achri-d;253940 Wrote: > > > I checked this now just to make sure and it does not work. Using the > internal clock of the Transporter works. >
OK... well if that is the case then it points to an interaction with one of the open bugs I am working on. It may be solved already for the new firmware that is in the works, but I will do some more testing and see if I can find an explanation. I still do not see any problem here, but some of these have been hard to reproduce. > Finally, I still can not understand your theory of internal vs external > clock (high precision oscillator) for a DAC. Please, notice that both > Esoteric and dCS promotes this idea - and for me it works well with the > Transporter and 44.1kHz. Which part of it is unclear? Just for the sake of argument, consider an absolutely perfect clock with zero jitter. No such thing exists, but let's just suppose for the sake of argument that your external clock source is such a device. Now, divide that clock signal down to word clock speed (/128 or /256), send it through a bunch of cables and connectors, through a PLL and across another circuit board to the DAC chip. How can that possibly still be a clean clock? How could it possibly be cleaner than if you placed the crystal oscillator right next to the DAC chip? It can not. Not by any stretch of the imagination, and not even if you consider a _perfect_ external clock source compared to the poorest imaginable local crystal clock source. It is not even close. The external clocking scheme is worse by about a factor of ten. In practice you would get about 15-50ps for the internal clock, versus 100-300ps for the external, PLL-recovered clock. The fundamental principle of word clocking, when used for the purpose of reducing jitter, is that you are eliminating all the crap between the clock source and the DAC. This is where jitter comes from. The quality of the crystal oscillator is actually not even a major factor. Finally ask yourself, if dCS can produce a better clock signal through such a convoluted means, why would they not then simply build this technology into their $18K(?) DAC? Maybe they just want to sell you yet another overpriced box. Look, I am not making this up and I have nothing more to sell you. What I am telling you is all solid theory that can easily be tested with suitable equipment. Have a look at this (and also be sure to jump back to part 1 for the introduction): http://www.tnt-audio.com/clinica/diginterf2_e.html What you need to do is shown in the "clock backwards" configuration. This is ideal - it puts the oscillator right at the DAC so that the clock signal does not flow through PLLs, dividers, or interconnects. If anywhere in my reasoning you have found a mistake, please point it out and we can discuss. Otherwise it's pretty silly to just not believe me because my conclusions conflict with what the high priced stereo vendors have told you. There are guys who will sell you lacquered knobs and granite isolation plates too. -- seanadams ------------------------------------------------------------------------ seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=39770 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
