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Contents
Thank you for purchasing this Azur 851W Class XD™ power amplifier.
We are confident that you will enjoy many years of listening pleasure
from it. Like all Cambridge Audio products the Azur 851W adhere to
our three core principles – stunning performance, ease of use and
incredible value.
The 851W features our unique proprietary amplifier topology; Class XD,
designed to eliminate crossover distortion at low signal levels.
By actively displacing the crossover point this technology creates a region
of pure Class-A operation where the crossover zone would otherwise
be before moving into an enhanced form of Class B at higher levels. It
should not be confused with Class AB, which gives a small area of Class
A, but at the cost of higher distortion as soon as the signal level moves
outside the AB area. Class XD circuitry not only removes crossover
distortion from the zero-crossing point but also joins the characteristics
of the output transistors together in a way that reduces distortion in
other parts of the amplifier’s output range.
A white paper on this patented technology is available on our website:
www.cambridge-audio.com
Please note that because of the Class XD technology the 851W runs
slightly warmer than a conventional Class B/AB amplifier and the
ventilation slots on the top of the unit must not be obstructed.
Other features include a low resonance acoustically damped chassis
for freedom from distortion inducing vibrations. Four pairs of very
high current output transistors per output are used for excellent load
driving ability, plus the unique fifth output transistor pair per channel
that provides the business end of the Class XD circuitry. High quality
polypropylene signal capacitors are used throughout, whilst multiple
copper bus-bars provide very low impedance conduits for the power
circuits and all resistors are 1% tolerance metal-film types.
Balanced audio input connections are fitted for the highest fidelity and
all inputs have loop outputs. The loop outputs can be used with the
851W’s Bi-Amp Mono and Bridged-Mono modes to allow two or more
851Ws to be used in very high quality systems.
The 851W features separate transformer secondaries for left and right
channels, twin rectifiers and separate PSUs for dual mono operation of
the left and right power amplifiers.
Your power amplifier can only be as good as the system it is connected
to. Please do not compromise on your pre-amplifier, source equipment,
speakers or cabling. Naturally we recommend models from the
Cambridge Audio Azur range, particularly the matching 851E pre-
amplifier. These have been designed to the same exacting standards as
this amplifier. Your dealer can also supply excellent quality Cambridge
Audio interconnects to ensure your system realises its full potential.
Thank you for taking the time to read this manual; we do recommend you
keep it for future reference.
Matthew Bramble,
Cambridge Audio Technical Director
and the 851W design team
Introduction
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This guide is designed to make installing and using this
product as easy as possible. Information in this document has
been carefully checked for accuracy at the time of printing;
however, Cambridge Audio’s policy is one of continuous
improvement, therefore design and specifications are
subject to change without prior notice.
This document contains proprietary information protected
by copyright. All rights are reserved. No part of this manual
may be reproduced by any mechanical, electronic or other
means, in any form, without prior written permission of the
manufacturer. All trademarks and registered trademarks are
the property of their respective owners.
© Copyright Cambridge Audio Ltd 2013.
Cambridge Audio and the Cambridge Audio logo are
trademarks of Cambridge Audio.
Other brands mentioned are trademarks of their respective
owners and are used for reference purposes only.
Introduction .................................................................................................2
Important safety instructions .....................................................................3
Limited warranty ..........................................................................................4
Rear panel connections ..............................................................................5
Front panel...................................................................................................6
Connections .................................................................................................7
Unbalanced stereo connections ............................................................7
Balanced stereo connections .................................................................7
Power syncing (On/Standby control) ......................................................8
Advanced connections ............................................................................8
Bi-wired stereo connections ...................................................................8
Bi-amped dual mono connections .........................................................9
Bridged dual mono connections ............................................................9
Powering On/Off the 851W ..................................................................... 10
Custom installation (C.I.) use .................................................................. 10
Configuration menu ................................................................................. 10
CAP5: Five-way protection system ........................................................... 11
Technical specifications ........................................................................... 12
Troubleshooting ........................................................................................ 12
