Cambridge Audio 851W Stereo Power Amplifier (Silver)

Despatched In 1 - 2 days

Large Toroidal Power Transformer Delivers Clean Current And Low Distortion.

Stereo Balanced XLR And Unbalanced RCA Inputs. Stereo Or Bridged Mode For More Flexibility.

The 851W is the best sounding amplifier Cambridge Audio has ever made. 200 Watts per channel of sheer class. Warning! Your speakers may never be the same again.

About Cambridge Audio 851W Stereo Power Amplifier

When Cambridge Audio set about developing their 851 Series of hi-fi separates, the brief was simple: to make a hi-fi that not only sounded better than anything else out there, but one that was flexible enough to meet the needs of every serious music lover. With this in mind Cambridge Audio created a system capable of delivering stunning results from all your music whether it's stored on CD, vinyl, your computer, or even your phone.

Developed at Cambridge Audio's R&D centre in London, the 851 Series offers the perfect balance of powerful performance, amazing levels of detail, and innovative features designed to tease the best from your music, however you choose to listen. Perhaps most importantly, the 851 Series has been developed as a complete system with complementing features and synergies. Not only does this give you the very best balanced system, but one that's incredibly easy to use despite its impressive technical performance.

Quality Components: The 851 Series is 100% focussed on delivering the purest, most realistic sound reproduction possible which is achieved through a carefully balanced combination of in-house design talent and the specification of custom developed components - crafted to Cambridge Audio's own demanding requirements. The Azur 851W is designed for top-flight musical performance. Separate, high-end toroidal type transformers - one for the power amplifier and the second for the input and other circuitry. By keeping power supplies entirely separate, audio performance is unaffected by the dramatic current output swings required to drive demanding speakers. The amp's dual mono design offers accurate stereo imaging and a wide soundstage across your listening area. So instead of designing-in gimmicks that only add showroom appeal and little else, they prefer to include expensive toroidal transformers, rather than the cheaper laminate designs that others use. Why? Because they deliver a smoother, purer sound that is almost free from interference and distortion.

By separating out power amplifier functionality, the engineers were able to give this amplifier the time and dedication that it needs to deliver the ultimate performance. By featuring both fully balanced XLR and unbalanced RCA analogue audio inputs, the robust 651W is, of course, designed to work in perfect synergy with a dedicated Cambridge Audio pre-amplifier. For example, by connecting a digital pre-amplifier such the Cambridge Audio CXN, the 851W provides the powerhouse in a truly astonishing digital music system! You'll get the benefits of room-filling, low-distortion power driving your speakers without adding unnecessary, signal-degrading circuitry into the path of your music.

Improved Design: The Azur 851W improves over its already highly respected predecessors in just about every way. At its heart is Cambridge Audio's innovative and proprietary Class XD system, with 12 output transistors per channel. Combining the best of Class A and Class A/B and removing the downsides of both, Class XD amplification eliminates crossover distortion like a Class A amp, while offering the power efficiency of Class A/B. Its performance has to be heard to be believed. It also uses our proprietary Terrapin impedance buffering modules to separate amplifier and signal impedance for absolutely consistent sound across sources. And CAP5 proprietary protection to avoid DC spikes, overheating, short circuits or clipping. The result is a stunningly accurate amplifier that's also amazingly powerful and versatile. The 851W offers a massive 200 Watts RMS per channel into 8 Ohms in stereo configuration, but can also be run in bridged mono mode to output 500 Watts RMS.

Class XD Amplification: Cambridge Audio's proprietary amplification system switches dynamically between Class A and AB systems. Class A amplification delivers the purest possible sound, using only one transistor to conduct, but can be energy inefficient. Class AB involves both transistors conducting simultaneously, but makes it impossible to maintain a balance of low crossover distortion and power efficiency. The Class XD system operates in both Class A and Class AB mode, dynamically moving the crossover point depending on the audio output volume. This combines the near zero crossover distortion of pure Class A with improved efficiency of Class AB at higher volumes, without any compromises in performance for the best of both worlds.

New touches also include a smart auto-standby mode that detects incoming audio signals, automatically coming out of its energy efficient (<0.5W) standby mode and simplifying integration with any Cambridge Audio preamplifier, such as the stunning 851E.

In The News

"Simply, this is one of the most transparent, thrilling and richly rewarding amplifier combinations I have encountered, with fine grip on the speakers with which it’s used, vast amounts of information delivered and never even the slightest sense of the music being held back or sold short." Andrew Everard UK 2014

Our Take

Just like everything they put their name to, the Azur 851 power amp was created from the ground up at Cambridge Audio’s Research and Development Centre on London’s Southbank. There the team of designers work with an uncontested passion for making whatever music you’re into sound sensational. Having had a long association and personal relationship with some in the headquarters team, we know this is not just rhetoric. The 851 Series has been developed strictly to Cambridge Audio's famous Sound First design principles something them and other European brands apart from most general offerings. The core aim of the series is to reproduce your music as faithfully as possible – nothing else matters. We believe the 851 Series achieves that and the critics seem to agree. 

The 851W has got plenty of get up and go even as a single stand-alone stereo power amplifier. Pumping out a massive 200 Watts RMS at 8 Ohms, it has enough under the lid for even the most inefficient speakers. That means you get 'control'. Want more and a second 851 with both working in bridged mode and your up for 500 Watts and that's per channel! So if you’re looking to upgrade every musical performance, it’s time to hot foot down to Audio Trends to listen to Cambridge Audio and hear and judge for yourself what you’ve been missing!

Main Features & Specifications

  • Design: Stereo Power Amplifier - Can be bi-amped or bridged to run in mono
  • Amp Design: Proprietary Class XD amplification incorporates Class A and A/B designs for signal purity, low crossover distortion, and improved efficiency
  • Terrapin Impedance Buffering Modules: Separating amplifier and signal impedance
  • Chassis: All-metal chassis with aluminum front panel to minimise vibration-induced distortion
  • Power Output: 200 Watts per channel into 8 Ohms; 350 Watts per channel into 4 Ohms
  • Power Output Bridged Mode: 1 x 500 Watts into 8 Ohms; 1 x 800 Watts into 4 Ohms
  • Selectable Stereo: Choose single or bi-wired for stereo or bi-amp in mono and bridged mono modes
  • Power Transformers: Two toroidal power transformers; one for the power amp stage and one for the input stages and other circuits
  • Protection System: CAP5 proprietary protection system prevents overheating and clipping
  • Inputs: Balanced XLR and unbalanced RCA inputs
  • Input Impedances: Balanced input 38 kOhm; Unbalanced input 68 kOhm
  • T.H.D (unweighted): < 0.001% 1 kHz; < 0.005% 20 Hz - 20 kHz
  • Frequency Response: 5Hz – 80kHz +-1dB
  • S/N Ratio (ref 1W / 8 Ohm): > 90dB (unweighted)
  • Sensitivity: 1.5V rms unbalanced; 1.5 + 1.5V rms balanced
  • Damping Factor: > 110 at 1 kHz
  • Speaker Terminals: Binding posts accept bare wire or banana plugs (recommended)
  • Auto-Standby Mode: Detects incoming audio signals for easy integration with your preamp
  • Infrared Control Input: Control bus in/out, and 12-Volt DC trigger in/out for integration with external control systems and components
  • Power Cord: Basic IEC power cable that can be easily upgraded
  • Maximum Power Consumption: 2400 Watts
  • Standby Power Consumption: < 0.5 Watt
  • Dimensions (WxHxD): 430 x 148 x 365mm - allow approx 100mm for cables.
  • Nett Weight: 19.1kg
  • Available Colours: Black; Silver
  • Manufacturer's Warranty: 2 Years

Note: Features & Specifications Subject To Change Without Notice. E&OE

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