> Interesting. What is the equations that describe this? > If it is too long to post, got an URL?
SNR (DBC)=–20 LOG10(2π.FIN.TJITTER), WHERE FIN IS THE ANALOG-INPUT FREQUENCY, TJITTER IS THE TOTAL SYSTEM JITTER IN SECONDS. Immediately it should be clear that the fIN factor gives result dependant upon the sampled frequency, using the figures mentioned, 20,000ps gives, assuming no other system errors, 98dB dynamic range (non-dithered CD spec) at 20Hz, but only 51dB at 20kHz. 100pS would meet the 20kHz non-dithered spec, but what about dithered input signals? Factor in a 15dB additional dynamic range from a properly dithered input signal, or a 24bit system (or worse still, a wide-bandwidth system) and you can see things rapidly becoming much harder. It's one reason why the newer, hi-res formats fail to live up to my expectations, they make the engineering, which is already bloody difficult, MUCH harder. It really isn't as easy as many so called 'experts' make out, jitter isn't that easy to measure (to the man in the street) and even when one can, it's not as simple as a headline figure. The recent volume rounding error problem of the Squeezebox gave rise to an error at the 16bit of the audio data - so many experts would tell you this is inaudible, yet people here (without knowledge of any change) found it wasn't. The human ear / brain interface is a really astonishingly complex thing, that can at one and the same time be both amazingly sensitive, yet easily fooled. What it isn't is measurable, in any quantitative manner. No-one, anywhere, with any experiment or test, can 'prove' the absolute audibility or inaudibility of anything when it comes to music. Realising that is crucial to avoiding the often prolonged debates that happen around these subject areas. Whilst the maths above, for example, explains a mechanism for audibility, it tells you nothing at all about an individual's ability to hear the effects, there are few absolutes of 'audiblity'. Andy. -- Andrew L. Weekes ------------------------------------------------------------------------ Andrew L. Weekes's Profile: http://forums.slimdevices.com/member.php?userid=573 View this thread: http://forums.slimdevices.com/showthread.php?t=18116 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
