The tests we typically use to characterize audio amps is very different from what people have tried to do to capture the intricacies of something like a classic soft-knee optical compressor with tubes and transformers in the signal path. People have tried alternating bursts of various amplitude sin waves over steps of ranges, and over steps of frequencies, and come up with ideas like dynamic convolution to try to reproduce what the compressor does in the digital domain. Never heard one that nails it. Of course, we don't expect such complex behavior from an amplifier, in large part because we have convinced ourselves that we understand amplifiers a lot better than vintage compressors. That is, we have a mental model of all the stuff an amplifier can possibly do in any situation, and we firmly believe the model to be complete. Well, except for JC and a few others. Having scientists and engineers who are firmly convinced their models are correct and complete later find out, "Oops!, there is a little something else," would be nothing new. It's happened before, and when it does, the true believers often have to be dragged kicking and screaming into the new reality. There is something about the human mind that often tends to demand certainty of beliefs. To have matters be settled and finalized. It can be hard even for reasoned scientists to overcome, much more difficult for others. I will sit on the fence on the amplifier distortion issue. I'm not ready to say that every unexplained thing some people claim to hear can be properly attributed to imagination, with the emphasis on properly.
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some of us do read Psychoacoustics, search for hints in perceptual loosy codec design, read pro mixing guru's like Moulton, Ludwig, Katz blogs, books...
and some of us also know EE, Signal theory and the evolution, approximate current SOTA of available electronics
the past few decades have seen ADC/DAC tech go from being clearly not up to the challenge of Pro Audio at the beginning of the CD era
to today (> 3 decades later) where -120 dB "all error" including THD, Spurs, IMD can be found in best in class monolithic ADC/DAC for Medical Imaging at 18-20 bits, MHz sample rates
when these are combined with recent process Vertical, Isolated, SiGe, input linearized op amps designed for the same 100s of kHz to Mhz demands we can look at numbers with ridculous resolution, test theories of Signal deterioration in markets that don't care about anything but pure objectively demonstable result
turns out that there simply aren't the problems in these ISM applications with many factors higher resolution, accuracy demands than Audio that some of our Audio Gurus pontifications would have you expect
the "room" for "unknown, unknowns" in Signal processing electronics in Analog and Digital domains have been, are tested in real world hardware, pushing previous Measurable boundaries
and left behind the most sensitive extrapolations from acutal Psychoacoustic controlled listening tests quite awhile ago
and some of us also know EE, Signal theory and the evolution, approximate current SOTA of available electronics
the past few decades have seen ADC/DAC tech go from being clearly not up to the challenge of Pro Audio at the beginning of the CD era
to today (> 3 decades later) where -120 dB "all error" including THD, Spurs, IMD can be found in best in class monolithic ADC/DAC for Medical Imaging at 18-20 bits, MHz sample rates
when these are combined with recent process Vertical, Isolated, SiGe, input linearized op amps designed for the same 100s of kHz to Mhz demands we can look at numbers with ridculous resolution, test theories of Signal deterioration in markets that don't care about anything but pure objectively demonstable result
turns out that there simply aren't the problems in these ISM applications with many factors higher resolution, accuracy demands than Audio that some of our Audio Gurus pontifications would have you expect
the "room" for "unknown, unknowns" in Signal processing electronics in Analog and Digital domains have been, are tested in real world hardware, pushing previous Measurable boundaries
and left behind the most sensitive extrapolations from acutal Psychoacoustic controlled listening tests quite awhile ago
John if you actually wanted to develop the mathematical chops to actually discuss this stuff it would be nice. I'm not that much younger than you I have no problem.
That may be. But most here don't have access to the most sensitive test equipment. In some actual circuits people build and that are sold commercially, there may be unknown quality issues. Also, sometimes in such circuits op-amp rolling produces audible results. Now of course, sometimes it should, the op-amp substitutions are silly. But other times not so silly. Maybe what's left is that there may be unknown layout, passive component, power, or other issues in some of these circuits that produce results that are subtly audible, and would measure so if test suitable test equipment were available. We don't know, because very few are equipped to measure and verify designs, builds, commercial products, etc., to, or near to, the state of art. So where do we go from here?
I am only reporting my listening experience, coupled with Richard Heyser's comments. I can do most of the math.
Agreed, but not universally. In the absence of test equipment, there is nothing else left but to listen. In the presence of audible distortion, for judging if the distortion sounds good or not, its hard to see how listening would not be essential.
Alternatively, the status quo may be more important for some than making progress. It wasn't for lack of evidence that they torched Giordano Bruno.
I'm not sure that was a status quo related issue. It likely had to do with things that we are not supposed to delve into too much here in the forum. The book, "The Righteous Mind" is highly recommended though, for those wishing to see a social science and evolutionary biology examination of the issues.
An interesting thought.
Question - it seems that based on the description in the second paragraph that one could use bandwidth limited "sources" to provide two or more sinewaves per the above, and then have an envelope with infinite bandwidth??
So, how does this differ from the various bandwidth limited signals intermodulating now in any given audio amplifier?
Clearly, one could record two sinewave or sine-like signals and play them back. But does the fact that they are coming from a single source, premixed differ from the case where they are fed and then mixed?
How about if one records two flutists (on purpose) and does the same thing?
_-_-
I also perceive a more general one across the audio industry. There is this mantra that we could reach acoustic zen through faithfully reproducing "the recorded material", down to the last detail, "as the recording engineer intended it". And that our insatisfaction with certain materials / equipment comes from the inability to reach the proper level of faithfulness. And the cure, as proposed by the industry, is "more faithfulness", through even more expensive equipment.
But guess what, it doesn't work as advertised. I once mentioned here that the easiest way to reach that "faithfulness" would be to buy the exact equipment that the studio has used. Bear dismissed it as a joke, however I am the living proof of that experiment. I happen to own the exact equipment, down to the make of cables, as one of the recording studios in Toronto had (and probably still has) in their audition/evaluation room (where they invite the artists etc for a final check of the master). (by now you probably have guessed the B ininitial in the brand name). Well I bought a few of their records and guess what - I wasn't floored, nor did they sound consistently better than those of other studios. I still felt the need to fiddle with the tone controls, except that the mentioned equipment doesn't have any.
the ongoing category error - perception vs accurate recorded signal reproduction
really is boring to see "realism", perception brought into the conversaiton so naively
if you are serious about "hearing like the mastering engineer" then you should have the Smyth SVS Realizer, personal HRTF calibrations at your favorite Mastering Studio mixing desk: http://www.smyth-research.com/
really is boring to see "realism", perception brought into the conversaiton so naively
if you are serious about "hearing like the mastering engineer" then you should have the Smyth SVS Realizer, personal HRTF calibrations at your favorite Mastering Studio mixing desk: http://www.smyth-research.com/
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Regarding faith, the preservation of purity (and original intent), and so on, again, I would refer those interested to "The Righteous Mind."
On the topic of the equipment used by the studio, unfortunately what you finally get to hear is what comes out of mastering. That may include transfer from tape to CD. Thus, the CD or vinyl you buy may or may not sound a lot like the studio product, despite your present equipment choices. Sometimes what comes out of mastering sounds better than the studio product, and sometimes not. In any case, the last guy to touch it, the mastering engineer probably used a very sophisticated playback system in a specially designed room. Very costly for most folks. Above my budget for sure.
Back in the days I was interested, but I've since learned that it doesn't matter. BTW I did visit a few studios and I'm aware of what's going on. Unfortunately those that should really have a look at the chart aren't doing it or are pretending it doesn't exist or that the measurement method was faulty etc.
Well, you know there is the question as to how those apparently varying frequency responses of those installed Genelec monitors is perceived? I'd bet that to someone experienced to listening to that model Genelec day and night that in any of those control rooms (within reason, things like reverberation time, and the like considered) they'd hear the sound as "Genelec" sound.
The other thing you need (I suppose) is a big slab of wood/aluminum immediately in front of you, with protuberances of the proper dimension to reflect and diffuse the sound reaching your ears? I propose that all serious listeners have such a thing made or installed forthwith!!
The other thing you need (I suppose) is a big slab of wood/aluminum immediately in front of you, with protuberances of the proper dimension to reflect and diffuse the sound reaching your ears? I propose that all serious listeners have such a thing made or installed forthwith!!
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