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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: RE: More correct info on DSD and other clarifications posted by Tom Schuman on July 12, 2007 at 13:37:31:
Howdy
The iar-80.com article used to come up over and over on the Hi-Rez forum. A search over their will net a boatload of contentious threads.
Moncrieff clearly didn't have a clue about DSD, one example: he kept talking about averaging which is related to delta modulation (where the slew rate is indeed limited) instead of sigma-delta (or delta-sigma) modulation which is the basis of DSD (where the slew rate is only limited by the output filter.) The whole averaging discussion is irrelevant in sigma-delta. Another related example, his rant about the sample rate of SACD being too low (only good enough to go to 8000) is just malarkey, in fact the more incredulous of us might just wonder if what he reports hearing at 8000 and above is colored by his (incorrect) belief that SACD can't deal with data over 8K.
http://en.wikipedia.org/wiki/Sigma-delta_modulation gives a very brief overview of the difference between delta modulation and sigma delta modulation.
One of the references I found reasonably easy to follow to as much detail as you like: http://www.beis.de/Elektronik/DeltaSigma/DeltaSigma.html
It is true that high freq noise from DSD can cause a problem for some systems, but people exaggerate it a lot. One problem is that the Stereophile tests use 1/3 octave averaging and they imply that the noise floor starts rising long before it really does. If you instead look at FFTs of the outputs of players you'll see the real noise floor staying down there till after 20kHz. Also the noise can't rise (by spec anyway) higher than -40dBFS under 100kHz.
There are certainly some systems that don't react well to the noise that's there (and is there in DVD-A as well.) I've heard some tubed output mods on SACD players that a lot of people love but when played with, say JMLab Be speakers, that noise sounds horrible to me. I've also heard some Lowther speakers with SACD sources that sounded horrible to me.
But, my system's preamp is flat to 200kHz, my amps to 100kHz, my speakers to 40kHz, I use silver interconnects and speaker wire and I've never heard anyone say that the treble is tipped up, that they hear hi-freq problems, that the top end is soft, etc. I have a friend with an excellent TT and his interconnects cause hi-freq problems that at times have caused me to leave the room. Who knows.
-Ted
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Follow Ups
- RE: More correct info on DSD and other clarifications - Ted Smith 07/12/0714:25:11 07/12/07 (1)
- RE: More correct info on DSD and other clarifications - Tom Schuman 02:41:55 07/13/07 (0)
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