Archimago wrote: > This is precisely why I still bother subscribing to Stereophile - John > Atkinson's technical take on the hardware. > > Notice that the jitter measurements are taken out of the analogue output > from the DAC (in the Feb issue you probably were looking at the review > of the AVM Evolution C9). This is the summation of all the jitter from > the computer/CDP --> cable --> DAC. Unless you run the signal again into > the digital domain (eg. further DSP or digital receiver which > re-digitizes the sound), that's the end of jitter being a problem. > Notice those peaks on Figure 6 and 7 for that review representing jitter > sidebands. The highest of them all is at -100dB or lower whether USB or > TosLink! As per the graph, the 11khz primary signal was at -6dB. This > means that ALL those sideband distortion products (ascribed to jitter) > were *94dB* or more below the signal itself. Notice also how the graph > starts at the top at -70dB, hence giving the impression that these > sidebands are larger than they should be compared to the center > frequency. Is this audible? As Ethan W argued in the debate, this > amount of distortion/noise below the primary signal is inaudible to > humans (heck there's no music that needs anywhere close to this dynamic > range!). > > Realize also that the measurements overall for the product above looks > decidedly average (actually the 24-bit performance looks worse than > average for decent hi-fi); that is, there could be problems with the > audio performance, but jitter as per the graph is not an issue > whatsoever. Yes, I looked at the AVM C9 graphs. I also looked at the Arcam FMJ D33. So just by looking at graphs, I would pick the Arcam :-) . Agree, as a single frequency signal these noise will not be audible. But music is multiple frequencies. Wondering what that effect would be ..
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