Which is more accurate: digital or vinyl?

Hi Terry,

I agree with your aside concerning filtering, but, would you not agree that every capacitor introduces distortion? And that therefore we should be concerned with physical measurements rather than idealizations?

Absolutely. The various non-idealities of low pass filters, in both the recording and playback parts of the chain (anti-aliasing and reconstruction filters, respectively) are a major issue in digital audio.

I also agree that the spectral components are all above 20KHz. Would you not agree that this creates a very rich ultrasonic environment? And further, that this is mainly generated from harmonies in a fairly narrow 4 octave range, suggesting that the ultrasonics are also clustered? I note that different frequencies "beat" against each other; e.g. 33KHz and 34KHz signals beat to form their difference, or 1 KHz. Further, these beats will be related to the fundamentals in no simple respect, producing distortions which have not been characterized.

Agreed. In fact, arguably the most important reason for low pass filtering the d/a output is to eliminate (or at least greatly attenuate) beat frequencies that would otherwise arise as a result of non-linearities downstream in the system (and perhaps to some extent in our hearing mechanisms as well).

Were it true that ultrasonic distortion was inaudible, SACD would be no improvement on CD, which is not observed. Therefore, I stand by the assertion that total distortion is what is important, until it is proved otherwise.

As indicated in this Wikipedia writeup:

Because of the nature of sigma-delta converters, one cannot make a direct technical comparison between DSD and PCM. DSD's frequency response can be as high as 100 kHz, but frequencies that high compete with high levels of ultrasonic quantization noise.[36] With appropriate low-pass filtering, a frequency response of 50 kHz can be achieved along with a dynamic range of 120 dB.[2] This is about the same resolution as PCM audio with a bit depth of 20 bits and a sampling frequency of 96 kHz.

So although comparison between the parameters of the two formats is not straightforward or precise, it would seem clear that the performance of DSD is, at least potentially, superior to that of redbook cd in terms of dynamic range, and also in terms of providing greater margin relative to the Nyquist rate. That increased margin can be expected, at least potentially, to lessen the side-effects of anti-aliasing and reconstruction filters that may occur at audible frequencies, just as it can for hi rez PCM, relative to redbook PCM.

In summary, I think that our positions are similar in a lot of respects, but we agree to disagree on the need for a sample rate that approaches the one you have advocated. My thanks to you, also, for a stimulating and mutually respectful discussion.

Regards,
-- Al

Almarg and Terry9, thank you for a fabulous exchange; extremely informative and a model of civility. Very impressive.

This is a technical question, and it can be answered with an accurate oscilloscope. Simply compare the two wave forms on a double trace scope. I would wager "digital" because of the consistency of reproduction.

Orpheous10, brings up a good point.
In practice rather than in theroy, how much distortion is produced in typical vinyl rigs?

Unsound and Orpheus - one can measure "distortion" all one wants. The problem is, some types of "distortion" are much more musically harmful than others. There is admittedly more "distortion" in analog, however the distortions of digital are much more musically objectionable because of the frequencies at which they occur, and for other reasons. So the measured amount is beside the point, really. IMO, too many audiophiles get hung up on measuring instead of training and using their ears to tell them what sounds more like the real thing.