Esoteric E-03 Phono Preamplifier


Equipment report
Solid-state preamplifiers,
Esoteric E-03
Esoteric E-03 Phono Preamplifier

Esoteric Audio is so well known and highly regarded for its series of remarkably articulate and involving multi-box digital-to-analog systems that it came as something of a surprise to me to learn that it had a phono preamplifier in its lineup. Given my experiences with Esoteric over the years, when the opportunity arose to audition that phono preamplifier, the E-03, I was more than just a little interested.

Welcome to the Machine
Measuring 17 3/8" wide, 14 3/8" deep, standing just 4 1/16" tall, and tipping the scales at just over 23 pounds, the E-03 has the form factor of most other phonostages in its class and price range. However, one look at its elegantly sculpted, rather Spartan faceplate will leave no doubt that it is a card-carrying member of the Esoteric family.

The heart of the E-03 is its power supply. Here Esoteric has chosen to use R-core type transformers, widely considered exceptional choices for powering signal circuits. Similar to a toroid, but with a core that has a nearly round cross-section rather than the typical square one, and with a tighter set of round solenoid coils, R-core transformers employ their copper windings more economically. The primary and secondary coil bobbins are wound totally separately from each other, on opposite sides of the core, significantly decreasing parasitic primary and secondary coupling capacitance, and offering improved isolation of high-frequency line noise from the signal-carrying circuits.

The E-03 is a pure left/right, dual-monaural design, using separate power supplies and fully symmetrical in both its mechanical and circuit layout. This global symmetry contributes to mechanical stability as well as channel-to-channel isolation, helping to simplify the signal path and maximize separation.

Both the RIAA and the output buffer amplifiers are built with all discrete components and use relatively high-voltage circuits to ensure abundant voltage headroom for all the active devices, allowing them to perform as linearly as possible. The 5⁄8"-thick sculpted front panel sports only a power switch in the lower left corner and three rotary knobs centered vertically and spaced evenly in a row across the faceplate. The centermost knob allows selection of either Input 1 or 2. To the left of the input selector is the Input 1 loading knob. This offers more versatile moving-coil-cartridge loading, with separate settings for 10, 50, 100, 300, 500, 1k, or 10k ohms. The Input 2 control knob is to the right side, and will accommodate loading for both moving-coil and moving-magnet cartridges, with mc ranges limited to 100, 500, 1k, or 10k ohms, and mm loading choices of 0, 100, and 300 picofarads.

Both input loading knobs offer another feature, a “DEMAG” option, located at the “bottom” of their range of settings. When either input knob is rotated fully counterclockwise, it engages a built-in cartridge-demagnetization circuit for your installed mc cartridges or step-up transformers. While this feature is uncommon, I would have readily forgone it in lieu of a polarity switch, something considerably more useful and almost standard fare on other phonostages of this class.

Like all of the company’s components, the E-03 chassis is supported via Esoteric’s unique isolation footer, an integrated two-piece quenched-steel cone/cup system. One difference here is that rather than employing four isolation feet, with one support located near each bottom corner of the component, the E-03 employs only three—one near each of the front two corners of the chassis, and one centered along its rear.

The logic of this isolation footer application is sound. Euclidian geometry teaches us that while two points are necessary to describe a line, only three are necessary to describe a plane, with more than three being superfluous. In fact, with four points, one of the four will almost certainly be “floating” off the surface under a device being supported by the first three. From an isolation standpoint, I wish more manufacturers would employ only a troika of isolation feet, as such an arrangement allows for the more stable support of any component. Kudos to Esoteric for adopting this stance (pun intended).