Implications of Esoteric G-0Rb atomic clock

It's a fascinating product review & survey of the jitter problem. If as Joe Harley observes, the ear can easily discern improvements in word clock accuracy down to +/-0.05 parts per billion (translating into jitter reductions on the order of tens of pico seconds), then it would appear that there's still a long way to go toward true SOTA in digital sound. Better clocks are far from an exercise in diminishing returns.

JH makes interesting observations. Unlike the crystal oscillators found in conventional CDP clocks, the rubidium-based clock in the Esoteric does not exhibit frequency fluctuations as a result of instability in the power supply. This correlates with my own experience that improving the quality of DC power into a VCXO Superclock greatly improves its sound. He recounts the luddite position of the Audio Engineering Society in the early 90's (opposing the very notion of jitter), and the gradual acceptance of the concept in the general community. He provides a nice working definition of the signature sound of jitter as "loss of space & depth; softening of the bass; hardening of timbre; a glassy sound on initial transients (most noticeably on the leading edge of upper-register piano attacks); a metallic sheen overlaying the treble; and an overall flattening of the soundstage & homogenization of instrumental images with the stage." Finally, JH notes that the rubidium clock option elevated the Esoteric P-03/D-03 well above the music servers that he had formerly favored over the Esoteric. Perhaps there is hope after all for ye olde compact disk.

Jitter occurs mostly at the DAC, whether with music server or CDP.

JH's point regarding frequency is that a crystal clock is subject to transient fluctuations in output frequency caused by power supply variations & ripple, whereas the output frequency of a rubidium clock is inherently stable. He states that a transient variation in clock output frequency is "the very definition of jitter." Timing errors in the clock translate directly into a misshapen waveform and amplitude errors in the reconstructed analog signal, as well as introduction of spurious sideband frequencies unrelated harmonically to the original signal.

While I accept the benefits of ultra low-jitter clocks, I wonder whether some jitter in clock frequency is reintroduced in the clock-link cables that connect the G-ORb to the transport & DAC.

Dazzdax, The mods I've made to my CDP that have obtained the most audible improvement are refinements to DC power into the digital section: power to master clock, but also separate discrete power circuits into DSPs and motor/servo control throughout the entire digital section. It's conceivable that some manufacturers do a better job than Esoteric to improve performance of the digital section in ways unrelated to accuracy of the master clock. But the benefits that one hears through these improvements to the digital section are still most likely related to a reduction in jitter. If not, how do I account for the audible improvements that I hear in my modded unit? I can rule out upsampling technologies as a consideration, as no changes were made in this area.

Mods to the digital section make digital sound far from awful and in most respects RBCD has surpassed vinyl in my system. My experience confirms JH's finding that short strokes related to banishing jitter really open up the true potential of digital. Problem is this may require heroic efforts like $15K clocks or 300lb. battery supplies.

Rather than open yet another thread on MP(I've heard MP & yes it does sound good), I'll address the post by observing that the manufacturer's claims concerning MP theory of operation remain opaque & controversial. There has been too much delay bringing MP to market to consider it at present a serious threat to existing technology. Finally, there appear to be questions as to whether its technology is unique and patentable. The latest AA thread below addresses the controversy & also includes Gordon J. Rankin's recipe on how to build a "DIY memory player" in several easy steps. As regards music servers in general, in his review RH elevates the Esoteric with rubidium clock above HD systems like Sooloos & Qsonic. In any event with servers there is still the need for a clock at the DAC.

http://www.audioasylum.com/audio/digital/messages/13/136279.html

I believe this is defined more by the time-base("atomic accuracy" as determined by atoms within an element shifting between discrete states of energy) than it is by the element per se. Clocks with atomic accuracy can utilize Rubidium, as stated by European Space Agency in its description of the Galileo satellite:

"The Galileo satellites will carry two types of clocks: rubidium atomic frequency standards and passive hydrogen masers. The stability of the rubidium clock is so good that it would lose only three seconds in one million years, while the passive hydrogen maser is even more stable and it would lose only one second in three million years. However this kind of stability is really needed, since an error of only a few nanoseconds (billionths of a second) on the Galileo measurements would produce a positioning error of metres which would not be acceptable.

An atomic clock works like a conventional clock but the time-base of the clock, instead of being an oscillating mass as in a pendulum clock, is based on the properties of atoms when transitioning between different energy states.

An atom, when excited by an external energy source, goes to a higher energy state. Then, from this state, it goes to a lower energy state. In this transition, the atom releases energy at a very precise frequency which is characteristic of the type of atom. This is like a signature for the type of material used. All that is needed for making a good clock is a way of detecting this frequency and using it as an input to a counter. This is the principle behind an atomic clock.

The transitions between energy states can take place by releasing or absorbing energy at optical or microwave frequencies. An atomic second corresponds to 9 192 631 700 counts of the frequency of the energy detected in the transition of the Cesium 133 isotope when exposed to suitable excitation."

Ehider, I agree that too few direct comparisons are made between RBCD and the benchmark of great vinyl when judging the performance of a CDP. However, I make this comparison every day, and have come to the conclusion that it is indeed possible for a traditionally architected CDP to equal or surpass an excellent vinyl front end. Moreover, as the CDP's analog section is critical, I would like to know more about the analog section of your USB WDP(Wet Dream Player).