JohnSwenson;692188 Wrote: > > > This brings up the issue of software upsampling and NOS DACs. First off > NOS does not mean no filter, just not a digital filter, you can still > put an analog filter on a NOS DAC. If the builtin digital filters are > the problem, it seems that a good NOS DAC playing upsampled files that > were generated with a properly implemented software filter should > provide good sound. And my experience is that indeed it does, > especially if you put a 2 or 3 pole analog filter after the NOS DAC to > get rid of residual high frequency noise. Note this has to be a GOOD > NOS DAC, not one of those cheap 16 bit ones from people that have no > clue what they are doing. > > There are a lot of people that are doing software upsampling and > feeding the results into soundcards and external DACs that I think are > trying to do the same sort of thing, but the data is still going > through the compromised digital filter in the DAC chip. It would be > much better if they fed it through a good NOS DAC. John this is fascinating stuff, but the terminology is getting confusing to me. NOS literally stands for non oversampling (?) - but tends to be associated with either no filter or analogue output filter.
Forgive my ignorance but how do "upsampled files that were generated with a properly implemented software filter" differ from the up/oversampling which would go on in an ordinary OS dac? It seems to me that you clearly have both oversampling and a digital filter here- your just doing it in software. For the sake of simplifying Inguz all my files are (courtesy of Phil's tweak) upsampled by sox to 96 kHz before streaming to my dac. Is this what you have in mind? I can't see how you can go beyond 96kHz via a squeezebox If the processing power in the dac is the limiting factor I see why it might be better to finesse this in software. I hope I am not making a fool of myself by I can't see how this differs in principle from the classic OS dac with a final analog filter to remove images above half the oversampling frequency. Would this be NOS in the sense that Kusunoki meant it http://www.sakurasystems.com/articles/Kusunoki.html Presumably with will only work with a multi bit dac this natively works at the upsampled frequency not a delta sigma one as those will presumably inevitably have their own filters. [I fear I am betraying my ignorance but I have never been able to grasp the difference between upsampling and oversampling] -- adamdea ------------------------------------------------------------------------ adamdea's Profile: http://forums.slimdevices.com/member.php?userid=37603 View this thread: http://forums.slimdevices.com/showthread.php?t=93483 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
