Rega Osiris User Manual

This OSIRIS amplifier has been hand assembled

and tested to the highest quality by:

Production Technician:

Electrical & Mechanical

Quality Assurance:

Serial number:

REGA RESEARCH LIMITED

QUALITY HI-FI DESIGNED AND BUILT IN ENGLAND

SINCE 1973.

Hi-fi for music lovers...

Rega Research Ltd first started making specialist Hi-Fi equipment in 1973. Back then life
and the Hi-Fi world were simpler; Rega produced just one product, a turntable. The
designer (and at that time production team) Roy Gandy had some very specific design
goals. First and foremost excellent sound reproduction, ease of use, strong reliability,
great value for money and finally a long life. Roy achieved his goal through elegant
technical solutions and clever production processes, often creating engineered
assemblies at unbelievably low prices. These savings were handed onto the consumer by
keeping the cost of the product as low as possible.

Roy is still the owner and a key member of the design team, a team which consists of
some employees whom have been at Rega for thirty years inheriting all of Roy’s
attributes in product design. Currently Rega makes more than 40 different products
including turntables, CD players, tuners, amplifiers, DAC’s, and Loudspeakers to name but
a few, all of which clearly demonstrate those early Rega virtues.

Having produced astounding sound quality and unrivalled value for money consistently
over the years you may ask how Rega keeps such tight control on the quality and
performance of the products we build? Easy, all are lovingly hand assembled in our own
factory here in Essex, England. In fact we are so confident in our ability that we offer a
lifetime warranty against manufacture defects on all of our products.*

Rega products, designed for music lovers by music lovers.

www.rega.co.uk

*Your statutory rights are not affected

INTRODUCTION, DESIGN HISTORY AND INNOVATION 1

TECHNOLOGY BEHIND THE OSIRIS 2-3

COOLING AND PROTECTION TECHNOLOGY 4

INSTALLATION 5

INPUT AND OUTPUT CONNECTIONS 6

OPERATION VIA THE FRONT PANEL 7

OSIRIS REMOTE HANDSET 8

TECHNICAL SPECIFICATIONS 9

GLOSSARY OF TERMS 10

LIFETIME WARRANTY 11

BASIC TROUBLESHOOTING GUIDE 12

INTRODUCTION

Thank you for purchasing the Rega Osiris amplifier the highest performance Rega
amplification to date. The Osiris is a 162 Watt 8 (250 Watt 4) super high performance,
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 speaker (ensuring the signal path remains
as short and clean as possible) the Osiris offers unrivalled performance, build quality and
styling.

DESIGN HISTORY AND INNOVATION

The main development objective was to create a no compromise audio amplifier. The
Osiris amplifier is the culmination of 32 years of our Rega engineers experience in
solid-state amplifier development. This expertise combined with the “clam shell” Elicit,
Exon and Hal amplifier circuits gave the foundations for the advanced amplifier circuit
found in the Osiris. All components selected during the design process (specialist audio
components were used throughout) were chosen for their sonic and electrical properties.
Using state of the art surface mount technology perfected whilst designing the latest
Elicit integrated amplifier we now arrive at Rega level IV amplifier circuitry and the Osiris
was created.

1

TECHNOLOGY BEHIND THE OSIRIS

Amplifier circuit.

The Osiris uses a fully symmetrical circuit throughout and 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. All these features amalgamate to create the supreme level of performance found
in the Osiris.

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, thus keeping the audio signal path as pure as possible.

2

TECHNOLOGY BEHIND THE OSIRIS (cont’d)

Input switching and Signal path

The input switching is routed by high performance relays offering minimum loss and sonic
colouration combined with maximum reliability. The input relays are controlled by a micro
controller, which has it’s own power supply galvanically isolating it from the audio
circuits. There is a direct input, which bypasses all the input switching and volume
control, this gives direct access to the input of the power amplifier. Mundorf Mcap poly­propylene capacitors and Alps Blue Velvet potentiometer are used in the input signal path.

Balanced input

Osiris Input 1 is fully balanced, and in keeping with the minimalist circuit topology, we

have opted to use a transformer as opposed to an electronically balanced input circuit.
This transformer is made to the same exacting standards to that of the transformer used
in the IOS MC amplifier.

Internal Wiring

High cross sectional area high quality wire is used in the internal speaker wiring and Klotz
low loss co-axial cable has been used in the low level signal path, these along with
gold-plated speaker and input sockets will yield the best sonic performance and musical
results when used the same high quality interconnects.

3

COOLING AND PROTECTION TECHNOLOGY

Ventilation

The heat produced by the Osiris amplifier is dispersed to the air via the case, particularly
from the heat sinks mounted on either side of the product. Please ensure the heat sink
section is always exposed to allow sufficient airflow to provide adequate cooling of the
amplifier. If the Osiris is driven at high volume for a long period, it will generate heat this
is entirely acceptable and as long as there is sufficient ventilation the amplifier will
continue to work quite normally. Never place the amplifier on carpet, rugs, bedding or
other hi-fi equipment or cover the heat sinks.

Thermal Cut-Out

If the amplifier reaches a temperature liable to cause internal electronic damage a
thermal protection sensor will shut the unit off. If this occurs there will be no sound
emitted from the speakers. The unit should be turned off for at least 30 minutes to allow
for cooling, After this period, the amplifier should automatically reset and continue to
work normally. If it does not, turn off for several hours before retrying. The thermal
cut-out should only occur with continuous driving of a difficult load. If it occurs under
normal conditions, there could be a problem with one of the components of your system,
or insufficient air flow around the unit.

Protection

The Osiris amplifier has a fully protected output stage, with DC, electronic thermal
protection and Load-line protection. Like the input switching this circuit is supplied from a
dedicated power supply. The DC protection will activate within milliseconds, protecting any
connected device. All the protection circuits are so designed that they are peripheral to
the signal path and not influencing the sonic qualities of the Osiris in anyway.

Short Circuit Protection
In the event of a speaker lead short, the load-line short circuit protection will guard the
output stage from excessive currents and voltages. This Rega protection circuit is not
placed in the audio signal path and therefore does not affect sound quality.

4

INSTALLATION

Ensure the operating voltage of the Osiris (stated on the base) is the same as that of

your local power supply.

The Osiris amplifier will work well on most surfaces, a high quality equipment stand which
provides plenty of space for air flow to prevent overheating is recommended. If using a
phono stage and turntable you can avoid magnetic interference by positioning the
amplifier as far away from the turntable as the interconnect will allow. If possible, place it
to the side of the turntable. Keep other equipment, such as tuners or CD players away
from the amplifier. Due to the layout of Rega’s amplifier circuit designs, they are virtually
insusceptible to electro magnetic interference, and by virtue of the custom aluminium
case, emit practically no electro magnetic radiation. However, placing any electronic
equipment close together may impair the performance of one or both items. Never stack
other hi-fi components on top of the Osiris amplifier.

WARNING: The OSIRIS weighs 25.6kg, please ensure the shelf or stand you are

using can safely support this weight. Please refer to your stand manufacturers

manual for maximum load capacity.

Mains lead (supplied)

A Rega designed fully shielded, high quality, high current capacity mains lead is included.

5

INPUT AND OUTPUT CONNECTIONS

Inputs

Input 1 is a standard line level balanced input. Inputs 2,3,4 and 5 are standard

line level and can be used with any line level source.

Note: Input 1 can be used as an un-balanced input by connecting pin 1 to pin 3 and connecting the input earth (screen)

to pin 1 & 3 and connecting the signal (core) to pin 2. This will require an XLR connector.

Rear Panel Connections

Input 1 is made via XLR connection.

Inputs 2,3,4 and 5 are made via RCA (phono) connectors.

The sockets on the Rega amplifiers are clearly marked red and black.

Record Input and Output

This is a line level input and output intended for use with a recording device. Selecting the
record function via the remote handset enables the input (RECORD MONITOR is displayed).

This input is completely independent to inputs 1-5. You can monitor the record function

and quality without affecting the source being recorded. The output is a record signal and

is the same signal as selected by the main input selector 1-5 and is not affected by the

Osiris volume control.

Direct Input

This input is routed directly to the power amplifier input with no volume control. The
intended use is with multi channel systems, where the traditional two-channel system is
used as the front speakers. This input can also be used with an external pre amplifier, if
so desired, or a source component if it is fitted with it’s own volume control. The level is
220mV for maximum output. CAUTION – As this input has no volume control, if a

source such as a CD player is connected to this input the speakers will be driven to
their maximum, this could potentially damage the speakers and amplifier.

6