Plinius A-300 User manual

PLINIUS REFERENCE A-300 1
Contents
Introduction .................................................................................... 2
Unpacking......................................................................................... 3
Placement & Ventilation ................................................................ 3
Care & Maintenance ....................................................................... 4
Precautions ..................................................................................... 5
Front Panel Functions .................................................................... 6
Rear Panel Functions...................................................................... 8
Installation & Operation ................................................................ 11
Product Features ........................................................................... 15
Loudspeaker Selection................................................................... 17
Troubleshooting.............................................................................. 18
Specications .................................................................................. 19
Index ................................................................................................. 20
All operational, technical and descriptive material in this publication
is subject to change at any time without notice. For further product
information or queries, please contact your Plinius dealer.
Plinius products are designed and manufactured by
Plinius Audio Limited, New Zealand.

2PLINIUS REFERENCE A-300
Introduction
Congratulations on your decision to become the proud owner of this Plinius Reference
A-300 power amplier.
This manual has been prepared to help you understand the operation of your amplier, and
to provide information about its design and the variety of ways it may be used.
We have designed and manufactured this amplier to reproduce your favourite music
faithfully and accurately. With a little care and a full understanding of the operating
recommendations in this manual, your Plinius Reference A-300 power amplier will provide
years of high-quality, trouble-free performance.
Please take the time to read this manual thoroughly before using your amplier.
SERIAL NUMBER
FINAL TEST CERTIFIED BY

PLINIUS REFERENCE A-300 3
Unpacking
The Plinius Reference A-300 power amplier is a very heavy amplier and so requires to be
shipped in a custom made crate. To open the crate you must locate and remove the 12 pozi
drive screws around the base of the crate. Once all of the screws have been removed, the
crate will lift o the base and expose the inner carton containing the amplier.
Please take care when opening the carton as the unit sits just below the surface of the
carton. Open the carton from the top and remove the accessories and polystyrene packing
from each end. You may now proceed to lift the unit from the carton. You will require help
with this as the unit is very heavy.
Placement & Ventilation
This Plinius product may operate at a moderately high temperature, especially during
extended listening sessions. With this in mind, we recommend the following guidelines
for placement and ventilation.
• The ideal location is upon a rigid stand, away from direct contact with any
temperature sensitive materials, furniture or deep pile carpets.
• Ventilation through and around the amplier should be kept unimpeded.
• Ensure heat vents (slots in the base and lid) are not covered or restricted in any way.
• Equipment racks should be of an open type with no closed side panels and no closed
front or rear panels.
• Ensure a minimum of 400mm clearance on all sides of your Plinius unit to other
equipment and the shelf above. Ensure the space between the chassis and shelf
below the unit is unobstructed at all times.
• DO NOT place this unit in an enclosed cabinet.
• DO NOT stack other audio components on top of this unit.
• NOTE: This unit has been designed for use in moderate climates only, not for tropical
conditions.
The design of this Plinius product incorporates a very high level of mechanical decoupling
of the input and output. It can however still be inuenced by acoustical feedback in the
operating environment. The use of acoustic cones or a suitably spiked amplier stand or
table may further enhance the performance of this amplier. Consult your Plinius dealer for
further advice if required.

4PLINIUS REFERENCE A-300
Care & Maintenance
With simple care and maintenance your Plinius product can be kept looking and
operating like new for many years to come.
MAINTAINING THE CONNECTORS
Exposed connectors such as the RCA connectors will be subject to environmental
factors, and over time the surface may degrade. This can be greatly reduced by tting
readily available ‘RCA caps’ to reduce the eects of environmental elements on the
RCA connectors. These RCA caps or RCA shorting caps can also provide sonic benets.
Connector cleaning products are also available to clean the RCA and cable connectors and
frequent checks and cleaning will help maintain a good signal connection.
NOTE: Do not use RCA shorting caps on output connectors or power amplier input
connectors. Use RCA shorting caps on unused preamplier stage input connectors only.
Standard RCA shielding caps can be used on any unused input or output connectors.
MAINTAINING THE SWITCHES
Switches should be maintained by using each various switch setting periodically. Even if a
switch or a switch setting is not used, it is a good idea to toggle small switches and turn
rotary switches though the full range of the switch several times in succession to keep the
contacts active. Performing this simple action will promote longevity of the switch contacts.
SURFACE CLEANING
From time to time you may wish to clean the surface of your Plinius equipment to remove
dust, or any material build up from the atmosphere or on commonly used controls. Your
Plinius product is made up of parts that have a hard anodised or a powder coat nish and
will clean easily without being damaged.
Cleaning should be carried out using a soft cleaning cloth, dry or with either a small amount
of water or a very mild surface cleaner, while observing the following guidelines:
• As a safety precaution, always switch the equipment o prior to cleaning
• Always use a cloth that is soft and clean
• Never use abrasives or polishing compounds anywhere on the unit
• Never apply liquid directly to the surface of the unit
• Use the cloth dry or with mild surface cleaners of either liquid or foaming type
• Apply only small amounts of cleaner to the cloth
• DO NOT rub the surface but wipe clean only. Excessive rubbing may dull powder coat or
wear the screen printed text

PLINIUS REFERENCE A-300 5
Precautions
PLEASE TAKE SPECIAL NOTE OF THE FOLLOWING PRECAUTIONS
BEFORE OPERATING YOUR NEW AMPLIFIER.
• The Plinius Reference A-300 power amplier can deliver up to 1000 watts into 8 ohms.
This amplier is also capable of a very large peak current delivery.
• The Plinius Reference A-300 power amplier is capable of generating heat that could
have an adverse eect on other electronic equipment, furniture, etc.
• This amplier is of direct-coupled design, and oers no protection from preampliers
that have a high DC component at their outputs.
• This amplier operates at hazardous voltage levels. There are some alterations that
may be made by you, the owner. However, we recommend that any work requiring
removal of the lid be referred to a suitably qualied and experienced service technician.
• DO NOT leave ammable material on the amplier whilst running, as this could pose a
serious re risk.
• DO NOT attempt to connect any input of this amplier 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 qualied assistance.
• DO NOT place this amplier 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 high delity loudspeakers) to the amplier output terminals.
• DO NOT expose the unit to dripping or splashing.
• DO NOT place objects lled with liquids on the unit, e.g. vases.
• DO NOT place sources of naked ame on the unit, e.g. candles.
Some preampliers, processors, CD players etc, produce large switching pulses when
switched on causing a loud click through the loudspeakers. For this reason, turn on all
other equipment in your system before turning on your Plinius Reference A-300, or ensure
that the amplier is in MUTE. You will not experience this phenomenon with Plinius
preampliers.

6PLINIUS REFERENCE A-300
Front Panel Functions
The front of the Plinius Reference A-300 power ampli er incorporates all the facilities
you will require on a daily basis.
1. DISPLAY LED
An LED in the centre of the front panel indicates the power is on. When  rst switched on,
the display will vary in brightness until the initialisation sequence is completed, after which
the LED remains lit. When an error condition occurs, the power LED will  ash until the error
has cleared.
2. MUTE SWITCH
It is not recommended practice to interfere with the input cables while the ampli er is
switched on and connected to the loudspeakers, so a Mute button is  tted to interrupt
the input signal. This allows you to connect and disconnect the input cables without the
necessity of turning the ampli er o , or to mute the signal momentarily when desired.
When the ampli er powers up from start, it will automatically go into Mute and disconnect
the speaker outputs. In this mode the Mute LED is ON. Press the Mute switch to take the
unit out of Mute and begin listening.
3. CLASS A SWITCH
This switch on the right of the panel alters the operating bias of the ampli er. Press once to
activate Class A, and again for Class AB. In Class A the LED is ON. Either mode may be used
for listening, with Class A preferred.
1
2 3

PLINIUS REFERENCE A-300 7
CLASS AB
This position reduces the bias on the output stage to operate the amplier in Class AB.
This is a bias conguration used by the majority of high delity ampliers. In Class AB the
Reference A-300 produces very high quality sound, suitable for all occasions where critical
listening is not a priority. A dual benet exists in that this facility provides the user with a
much cooler operating temperature, and a much reduced demand on the mains electricity
supply, particularly at idle while the amplier is not reproducing music. This feature allows
you to leave the Reference A-300 switched ON at all times, rendering the amplier ready
for use and requiring only a few minutes of warm-up in Class A before the very best of the
amplier’s sonic qualities may be experienced.
CLASS A
This position provides Class A bias to the output stage therefore ensuring the optimum
performance of the amplier during all listening events.
Class A ampliers run hotter than Class AB ampliers, hence our specially designed and
distinctive heat sinks. Operating the amplier in Class A necessitates two precautions that
should be observed.
• On switching to Class A, the temperature of the amplier will quickly increase and the
amplier will become quite hot. Ensure that you have left adequate space around the
amplier for ventilation.
• The power required from the mains supply in Class A is approximately 1,000 watts,
similar to a small electric heater. The amplier should not be connected to a wall outlet
that is shared with other heavy current appliances such as heaters or electric motors. If
in doubt, check with your Plinius dealer for advice.
WHY CLASS A IS BETTER
Class A has always been regarded as the perfect operating mode for audio ampliers. Many
leading amplier designers and manufacturers world wide recognise that a well designed
Class A circuit has inherently lower distortion than any other design.
Class A circuit topology is one in which the total current the amplier is capable of
delivering, is kept owing in the circuit regardless of demand. In a conventional or Class AB
amplier circuit this current ow varies when demand varies. Furthermore, as current varies,
the voltage on the power supply rails (as seen by the output stage) varies too.
In a Class A circuit, current draw should be constant therefore there is an absence of the
power supply modulation common in Class AB design ampliers. Pinpoint images, tonal
clarication, inter-transient silence, more readily dened dynamic shadings, inner detail and
authority are all inherent advantages of good Class A design.

8PLINIUS REFERENCE A-300
Rear Panel Functions
This panel incorporates all the terminals for connecting the input signals from your
preampli er and output to the loudspeakers and mains supply. Be sure you understand
your system’s requirements fully before you make any connection to this ampli er.
1. INPUT TERMINALS
Input terminals for your Plinius Reference A-300 power ampli er are easily accessible and
 tted near the top centre area of the rear panel.
RCA INPUTS: These standard RCA terminals are for use with unbalanced signals from most
signal sources such as audio preampli ers.
XLR BALANCED INPUTS: XLR connectors  tted to this ampli er are for use with balanced
line signals from audio preampli ers. Balanced signals are carried via a three way cable that
connects all three pins at each end of the interconnect cable.
The XLR input pin con guration used in all Plinius products is as follows:
PIN 1 to GND
PIN 2 to +Signal
PIN 3 to -Signal
NOTE: Because of the way balanced XLR inputs are con gured it is not possible to connect
both XLR and RCA at the same time.
1
4 5
3 3
1
2
6 7

PLINIUS REFERENCE A-300 9
2. AMPLIFIER CONFIGURATION SELECTOR (ACS)
The Ampli er Con guration Selector (ACS) is a unique switching method that exploits all
of the operational features of your Plinius Reference A-300 power ampli er. By using this
switch it is possible to operate your ampli er with either balanced or unbalanced signals and
achieve a stereo or mono output.
Stereo or Mono use of this ampli er will depend on the type of ancillary equipment
employed with your system. If you wish to use this ampli er as a single channel (mono)
power ampli er in a stereo high  delity system, then another Reference A-300 will be
required for the other channel. This will provide an extremely high performance option.
The ACS switch options are:
• RCA STEREO: This option provides a stereo output via both left and right output
channels from a stereo signal connected to both left and right input RCA inputs.
• RCA BRIDGED MONO: This option con gures your ampli er to drive one loudspeaker
from one unbalanced signal fed to the RIGHT RCA input.
• XLR STEREO: This option provides a stereo output signal from a balanced stereo input
signal connected to both the left and right XLR inputs.
• XLR BALANCED MONO: In this mode both channels of your Reference A-300 combine
to operate as a true balanced mono ampli er, from input to output. This con guration
provides the highest quality mono performance from a balanced line input connected
to the RIGHT BALANCED XLR INPUT.
BALANCED/UNBALANCED SIGNALS
Balanced or unbalanced input options will depend on the type of signal available from your
preampli er or other equipment. The Plinius Reference A-300 provides both options to
allow you to choose the most suitable preampli er for your purposes. Plinius preampli ers
o er both balanced and unbalanced output options.
Balanced line is normally used to transmit signals in a professional environment. Because
balanced line e ectively reduces or eliminates noise pick-up by the system cabling, it has
become increasingly more important in high-quality domestic high  delity systems.
Unbalanced leads such as single ended, RCA or coaxial are common and are used in the
majority of audio signal systems. The terminal plug and socket are most commonly called
RCA and can be found on your Plinius Reference A-300 for use as the standard input
terminals for both left and right inputs.

10 PLINIUS REFERENCE A-300
3. OUTPUT TERMINALS
Output connections for the loudspeakers are provided on the left and right hand side of the
rear panel. Two parallel pairs of binding posts for each channel are tted – these provide
ease of use with bi-wiring and multiple cables requiring a large contact area.
4. MAINS SWITCH
This heavy-duty rocker switch in the centre of the panel turns the Mains/Line Power to
the amplier ON or OFF. An LED in the centre of the front panel indicates that the power
is on. When rst switched on the power LED will vary in brightness for ten seconds – this
is an initialisation sequence, after which the power LED remains lit. The amplier draws
a moderately high current when switched on. Despite the “Soft Start Circuit” within the
amplier reducing current demand on the mains as the amplier is switched on, it is not
good practice to rapidly turn the Mains switch on and o repeatedly.
5. MAINS POWER CORD IEC CONNECTOR
This connector is where the mains supply cable from your wall connects to the amplier.
You will notice that a fuse holder is mounted within this connection, and it holds a mains
fuse to provide surge and overload protection for your amplier.
6. REMOTE TRIGGER SOCKET
In order to integrate more eectively into a home theatre or multimedia system, the Plinius
Reference A-300 has a remote trigger socket on the rear panel. By connecting a preamplier
or processor with a remote trigger output signal to these terminals, the Reference A-300
can be put in and out of Class AB/Mute by the component to which it is connected. When in
Class AB/Mute the amplier draws less current and will operate at minimum temperature.
The output relays are also open, disconnecting the loudspeakers. This may be of advantage
in a multi-amplier and/or remote installations.
7. GROUND LIFT SWITCH
This switch is located adjacent to the Mains Input Socket, and allows the signal ground to be
disconnected from the chassis. In some installations a hum loop may exist due to duplicate
ground paths from dierent equipment. Use this switch to remove the connection from
0V to ground thus allowing some exibility in your particular set-up. Note that when using
Balanced XLR inputs, the ground lift switch should always be set to ‘chassis’.

PLINIUS REFERENCE A-300 11
Installation & Operation
WARNING: RISK OF ELECTRIC SHOCK. TERMINALS MARKED WITH
SHOULD BE CONSIDERED HAZARDOUS LIVE AT ALL TIMES.
This amplier operates at hazardous voltage levels. We recommend that any work requiring
removal of the lid be referred to a suitably qualied and experienced service technician.
DO NOT place this amplier in any position where liquids or any foreign material may
accidentally enter it.
PLEASE READ & UNDERSTAND THE PRECAUTIONS WITHIN THIS MANUAL
FOR PLACEMENT & OPERATION OF THIS PRODUCT.
CONNECTIONS
Connections to your Plinius Reference A-300 should be made in the same order as they are
listed in this section. DO NOT attempt to connect your Plinius Reference A-300 until you
have read and fully understood these instructions. Although these instructions refer to
the connection of a preamplifier, the Reference A-300 can also be safely installed into
multimedia systems by following the same installation guidelines. Should you require
any further assistance, please contact your Plinius dealer.
IMPORTANT: DO NOT POWER UP YOUR AMPLIFIER UNTIL YOU HAVE
CONNECTED YOUR INPUT/OUTPUTS CORRECTLY FOR YOUR SYSTEM.
PREAMPLIFIER INPUTS
Connect your preamplier to the input of the Plinius Reference A-300 using suitable single-
ended RCA or Balanced XLR interconnect cables only. If using single-ended RCA inputs,
connect your preamplier to the RCA inputs on the back of the Plinius Reference A-300.
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 the RCA connectors are a snug t
and are inserted all the way in.
For XLR input connection, make sure you connect the RIGHT XLR input and LEFT XLR
inputs to the right and left outputs from your preamplier respectively. Use the Amplier
Conguration Selector switch to select RCA STEREO if you are using unbalanced RCA inputs
or to select XLR STEREO if you are using balanced XLR inputs.
NOTE: DO NOT connect XLR and RCA at the same time, use only one or the other.
Detailed instructions for using the Reference A-300 in RCA BRIDGED MONO, and XLR
BALANCED MONO modes are later in this section.
LOUDSPEAKER OUTPUTS
The connection of your loudspeakers to the output posts of the Plinius Reference A-300
must be made by an ‘instructed person’ or by ready made loudspeaker cables only. Connect
your left loudspeaker (i.e. the one on your left when seated in your normal listening
position) to the left output terminals, ensuring that the red positive (+) terminal on the
amplier is connected to the red positive (+) terminal on your loudspeaker. Do the same
with the black or negative (-) terminals. Repeat this process for the right outputs.

12 PLINIUS REFERENCE A-300
TERMINATION QUALITY
Quality of the connections must be examined to ensure that high performance trouble free
operation is enjoyed. Check that the connections are tight but do not over tighten. If bare
wires are used make sure that no loose strands of wire short cross the other terminals or the
amplier chassis. When using plugs such as bananas, be sure to use good quality plugs with
a rm t.
BI-WIRING
Bi-wiring uses two pairs of loudspeaker cables for each channel loudspeaker. You will notice
that the rear panel of your Plinius Reference A-300 has two pairs of output terminals for this
purpose. Be sure to follow correct practises for stereo and mono congurations when using
bi-wiring.
When using bi-wires in a STEREO installation, connect each wire pair to a corresponding
pair of binding posts (one cable + and - to the top pair, one cable + and - to the bottom pair)
paying special attention to positive (+) red and negative (-) black polarity.
With a MONO setup bi-wring can still be achieved, but uses only the positive (+) red binding
posts. Use the upper red binding post for the rst bi-wire pair and the lower red binding
post for the second bi-wire pair. Details for MONO setup are later in this section.
NOTE: be sure to disconnect the bridging plate from the speaker input. Consult the
instructions that came with the speaker, or your Plinius dealer for further assistance.
PHASING (OR POLARITY)
It is important to achieve good stereo imaging in your listening room. By observing
the wiring instructions above, each power amplier/loudspeaker combination should
be in phase. If you experience poor stereo image and/or a lack of bass, check that the
loudspeaker wiring has been connected correctly. We recommend that you use one of the
easily obtainable ‘test discs’ to help you ensure both phasing and channel orientation are
correct. If in doubt, consult your Plinius dealer for advice.
To achieve a sound performance that is correctly aligned to your room, make sure all of the
leads carrying signals for the right channel loudspeaker are connected to the right input to
the amplier from your preamplier or CD player etc. Signals for the left channel should be
wired in a similar fashion.
BRIDGED/MONO CONNECTIONS
There are essentially four dierent ways that you can connect your system components to
the Plinius Reference A-300 power amplier:
1. RCA STEREO
2. RCA BRIDGED MONO
3. XLR STEREO
4. XLR BALANCED MONO

PLINIUS REFERENCE A-300 13
RCA BRIDGED MONO:
This option congures your amplier to drive one loudspeaker from one unbalanced
signal fed to the red RIGHT RCA input. In bridged mono mode the only input made to your
preamplier is to the red RIGHT channel RCA input. The black LEFT channel RCA input of the
Reference A-300 is not used in RCA Bridged Mono mode.
In Mono mode, the loudspeakers are connected to positive (+) red output terminals only.
The positive (+) connection on your loudspeaker is connected to the RIGHT positive (+) red
amplier output. The negative (-) connection on the loudspeaker is connected to the LEFT
positive (+) red amplier output.
DO NOT CONNECT ANYTHING TO THE NEGATIVE (-) TERMINALS. MAKING A
CONNECTION TO THE NEGATIVE (-) TERMINALS OF THE AMPLIFIER IN THIS
MODE CAN CAUSE SERIOUS DAMAGE!
You can still connect two loudspeakers using the lower positive (+) amplier output
terminals. This is explained in the bi-wiring section previous. Now turn the ACS switch
fully clockwise then one position counter-clockwise so that it is in the RCA Bridged Mono
position.
XLR BALANCED MONO:
As with RCA Bridged Mono, this option congures your amplier to drive one loudspeaker,
but from one balanced line input connected to the RIGHT XLR Input. In balanced mono
mode the only input made to your preamplier is to the RIGHT channel XLR input. The LEFT
channel XLR input of the Reference A-300 is not used in XLR Balanced Mono mode.
In Mono mode, the loudspeakers are connected to positive (+) red output terminals only.
The positive (+) connection on your loudspeaker is connected to the RIGHT positive (+) red
amplier output. The negative (-) connection on the loudspeaker is connected to the LEFT
positive (+) red amplier output.
DO NOT CONNECT ANYTHING TO THE NEGATIVE (-) TERMINALS. MAKING A
CONNECTION TO THE NEGATIVE (-) TERMINALS OF THE AMPLIFIER IN THIS
MODE CAN CAUSE SERIOUS DAMAGE!
You can still connect two loudspeakers using the lower positive (+) amplier output
terminals. This is explained in the bi-wiring section. Now turn the ACS switch fully counter-
clockwise so that it is in the XLR Balanced Mono position.
CONNECTING THE MAINS SUPPLY
Firstly, check that the mains supply voltage printed on the rear of this amplier 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 plug-in lead supplied with your Plinius Reference A-300.
Check the wall outlet is switched OFF, then connect the local mains plug end of the lead to
the wall outlet. Check the Reference A-300 is switched OFF, and connect the IEC end of the
cable to the IEC socket at the back of the Reference A-300. With the cord fully connected,
switch the wall outlet ON.

14 PLINIUS REFERENCE A-300
Now that your Plinius Reference A-300 is congured correctly, switch the power switch on
the rear panel to ON. The display LED will cycle in brightness for approximately ten seconds
as the internal circuitry stabilises. Use the MUTE switch on the front panel to take the unit
out of MUTE and you can now enjoy your new Plinius Reference A-300 power amplier.
NOTE: This unit must be connected to a mains socket outlet with a protective earthing
connection. The wall outlet socket or Reference A-300 mains switch must be accessible at all
times in case of emergency.
WARM-UP PERIOD
You will nd that the Plinius Reference A-300 will become noticeably ‘purer’ in sound after
being on for a period of time. We recommend waiting at least 24 hours before expecting
the best quality of sound reproduction from your amplier.

PLINIUS REFERENCE A-300 15
Product Features
ERROR DETECTION
The Plinius Reference A-300 power amplier has in-built error detection. This will function
under the following conditions:
• When the amplier is overdriven/clipped
• If any internal fuse is damaged.
Should either of these circumstances arise the amplier will disconnect both channels and
mute the input. When error detection is triggered the mute and Class A LEDs will turn o
and the power LED will ash. The internal error LED (located towards the front of the circuit
board in the top cavity of the amplier) will also light. This condition will remain until the
cause of the error is resolved or the amplier is switched o.
FUSE PROTECTION
When any internal fuse is damaged one or more fuse warning LEDs will light. These LEDs
are under the amplier lid located to the front right of the main circuit board. If any of the
internal fuse LEDs are glowing ensure that your amplier is switched OFF and disconnected
from the mains supply for at least 30 minutes. The base of the amplier will need to be
removed and the fuses located. The rail fuses are near the middle of the circuit board.
Replace them with the same type only.
IMPORTANT: DO NOT FIT A FUSE WITH A HIGHER RATING.
NOTE: Fuse failure may indicate a severe problem. Check all speakers and speaker cables for
damage etc. Should the amplier continue to exhibit rail fuse failure, contact your Plinius
dealer.
ECOLOGIC CONTROL
The Plinius Reference A-300 is also tted with a microprocessor which monitors and performs
the Bias and Mute functions. It is programmed to switch the amplier back into Class AB if
no signal has been present at the input for a predetermined time. This time can be adjusted
to O, 15, 30 or 60 minutes. During the last minute without signal the bias LED will pulse to
indicate the unit is about to return to Class AB. The purpose of this function is to prevent the
amplier being left in Class A while unattended for a long period of time.
Before adjusting this time constant, ensure that your amplier is switched OFF and
disconnected from the mains supply. Remove the amplier lid and locate the small jumper
JP1 on the main circuit board at the front left. Adjustments are then made by shifting the
jumper to the appropriately labelled pins. The factory setting is 30 minutes.
ADJUSTABLE FEET
The feet at the base of the unit are a two-piece design with an integral thread that allows
the height of the unit to be adjusted up from the platform it sits on. You may wish to
increase this distance to clear brackets or shelving details, or to improve ventilation under
the unit.

16 PLINIUS REFERENCE A-300
To access the feet the unit will need to be turned on it’s side. Do this on a clean rm surface.
To raise the unit, turn the internal part of the foot counter-clockwise. To lower the unit, turn
the internal part of the foot clockwise. One full rotation of the internal part is equal to 1mm
(3/64”). A maximum adjustment of approximately 5mm (0.2”) is possible.
IMPORTANT: Maximum adjustment is indicated by the start of the thread. When the
threaded section of the internal part becomes visible, do not adjust further or damage to
the thread could occur.
MAINS/LINE FUSE
A Mains/Line fuse is fitted within the IEC Mains/Line socket on the rear of the amplifier.
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 as specified on the rear panel.
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.
IMPORTANT: DO NOT FIT A FUSE WITH A HIGHER RATING.
NOTE: Fuse failure may indicate a severe problem. Should the amplifier continue to
exhibit mains fuse failure contact your Plinius dealer.

PLINIUS REFERENCE A-300 17
Loudspeaker Selection
Your Plinius Reference A-300 power amplier is designed for use with high delity
loudspeakers. It should not be used to operate any other type of appliance or equipment.
Be certain that your loudspeakers can handle most of the rated output power of this
amplier. You may nd loudspeaker specications confusing or misleading, so you should
discuss this with your audio dealer prior to purchase. As a general rule, the use of high
power (200 Watt RMS or greater) loudspeakers is recommended and desirable. However,
our experience indicates that medium to low power loudspeakers (100 to 200 Watt RMS)
are quite often suitable for use on this amplier, provided the volume is maintained at a
level where no distortion is audible.
Impedance of the loudspeaker load is important to ensure the rated performance of this
amplier. If you have doubts about the impedance of your loudspeaker conguration, we
recommend you speak to your Plinius dealer.

18 PLINIUS REFERENCE A-300
Troubleshooting
NO SOUND FROM THE UNIT
If the unit is not reproducing audio take the following steps:
• Check the preamplier is correctly connected to an appropriate input on the unit.
• Check the source is playing, and not paused or muted. If it has adjustable volume, check
this is at the usual output level.
• Check the preamplier is set to select the correct source input. Adjust the source
selector for the correct source component.
• Check the volume. Turn the unit volume on the preamplier up to a point just below
the normal listening level. DO NOT turn the volume up to maximum in case the sound
begins to come through the speakers.
• Check the unit is not in Mute. If the Mute LED is ON this indicates the unit is in Mute
mode. The Mute LED should be OFF for operational mode.
SOUND IS QUIET OR DISTORTED
Check the ACS is set correctly. If the switch is set incorrectly the output may be quiet or
inverted.
If the sound is quiet or distorted a rail fuse may have failed. While the unit is ON look
through the ventilation slots in the top cover. A Red LED being on will indicate a fuse failure.
If the fuse has failed, see Fuse Protection in the Product Features section of this manual.
NOTE: If the unit immediately or repeatedly suers rail fuse failure, there may be a major
problem and you should contact your Plinius dealer.
POWER FAILURE
The unit may have suered mains fuse failure.
• Check the mains fuse and replace if needed. Refer to the Product Features section for
further information.
NOTE: If the unit immediately or repeatedly suers mains fuse failure, there may be a major
problem and you should contact your Plinius dealer.

PLINIUS REFERENCE A-300 19
Specications
POWER
300 watts RMS per channel into 8 ohms.
Both channels driven from 20Hz to
20kHz at less than 0.05% total harmonic
distortion
MONO OUTPUT
1000 watts RMS into 8 ohms
FREQUENCY RESPONSE
20Hz to 20kHz ±0.5dB
-3dB at 70kHz
DISTORTION
<0.05% THD at rated power
RISE TIME
Typically 5µs
CURRENT OUTPUT
100A short duration peak per channel
Fuse protected
HUM & NOISE
100dB below rated output 20Hz to 20kHz
A weighted
INPUT IMPEDANCE
47k ohms
GAIN
RCA Inputs: 32dB
Balanced Inputs: 38dB
POWER/CURRENT CONSUMPTION
1400W
4.8A (1100W) Class A Idle
0.8A (184W) Class AB Idle/Standby
DIMENSIONS
Height: 285mm (11.25")
Width: 510mm (20")
Depth: 550mm (21.75")
Weight: 57kg (125lbs)

20 PLINIUS REFERENCE A-300
Index
ACS (Amplier Conguration Selector............................9
Balanced Signal....................................................................9
Bias Class A...........................................................................7
Bias Class AB ........................................................................7
Bias Switch ...........................................................................6
Bi-wiring................................................................................12
Care & Maintenance ...........................................................4
Display LED...........................................................................6
Ecologic Control..................................................................15
Error Detection ...................................................................15
Front Panel Layout..............................................................6
Fuse Protection ...................................................................15
Ground Lift Switch ..............................................................10
IEC Power Connector .........................................................10, 13
Input Terminals....................................................................8, 11
Loudspeaker Impedance ...................................................17
Loudspeaker Power............................................................17
Mains/Line Fuse...................................................................16
Mains Supply Connection ..................................................13
Mains Switch ........................................................................10
Mono Operation..................................................................9, 12
Mute Switch.........................................................................6
Operating Temperature ....................................................3, 5
Output Terminals................................................................10, 12
Phasing .................................................................................12
Placement ............................................................................3
Rail Fuses..............................................................................15
RCA Bridged Mono Input...................................................9, 13
RCA Stereo Input ................................................................9, 11
Rear Panel Layout...............................................................8
Remote Trigger ...................................................................10
Safety Precautions..............................................................5
Serial Number......................................................................2
Terminations........................................................................12
Troubleshooting..................................................................18
Unbalanced Signal ..............................................................9
Ventilation............................................................................3
XLR Balanced Mono Input .................................................9, 13
XLR Stereo Input .................................................................9, 11
Warm-Up Period..................................................................14