Post by azure October 3, 2009 (171 of 178)
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Edward Foster, "Super Audio CD: Evolutionary or Revolutionary?, Audio, November 1999, Vol. 83, No. 10, pp. 40-47 :
. . .It's not what DSD has, but what it doesn't have, that makes the difference: a case where less may be more and where 1 bit may be better than 20. Nor did DSD emerge from the seashell as a fully formed Aphrodite. DSD is a byproduct of developments that led to the modern PCM converter. In fact, DSD analog-to-digital converters and most modern high-resolution PCM A/D converters start off the same way. Both use high-speed, oversampling 1-bit [or "low-bit"] delta-sigma modulation, and noise-shaping, to transform analog signals into the digital domain. DSD samples incoming signals 2,822,400 times a second [64 times the 44.1-KHz CD rate], an oversampling rate typical of PCM converters as well. Where DSD and PCM part company is in what they do with the 1-bit data stream.
To record PCM, the high-speed, 1-bit data are converted into multibit words at a lower sampling rate. In the conversion, data are decimated and digitally filtered to avoid aliasing [Aliasing is a form of intermodulation distortion, or beating betwen the signal and the carrier, that produces new signals at the sum and difference frequencies.], because the sampling rate is being reduced. Although a brick-wall digital filter is easier to implementthan its analog equivalent = it simply involves a series of mathematical calculations = its effects are not benign.
Digital filters overshoot and ring both before and after transients, and each mathematical calculation increases the word length. If the accumulators in the filter cannot accommodate the longer words, overshoots caused by the calculation can be clipped or the least significant bits of calculated data can be truncated. In a complex, multistage brick-wall decimation filter, internal word length can reach or exceed 100 bits! To constrain the word length, well-designed multistage decimation filters requantize (to reduce the word length) at each stage. In any case, the output data must be requantized to fit the system parameters = i.e., word length must be reduced to 16 bits for CD or 16, 20, or 24 bits for DVD-Audio. Each requantization produces distortion, dither raises the noise floor slightly. No Free Lunch!
When played back through delta-sigma D/A converter (the dominant method nowadays), multibit PCM words are converted back to a high-speed 1-bit, data stream by an interpolation filter and returned to analog by a delta-sigma modulator and reconstruction filter = hence more calculations , more overshoot and more phase shift. [. . .] Why use this approach? The simple answer is that delta-sigma modulators have been found to be the most practical and cost-effective way to convert digital information back to the analog domain. A 1-bit modulator is inherently linear and, properly implemented, can have wide dynamic range. Ladder DACs have problems achieving 16-bit accuracy, never mind 20 or 24 bits!
The study should have also included comparisons with an analog source.
As that is the true beauty of SACD, for me, its closer to "analog fidelity" than CD.
ie it does not exhibit (to my hearing) the same "tinniness " or "harshness" found with CDs.
I grew up with analog.. maybe thats the difference??
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Post by DSD October 3, 2009 (172 of 178)
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I've thought a lot about this and the problem I see with A/B/X is it may be humanly impossible to compare three things at once, no matter how many times one can go back and forth or how long one can listen to any one sample.
I believe the human ear is limited to comparing only two things at one time (A/B). This may be why A/B/X tests always seem to get nil results. Why all amps sound the same, why expensive speaker cable sounds the same as a coat hanger. Why MP3 sounds the same as CD and why listeners cannot hear the "very obvious" differences between low resolution and high resolution digital. In short I do not believe A/B/X works, as it goes beyond what human brains are capable of.
Instead A/B tests should be done and instead of asking what sounds different, we should be asking what sounds better, more relaxing, smoother, etc.
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Post by rammiepie October 3, 2009 (173 of 178)
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It just seems INCOMPREHENSIBLE to me that so much "ink" has been lavished on the Meyer-Moran findings as if readers of this forum need convincing that SACD is indeed superior to RBCD. People, it was a flawed comparison to begin with using substandard SACDs as comparative tools so why belabor the issue? Just enjoy the many treasures you have in your collection. This reminds me of the politicians who don't believe that Global warming is a reality. Just look outside your windows. Or should we start a thread on that?
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Post by RWetmore October 3, 2009 (174 of 178)
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rammiepie said:
This reminds me of the politicians who don't believe that Global warming is a reality. Just look outside your windows. Or should we start a thread on that?
Oh please no. Global warming is the biggest scam ever perpetrated on mankind.
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Post by krisjan October 3, 2009 (175 of 178)
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RWetmore said:
Oh please no. Global warming is the biggest scam ever perpetrated on mankind.
I absolutely agree that man-made global warming is a huge scam.
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Post by rammiepie October 3, 2009 (176 of 178)
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RWetmore said:
Oh please no. Global warming is the biggest scam ever perpetrated on mankind.
And then there is Darwin's theory of evolution.....if so why are there still monkeys around? They're born monkeys, live as monkeys and die as monkeys.....no evolution here! But don't you gentlemen agree that reducing carbon emissions would contribute to the general welfare (especially in large cities) or is that a myth, too? As a homo sapiens, I know no more than you do...but some things just make perfect sense and what this has to do with the Meyer-Moran debacle is anyone's guess! Does listening to a well-replicated SACD induce EUPHORIA.....you betcha! There, I've singlehandedly solved the Meyer-Moran controversy!!!!!!!!!
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Post by RWetmore October 3, 2009 (177 of 178)
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rammiepie said:
But don't you gentlemen agree that reducing carbon emissions would contribute to the general welfare (especially in large cities) or is that a myth, too?
It's a total myth. There is absolutely no scientific basis for any of it. Zip, zero, nada. I suggest anyone who believes in it to actually do some research on the subject.
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Post by rammiepie October 3, 2009 (178 of 178)
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RWetmore said:
It's a total myth. There is absolutely no scientific basis for any of it. Zip, zero, nada. I suggest anyone who believes in it to actually do some research on the subject.
GOD HAS SPOKEN!
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