and how intellectually honest those folks are!

I just don't see any downside to leaning heavily into objective tests. I've only seen poorly-designed tests (often headphone tests are impacted by problems with the ear cups, for instance) that were problematic.

Anyway, I learned some new stuff today! Always a good day...