Meridian 558 User manual

Meridian 558 Multi Channel Power Amplifier
user guide

i
Preface
Meridian 558 Multi
Channel Power
Amplifier User Guide

Preface
ii
Sales and service in the UK
Meridian Audio Ltd
Stonehill
Stukeley Meadows
Cambs
PE18 6ED
England
Tel␣ ␣ (01480) 52144
Fax␣ ␣ [phone]
World Wide Web
http://www.meridian-audio.com
Sales and service in the USA
Meridian America Inc
3800 Camp Creek Parkway
Building 2400
Suite 122
Atlanta
GA 30331
Tel [phone]
Fax [phone]
Designed and
manufactured in the UK by
Digital Gramophone and Wireless Ltd
Stonehill
Stukeley Meadows
Cambs
PE18 6ED
England
Copyright © 1993–2000 Digital
Gramophone and Wireless Ltd
Part no: 557/1
This guide was produced by
Human-Computer Interface Ltd,
http://www.interface.co.uk

iii
Preface
Contents
Introduction 1
Introduces the 558 Multi Channel Power
Amplifier, and provides an overview of the
other products available in the Meridian
500 Series.
The Meridian 500 Series ........................ 2
Sample configurations ........................... 3
Specification and accessories ............... 4
Setting up the multi
channel power amplifier 5
Describes how to unpack, install, and use
the multi channel power amplifier, and
explains what you should do if it requires
servicing.
Unpacking .............................................. 6
Connecting the multi channel power
amplifier ................................................. 7
Connecting a source .............................. 10
Connecting speakers ............................. 11
Troubleshooting 15
Provides suggested solutions to typical
problems.
Troubleshooting ..................................... 16
Maintenance .......................................... 17
Service and guarantee ........................... 18
Index ...................................................... 19

Preface
iv

Introduction
1
Introduction
The 558 Multi Channel Power Amplifier provides five discrete power
amplifiers in a single enclosure, and is ideal for multi-channel surround
systems. Two pairs of channels can also be operated in bridge mode, for
over twice the power output.
The 558 Multi Channel Power Amplifier uses a unique feedback topology
and precision local error correction system. It includes two massive twin
wound toroidal transformers, and the unit has full thermal, load, and DC
protection on every output.
Each of the five channels provides either balanced or unbalanced inputs,
and these can be selected individually.
This guide is designed to enable you to obtain the best possible results
from the unit in conjunction with the other units in your system.

2
Introduction
The Meridian 500 Series
The Meridian 500 Series is a unique system of digital, analogue,
and video components designed to meet the demand for
absolute quality, ease of use, and lasting value.
The flexibility of the Meridian 500 Series is such that you can
assemble a system as simple or as complex as you need,
perfectly suited to your musical and environmental requirements,
and with the ability to add to it or change it at a later date should
your requirements change. The 500 Series is also compatible
with the existing Meridian 200 Series and 600 Series
components.
Each Meridian 500 Series component is housed in a matching
slim line case. Front panel controls provide access to the most
important functions, and the full range of functions is available
from the Meridian System Handset using a simple and intuitive
control interface.
500 Series communications
The Meridian 500 Series includes a sophisticated
communications link, to ensure that any configuration of units
will work together as a fully integrated system.
The 500 Series communications system allows you to control
any combination of units using a single remote, and ensures that
your commands from the remote are interpreted unambiguously.
The communications system also allows you to extend your hi-fi
system into two or three rooms, with the ability to control the
sources in one room from the controller in another room.
Professional features
The 500 Series also provides features for professional users,
including RS232 computer control, and balanced connections.
The following pages give a sample configuration illustrating the
flexibility of the Meridian 500 Series.

Introduction
3
Sample configuration
558 Multi Channel Power Amplifier
The 558 Multi Channel Power Amplifier is ideal for use with the
Meridian 561 Digital Surround Controller or the 568 Digital
Surround Processor, to drive five analogue loudspeakers in a
high-quality surround system. The 568 provides balanced
A500
558
A500
A500 A500
568/561
Meridian DVD Player
A500
outputs from the front left, right, and centre channels, and so is
ideal for use with the balanced inputs of the 558 Multi Channel
Power Amplifier.

4
Introduction
Specification
Input 1.4V RMS.
Output (bridged Greater than 200W per channel into 8Ω.
mode off) Greater than 300W per channel into 4Ω.
Output (bridged Greater than 400W into 8Ω.
mode on) Greater than 600W into 4Ω.
Distortion Less than 0.05%.
Noise Less than -90dB.
Trigger input 5 to 30Vdc or 5-30Vac peak to peak,
polarity independent.
Finish Black textured enamel and brushed
aluminium.
Dimensions 442mm x 174mm x 450mm
(17.4" x 6.8" x 17.7") (W x H x D).
Weight 50kg.
Consumption 30VA quiescent, 1200VA max.
Meridian Audio reserves the right to amend product
specifications at any time.
Specification and accessories
Available accessories
The following accessories are available from your dealer:
❍Power cord Europe.
❍Power cord Canada and USA.
Rack mount kit
The Meridian 500 Shelf is a tray produced by Middle Atlantic
Products which will allow the 558, or any other 500 Series unit,
to be fitted in a standard 19" rack. For more information please
contact Middle Atlantic products, Inc., Riverdale, NJ 07457,
USA, [phone]-1011, or their local distributor.

Setting up the multi channel power amplifier
5
Setting up the multi
channel power amplifier
This chapter explains how to install the multi channel power amplifier. It
describes what you should find when you unpack the multi channel power
amplifier, how you should connect it to your other audio equipment, and
the siting constraints.
You should not make any connections to the multi channel power amplifier
or to any other component in your system whilst the AC power supply is
connected and switched on.

Setting up the multi channel power amplifier
6
Unpacking
The 558 Multi Channel Power Amplifier comes in a box
containing the following components:
❍558 Multi Channel Power Amplifier.
❍1 power cord.
❍2 bridged mode links.
❍This manual.
You are advised to retain the packing in case you need to
transport the unit.
The 558 Multi Channel Power Amplifier weighs 50kg. Do not
attempt to lift it without assistance.
Before connecting power
Before you begin installation you should ensure that your multi
channel power amplifier is set to the correct voltage for your
local AC supply. If it is not, do not try to install the unit, and
contact your dealer.
Do not make connections, or insert or remove plugs, while
the unit is connected to the supply and switched on, as the
transients generated could damage the loudspeakers.
To position the multi channel power
amplifier
During normal operation the internal heatsinks may become
quite hot. The multi channel power amplifier should therefore be
positioned to allow a free flow of air through the cooling vents
from the base to the top.
Do not place the multi channel power amplifier:
❍In direct sunlight.
❍Near heat sources, eg a radiator.
❍Stacked with any other audio products, as the heat it
generates may damage the other products.
Do not restrict airflow through the top and bottom vents.

Setting up the multi channel power amplifier
7
Back panel
Connecting the multi channel power amplifier
OFFON
TRIGGER INPUT
INPUT SELECTOR
BALANCED
UNBALANCED
BALANCED
UNBALANCED
++
––
BRIDGED MODE
INPUT
CHANNELS 4/5
INPUT SELECTOR
BALANCED
UNBALANCED
BALANCED
UNBALANCED
++
––
INPUT SELECTOR
BALANCED
UNBALANCED
BALANCED
UNBALANCED
++
––
INPUT SELECTOR
BALANCED
UNBALANCED
BALANCED
UNBALANCED
++
––
BRIDGED MODE
INPUT
CHANNELS 1/2
INPUT SELECTOR
BALANCED
UNBALANCED
BALANCED
UNBALANCED
++
––
CHANNEL 5 CHANNEL 4 CHANNEL 3 CHANNEL 2 CHANNEL 1
LINK FOR
BRIDGED OUTPUT MODE
BRIDGED OUTPUT MODE
+–
LINK FOR
BRIDGED OUTPUT MODE
BRIDGED OUTPUT MODE
–+
BRIDGED MODE
ON
OFF
BRIDGED MODE
ON
OFF
Outputs
channel 5
Balanced
inputs
Outputs
channel 4
Outputs
channel 3
Outputs
channel 2
Outputs
channel 1
Unbalanced
inputs
Select bridged mode
for channels 1/2
Select bridged mode
for channels 4/5
Power
and fuse
Select balanced/
unbalanced input

Setting up the multi channel power amplifier
8
Outputs
The following table gives details of the output connections:
Use this output To connect to this
CHANNEL 1 to Loudspeakers of 4Ωto 15Ω, using
CHANNEL 5 either plug or bare wire connections.
The recommended assignment of channels, to make best use of
the capacity of each power supply, is as follows:
Channel Assignment
CHANNEL 1 Main left
CHANNEL 2 Main right
CHANNEL 3 Centre
CHANNEL 4 Rear left
CHANNEL 5 Rear right
Alternatively, channels 1/2 and 4/5 can be used in bridged
output mode; see To wire to A500 Loudspeakers in bridged
mode, page 12.
Each channel of the 558 Multi Channel Power Amplifier provides
twin outputs for bi-wiring. On speakers that provide separate
connections to the bass/mid and tweeter units this allows the
units to be connected independently to the multi channel power
amplifier, for optimum sound quality.
Alternatively, for loudspeakers providing a single pair of inputs,
either of the output terminals can be used.
Inputs
The following two alternative audio inputs are provided for each
channel:
Use this input To connect to this
UNBALANCED A preamplifier, using phono connectors
and high-quality screened cable.
BALANCED A balanced analogue output, using
XLR connectors:
1 (Green) = GND
2 (Red) = +ve
3 (Black) = -ve
Select the appropriate input using the INPUT SELECTOR for
each channel.

Setting up the multi channel power amplifier
9
Standby
Once set up, the multi channel power amplifier can be left in
standby as it consumes negligible power in this mode.
To bring the amplifier out of standby press the button on the
front panel. Alternatively, the 558 can be brought out of standby
automatically using the TRIGGER INPUT; see below.
If you are not going to use the multi channel power amplifier for
a period of several days you should switch the unit completely
off, at the back panel, and disconnect it from the AC power
supply.
Trigger input
The TRIGGER INPUT can be used to bring the multi channel
power amplifier out of standby by applying a signal from a
control unit.
The trigger input should be an AC or DC signal of between 5 and
30V. Suitable trigger signals are provided by the Meridian 561,
562, 568, 800, or 861.

Setting up the multi channel power amplifier
10
To connect to a 568 Digital Surround
Processor
558 Multi Channel Power Amplifier
568 Digital Surround Processor
RIGHT CREAR-L
REAR-R
LEFT
OFFOFF
●Switch the two BRIDGED MODE switches to the OFF
position.
●Connect the LEFT, RIGHT, and CENTRE balanced outputs
from the 568 to the CHANNEL 1, 2, and 3 BALANCED inputs
on the 558.
●Switch the INPUT SELECTOR switches for CHANNEL 1, 2,
and 3 to BALANCED.
●Connect the REAR-L and REAR-R phono outputs from the
568 to the CHANNEL 4 and 5 UNBALANCED inputs on the
558.
●Switch the INPUT SELECTOR switches for CHANNEL 4 and 5
to UNBALANCED.
To connect to an analogue
preamplifier (eg Meridian 501/501V)
558 Multi Channel Power Amplifier
501/501V Control Unit OFF
OUTPUT
●Switch the BRIDGED MODE switch for channels 1/2 to the
OFF position.
●Connect the sockets marked UNBALANCED on the back
panel of the multi channel power amplifier to the outputs from
your preamplifier.
●Switch the INPUT SELECTOR switches for the corresponding
channels to the UNBALANCED position.
You should either use a twin-screened audio cable, or a pair of
single-screened audio cables. These cables can have a
considerable effect on the quality of the sound, and you are
advised to seek your dealer’s advice on the best type of cables
for your system.
Connecting a source

Setting up the multi channel power amplifier
11
To connect to A500 Loudspeakers
558 Multi Channel Power Amplifier
A500 LoudspeakerA500 Loudspeaker
OFFOFF
●Set the BRIDGED MODE switches to the OFF position.
●Connect one of each pair of the red and black terminals from
the appropriate channel of the 558 Multi Channel Power
Amplifier to the red and black terminals on the A500
Loudspeakers.
To bi-wire to A500 Loudspeakers
558 Multi Channel Power Amplifier
A500 LoudspeakerA500 Loudspeaker
OFFOFF
●Set the BRIDGED MODE switches to the OFF position.
●If necessary, remove the links bridging the LF and HF
terminals on the back of each loudspeaker.
●Connect the LF red and black terminals from each
loudspeaker to the red and black terminals on the appropriate
channel of the multi channel power amplifier, using twin
loudspeaker cable.
●Connect the HF red and black terminals from each
loudspeaker to the other pair of red and black terminals on
the appropriate channel of the multi channel power amplifier.
Connecting speakers

Setting up the multi channel power amplifier
12
To wire to A500 Loudspeakers in
bridged mode
558 Multi Channel Power Amplifier
A500 LoudspeakerA500 Loudspeaker
ONON
InputInput
You can wire channels 1/2 and 4/5 in bridged output mode, to
obtain more than twice the power output.
●Switch the BRIDGED MODE switches to the ON position.
●Connect the audio inputs to the BALANCED or
UNBALANCED CHANNEL 1 and CHANNEL 5 inputs, as
appropriate.
●Connect the supplied bridged mode links between the black
(-) CHANNEL 1/2 and CHANNEL 4/5 terminals, as marked on
the back panel.
●Connect the loudspeakers between one pair of the red (+)
CHANNEL 1/2 and CHANNEL 4/5 terminals.
You can bi-wire in bridged mode by using the other pair of red
terminals to connect separately to the loudspeaker treble unit.

Setting up the multi channel power amplifier
13
●If necessary, remove the links bridging the LF and HF
terminals on the back of each loudspeaker.
●Connect the red and black terminals from the LF and HF units
on the left loudspeaker to the red and black terminals on
channels 1 and 2.
●Likewise, connect the LF and HF units from the right
loudspeaker to channels 4 and 5.
To bi-amp to two A500 Loudspeakers
558 Multi Channel Power Amplifier
A500 LoudspeakerA500 Loudspeaker
OFFOFF
InputInput
Extremely high sound quality can be achieved using two
separate channels of the multi channel power amplifier to drive
the LF and HF units in each loudspeaker.
●Switch the BRIDGED MODE switches to the OFF position.
●Connect the left audio output from the preamplifier to both
inputs on channels 1 and 2.
●Connect the right audio output from the preamplifier to both
inputs on channels 4 and 5.

Setting up the multi channel power amplifier
14
To connect two 558s to a
seven-channel surround system
ON
OFF
2 x 558 Multi Channel Power Amplifiers
ONON
Centre
Main left
Main right
Rear left
Rear right
Main right
Centre
Rear
left
Rear
right
Side
left
Main left Side right
Side left
Side right
Two 558 Multi Channel Power Amplifiers can be used as the
basis of a superb seven-channel surround system, taking
advantage of bridged mode operation to give more than twice
the power output for the three front channels.
●Switch channels 1/2 and 4/5 of the first 558 to bridged mode,
and use these for the main left and right loudspeakers.
●Switch channels 1/2 of the second 558 to bridged mode, and
use these for the centre loudspeaker.
●Use the remaining channels for the side and rear
loudspeakers, as shown in the diagram.

Troubleshooting
15
Troubleshooting
This chapter provides suggested solutions to typical problems that may
occur when setting up or using the multi channel power amplifier.
If you are still not able to resolve a difficulty with the help of this guide and
the suggestions in the following pages, please contact your Meridian
dealer or Meridian Audio Ltd.