Post by Jonty May 28, 2008 (1 of 5)
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In an news article on the Stereophile web site Dr. Mark Waldrop of AIX Records, a supporter of PCM / DVD-A, claims "it is not uncommon for engineers to roll off DSD above 20kHz in order to successfully encode discs and diminish the artifacts that result from DSD shaping."
Perhaps the engineers that look in on this site may care to comment.
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Jonty,
That's not the rarefied air that I work in, but it sounds like a load of hooey to me. There isn't much audio signal above 20k to worry about - there is some, and it may be important, but what's at issue (or so I've read) is not the signal, but the noise generated by the 1-bit code. Reduce the signal and leave the noise untouched? Nah, I don't buy it.
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Dan Popp said:
Jonty,
That's not the rarefied air that I work in, but it sounds like a load of hooey to me. There isn't much audio signal above 20k to worry about - there is some, and it may be important, but what's at issue (or so I've read) is not the signal, but the noise generated by the 1-bit code. Reduce the signal and leave the noise untouched? Nah, I don't buy it.
I am not a recording engineer, but it would seem that the purpose of SACD was to extend the frequency response to the 40,000Hz and beyond limits, a place where ambience, "air" around the instruments etc. (which is supposedly the eminent domain of well-pressed vinyl on a state of the art system) resides. The specs on my Parasound Halo D3 state the frequency response of DVD-A at 4 Hz to 88Khz, SACD at 2 Hz-100kHz and cd at 4Hz-20kHz (with the brick wall filter limiting any range beyond that). Since none of us has "dog" ears, it is said that vinyl does indeed extend to 40,000 kHz so I really doubt that Dr. Waldron's (who is 100% entrenched in DVD-A recording) assumption would be correct (a private joke intended for Mr. Popp: treating your discs would extend the frequency range to 50,000 kHz and beyond).
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Post by Claude May 31, 2008 (4 of 5)
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rammiepie said:
I am not a recording engineer, but it would seem that the purpose of SACD was to extend the frequency response to the 40,000Hz and beyond limits, a place where ambience, "air" around the instruments etc. (which is supposedly the eminent domain of well-pressed vinyl on a state of the art system) resides.
I think the purpose of SACD (besides adding multichannel content) is rather to increase resolution (and to a lesser extent the dynamics) over the whole audible frequency range. Limited PCM resolution (by current standards) is the main flaw of the CD format. Whether a frequency range extended above 20kHz benefits the audio reproduction is debatable.
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Mr. Pie,
Thanks for the recommendation. I'll poke around on the forum and see whether I can find some good info on treating discs.
As to the ultra-20k range, we have to make a guess about what is causing the improvement (if any - thanks, Claude). In my experience, generally, audio components designed with a wider bandwidth sound better, even when the spectrum is widened beyond what is thought to be the audible range for humans. BUT... is this because they are enabling us to hear things above the so-called "audible range"; or is it, as I suppose, because products designed to have wide bandwidth are just better-designed products? In other words, is the (assumed) improvement in HF fidelity actually the result of better reproduction of the ultrasonics, or is it just coincidental?
Audiophiles who obsess over the information at 40k and 80k and 100k, seem to be unaware of how truly infinitessimally small is the amount of that information. Their comments read to me like a person taking years to decide whether to buy a 40W power amp or an 80W amp. There's not as much difference as one might think.
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