opaqueice;238369 Wrote: > Pat, do you think it makes an audible difference? > > Going into a Benchmark DAC1 I can't hear any change; same with a NOS > DAC I experimented with.
That is actually a darn good question. A DAC that has all sorts of fancy reclocking and stuff may not sound much different with crappy interfaces. That is the purpose of all of that stuff, and why it costs more to implement. While the absolute amount of jitter may not be significantly worse for poor interfaces, the spectral distribution will be. And there is the key. Not all forms of jitter will sound exactly alike. Close-in jitter, or heavily data correlated will stand out more than random jitter, with an even spectral distribution. So, it will depend on the system. I know.......sounds like a cop out, which leads to proliferation of brash statements like "Well, I can't hear any difference, so it does not exist." With the Benchmark, I am not surprised. I talked to the guy from Audio Circle last night about how the modded unit sounded. He said that both transformer outputs were susbstantially better than stock, but they did not sound any different in relation to each other. He does have a fancy D/A box, with all of that fancy circuitry. So, from that, it seems plausible that gross interface problems are very audible, but minor ones are not. At least not on a fancy unit. As for the non-o/s one..........I am not fond of them. Yes, they have a sound that appeals to many. I am not sure that they are capable of enough resolution to enable you to tell for sure. So, any thoughts regarding that one would be a pure guess. Based partially on bias, so I could be mistaken. Part of the misconception about the usefullness of optical interfaces comes from the "bits is bits" assumption. Even the poorest of TOSLINK connections will pass data, and probably at 99.999999% accuracy. But that is a far cry from being able to extract the clock with a minimal amount of jitter. One of the problems comes from pulse dispersion. An optical output will have mulitple "spectral lines", that travel at just a slightly different velocity, due the minute differences in the paths it takes to reach the RX end. This spreads out the pulse, which of course, mucks up the rise time. (And other stuff.) When things get interesting is when you pick the fibre up, and start to move it around! Yeah, I know........how likely is that to happen when you are listening to music. Well, that happens to a lesser degree when it is just sitting there. When we were in the evaluation stages of that big fibre install, we fought amoung ourselves constantly over how the best way was to come up with a measurement for pulse dispersion. Single-mode fibre is NOT designed to work under 1 km or so. We were never able to resolve whether or not we could put 1 km of fibre on a spool, or if it had to be spread all over the lab, similar to how it would be in the field. Ah.......but that would still require some bending of the fibre. Anyway.......while we continued to argue about it, the system went in. We eventually sent one of our worst Ph.D. weenies to the field to measure it. He screwed up somehow, and not sure we ever got a number to compare. Too bad, because that would have answered our question. Not that any of that addresses your question, but it was rather funny for those of us involved. But it does highlight that fibre is not perfect. It has dispersion and reflection problems just like coax. Immune to EMI, generates no EMI, isolates things electrically. Has some problems of its own. Pat -- ar-t http://www.analogresearch-technology.net ------------------------------------------------------------------------ ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=33146 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
