Winner of The 2012 Absolute Sound Editor's Choice Award!The Osiris is the culmination of Rega engineers 32 years experience in solid-state amplifier development. A no compromise audio amplifier using state of the art surface mount technology and a fully symmetrical circuit.
DesignA super high performance, 162 Watts into 8 Ohms (250 Watt 4 Ohms) dual mono amplifier housed in a custom Rega CNC machined aluminium case with high thermal efficiency heat sinks. Designed around "minimalist" high gain power amplifier and "passive pre-amplifier" circuit topology, a passive volume control and a single stage of power amplification between the input and the speakers the Osiris offers unrivalled performance and build quality.
TechnologyThe Osiris uses a low distortion high linearity and 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 cascoded differential input amplifier uses two low noise LED referenced current generators. The open & closed loop feedback levels and gain bandwidth product components are optimised 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 decoupling 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.
Power SupplyThe 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 utilise 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 stabilised 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 & micro controller and protection circuits have their own dedicated supplies, keeping the audio signal path as pure as possible.
Tech Radar Review...what we actually have here is an impressive double-act from Rega; an outstanding CD player – featuring a very useful USB input – and a partnering amplifier, which is a suitably capable performer.
TAS ReviewAs I mentioned earlier, I approached this review with skepticism and doubt, I suppose because—down deep—I feared Rega might build merely “good” components for a market segment where sonic greatness is required. But now that I’ve lived with the Isis and Osiris for months and experienced their capabilities firsthand, I see them in a completely different light. Where once I wondered whether the Rega pieces could keep up with established, pedigreed leaders in their class, I now find myself asking whether competitors can in fact keep up with the Isis and Osiris. They really are that good.
Rega Isis User Manual 
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