Cambridge Audio Azur 851A Integrated Class XD Amplifier

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  • $1,699.99

  • $1,850.00

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Quite literally in a class of its own, the new 851A Class XD integrated amplifier is designed to offer power, finesse and astonishingly low distortion. At its heart lies our own proprietary Class XD technology, which has been refined and enhanced since its inception in the 840 series, allowing even greater musical detail to be delivered to your speakers.

 Like all Cambridge Audio products, the 851A adheres to our three core values: stunning performance, ease of use and incredible value.

Capable of delivering an enormous 120 watts of high-quality power, it benefits from two audiophile-grade mains transformers: one for the sensitive preamp section and one for the power stages allowing the 851A to deliver its immense output without stress. This incredible speaker-taming amount of power can be precision-controlled with another innovation found in the 851A – the new fully balanced silicon gate volume control, which gives very fine adjustment across the volume range and highly accurate channel-balancing.

 Because everyone’s needs are different, the 851A offers two main types of connectivity: the more commonly found RCA/Phono inputs, plus two pairs of fully balanced XLR connections. Our matching 851C upsampling CD player also features both types of connection, allowing you to connect your system in the very highest quality possible.

Our casework is more than just an exercise in great design, too. The full-metal chassis is acoustically damped for greater performance, with a striking yet robust brushed-metal fascia.

And because we know everyone chooses different source components, we’ve developed an intuitive display which enables you to customise the names of your components – CD player, PC, TV etc. removing that perennial problem of having to remember which device is connected to which input!
Speaking of flexibility, you can even control your iPhone, iPad or iPod using the 851 Series remote control when they’re docked in our matching iD100 digital dock.

Unlike many high end amplifiers which excel in one area over another, we believe the 851A offers the perfect combination of high performance, flexibility and ease of use. It’s designed to take your listening experience to an entirely different level and we invite you to audition our best amplifier to date at your nearest Cambridge Audio specialist.

Azur 851A Integrated Class XD amplifier Features

Class XD™ amplification designed to eliminate crossover distortion at low signal levels

New balanced volume topology controllable in 1dB steps, giving very fine control, and superbly accurate channel balance

Audiophile grade oversize toroidal transformer and substantial extruded heatsink allowing 2 x 120 Watts RMS into 8 Ohms or 2 x 200W into 4 ohms.

Separate transformer taps for left and right channels, twin rectifiers and separate PSUs for dual mono operation of the left and right power amplifiers

A separate toroidal transformer supplies the preamp making the 851A effectively a Pre and Power amp combination in one box

CAP5 protection technology for trouble free operation

Acoustically damped full metal chassis with thick brushed aluminium front panel

Customisable front panel display

Balanced and unbalanced analogue audio inputs for superior connectivity

RS232 controllable

Eco-friendly <0.5W Standby power consumption

Available in black and silver finishes

Class XD, a proprietary Cambridge Audio technology, is a unique amplifier circuit design created to offer the optimum sound quality currently available from existing amplifier configurations, whilst retaining the high power levels required for truly dynamic performance. It was conceived by our London-based engineering team to combine the best of both worlds from Class A and Class A/B amplifier operation.

Class XD (crossover displacement), gives the benefits of pure Class A operation at low levels and eliminates the distortion associated with conventional Class B operation as the fragile audio signal passes though the zero crossing point from transistor to transistor. Distinct from Class AB, XD technology feeds a controlled current into the output stage in such a way that the usual Class B crossover points no longer occur either side of zero volume - the worst possible position in terms of distortion – but displaced to a point where the transfer functions of the transistors are better matched, at a significant output level where it is less audible. The system operates outside of the feedback loop so is not directly involved in the signal amplification itself.
The result is a smooth and linear transition between the two key operating modes, Class A and B.

The benefits of this approach give the sonic refinements of Class A operation and the uncompromising efficiency and power of Class B operation. In fact, the new 851A delivers a gigantic 120 watts per channel - enough for the most demanding speaker set-up.

Shunning cheaper power supplies that many of its peers use, the 851A benefits from two, custom-designed torroidal transformers. Following a painstaking assessment period, our engineers have selected uncompromising, oversized, ‘audiophile-grade’ designs for benefits such as lower noise, quieter PSU operation and excellent bass response

Towards the back of the amplifier is a separate, completely isolated unit supplying the pre-amp stage, and located in the centre is a colossal torroid supplying the main power-amp stage.

These critical components are key to delivering the sonic performance and the power reserves to the 851A.

The 851A also benefits from the latest version of our sophisticated proprietary protection system. CAP5 (Cambridge Audio Protection 5-way) is an innovative and intelligent circuit that constantly monitors the amplifier, without degrading signal purity, ensuring ultimate reliability. Designed to protect the amp in operation, the system has been developed to leave sound quality unaffected. It incorporates a clipping sensor that reduces the volume to keep levels in a safe range, short-circuit detection, and current and voltage overload detection plus a solid-state temperature sensor for over-heat cut out. Combined, these technologies ensure that Cambridge Audio amplifiers will go on to deliver years of reliable, high-performance sound.