The Osiris is the culmination of 32 years’ experience in solid-state amplifier development. A no compromise, super high performance, 162 Watts into 8 Ohms (250 Watt 4 Ohms), dual mono amplifier housed in a custom Rega CNC machined aluminum case. Designed around “minimalist” high gain power amplifier and “passive pre-amplifier” circuit topology, passive volume control and a single stage of power amplification between the input and the speakers, the Osiris offers unrivalled performance and build quality.
The Osiris uses a low distortion high linearity and a bandwidth common base voltage amplifier driver stage. This type of symmetrical circuit topology will provide the necessary voltage swings to enable the Osiris to drive any speaker system with the minimum of distortion. Eight Sanken 200 Watt output transistors are used in a “triple” high current output stage enabling the Osiris to drive even the most awkward of speaker systems with ease. The cascaded differential input amplifier uses two low noise LED referenced current generators. The open & closed loop feedback levels and gain bandwidth product components are optimized to give a tight and controlled sound stage, especially at the low-frequency end of the audio range. Nichicon audio grade capacitors are used in bypass and de-coupling positions. Electrolytic capacitors have been bypassed with polyester capacitors where necessary, improving on the HF performance. Low inductance film SM power resistors are used in the output stage.
The Osiris uses two low noise, purpose designed 400VA toroidal transformers using high-grade, fully bonded core material. The transformers are mounted to the chassis using Rega’s innovative mounting technique which eliminates noise being transferred from the transformer to the case when the transformers are operating under arduous mains (line) conditions with high levels of asymmetric mains (line) distortion.
These transformers combined with 40,000 Micro Farads of Rega K-Power smoothing capacitors per channel, provide more than enough current to drive the hardest of loads. All the power supplies utilize fast recovery rectifier diodes throughout. (Fast diodes generate less high frequency switching noise, therefore, giving rise to a cleaner DC).
The input and low-level driver stages are fed from a regulated symmetrical tracking power supply with a low noise voltage reference, which provides a fully stabilized low noise voltage, ensuring the highest level of sonic purity. All the dedicated audio power supplies feed only the audio circuits. The input switching, display & microcontroller and protection circuits have their own dedicated supplies, keeping the audio signal path as pure as possible.
Specifications at 160w into 8Ω