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peeder · 19th June 2007

Well one result that could come out of studying this phenomenon is that it's all (or mostly) about the converter's PLL, and (some? many?) converters will have the same performance on any external clock. In which case, you could get the same effect with the $100 Hosa word clock box as the $1300 Apogee. Or just use the clock out of your old digital reverb.

Or that any beneficial effect would be even better with a combination you might think was worse when you looked at it. I.e. clocking your fancy converter to your cheapo would sound better overall. Etc.

We can study an audio signal, we can show skews in frequency distribution, in harmonic (and non-) distortion, in the noise floor and its frequency distribution, in impulse response, etc. We can contrast those results with subjective studies, done properly double-blind with enough of a sample size to reject the null hypothesis, and come up with observations such as "people like certain distributions of harmonic distortion." Then we can take the equipment in question and characterize its performance in those areas, precisely. We can at the very least use nulling/subtraction to determine if there is a difference in performance or not.

Surely everyone would like to spend the very minimum to get identical performance. If performance is not identical, in what ways, precisely, is it different, and are those ways significant enough, and beneficial enough, for us to justify the added expense? What is, in fact, the best way of configuring our systems?

Many people would like conversion to be as transparent as possible, and the argument certainly has been made that internal clock is the thing that does that. Generation tests over a series of DAC/ADC loopbacks should reveal that. The same goes for cables.

The most critical question is, why are the manufacturers coy about doing these quantifications and displaying the results? They at least probably have AudioPrecision gear that they are developing these things with, and I'd think they know full well what is happening and not. Care to share?

Anyone? Anyone? Bueller?

19th June 2007	#82
peeder Lives for gear Joined: Aug 2006 Location: No longer participating here. Posts: 6,705	Well one result that could come out of studying this phenomenon is that it's all (or mostly) about the converter's PLL, and (some? many?) converters will have the same performance on any external clock. In which case, you could get the same effect with the $100 Hosa word clock box as the $1300 Apogee. Or just use the clock out of your old digital reverb. Or that any beneficial effect would be even better with a combination you might think was worse when you looked at it. I.e. clocking your fancy converter to your cheapo would sound better overall. Etc. We can study an audio signal, we can show skews in frequency distribution, in harmonic (and non-) distortion, in the noise floor and its frequency distribution, in impulse response, etc. We can contrast those results with subjective studies, done properly double-blind with enough of a sample size to reject the null hypothesis, and come up with observations such as "people like certain distributions of harmonic distortion." Then we can take the equipment in question and characterize its performance in those areas, precisely. We can at the very least use nulling/subtraction to determine if there is a difference in performance or not. Surely everyone would like to spend the very minimum to get identical performance. If performance is not identical, in what ways, precisely, is it different, and are those ways significant enough, and beneficial enough, for us to justify the added expense? What is, in fact, the best way of configuring our systems? Many people would like conversion to be as transparent as possible, and the argument certainly has been made that internal clock is the thing that does that. Generation tests over a series of DAC/ADC loopbacks should reveal that. The same goes for cables. The most critical question is, why are the manufacturers coy about doing these quantifications and displaying the results? They at least probably have AudioPrecision gear that they are developing these things with, and I'd think they know full well what is happening and not. Care to share? Anyone? Anyone? Bueller?