Implications of Esoteric G-0Rb atomic clock


The latest TAS (March 2008) has an excellent piece by Robert Harley: a review of the Esoteric G-0Rb Master Clock Generator, with sidebars on the history and significance of jitter. This Esoteric unit employs an atomic clock (using rubidium) to take timing precision to a new level, at least for consumer gear. It's a good read, I recommend it.

If I am reading all of this correctly, I reach the following conclusions:

(1) Jitter is more important sonically than we might have thought

(2) Better jitter reduction at the A-D side of things will yield significant benefits, which means we can look forward to another of round remasters (of analog tapes) once atomic clock solutions make it into mastering labs

(3) All of the Superclocks, claims of vanishingly low jitter, reclocking DACs -- all of this stuff that's out there now, while probably heading in the right direction, still falls fall short of what's possible and needed if we are to get the best out of digital and fully realize its promise.

(4) We can expect to see atomic clocks in our future DACs and CDPs. Really?

Am I drawing the right conclusions?
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Lapaix, having worked for several years trying to get the ultimate jitter-free sound from a computer source, I can say that it remains better, audibly better, to play files from USB RAM rather than from hard drives. Yes, hard drives are read in packets, and yes, they are buffered extensively throughout a computer system's busses and operating system and playback software and hardware drivers, but the sound remains better from a USB RAM. And this remains worse than the sound achieved when slaving a CD player to a master dac synchronously. The ultimate point in buffering is not the size of the buffer, but the quality of the clock signal. And the quality of the clock signal depends ultimately on all of the surrounding factors including: its own power supply, the radiating ambient high frequency EM signals from other quartzes and other busses, vibrations (hard disks vibrate), and many other things knowns and possibly unknown. THere are several forums on the internet where people have been discussing computer audio for years and some have reached a very high end sound this way. However, once you put all the solutions up to the line and really compare, it remains improbable that merely enlarging a buffer will take away all the digital nasties. Another way of looking at it is that a CD already is a buffer. It is the buffer that is holding the DATA which was recorded at the finite moments of A/D sampling (during the recording). Whether CD, DVD, hard disk, ram, or anything else, the playback depends on the quality of clocking it.
The G-0Rb uses a Rubidium clock. That is not an atomic clock. An atmoic clock is a Caesium clock!
Rhagen, WRONG! NASA uses both Rubidium and Caesium atomic clocks. As a matter of fact most of the recent space probes and satellites use the Rubidium Atomic clock that I use in my system, it is built by EG&G.
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."