You keep suggesting the same tests over and over ... do you understand the difference between frequency (what you are suggesting) and time domain? Jitter is essentially in the time domain, so it is pointless and stupid to suggest a test using only the frequency response.
Yes I know the difference, thanks. Read Bob Adams (Analog devices) papers on jitter. He demonstrates how any jitter will be apparent in downstream distortions. B and G also very clearly show that jitter causes distortion in the frequency domain, you have seen the graphs yourself.,. See also Stereophile's measurements of jitter they always show jitter as deviations in the frequency domain as well, why because that is where the problem occurs from the listener point of view, it is the distortion sidebands and noise in that frequency domain that would be audible (except they are not in fact audible) not any ps or ns time shifting itself which is way beneath human discrimination.
I bought the Benjamin and Gannon paper (following your advice on another thread) and I find that paper pointless.
Okay I'll bite, why ?
It is an old research study that was conducted poorly. None of the equipment being used was of "audiophile" quality. How can you suggest that a paper that use unknow quality dac and headphone amps as being accurate?
Old does not mean redundant unless better studies have come along to challenge their findings, the only later real jitter research puts thresholds much higher (admittedly random , not signal correlated) , just as a thought there are research papers from the 1950s and 1960s that are still relevant today.
The headphones being uses were cheap, entry level $50 sony headphones. I don't judge equipment by the price but there is a point where you can't make definitive and serious generalizations when the test equipment is so subpar.
You obviously do use price as part of your judgment or you would not mention the price of the Sonys, which as I understand it have an admirably flat FR for headphones and low distortion, two characteristics I would think would be vital for serious tonal discrimination tasks, no ?
Many audiphiles and (especially) spend a lot of time and money choosing the best dac chip, opamp, capacitor, piece of wire, power cord, headphone amp, headphone cable... all of which are considered as useless in such studies.
If you want to apply logic and science, you should, for the sake of generalization, assume that all the audiophool claims are true (even if you think they are not).
In order to prove that jitter do not exist, you cannot assume that all interconnects, opamps, capacitors, dac chips sound the same as long as they "measure" the same. You are just using a bunch of flawed studies to validate another flawed study.
When I will start seeing studies about jitter conducted in the same rigourous and open minded way as Kunchur conducted his studies (see here:
http://www.physics.sc.edu/~kunchur/informat.htm#papers), then I will start taking those studies seriously.
?????? - this is all about superconductors not audio ?
Kunchur's paper is interesting, he uses a source with 68ns jitter, so he obviously does not consider jitter a big problem or he would get better kit . I would be more interested though if he used music and not square waves. He does get some things a bit wrong though, for instance JND at 69 db is about 0.35db not 0.7 (Backus) so is perilously close to the level differences caused by speaker displacement, but his lack of music based listening tests is the real flaw for us. I am also concerned about the effect of moving two powerful electromagnets (hum ?). Even with all this he moves the threshold down 3 microseconds from 9 to 6 under extraordinary conditions that no-one outside of a lab will ever experience, is this a big deal ?
It is not because you follow a "scientific" method that you always end up with the truth. When making the wrong assumptions (about what is audible and not) and using cheap and non representative equipment, it is easy to imagine how flawed such studies can be.
If you read Kunchur's paper, you will see that in order to test the temporal resolution (time domain) of humans, he couldn't find a CD player that was good enough. He had to use a high quality analog wave generator to test the human ears at the highest frequencies. What it means is pretty obvious if you can't (or don't want to) understand it: the human ear is better than most CD players out there. If CDs were good enough, he wouldn't have needed to look for something better.
Of course, he didn't just assume that a cheap $200 "pro" monitors were good enough because some cheap studios use it. He used a high quality ribbon tweeter and custom made electronics.
If he had used poor equipment (because they are good enough according to him) like Benjamin and Gannon, he would have reached a different conclusion.
Nick Charles, I really hope that one day you will try to do some serious research on the subject and not just throw at people outdated research about jitter. Recommending to people to buy an outdated research paper that used the wrong equipment and wrong assumptions doesn't reflect very well on you.
Can you demonstrate to me empirically that jitter is audible at levels lower than that found by B and G ?.
Can you prove to me empirically that jitter detection is significantly improved by "serious" kit ?
If you can find a paper that conducts a research using "serious" equipment (DCS, Esoteric ... dacs; Stax, HD800, LCD2, T1 ... headphones) then I will take those papers seriously. Untill then it is a bad advice to recommend people spending their money on a poor and outdated study, even if it one of the only ones on the subject.
