opaqueice;343819 Wrote: > I might be misunderstanding you, but it sounds like you're missing the > point. The issue isn't missed or false triggers - those basically > never happen under reasonable (audio) circumstances. S/PDIF is easily > capable of transmitting bit-perfect information; that's been tested > many times. > > The issue is at what instant precisely the circuit decides the edge has > arrived. If the signal were perfectly square and even, those instants > would be perfectly evenly spaced in time. Since instead the edges are > rounded off a bit, those times are smeared out - they don't occur at > perfectly even intervals. The difference between when they should > occur and when they actually occur is called jitter, and when jittered > times are then used as a clock for the DAC the jitter distorts the > resulting waveform.
Ah, yes I missed your point. Let's rewind a bit... I wrote: "Timing should not be an issue anymore since they started encoding the timing into the digital signal... (correct me if I'm wrong there)." What I meant by that is the last sentence in the 3rd paragraph in this link: http://en.wikipedia.org/wiki/Analog_sound_vs._digital_sound#Main_differences It says: " As of 2008, all audiophile and consumer grade digital systems now encode the clock (which if independent from the bit stream is the source of jitter) into the coded data itself." This would eliminate jitter for good as you can even use asynchronous transmission without having timing problems. Another method that's used by some DAC's (no source but I read it somewhere) is re-sampling the incoming data... basically what you do is remove timing issues. Remember that it will only be as good as the clock-source in the DAC. A really good one would be a constant-temperature crystal oscillator using an "oven". Good HAM radio's have this or you can order it as an option, it's no joke. I never heard of any DAC having it but I wouldn't be surpised if some have it. Also, about jitter as the result from timing issues in toslink: yes, echo's can cause this so you should have a good cable, but plastic vs glass is no issue here. What I really think is that the IR-transmitter on one end and/or the IR-receiver on the other end are to blame. Remember that the transmitter is just a flashing LED and the receiver is just a light-cell and they come in a zillion qualities. What you want is them to be rated for a very high frequency. I read that people can hear jitter when timing is only a couple of nanoseconds off... I can see manufacturers using el cheapo IR for saving bugs and causing this. Now we come to what I don't see: An imperfect square-wave, like with rounded edges as we see on those scope-photo's will cause timing-issues on level-triggering. But this isn't used here, we do edge-triggering. The target for the "point of trigger" is halfway up the up-going slope. So if done reasonably well, a rounded corner is way above or below that point and should not cause problems. If the slope isn't vertical you would get bigger problems. So, my conclusion: yes, I think that in general coax will sound better than optical. My reasoning for this is that manufacturers try to save bucks and select under-rated IR components (not enough bandwidth). You will have the same issues with coax but it's easier to implement because you do not have the electric->IR and IR-electric conversions. Maybe they under-estimated the effects of jitter and specified IR that's not good enough at the time of defining the toslink standard. Also: when that "2008" info about encoding timing into the digital stream is right, the issue will be behind us soon as this will completely eliminate jitter. about the Glenfarclas: yes, that's the one but make sure it's the 15yr version. They also have the "101" at cask strength but we rate it well below the 15yr ;-) cheers, Nick. -- DeVerm ------------------------------------------------------------------------ DeVerm's Profile: http://forums.slimdevices.com/member.php?userid=18104 View this thread: http://forums.slimdevices.com/showthread.php?t=52817 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
