Plinius KORU User manual

CONGRATULATIONS on your decision to become the proud owner of this
Plinius Koru Phono Preamplifier.
This manual has been prepared to help you understand the operation of your amplifier, and to provide
information about its design and the variety of ways it may be used.
We have designed and manufactured this preamplifier to reproduce faithfully and accurately, your
favourite music. With a little care and a full understanding of the operating recommendations in this
manual, your Plinius Koru Phono Preamplifier will provide years of high-quality, trouble-free performance.
Serial Number: ................................................................................
Final Test Certified By: ................................................................................
IMPORTANT: PLEASE TAKE THE TIME TO READ THIS MANUAL
THOROUGHLY BEFORE USING YOUR PREAMPLIFIER.

2
DESIGN PHILOSOPHY
From a distance you can see that the design of the Plinius products is more than an applied styling
exercise to the front panel. We have started from the ground up to produce a casing for our electronics
that is unrivalled in its physical strength and visual simplicity. Wherever possible we have reduced the
number of parts needed and then invested massively in refining and producing the remaining parts to the
highest quality achievable with state of the art computer controlled machines allied with expert craftsman.
Examples of this approach include the hydraulically formed corners on the amplifiers giving much greater
strength and the one piece housing for the remote control unit that eliminates large joints and potential
creaks.
The very process of holding the remote tells you that you are controlling both a powerful and precise
product. It is designed specifically for the act of listening to music, not channel surfing on a television or
changing the room temperature. The distinction is important because we believe that listening to music is
a highly selective and emotional experience that requires a much greater level of concentration and
precision to fully appreciate and enjoy.
As with music that you are not familiar with, truly innovative new designs can take time to understand and
enjoy. How often have you heard music that you were first unsure of, that over repeated listening, has
become a firm favourite. Our designs are fundamentally different to many other companies, and we hope
that you will take the time to explore their unique character and qualities because we have not made them
different simply to be different. We genuinely believe that their visual and tactile qualities do improve the
experience of listening to music and that is our design goal!
Ross Stevens
Design Director.

3
CONTENTS
Introduction ............................................................................................................................... Page 3
Precautions ................................................................................................................................ Page 5
Preamplifier Features .................................................................................................................. Page 6
Installation and Operation ............................................................................................................ Page 9
Input/Output Connection............................................................................................................ Page 10
Koru Features ........................................................................................................................... Page 12
Specifications .......................................................................................................................... Page 14
Index ....................................................................................................................................... Page 15
Contact Details ......................................................................................................................... Page 16

4
PRECAUTIONS
Please take special note of the following precautions before operating your new preamplifier:
• This preamplifier operates at hazardous voltage levels. We recommend that any work requiring
removal of the lid be referred to a suitably qualified and experienced service technician.
• DO NOT attempt to connect any input of this preamplifier to its own outputs.
• DO NOT earth any output terminal or connect any of these terminals together without following the
instructions in this manual or seeking qualified assistance.
• DO NOT place this preamplifier in any position where liquids or any foreign material may
accidentally enter it.
• DO NOT connect any voltage source, short circuit, earth/ground or appliance (other than suitable
audio preamplifiers) to the phono preamplifier output terminals.
• DO NOT connect any voltage source, short circuit, earth/ground or appliance (other than suitable
phono turntable) to the phono preamplifier input terminals.

5
PREAMPLIFIER FEATURES – FRONT PANEL
Front Panel Layout Showing Power LED
POWER LED
An LED on the front panel indicates that the power is on. When first switched on, the display LED will
immediately light and will remain lit during the time the amplifier is powered on.

6
PREAMPLIFIER FEATURES – REAR PANEL
This panel incorporates the terminals for connecting the input signal from the Turntable, outputs to the
Preamplifier, loading and gain switches, and also the mains supply.
Please remember that your Plinius Koru Phono Preamplifier is a high quality electronic instrument
capable of an exceptional level of performance. Be sure that you understand your system’s requirements
fully before you make any connection to this amplifier.
REAR PANEL SHOWING INPUT AND OUTPUT TERMINALS, LOADING SWITCHES,
GAIN SWITCHES, MAINS IEC SOCKET AND MAINS SWITCH.
LOADING SWITCHES
The phono input capacitance and cartridge load can be adjusted to suit your particular phono cartridge,
using the 8-way mini-switches at the lower left of the diagram. These switches can be used to set the
input capacitance to 100pF or 570pF, and the cartridge load to 22Ω, 47Ω, 100Ω, 220Ω, 470Ω, 1KΩ,
22KΩor 47KΩ.
For a detailed description of how to use these settings, see page 12.
GAIN SWITCHES
The phono gain can also be set to your phono turntable specifications using the 2-way mini-switches next
to the loading switches.
The Gain settings are 66dB, 60dB, 56dB or 50dB.
For a detailed description of how to use these settings, see page 12.

7
INPUT TERMINALS
The input terminals of your Plinius Koru Phono preamplifier are easily accessible at the lower left of the
rear panel diagram.
RCA INPUTS LEFT & RIGHT: These standard RCA terminals are for use with unbalanced signals from
Turntable.
EARTH POST
This is a chassis connected gold-plated earth post for use with most vinyl turntables.
OUTPUT TERMINALS
Connections for line level preamplifiers are provided in the centre of the rear panel. Connections are
available for both single ended (RCA type) and balanced (XLR type) cables.
The XLR pin configuration used in all Plinius product is:
PIN 1 to GND
PIN 2 to +Signal
PIN 3 to -Signal
NOTE: BECAUSE OF THE WAY OUR XLR AND BALANCED INPUTS ARE CONFIGURED IT IS NOT
POSSIBLE TO CONNECT BOTH XLR AND RCA AT THE SAME TIME.
MAINS SWITCH
The heavy-duty rocker switch on the right of the panel diagram turns the Mains/Line Power to the amplifier
ON or OFF. For your safety, this switch should remain accessible at all times in case of an emergency.

8
INSTALLATION AND OPERATION
PLACEMENT AND VENTILATION
Ventilation through and around your Plinius Koru Phono Preamplifier should be kept unimpeded, so
ensure that the heat vents (slots in the lid) are not covered or restricted in any way. Also refrain from
placing the Plinius Koru on top of other electronic equipment to avoid hum being introduced to the highly
sensitive phono stage circuitry.
The Plinius Koru design incorporates a very high level of mechanical de-coupling of the input and output.
However, it can still be influenced by acoustical feedback in the operating environment. The use of
acoustic cones or a suitably spiked preamplifier stand or table, may further enhance the performance of
this preamplifier. Consult your PLINIUS dealer for further advice if required.
MAINS VOLTAGE CONNECTION
Firstly, check that the mains supply voltage printed on the rear of this preamplifier power supply is similar
to the mains supply voltage in your area. If in doubt, please consult your PLINIUS dealer.
Mains supply power connection is via the supplied plug-in lead. A standard IEC socket connects the
mains power at the preamplifier end, while a local mains plug is required at the wall end.
The wiring code used inside all Plinius product is:
Green to Earth/Ground
Blue to Neutral
Brown to Phase/Live
Should a local market plug specific to your country’s requirements need fitting to the wall end of the lead,
ensure that a suitably qualified service technician wires the plug correctly.
IMPORTANT: DO NOT POWER UP YOUR PREAMPLIFIER UNTIL YOU HAVE
CONNECTED YOUR INPUT/OUTPUTS CORRECTLY FOR YOUR
SYSTEM, (AS EXPLAINED IN THE NEXT SECTION).

9
INPUT / OUTPUT CONNECTION
It is important that you connect your preamplifier (outputs) and phono turntable (inputs) to your Plinius
Koru Phono Preamplifier correctly to ensure the preamplifier is not damaged, and sounds its best within
your system.
Connect your phono turntable to the inputs on the back of the Plinius Koru. Make sure you connect the
red coded cable to the red RIGHT RCA input, and the black (or white) cable to the black LEFT RCA input.
Also, make sure all the RCA connectors are a snug fit and are inserted all the way in.
Now connect your preamplifier interconnects to the outputs on the Plinius Koru, again ensuring you have
left and right channels of your single ended RCA interconnects or Balanced XLR interconnects connected
correctly.
Note that the output of the Koru Phono Preamplifier is at ‘line level’ or the same as that of normal CD
players, tuners etc. DO NOT connect the output from your Koru to a dedicated preamplifier phono stage
as the gain of the Plinius Koru and Preamplifier will be mismatched, which could damage the preamplifier
phono stage. Use only normal line level preamplifier inputs when connecting the Plinius Koru.
If your phono turntable has an earth cable, this can be connected to the gold earth post on the back of the
Plinius Koru, next to the input terminals.
TERMINATION QUALITY
Connections between your phono turntable, Plinius Koru, and Preamplifier should be made with ready
made interconnect cables designed for this purpose.
Quality of the connections must be examined to ensure that high-performance, trouble-free operation is
enjoyed. Check that all interconnection cables are snug fitting and inserted all the way in.
CONNECTING THE MAINS SUPPLY
Now that your Plinius Koru Phono Preamplifier is configured to your system correctly, the mains cable can
be plugged into the IEC socket on the back of the unit. Connect the other end to a suitable wall outlet.
Re-check all interconnection cables are fitted correctly. Turn the switch on at the wall outlet. Next turn the
Mains switch on the back of the Plinius Koru to ON.
The front LED should light and the Plinius Koru is ready to use.
For your safety, this outlet and switch should remain accessible at all times in case of an emergency.

10
WARM-UP PERIOD
You will find that the Plinius Koru will become noticeably ‘warmer’ in sound after being on for a period of
time. We usually recommend waiting at least 24 hours before expecting the best quality of sound
reproduction from your preamplifier. Also, as the Plinius Koru uses very little power while on, we suggest
leaving the unit turned on so that it will always be at it’s sonic best.

11
KORU FEATURES
PHONO CARTRIDGE LOADING ADJUSTMENT
The phono cartridge load can be adjusted to suit your particular phono cartridge, using the 8-way mini-
switches labelled ‘LOADING’.
For all individual mini switches, when UP, the corresponding loading is OFF, When Down, the
corresponding loading is ON.
Switch ‘1’ labelled ‘470pF’, is the adjustable input capacitance.
With switch ‘1’ OFF the input capacitance is 100pF for use with higher output Moving Magnet (MM)
cartridges.
With switch ‘1’ ON there is an additional capacitance of 470pF to give 570pF total input capacitance. This
is an optional setting as there may be some additional interference rejection for lower output Moving Coil
(MC) cartridges when 470pF is ON.
Switches ‘2’-‘7’ allow the load impedance to be set to suit your particular phono cartridge. Once the
correct loading value has been determined, use the corresponding mini-switch to set the load value to
one of 22kΩ, 1kΩ, 470Ω, 220Ω, 100Ω, 47Ω, or 22Ω.
With none of the switches ON, the loading will be set to 47KΩ.
Please consult your cartridge manufacturer for specific recommendations.
PHONO GAIN ADJUSTMENT
The Koru Phono Preamplifier can also be set to one of four gain settings to suit your phono turntable
specifications using the 2-way mini-switches labelled ‘GAIN’.
Using the 2-way mini-switches, the gain can be adjusted as low as 50dB, to suit high output Moving
Magnet (MM) cartridges, or as high as 66dB for low output Moving Coil (MC) cartridges.
With a total of four settings available, you will be able to make gain adjustments to best suit your system.

12
MAINS/LINE FUSE
A Mains/Line fuse is fitted within the IEC socket on the rear of the power supply pack. A small drawer at
the bottom of this socket may be removed (after the IEC plug is removed) by levering it out with a flat
blade screwdriver. The fuse fitted should be rated at no greater than that specified on the rear panel.
IMPORTANT: DO NOT FIT A FUSE WITH A HIGHER RATING.
In the unusual event that this fuse should blow, you must first establish the cause of this failure (such as
power surges, damaged mains cable, etc.) before replacing the fuse with one of the same rating and type.
Should the mains fuse continue to fail, contact your PLINIUS dealer.

13
SPECIFICATIONS
 FREQUENCY RESPONSE:Within RIAA Specifications, +/-0.2dB 20Hz to 20kHz
 DISTORTION:Typically <0.01% THD at all levels below clipping.
 SIGNAL TO NOISE RATIO:-80dB, A weighted with 5mV input.
 INPUT CAPACITANCE:User selectable, 100pF or 570pF.
 INPUT IMPEDANCE: User selectable, 47kΩ, 22kΩ, 1kΩ, 470Ω, 220Ω, 100Ω, 47Ω, or 22Ω.
 HEIGHT: 70mm (2 3/4")
 WIDTH: 450mm (17 3/4")
 DEPTH: 400mm (15 3/4")
 WEIGHT: 5.5kg (12lbs)

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INDEX
IEC Power Connector.............................................................................................................Pages 9,11
Input Terminals ........................................................................................................................... Page 8
Mains/Line Fuse ....................................................................................................................... Page 13
Mains/Line Voltage ..................................................................................................................... Page 9
Mains Supply Connection......................................................................................................Pages 9,11
Mains Voltage Configuration ........................................................................................................ Page 9
Output Terminals......................................................................................................................... Page 8
Phono Cartridge Load Adjustment.............................................................................................. Page 12
Phono Gain Adjustment............................................................................................................. Page 12
Safety Precautions....................................................................................................................... Page 5
Serial Number............................................................................................................................. Page 3
Specifications ........................................................................................................................... Page 14
Terminations............................................................................................................................. Page 10
Ventilation .................................................................................................................................. Page 9
Warm-Up Period ....................................................................................................................... Page 11

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CONTACT DETAILS
All operational, technical and descriptive material published here is subject to change at any time without
notice. For further product information or queries, please contact us at the address below.
PLINIUS products are designed and manufactured by:
Plinius Audio Ltd.
P.O. Box 1836
Palmerston North
New Zealand
Phone: [phone]
Facsimile: 64 6 354 8586
Email: [e-mail]
Internet: www.pliniusaudio.com
©2006 Plinius Audio Ltd.