Esoteric g-orb rubidium master clock generator

The G-0Rb is an atomic clock in your equipment rack that provides an ultra-precise timing reference for the digital-to-analog conversion process.The G-0Rb looks at first glance like it could be a digital-to-analog converter. The unit is sheathed in Esoteric’s gorgeous metalwork, matching the P-03 universal transport and D-03 digital-to-analog converter in my equipment rack. The rear panel, however, reveals its uniqueness in the audio world—it holds eight BNC clock-output jacks, a BNC clock-input jack, and an AC power socket. A narrow front-panel display indicates the G-0Rb’s output frequency, which is adjustable via a row of buttons (see sidebar for specifics).

The G-0Rb can be used with Esoteric transports and processors that accept an external clock signal, as well as with products from other manufacturers that have a word-clock input. The G-0Rb’s outputs feed the clock-input jacks on a transport and digital-to-analog converter. In my case, front-panel switches on the P-03 and D-03 disengage the units’ conventional on-board clocks and accept the clock from the G-0Rb. Consequently, comparing the sound of the digital front end with and without the clock is as simple and fast as pushing two buttons.

And pushing those two buttons renders a staggering improvement in virtually every aspect of the music presentation. In fact, engaging the G-0Rb catapults the sound of the already great P-03/D-03 into another league, particularly with recordings that have a good sense of space and depth to begin with.

Features and Technology

The G-0Rb has three separate clock-output sections, each of which can be independently set to 1x, 2x, or 4x the base frequencies of 44.1kHz and 48kHz. (An additional frequency is available for synchronizing PAL-based video products.) Each section has two outputs, allowing up to six products to be locked to the G-0Rb. These clock-output frequencies correspond to the common sampling rates of 44.1kHz (CD and SACD) and 48kHz (DVD). An additional output frequency of 100kHz is also available, which Esoteric thinks might become a universal standard in the future. The 100kHz output also simplifies operation by obviating the need to change the clock-output frequency when switching between sources (CD and DVD-A, for example) or between different oversampling frequencies. The selected output frequencies are shown on a front-panel display that also has a small “Rb” indicator to show when the rubidium clock is stabilized, which takes a full ten minutes after turning on the G-0Rb. A clock input jack is provided for future applications; Esoteric mentions that the G-0Rb can be connected to an even more precise clock based on the element cesium.

The heart of the G-0Rb is a rubidium core housed in a sub-enclosure filled with gas that is tuned to a microwave frequency. Rubidium is a naturally occurring element that happens to vibrate at a super-precise frequency. Rubidium clocks have been used in commercial and aerospace applications for years. Interestingly, the great recording engineer Roger Nichols (Steely Dan’s Aja and Gaucho, to name two) once created and sold a rubidium clock to synchronize digital-audio gear in recording studios.

Most other digital-audio products employ a voltage-controlled crystal oscillator (VCXO) to generate a clock. A VCXO is a crystal that vibrates when a voltage is applied across it. Because the VCXO’s output frequency is a function of the voltage across it, any ripple or variations in the power-supply voltage will cause the frequency to change—the very definition of jitter. Moreover, the VCXO’s output frequency will vary if the crystal is subject to vibration. A rubidium-based clock is not only more precise and stable than a VCXO, it is not subject to such variability in its output frequency.

The G-0Rb’s build-quality is beyond reproach. The chassis is made from thick aluminum, reinforced internally, with a 5mm-thick steel bottom-plate. The feet are the same Esoteric-developed units employed in the D-03/P-03, which are designed to provide a stable, vibration-free platform for the chassis.

The difference in the timing accuracy between the clock built into the Esoteric D-03 D/A converter and the G-0Rb must be small in an absolute sense (tens of picoseconds I would guess), but the sonic and musical differences couldn’t be more profound.

The idea of an atomic clock sitting in your equipment rack to make digital sound more like analog appears bizarre on the surface, but one listen to the G-0Rb will convince you that such a precise timing reference is a fundamental requirement of state-of-the-art digital playback.

SPECS & PRICING

Esoteric G-Orb Rubidium Master Clock Generator

Output frequencies: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz, 100kHz (universal frequency)

Terminals: BNC coaxial

Power consumption: 81W

Dimensions: 17.4″ x 6″ x 13.8″

Weight: 40 lbs.

Price: $15,000 in 2009

TEAC/Esoteric Company

7733 Telegraph Road

Montebello, CA 90640