How close to the real thing?

This is incorrect. The Ampex 351 tape machine, used by both RCA and Mercury (and a host of others) has a zero-feedback recording circuit. Neumann microphones use small tube preamps which are zero feedback. I can go on but you get the point.

Sorry Atmasphere, but you're mistaken - recording, mastering, and broadcast equipment all does indeed use a variety of "feedback design techniques and circuitry, going back to almost the very start of electronic recording," as Fas42 states. Specifically, the Ampex 350 and 351 used frequency-dependent negative feedback in the cathode circuit of the record output tube, and negative feedback around the playback head amplifier for playback EQ. Additionally, the 351 had a push-pull (12AU7?) transformer-coupled line-output amp with a separate feedback winding for global NFB, very similar to a little transformer-coupled power amp.

And then there's the record cutting lathe - virtually all high-fidelity cutting heads use negative feedback from a separate winding to provide global negative feedback from the motion of the cutterhead back to the cutting amplifier.

I think the most interesting aspect to the original poster's question is the fact that it forms the logical basis to objectively improve our art - that is, "Does it sound real?" is actually a falsifiable question. The answer is definitely highly dependent on an unfathomably large number of personal differences in perceptional acuity . . . but one can always ask oneself this question and come up with a relevant answer. So the main thing we *should* be striving for in the technical studies of audio (i.e. measurement and controlled listening tests) is repeatability.

For reading on some of the logical basis of falsifiability, I'd recommend starting with the work of Karl Popper, or at least his Wikipedia page:
http://en.wikipedia.org/wiki/Karl_Popper
http://en.wikipedia.org/wiki/Falsifiability

Under the logic of falsifiability, it takes just ONE instance of having experienced reproduced sound as being real . . . to validate the conditional plausibility of all the technical and methodological basis for its reproduction. Not that the reverse isn't true as well, but if "reproduction" as an abstract is the goal, then at least for me its occurrences are much more noteworthy than its absences.

Here's the problem I have with setting up camp in any of audio's little belief-systems (i.e. tubes/transistors, cones/panels, feedback/no-feedback, analog/digital, etc.). If I'm truly honest with myself, I have at times been dumbfounded by amazing experiences from really crappy stuff, and also underwhelmed by my experiences with some really beautiful machinery.

And since audio is really a trivial pursuit (no lives at stake, no big "origins of the universe" questions), I view the the craft of audio thusly (my quote):

To examine a wide variety of data from both measurement equipment and listening experiences, and establish correlations that logically fit as much of the data as possible . . . then assume causality based on well-established principles of physical science.

This is why I think audio is so interesting in general -- we get to explore a truly genuine frontier, consisting of abstract and profound questions of the limits of human perception in sound and music. We also get to explore many aspects of human psychology in the listening process, and sociology in the marketplace and hobbyist communities. And really, the assemblages metal, wood, plastic, paper, and whatnot that we fashion to this pursuit are not really so profound . . . after all, it's all going to be in a landfill in a couple hundered years at the very most.

Atmasphere, here's the main reason why I'm so routinely perplexed by your dogged determination to proselytize the whole anti-feedback thing . . . What do you do when you have an amazing experience listening to music through a system, and THEN learn that it's a solid-state amplifier using a pile of global NFB? Because it's happened for me often enough that I can't imagine it hasn't happened at least a few times to anybody that's made a career in audio.

The system was entirely solid state. The format was a digital reel to reel, 1/2" wide. I really did not hear the system, it was only the experience of the music. So what would it have been like if it was 2" analog with my amps on each speaker? Hey, maybe it would have been better.

Atmasphere, I'll admit I don't quite know what to make of this. Although I respect that you have sufficient confidence in your design approach that you feel your products could ALWAYS make a subjective improvement over anything else, it seems that your judgement (or at least your recollection) of this particular experience is totally dependent on your knowledge of the technical matters of its presentation.

This is what I would call a "Maggie Blackamoor" conclusion, after the character on Little Britain: http://www.youtube.com/watch?v=hUpHDtpoY9w

But since I brought up the subject of scientific philisophy (and also to avoid at least a bit of the well-trampled "NFB argument" road). . . to be a bit more precise this would thought of as a plainly "coherentist" argument. That is, the truth or validity of a given conclusion is based upon how coherent it is with an existing perspective or set of beliefs. For the coherentist, the method by which a theory is refined (made more precise) is when data is presented that incoherent with the current belief system, the belief system is revised to restore coherence with new data.

But the logical problem is obvious, it's the same with all theories of justification: it fundamentally relies on one's intellectual "concience" to formulate ideas that evolve beyond one's own belief system. In the field of audio this is particularly problematic, becuause our understanding of many of the perceptual and psychological mechanisms lags far beyond our practical understanding of the physical science on which our technology is based . . . technology that we so routinely use to (attempt to) fool these perceptual and psychological mechanisms.

But we can also see from this line of reasoning that the traditional audio "objectivist" arguments have NO better grounds in modern scientific practice than the "subjectivist" . . . they are both in actuality simply "justificationist". It's simply that "objectivist's" belief system usually can't include a reality outside simple regurgations of common-practice electrical analysis found in an average undergraduate EE textbook, and the "subjectivist's" belief system is so fundamentally undisciplined as to be able to include some really silly, wacky sh*t.

Atmasphere, maybe I did miss your point, but I did re-read your post . . . and I think my quote was verbatim. But the logical problem remains -- I'll see if I can't address it first via Mapman's quote:

Human ears (and brains)are complex sensors and information processors of an order far exceeding science or technologies ability to model exactly.

Given this truth, any hypothesis regarding being able to accurately predict the outcome of an individual's listening experience based on science alone, even in a properly executed scientific experiment or series or experiments, has to come into question.

This argument is closely akin to Progress ad Infinitum, one of the tropes of skepticism as outlined by Roman philosophers (Sextus Empericus?) in the first century A.D. . . . that is, anything that can be regarded as proof must in and of itself be proved, on and on to infinity. So under this line of thinking, knowledge in and of itself cannot advance or become closer to the truth . . . leading to the trope of Assumption, that all scientific knowledge is merely theory and not truth.

But our entire craft of audio is among countless obvious artifacts that indicate that our knowledge of the physical world is indeed expanding and becoming more precise, thus closer to the truth. Karl Popper dealt extensively with the logical basis for this through his concept of "verisimilitude", or the extent to which a scientific theory resembules the truth.

It is through this concept that we can look at the evolution of ideas from Copernicus, to Galileo, and to Newton . . . with today's knowledge that all their views of the physical world were false. But each of them was able to formulate ideas with greater verisimilitude, building on the work of those that preceeded them. And for the original topic of this thread, I think it's indeed undeniable that our ideas about the understanding of sound perception and reproduction have greatly increased in verisimilitude, and gotten us closer to the truth . . . especially when viewed over the span of the last 150 years or so.

It is on this basis that I fundamentally disagree with the popular audiophiles' notion that Mapman articulated. We can indeed use science to predict the outcome of an individual's listening experience, even though the extent to which we can is still significantly inconsistent and variable. But we are continuously improving our ability to do so, as the logical result of our scientific theories ever evolving toward increasing verisimilitude.

My point to Atmasphere is this: as people involved in the design and manufacture of artisan audio equipment, we are of course required to evaluate the "truthiness" (Stephen Colbert's word) of the performance of our own, and others', equipment. And we then use such an asessment to determine the verisimilitude of our theoretical ideas.

It's my impression from many of your past postings that there are a handful of conceptual errors in your understanding of the traditional application of negative feedback and its Nyquist stability criteria . . . to the point that a discussion of the associated theory and measurement performance is moot.

But I (very respectfully) remain curious as to whether or not you've ever had an auditory experience that pegs the needle on your own personal, internal "sonic truthiness" scale? And has it ever been delivered by equipment that has a design approach that's incongruous with your own? (Please note that the phrase "pegs the needle" is an important one, meaning that at the time of the experience, an experience closer to the truth cannot be imagined and/or is simply irrelevant).