Contents
Thank you for purchasing the Azur 851A Class XD Integrated Amplifier.
The 8 series range is fundamental to our commitment to the continual
development of the Azur range. We hope that you will appreciate
the results and enjoy many years of listening pleasure from it. Like
all Cambridge Audio products, the 851A adheres to our three core
principles – stunning performance, ease of use and incredible value.
The 851A 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 reduces distortion in the
other parts of the amplifier’s output range.
This 851A features our latest development of Class XD with many tweaks
and enhancements from our on-going research resulting in our best
sounding implementation to date.
A white paper on this patent pending technology is available on our
website: www.cambridge-audio.com
Please note that because of the Class XD technology the 851A runs
slightly warmer than a conventional Class B/AB amplifier and the
ventilation slots on the top of the unit must not be obstructed.
A new balanced volume topology has been implemented for this model,
controllable in 1 dB steps over most of the range, giving very fine control,
an accurate logarithmic law and superbly accurate channel balance.
Input switching is by high quality gold contact relays.
The 851A features separate transformer secondaries for left and right
channels, twin rectifiers and separate PSU’s for dual mono operation of
the left and right power amplifiers. A separate transformer supplies the
preamp making the 851A effectively a Pre and Power amp combination
in one box.
Balanced as well as unbalanced inputs are featured for Sources 1 and 2
giving optimal performance with equipment such as the matching 851C
Upsampling CD player which features balanced outputs.
The casework combines massive structural rigidity with careful damping
and control of acoustic resonance. An Azur Navigator remote control is
also provided, giving full remote control of your amplifier in an attractive
and easy to use handset.
Control Bus Input/Output, IR Emitter Input and RS232 control are
featured making it easy to integrate the 851A into a Custom Installation
system if desired.
Your amplifier can only be as good as the system it is connected to.
Please do not compromise on your source equipment, speakers or
cabling.
Naturally we particularly recommend models from the Cambridge Audio
Azur range. 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 8-Series 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 2012.
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.
Cambridge Audio’s policy of continuous improvement means
design and specification may change without notice.
Introduction .................................................................................................2
Important safety instructions .....................................................................3
Limited warranty ..........................................................................................4
Rear panel connections ..............................................................................5
Front panel controls ....................................................................................6
Remote control ............................................................................................7
Connections .................................................................................................8
Operating instructions ................................................................................9
Amplifier setup ......................................................................................... 10
CAP5 - Fiveway protection system ........................................................... 12
Custom installation (C.I.) use .................................................................. 13
Technical specifications ........................................................................... 13
Troubleshooting ........................................................................................ 13
2
