Not sure what you mean by "resolving timing differences" here. Any competent audio amplifier should be able to time resolve, say a close pair of impuses, way beyond the ability of a listener to resolve them (especially a listener that is sitting in a real room listening to a stereo pair with reflections arriving left, right and centre). Extending the bandwidth of the amplifier beyond the audible region doesn't help here. It's exactly analogous to the discussion about display panel resolution we've just been having - this is an analogy that does work.
Do amplifiers really sound the same?
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Well the problem is knowing or agreeing where the limit of audibility is. If two amplifiers, correctly tested, test identically then I think we can be sure that differences people hear are imagined.
BUT, if there are measured differences , it is very difficult to assert confidently that they are such that they lie below the limit of audibility for all (or for the average, or for the trained) listener without separately testing what that limit of audibility is. Of course we do have evidence for some limits - we can't hear above a certain frequency (which limit falls with age), we can't hear frequency related phase, we can't reliably level match by ear below about 1.5dB etc. But in general, if a test shows a difference, say frequency response in the audible region, however small, how can we be sure that it will be inaudible? The assertion that all competent amplifiers into good speakers in a real listening environment are audibly identical can only be shown to be true by an extensive series of DBTs which ain't going to happen (and wouldn't be accepted by the extreme subjectivistas anyway) and so the argument goes round.
My position is that amplifiers that measure the same, sound the same, but that we don't really know at what level measured differences become audible.
Well if you extrapolate the 2160p line down past the 20" axis it comes to around 1ft viewing distance required to get the full benefit of that resolution on a 15" screen (assuming widescreen ratios). So 1800 pixels would probably be of full benefit at around 1.25ft or so (at a guess). Certainly at the 2-3ft that you're most likely to be viewing the screen from an 1800 pixel resolution on a 15" screen is pointless.
It's kind of the same with cameras and their MP selling points. All more pixels actually means to the majority of people (who never print their photos), is that they can't view their pictures on their computers without shrinking them down to fit. Given that that is the way 99% of users of 99% of cameras will ever view their photo's it's totally pointless them using a camera with a resolution greater than their screen can display. Which even for a ultra high resolution monitor is 4.1MP (2560x1600). Yet it doesn't stop people swapping their 1 year old 12MP cameras for the next generation "must have" 14MP ones, because the marketing depts tell you that need should
+1Yet it doesn't stop people swapping their 1 year old 12MP cameras for the next generation "must have" 14MP ones, because the marketing depts tell you that need should
Nor does the fact that the zoom lens on a compact camera will not be able to provide an image with a spatial resolution anything like the pixel spacing on 14MP colour sensor even on axis as quite apart from aberrations the system will be running into its diffraction limit.
or worse, phone cameras with 5, 8 or more MP and a tiny 1mm lens!!
No, according to the chart you'd need a 55" to get the full benefit of 720p resolution at 11ft. The chart shows that you should start to see the difference over and above 480 lines resolution at a screen size of about 36" at 11ft. So that ties in totally with your experience.
Again, that chart is calculated for people with 20:20 vision. Which is not, (as many people would have you believe), "perfect vision", it is just a reference standard. So it is a guide, not an absolute for every individual. It's generally accepted however that the limit of human acuity is around 20:15. Which means you can see as well as some one with 20:20 vision but at 33% further away.
dave
Plywood King
Your bolded bit is the essence of all subjectivists' arguments on the matter if the other side would stop ignoring this fact. We'd also suggest the objectivist may not be able to measure all that distorts what may be audible.
P.S. Welcome to PFM!
Thanks for the welcome.
I refute the idea that there are discernible differences in amplifier performance that cannot be measured. There isn't a shred of evidence that that is the case just as discernible differences in lens performance that cannot be measured don't exist. Measurement capability goes way beyond perceptibility in bandwidth, distortion, temporal resolution, phase and amplitude response as a function of frequency, and impulse response. We can know this without knowing exactly where the limits of peceptibility lie for measurable differences.
My statement is that we cannot formally say at what level many (not all) measurable differences become reliably audible for different classes of listener because the work to demonstrate where those thresholds lie simply hasn't been done. However we shouldn't deny those cases where thresholds of perception have been established and claim some sort of magical superbiological ability to hear, for example, ultrasonics or absolute phase. In some cases the limits of audibility are subject to active controversy - eg the audible effects of jitter in digital systems. Nevertheless, I think that the measurable differences between competent amplifiers (in terms of output versus input) are so tiny that they are likely to be inaudible or audible at such a subtle level that they simply don't matter (given people's demonstrably poor auditory memory) - however, that is not an opinion that I (or I believe anyone else) can demonstrate empirically today. It is a reasonable prediction given the facts but a claim that it is absolutely true is not warranted.
dave
Plywood King
We're not in total disagreement. I have no problem with this:
My statement is that we cannot formally say at what level many (not all) measurable differences become reliably audible for different classes of listener because the work to demonstrate where those thresholds lie simply hasn't been done.
...but I do have a problem with this:
However we shouldn't deny those cases where thresholds of perception have been established and claim some sort of magical superbiological ability to hear, for example, ultrasonics or absolute phase.
I'm not disgareeing specifically with respect to ultrasonics or absolute phase but I do take exception to there being no differences in the sound of cables and amplifiers, CDPs, etc.
FWIW, I don't believe in magic. There is an explanation for everything without exception IMO. That doesn't mean we can currently explain everything however.
regards,
dave
James
Lord of the Erg\o/s
They matter to the golden-eared, hard-core subjectivist. Oh wait, Dave has already replied.
dave
Plywood King
They matter to the golden-eared, hard-core subjectivist. Oh wait, Dave has already replied.
I give no weight to sonic descriptions of most any kind from folks on the Internet regarding audio equipment. They're almost always wrong or attributed to the wrong thing if negative.
Disappointing I know;-)
dave
How can you know that something does not exists if you cannot measure it?
Take mountains. You can devise an instrument to precisely measure the hight, weight and area of the mountain but does this instrument reveal every bit of detail visible on the face of that mountain? No. You are measuring the mountain accurately but because you are not measuring it in the same way as the eye does you might not see the same results.
Or even if you take a photograph of the face of the mountain, will that reveal as much as the eye can see? Not exactly. I'm sure that a mountain rescue team would rather look for the lost climber with their own eyes rather than look at photographs.
You can never know that you have measured every aspect of a sound signal because you have to transpose that energy into a different kind of energy to measure it and are not measuring it in the same way the ear and brain do. You can only ever say that there is no difference between the two sets of measurements you have taken. It's a leap of faith to extend that to the conclusion that the objects being measured are therefore the same.
So if we haven't done the work then we shouldn't make claims as fact that rely on the work, but if we have done the work and the conclusion doesn't agree with our preconceived ideas then we should ignore it? I am not saying anything about cables, amplifiers or CDPs in this - that's a separate discussion - I am just saying that where the threshold of perception has been established then we shouldn't ignore that fact. If someone claims that ultrasound at 35kHz is audible thay are simply as mistaken as someone who claims that EM radiation at 250nm is visible.
I absolutely agree with that. But it also doesn't mean that we can explain nothing.
Weren't there tests that showed that ultrasonics did have an affect on humans? Brain scans etc?
I remember reading one of the hifimags had an interview with Tim de Paravicini years ago when he mentioned work he did on an utrasonic cleaner. He said something along the lines of "You couldn't hear it, but you knew when it was on".
A quick google came up with this: http://jn.physiology.org/content/83/6/3548.full
I remember reading one of the hifimags had an interview with Tim de Paravicini years ago when he mentioned work he did on an utrasonic cleaner. He said something along the lines of "You couldn't hear it, but you knew when it was on".
A quick google came up with this: http://jn.physiology.org/content/83/6/3548.full
Well, we are getting into epistemology here, but all knowlege about the world is provisional. We can only be absolutely certain about the truth of, for example, mathematical theorems or purely logcal constructs. So when it comes to knowledge of the world, all we can do is to make statements that more or less accord with the evidence and with reason.
So you are right to say that we can never be absolutely certain that something doesn't exist if we can't measure it. There are almost certainly things that we can't measure or detect that exist; and there are things that we can't measure or detect that are extremely unlikely to exist. Reason and evidence helps us to distinguish between the two extremes. An example of the former is a planet orbiting a star in another galaxy - reason and evidence from our own galaxy makes it extremely probable that such a thing exists even though we can't measure or detect it. An example of the latter is teapot decorated with red roses orbiting a star in another galaxy - I can't say with 100% certainty that such a thing doesn't exist but reason and evidence lead me to think it extremely improbable and in fact I am warranted in behaving as though such a thing doesn't exist.
Now take hifi: sound is pretty well understood - it consists of longitudinal pressure waves in air. We can measure the pressure as a function of time at frequencies way above the threshold of hearing and at levels way below the threshold of hearing; and we can measure the analogue electrical signals from which those pressure waves ultimately derive with a precision and a range way beyond the known threshold of hearing. It's pretty simple stuff and reason and evidence lead me to the conclusion that there is no audible effect that results from differences in amplifier performance that is beyond detection.
By the way, in your search for your lost climber you might use an infrared camera, which measures and presents data from an otherwise invisible part of the spectrum or a pair of binoculars which in effect measures and presents optical data in a form more sensitive than the naked eye. I don't listen to music on an oscilloscope, and I dare say mountain rescuers rely on their eyes as much or more than other measurement methods - but it is certain that any visible object will affect the electromagnetic field in a measurable way - you cannot see things that are unmeasurable and in the same way you cannot hear things that are unmeasurable.
dave
Plywood King
hec,
I'm not making claims as such in the absolute sense -merely reporting observations which are experienced repeatedly and consistently over a lifetime of listening.
We can explain alot of what exists around us - and there's alot we can't explain...yet.
regards,
dave
Brian
Eating fat, staying slim
I agree, as will everyone else because not one person is saying that, sadly a few are saying we can explain everything though and that's the problem.
cooky1257
pfm Member
I have used 3 different active xovers in my system, they all had published figures way better than those posted here as a benchmark.
They were a Tannoy x5000, a JBL 5234 and a BSS FDS360, all pro pedigree all auditioned at 800 hz @24db/LR each sounded very different, the BSS was cleanest-most transparent. None of them matched my XTA 226 (which is a 24bit/48khz digital job) however.
I can only conclude I'm imagining it.
They were a Tannoy x5000, a JBL 5234 and a BSS FDS360, all pro pedigree all auditioned at 800 hz @24db/LR each sounded very different, the BSS was cleanest-most transparent. None of them matched my XTA 226 (which is a 24bit/48khz digital job) however.
I can only conclude I'm imagining it.
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