3DSonics said:
Could you kindly advise as to how and why the specific measurements you have quoted are relevant measures of quality?
Because frequency response, noise, distortion, loudness and to a very limited extent phase, are
all that can be heard. Flat frequency response, along with low noise and distortion completely characterize a CD player as far as human hearing is concerned.
Simply the noise level appears appalingly high (--75db A weighted is likely much worse unweighted and at best it is 95dbh S/n Level. Hell, I getter noise levels UNWEIGTED from SE Valve Amplifiers.
Look again. It's relative to
minus 20dbFS... (Omitted from the original figures, but it is obvious from the context).
Also, omited are several relvant measurements:
1) Jitter
2) Level of IMD
3) Level of "noisefloor modulation" (aka what I prefer to call noiseload test)
Jitter as a standalone measurement is meaningless - the same amount of jitter affects different DAC architectures in different ways. Moreover, if there is an
effect of jitter it shows up in the THD+N number.
Why the concern over IMD? THD and IMD are just different manifestations of the same underlying distortion in the transfer function. If you can argue a case to show that for a CD player it is possible to have a high level of IMD, but a small level of THD, then go ahead.
Noise modulation is less than <0.5dB for the sony unit.
To be precise one would have to apply extensive analysis, but at an educated guess I would thinks that following are likely true:
1) Grossly bad powersupply design
2) Incompetent ground routing
3) Inadequate quality in core areas (DAC, Digital filter)
4) Analogue stage inadequate to ahndle the RF noise from the converter without IMD products folding back into the audible range (a little difficult to measure, but easy to hear)
5) grossly incomptetent implementation of the master clock and other digital circuitry, resulting in High Jitter
Well, if those "problems" don't show up in the measured peformance
at the output, then they aren't really problems at all are they? Sure you can take the lid off it and do "extensive analysis", but you're chasing your tail if the output measures this well. I might also add that your extensive analysis might well be pointless given the sophistication of the chips involved, and would require 100's of thousands of dollars of test equipment (especially to measure pico-seconds of jitter) - gear that makes Audio Precision boxes look like toys I might add.
While were on the subject of test equipment, it's worth noting that simply going into these units and swapping components for "better" ones may well lead to an audibly different product, but without the (expensive) test equipment required to show a measured
improvement it is quite likely that any audible difference is the result of a degradation in the units performance: at best the addition of a tone control, and at worst a significant increase in the distortion and noise performance of the unit.
Your assertion that there are effects that are "difficult to measure", but "easy to hear" holds no merit. Human hearing is quite flawed and a whole lot of research has been done on hearing using grossly distorted signals, which are easy to generate and verify (measure), yet are inaudible to the ear.
good engineering is doing for a nickle what any fool can do for a dollar. What you are asserting to be "grossly incompetant" is merely expedient design in order to reduce cost at no audible loss in performance.
Just to illustrate, for "accurate" CD replay (eg 16 Bit resolution) we ABSOLUTELY REQUIRE the following easily measured qualities:
1) THD & S/N better than -96db reference to digital full scale, unweighted
2) Jitter below 100pS
3) Absence of noisefloor modulation effects in Digital Filter, DAC and analogue stage
Just how much better than -96dB are you expecting? BTW, it make sense to use A-weighting, so why are you objecting to it? [State your assumptions about the use of dither (and it's probability distribution) to support your case for performance beyond 96dB SNR.]
Jitter is meaningless, unless you have considerably more to say about the chips you are using, and even then, your unlikely to be able to make any bold claims about the effect of input side jitter on the analog output unless you are either the chip designer or the manufacturer.