Rega – Isis CDP Reference CD Player

Rega Isis CD Player Features Class A Op Amps and Filters, Burr Brown DACs in Parallel Dual-Mono Mode, Balanced Outputs: Obsessive Build Leads to Optimal Performance

Few CD players take disc playback more seriously than the U.K.-made Rega Isis. Obsessively engineered, loaded with reference-grade components, and built to specialist levels, the flagship product weighs nearly 42 pounds (!) and takes practically every conceivable precaution imaginable to play CDs with optimal bandwidth, accuracy, stability, quiet, and integrity. Five years in the making, it delivers realistic, involving sound that borders on surreal.

At its core, a pair of Burr Brown PCM1794 DACs running in parallel dual-mono mode fuels a discrete Class A current-to-voltage amplifier, resulting in fantastic dynamics, black backgrounds, and linearity. The combination then drives a discrete Class A output amplifier, with fully balanced circuitry spanning the DACs to the balanced XLR outputs. The analog stage itself benefits from its own dedicated 50VA mains transformer, ensuring galvanic isolation between the digital and analog sections. In addition, no fewer than 10 separate power supply regulators are found in the analog circuit while each individual amplifier stage boasts its own dedicated low-noise voltage reference.

In the blue-printed digital stage, Rega houses another 10 separate power-supply regulators and affords the motor, user-interface processor, and display their own individual power supply. Another 50VA transformer abets a graded mechanism matched to the servo circuits, enhancing error correction and playability. Isis’ cutting-edge servo controller uses the advanced signal processing to ensure that raw data recovered from the disc meets exceptional sonic standards. Because the fully digital servo uses sophisticated algorithms, the laser spot is kept in the optimum position for data recovery in terms of focus, size, and tracking.

And that’s not all. You are welcome to read more about Isis’ PCB construction, capacitors, and IC below. From the photo, we’re sure you can get an idea of the exquisite craftsmanship that extends to the black chrome lid, solid CNC-machined aluminum case, and anodized finish. A USB input with isolated double-clocked USB interface for computer streaming (using the Isis DAC) and CNC-machined remote control are also part of the Isis experience. As to the latter, there’s nothing like it. 100% Music Direct Guaranteed.

“[What] makes the Rega [Osiris and Isis] so special – so natural and magical at the same time – is that they continually supply streams of contextual information that helps make the music more intelligible, richer in meaning.”
– The Absolute Sound

“Used as a pair (surely the way most [Osiris and Isis] will be bought), this is a cracking combination that sounds massively entertaining without being particularly showy about the way it delivers music.”
– What Hi-Fi?

Isis Technology and Design
One of Rega’s important design goal with Isis was to take the current output, with no internal amplification within the DAC, and convert it to analog voltage using discrete Class A operational amplifiers and filters. The circuit can then be optimized for sonic performance. (With most CD players, the use of standard operational integrated circuits locks you into the sound of those particular integrated circuits, narrowing the scope for improvement). It shares identical demands of low-noise, high-drive capability and gain bandwidth required of the voltage to current amplifier. Careful choices were made for every component in the digital and the analog signal path to ensure the integrity of the signal.

The analog and digital sections are bonded together using a substantial ground plane. It was found during the development that adoption of RF ground plane techniques aided the sonic quality. Careful design of the PCBs ensures isolation of not just the digital and analog sections, but also the motor, display, and user interface processor. All sonically critical electrolytic capacitors are bypassed with polypropylene or polyester film capacitors. In addition, large value electrolytic capacitors are bypassed with audiophile-grade electrolytic capacitors. In Isis, the entire IC is clocked via a special PLL of Rega design. It allows better CD data recovery as well as a substantial improvement in the quality of the data delivered to the DAC.

Power-supply impedances in the DAC are kept very low by the use of solid polymer capacitors. All power supplies utilize custom Rega K-Power smoothing capacitors, along with fast diodes – used throughout in power-supply rectification. Isis also uses enhanced and optimized control code for the control of the CD processor and user display, an approach that speeds up the initialization process by means of a tighter control interface between the user micro and CD processor.