Description
Features
- Laser Semiconductor
- Wavelength 780nm
- Digital sampling frequency 44.1kHz
- Power Consumption 46w
- Phono Unbalanced 2.4V source impedance 600 Ohms
- XLR Balanced 2.4V source impedance 600 Ohms
- Co-Axial SPDIF 0.5V source impedance 75 Ohms
- Toslink compatible output
- USB 16bit 44.1/48kHzTHD+Noise< 0.06%
- Frequency Response 30Hz - 20kHz +/-0.5dB
- Rega custom designed and CNC machined aluminium case work
- High quality anodised finish
- Aesthetic high gloss black facia and lid
- CNC machined matching remote control
- Dimensions W 434mm x D 350mm x H 112mm
- Dimension needed to operate W 434mm x D 350mm x H 200mm
- Weight 19.5Kgs
[TABS]
Description
Rega's now legendary head electronics engineer Terry Bateman spent 10 years researching the concept of a CD player using valves in the output amplifier. Valves have been widely used in musical instrument and recording amplification from the 1950's to the present day, therefore it made great sense to develop a valve based CD player to match that of the signal chain found in such applications.
This approach kept the circuit straightforward. This is mainly because musical instrument amplification is not excessively hindered by some of the folklore surrounding certain aspects of valve audio design. He took the approach of combining the technical and sonic attributes of valves in a differential instrumentation amplifier circuit driven from differential output DAC with a passive LC filter.
Design
The valve Isis shares the same digital and USB sections as found in the solid state version, however, the analogue stage is valve based with passive filtering. This stage uses two military specification triple mica 5814A (ECC82/12AU7) triodes being driven by the revolutionary Wolfson WM8741 ultra high performance digital to analogue converter.
The output buffer and transformer driver stage uses two ECC88 (6DJ8/6922) triodes. This, like its solid-state stable mate, is of an un-orthodox design. The design goal with this player was to keep away from the normal design approach of lets run it through a valve to make it sound warm, but take advantage of industrial valve circuits to make an articulate and competent valve based CD player. Careful choice has been made for every component in the digital and the analogue signal path to ensure the integrity of the signal.
Careful design of the PCB's ensures isolation of not just the digital and analogue sections, but also the motor, display and user interface processor. All sonically critical electrolytic capacitors have been by-passed with polypropylene or polyester film capacitors.
In addition to this, large value electrolytic capacitors have also been by-passed with audio grade electrolytic capacitors. Power supply impedances in the digital to analogue converter are kept very low by the use of solid polymer capacitors. All power supplies utilise custom Rega K-Power smoothing capacitors, and fast diodes have been used throughout in power supply rectification.
The Isis uses enhanced and optimised control code for the control of the CD processor and user display; this will speed up the initialisation process by means of a tighter control interface between the user micro and CD processor.
Technology
The differential output of the digital to analogue converter drives a valve differential (operational) amplifier, with a very modest amount of feedback to stabilise the operating conditions. The 5814A based differential amplifier, with a solid-state current generator in its tail, takes full advantage of the differential output from the digital to analogue converter. This is followed by a passive Butterworth second order LC filter. Finally, this signal is buffered using a low anode resistance ECC88 triode to drive the output and balancing transformer.
In design it was felt that unnecessarily high levels of THD would unduly
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