Textbook theory is very often just a shortcut. When people say something like In theory, it should happen like this . . . , what they actually mean to say is, In the very first approximation, on a basic level, this is how it should go. Thats oversimplification, not theory. Real theory isnt so simple.
It is like you say: in theory, cables shouldnt make any difference. Well, hang on. Does that imply that youve actually looked at all of the established textbook physics that explains exactly what happens within a cable? I dont mean new physics, like microdiodes or what have you . . . but, really, all the things you know happen when you, for instance, intersperse two conductors with a dielectric between them. How will that behave, for instance, when you actually put it up in a listening room and subject it to the vibrations that are caused by the speakers -- the triboelectric effect? Or just ordinary electromagnetic noise pickup from nearby mains cables? All these things are entirely known by physics and fully understood by theory. But the people who say that in theory it shouldnt matter, they just look at one small corner in one particular textbook, where it doesnt mention all these other things.
Usually, where theory and practice deviate, it just means that your theory hasnt gotten into enough theoretical detail.
So far, I have not yet bumped into anything in terms of audible differences that I, or anyone with me, could hear that did not at some point connect with established theory and known physics -- by which I mean ordinary street-level physics, none of your fancy quantum stuff. You really do not need to invent laws of physics from a parallel universe to explain things. And you dont have to excuse yourself to say that theory does not connect with practice. If you look close enough, you will find [the connection]. If practice and theory seem to deviate, you better have a sharp look at your theory.
I very often have to invent new measurements on the fly when I suspect there might be something going on that doesnt show up clearly on standard measurements.
To give one example, you could take a DAC and do something very classical, like sweep the level of a sinusoidal signal from full scale to nothing, and then look to see how distortion changes with signal level. You might find some minuscule squiggles at lower levels and shrug them off as measurement errors, like, OK, that is just the machine not correctly measuring noise. But I got suspicious at some point and said, Hang on, let me try to find explicitly whether something happens in the noise floor with the signal modulation, but then I have to do so without a signal present. How do you do that? Well, you sweep a DC input to a DAC. You feed it a constant code, some small value, and measure the noise. Increase that code and repeat. Suddenly youll find that some of these D-to-A converters will do these frightening things, like the noise floor suddenly shooting up or an audible whistle actually just walking through the audioband as you sweep, going from supersonic down to zero and then back up. You have to be creative when you measure, not just do the standardized battery.
Its a bit like real science. When you have a scientific hypothesis, what you do in order to make it stick is try everything you can to push it over, and only if it doesnt topple, then it might be correct.
Same thing in audio -- if your hypothesis is that this particular D-to-A converter is a really good converter, then youll test it, and youll measure, and youre actively going to look for bad news. If, after not finding any bad news despite how hard youve tried, then you can start to say this is probably good. That simple example shows that, very often, the standard measurements might simply cover something up that is very measurable and very glaring, but just happens to be under the radar of regular test methods. You might then have this DAC which listeners feel has a shine, that puts an unnatural shine everywhere, and then suddenly you find this noise modulation when digging deeper, and you realize that might be the answer for why.
It is my experience -- confirmed by every new thing I do -- that when you get into really high measured performance, really low distortion, superlow noise, then the ultimate subjective sound quality starts improving and continues to improve in step with the measurements. At some point you will find that a product that measures absolutely perfectly under an extensive battery of tests will sound a lot better than a product with more typical high-end audio performance that has been tuned by ear for years. The upshot is that measurements do matter. The way you should translate this into a development process is not to listen and tweak your circuits, but rather to measure and adjust, measure and adjust, and then listen. If, at that point, something sounds off or is not quite working, that tells you something about what and how you measure. You calibrate by ear your set of measurements and the methods by which you measure, but you optimize your circuit by measurement. That is much more logical. You should take science to the absolute limit and crosscheck your scientific, technical procedures with what you are hearing, to make sure youre not forgetting anything. The purely technical road in the end will yield a circuit that really sounds better than what you can get by mere philosophy and tuning parts. Start shooting for fantastically low distortion, fantastically low noise.
- http://www.ultraaudio.com/index.php...s-of-mola-mola-hypex-and-grimm-audio-part-one
It is like you say: in theory, cables shouldnt make any difference. Well, hang on. Does that imply that youve actually looked at all of the established textbook physics that explains exactly what happens within a cable? I dont mean new physics, like microdiodes or what have you . . . but, really, all the things you know happen when you, for instance, intersperse two conductors with a dielectric between them. How will that behave, for instance, when you actually put it up in a listening room and subject it to the vibrations that are caused by the speakers -- the triboelectric effect? Or just ordinary electromagnetic noise pickup from nearby mains cables? All these things are entirely known by physics and fully understood by theory. But the people who say that in theory it shouldnt matter, they just look at one small corner in one particular textbook, where it doesnt mention all these other things.
Usually, where theory and practice deviate, it just means that your theory hasnt gotten into enough theoretical detail.
So far, I have not yet bumped into anything in terms of audible differences that I, or anyone with me, could hear that did not at some point connect with established theory and known physics -- by which I mean ordinary street-level physics, none of your fancy quantum stuff. You really do not need to invent laws of physics from a parallel universe to explain things. And you dont have to excuse yourself to say that theory does not connect with practice. If you look close enough, you will find [the connection]. If practice and theory seem to deviate, you better have a sharp look at your theory.
I very often have to invent new measurements on the fly when I suspect there might be something going on that doesnt show up clearly on standard measurements.
To give one example, you could take a DAC and do something very classical, like sweep the level of a sinusoidal signal from full scale to nothing, and then look to see how distortion changes with signal level. You might find some minuscule squiggles at lower levels and shrug them off as measurement errors, like, OK, that is just the machine not correctly measuring noise. But I got suspicious at some point and said, Hang on, let me try to find explicitly whether something happens in the noise floor with the signal modulation, but then I have to do so without a signal present. How do you do that? Well, you sweep a DC input to a DAC. You feed it a constant code, some small value, and measure the noise. Increase that code and repeat. Suddenly youll find that some of these D-to-A converters will do these frightening things, like the noise floor suddenly shooting up or an audible whistle actually just walking through the audioband as you sweep, going from supersonic down to zero and then back up. You have to be creative when you measure, not just do the standardized battery.
Its a bit like real science. When you have a scientific hypothesis, what you do in order to make it stick is try everything you can to push it over, and only if it doesnt topple, then it might be correct.
Same thing in audio -- if your hypothesis is that this particular D-to-A converter is a really good converter, then youll test it, and youll measure, and youre actively going to look for bad news. If, after not finding any bad news despite how hard youve tried, then you can start to say this is probably good. That simple example shows that, very often, the standard measurements might simply cover something up that is very measurable and very glaring, but just happens to be under the radar of regular test methods. You might then have this DAC which listeners feel has a shine, that puts an unnatural shine everywhere, and then suddenly you find this noise modulation when digging deeper, and you realize that might be the answer for why.
It is my experience -- confirmed by every new thing I do -- that when you get into really high measured performance, really low distortion, superlow noise, then the ultimate subjective sound quality starts improving and continues to improve in step with the measurements. At some point you will find that a product that measures absolutely perfectly under an extensive battery of tests will sound a lot better than a product with more typical high-end audio performance that has been tuned by ear for years. The upshot is that measurements do matter. The way you should translate this into a development process is not to listen and tweak your circuits, but rather to measure and adjust, measure and adjust, and then listen. If, at that point, something sounds off or is not quite working, that tells you something about what and how you measure. You calibrate by ear your set of measurements and the methods by which you measure, but you optimize your circuit by measurement. That is much more logical. You should take science to the absolute limit and crosscheck your scientific, technical procedures with what you are hearing, to make sure youre not forgetting anything. The purely technical road in the end will yield a circuit that really sounds better than what you can get by mere philosophy and tuning parts. Start shooting for fantastically low distortion, fantastically low noise.
- http://www.ultraaudio.com/index.php...s-of-mola-mola-hypex-and-grimm-audio-part-one
