Rega Ios User manual

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Contents
Introduction..............................................................................1
Design Innovation.................................................................2-3
Installation................................................................................3
Ventilation................................................................................4
Connections.............................................................................4
Earthing...................................................................................5
Cartridge Selection..................................................................6
Powering Up............................................................................7
Controls.............................................................................8- 10
Troubleshooting................................................................11-14
Specifications....................................................................15-16
Owners Log...........................................................................17
Mission Statement
Rega’s philosophy is to make high quality products at sensible prices, as a means
of reproducing music as faithfully as possible. Rega is committed to the design and
development of new and existing products, both in hi-fi and other areas, that will
perpetuate Rega’s values of quality and value for money.
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1
Introduction
The function of a phono pre amplifier is to match the output
from a pick up cartridge to the input of a line level amplifier. It
is required to amplify the very low signals produced by the
cartridge and also to equalise the in accordance with RIAA
record cutting standard.
Rega believes that moving coil and moving magnet cartridges
require different types of phono pre amplifiers to achieve
optimum performance.
The Ios is therefore dedicated to moving coil cartridges and
avoids compromises.
We have avoided including any superfluous gadgets as they
obstruct the signal path and degrade the sound quality.
The Ios phono pre-amp incorporates remarkable and
innovative design ideas. For those interested in the technical
details, these innovations are described more fully in the
nextsection of this manual.
Alternatively, you can simply switch on, sit back and let your
Ios speak for itself.
Please Note: Read this manual with care - failure to do so may result in operational
difficulties not covered by any warranty.
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2
Design Innovation
The Rega Ios is a four stage all symmetrical amplifier. To
provide optimum performance it is dedicated to amplifying the
very low level signals that are generated by moving coil
cartridges.
The first stage uses a 1:10 step-up transformer, which can be
optimised to the cartridge by the selection of the correct
loading and zobel DC resistance correction network connected
across the MC transformer secondary.
The second stage is symmetrical compound pair class A
amplifier, using paralleled low noise Hitachi transistors in the
input stage. This drives the passive high frequency part of the
RIAA equalisation stage.
The third stage is a symmetrical class A differential amplifier
with a common base driver stage; this is also used as the
active amplifier in the low frequency part of the RIAA
equalisation stage.
The fourth stage is the active filter, this configuration uses the
same circuit as found in the second stage. The filter element
uses a very high bandwidth operational amplifier gyrator as the
simulated inductance part of the tuned filter.
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3
The power supply is a symmetrical discrete tracking power
supply using fast diodes and a low noise voltage reference.
Each stage has it’s own localised power supply, and LED
referenced current generators.
Very high quality, polyproplene capacitors have been used in
the signal path. 1% tolerance polypropylene capacitors are
used in the RIAA EQ stages and audio grade capacitors are
used in the rest of the circuit.
Installation
Ios will work well on most surfaces, such as a shelf or a table,
provided there is sufficient air around it to prevent overheating.
To avoid any possible magnetic interference and increased
hum levels, site the Ios as far away from the turntable as the
tonearm lead will allow. If possible, try to place Ios to the left of
the turntable. Ideally the equipment should be placed next to
one another in a line (Ios to the right). This keeps Ios’s most
delicate electronics away from other transformers.
Try not to stack other Hi-Fi components, (tuners, cassette
decks, power amps or CD players), on top of, or underneath
Ios. If this is unavoidable, use an equipment stand.
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4
entilation
The heat produced by the amplifier, although minimal, is
dispersed to the air by the case, particularly the underside.
Ensure that the case has an uninterrupted air passage around
it.
Connections
The inputs and outputs are made via RCA (phono) type
connectors. The input and output sockets are marked by colour
to indicate left and right channels, Black for LEFT and Red for
RIGHT.
If your turntable has a separate Earth wire, firmly connect it to
the terminal provided on the rear panel. (see illustration above)
NB. Always switch both pre and power amps off before
changing the leads.
Phono inputs Phono outputs Power input socket
Turntable earth connection
View of rear panel
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5
Earthing
The Ios uses a Class I earth system, where the case metal
work and earth screen between the primary and secondary
windings in the toroidal transformer, are connected to the line
safety earth, by means of the mains lead.
The internal signal earth is linked to this earth by the use of a
network to eliminate the risk of earth/ground loops.
This earthing method provides a safe and efficient discharge
path for any static charge generated by the cartridge.
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6
Cartridge selection
The Ios phono pre amplifier is not suitable for use with any
Moving Magnet (MM) cartridges, it can only be used with
moving coil (MC) cartridges.
The Ios has been designed to work with most manufacturers
moving coil (MC) cartridges.
There are five different input load settings, select the required
load to match to that specified by the cartridge manufacturer.
The Ios has five different DC resistance settings 1-5.
Note: It is permissible to try different loading conditions and
resistance settings as sometimes changing the load gives a
different sonic performance more suited to your personal taste.
These variables are explained in greater detail in the controls
section of this manual.
Your Rega dealer will be able to give guidance to help match
your specific cartridge to the correct gain settings.
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7
Powering Up
Ios is activated by depressing the On/Off button situated to the
left of the control panel. The power indicator LED will glow
steadily.
Always activate Ios before the power amplifiers and de-
activate after they have been switched off.
After switching off, the indicator will extinguish.
Due to the nature of the circuit topology, there is a short period
immediately after switching on when the quiescent current has
not stabilised. This condition results in reduced output from the
pre-amp.
This Rega amplifier circuit has been carefully designed to work
with a minimal “ warm up” period. Some manufacturers and
retailers may recommend leaving amplifiers permanently
switched on, Rega cannot condone such practise in these
environmentally sensitive times.
We would recommend that your Rega amplifier is always
switched off after use. Full sound quality is attained after less
than ten minutes (a process speeded up by playing music!)
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8
Controls
The Load Switch
The DC resistance of the cartridge affects the transient or
square wave response of the transformer; this network has to
be optimised to get the best out of the cartridge and
transformer combination.
There are five different input load settings of 50, 100, 150, 300
& 400 Ω . Select the required load to match to that specified by
the manufacturer in the cartridge specifications. It is
permissible to try different loading conditions as sometimes
changing the load gives a different sonic performance more
suited to your personal taste.
The 100 Ω setting is optimised for the Rega Apheta cartridge.
Load switch
Filter switch DCΩswitch
On/Off button ain setting
Filter On/Off
Ω
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