bhaagensen;694440 Wrote: > Its a nice read and he's probably right in his conclusions - however one > of his main poinsts, as I see it, can not be inferred (only) from what > he's writing. In particular, the reconstruction of a discrete signal > into a continuous one c.f. Nyquist. In fact to the contrary - the > reconstruction part of the theorem directly requires an infinite sum. > This is easy in mathematics, but how the engineers implement it is > still something even folks like Monty does not explain in any detail - > in fact, its often completely ignored... But why??? > > > Edit: So basically his whole sampling-rate argument relies on the *one* > statement that "the analog signal can be reconstructed losslessly". > There is not a single word of argument in favor of this... its not > enough to reference Nyquist, is it.
Yes it is enough in this case. Nyquist-Shannon Sampling Theorum came long before the advent of digital audio. Somewhat like Einteins theories of Relativity coming before space travel. For example, Einstein predicted (amongs many things) that time would slow down in a fast moving clock relative to a fixed observer. Very few people believed this counter-intuitive assertion. Experiments in the 50's later proved this assertion to be in fact true. Sampling Theorum predicts perfect reconstruction provided that the lowest frequency to be reconstructed is below the Nyquist limit. The ONLY people who DON'T believe this to be true are: 1) some people selling outrageosuly priced audiophile snake oil 2) some people who write for hi-fi mags. 3) some people who have been listening to the nonsense spouted by 1 or 2 above. The point is that increasing the sampling frequency does not and cannot alter the sampling and reconstruction of frequencies below the Nyquist limit. What it does do is to move the Nyquist limit. That's all it does. As others have mentioned, moving the limit upwards can be useful when engineering to avoid side-effects from the necessary recovery filters for a DAC... but this is only really relevant to analogue filters (which are generally no longer used). It is certainly NOT necessary to set a Nyquist limit 4x higher than the extreme upper limit of human hearing!. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables Stax4070+SRM7/II phones Kitchen Boom, Outdoors: SB Radio, Harmony One remote for everything. ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=93990 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
