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09.12.09
THE REGA OSIRIS 162W INTEGRATED AMPLIFIER :
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.
Design:
A super high performance, 162 Watts into 8Ω (250 Watt 4Ω) 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.
Technology:
The 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 Supply:
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 40,000μF 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.
All these features amalgamate to create the supreme level of performance found in the Osiris and provide a perfect partner for the REGA ISIS Cd player.
THE ISIS CD PLAYER:
Combining our unique CD design technology with blue print design improvements to the digital section and an innovative analogue section we bring you the 7th generation Rega CD player, the Isis.
One important design goal was to take the current output, with no internal amplification within the converter, and convert this to an analogue voltage, using discrete class A operational amplifiers and filters. This circuit can then be optimised for sonic exactness, the use of standard operational integrated circuits locks you into the sound of those particular integrated circuits, thus narrowing the scope for improvement. Interestingly, the class A current to voltage conversion amplifier evolved out of the development of the first stage of the Rega IOS MC amplifier. It shares identical demands of low noise, high drive capability and gain bandwidth required of the voltage to current amplifier.
The analogue section employs two Burr Brown PCM1794 digital to analogue converters, running in a parallel dual mono mode, driving a high performance discrete class A current to voltage amplifier. This combination generates an exceptionally wide dynamic range, low distortion, and linear signal. This drives an enhanced version of the discrete class A output amplifier developed for our Saturn CD player. The circuit is fully balanced from the digital to analogue converters to the balanced analogue XLR outputs. The analogue stage has its own dedicated 50VA mains transformer (twice the capacity of the Saturn), which ensures galvanic isolation (where two or more electric circuits must communicate) between the digital and analogue sections of the player. You will find 10 separate power supply regulators are used in the analogue circuit and each individual amplifier stage has its own dedicated low noise voltage reference.
ISIS Digital section
The digital section is a blue print version of the Saturn circuit, with major improvements to the mechanism, optical amplifier, DSP core, PLL, master clock & motor power supplies. Another 10 separate power supply regulators are used in the digital circuit. The motor, user interface processor & display also have their own power supply. The digital stage also has its own 50VA transformer again ensuring galvanic isolation. The mechanism is graded and matched to the servo circuits, to ensure the servo and optical amplifiers are working at their optimum point, thus improving error correction and playability. The headroom of the optical amplifier has also been improved by 10% by increasing the voltage in the power supply.
USB Input:
The USB input uses an isolated double-clocked USB interface, which permits the digital to analogue stage to be used with a computer USB interface and it’s own regulated power supply. The USB benefits once again from galvanic isolation from the main circuitry of the ISIS player which eliminates the flow of earth currents between the CD and host computer, and keeps the THD+Noise levels to that obtained using the CD player section of the ISIS.
Full details on both products can be found www.rega.co.uk
