JohnSwenson;682870 Wrote: > For those taling about modding the S/PDIF out of a Touch a few thoughts: > the S/PDIF stream is generated in the processor chip itself, it then > goes to a reclocking flop, its in a very tiny single gate package, from > there it goes to a network of a couple resistors and a cap, which I > presume are doing an impedance match from the flop to the output. Do > NOT bypass that flop! The signal coming directly out of the processor > is quite bad, the flop reclocks it with the raw clock. > > As to putting in a BNC jack, it certainly can be done, but make sure > you use a real 75 ohm jack, BNCs come in both 50 and 75 ohm types, the > 50 ohm types are far more prevalent than the 75 ohm types, if you just > get something that says its a BNC jack it will probably be a 50 ohm > type, it has to explicitely say its 75 ohms. > > As to the clock in the Touch being almost perfect, its not. Its a > normal cmos inverter and xtal oscillator, they are not "BAD" but they > are not great either. Its definately possible to get oscillators that > are MUCH better. And going with a better clock does significantly > improve the sound. > > A while back I was doing a I2S out, clock fed back from DAC scheme and > decided to listen to the analog outs just for kicks, I was blown away, > the sound was way better than normal. I actually expected it to be > worse, what with the issues of sending the clock over the cable I > expected the clock jitter to be worse. Even with the cable the clock > was better than the built-in one and it was quite obvious. > > So I would say that improving the clock is actually quite a worthwhile > mode if you can do it. Unfortunately there is VERY little room in there > to do it. > > John S.
thanks for a very informative post, John. Soundcheck recommended connecting the digital coax directly to the board, can you comment on whether this is a good idea as it would get rid of the bnc/rca connection issue, but I don't know how critical the 75 ohm impedences are ? reading up just now about your SBT I2S out, but have a benchmark dac1 which does not have I2S and have not found any info on the web. I2S seems the way to go if those that have reviewed it are to be believed. -- SBGK ------------------------------------------------------------------------ SBGK's Profile: http://forums.slimdevices.com/member.php?userid=52003 View this thread: http://forums.slimdevices.com/showthread.php?t=91322 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
