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Cambridge Audio Azur 851W

Stereo power amplifier (Black)

6 Reviews | 1 question - 1 answer

Item # 779851WB

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Overview

Our take on the Cambridge Audio Azur 851W

Pure power. When it comes to music, it's about more than sheer brute force. A power amp should take great care in delivering music to your speakers. That's the strength of the Cambridge Audio Azur 851W. Sure, it packs plenty of muscle with 200 watts per channel driving 8-ohm speakers. But the real magic is how it delivers that load — by preserving the purity of the signal through a sophisticated design made for audiophiles seeking sonic perfection.

More than just brawn

Pure power. When it comes to music, it's about more than sheer brute force. A power amp should take great care in delivering music to your speakers. That's the strength of the Cambridge Audio Azur 851W. Sure, it packs plenty of muscle with 200 watts per channel driving 8-ohm speakers. But the real magic is how it delivers that load — by preserving the purity of the signal through a sophisticated design made for audiophiles seeking sonic perfection.

Combining Class A and AB

The Azur 851W uses Cambridge Audio's proprietary Class XD™ power system. It combines the unimpeachable sound quality of Class A amps with the efficiency of Class AB technology. That means you get fantastic sound with minimal crossover or switching distortion from an efficient amp that doesn't run too hot. The 851W's power is generated by not one, but two toroidal transformers. One is purely dedicated to the power amp stage, while the other handles the input stage as well as the rest of the amp's circuitry. That gives this amp the dexterity to handle dramatic changes in dynamics as well as high output levels for when you want to rock the rafters.

Cambridge Audio Azur 851W 2-channel power amplifier

The Azur 851W offers lots of connection options, including XLR inputs, 4 pairs of binding posts for bi-wiring speakers, and plenty of integrated control possibilities.

Sonic synergy with your preamp

Cambridge Audio's innovative Terrapin amp modules forms an impedance buffer between the incoming source signal and the amplifier stage of the 851W. This ensures accurate signal transfer from preamplifier to power amp, offering optimum performance and very low distortion with a wide variety of preamps. Of course, Cambridge Audio's Azur 851E preamplifier is the ideal mate for the 851W if you're looking for matching components with integrated control features.

Stereo, bi-amp, and bridged mono modes

You'll find balanced XLR and unbalanced RCA inputs on this power amp's rear panel as well as speaker terminals for single- or bi-wired connections. There's also a switch that lets you configure multiple 851Ws for bi-amping your speakers or bridging them for use as monoblock amps pushing a whopping 500 watts per channel into 8-ohm loads. A new auto-detect feature allows this amp to turn on and off automatically by recognizing input signals. Cambridge Audio's protection circuitry guards your investment against overheating, short circuits, and clipping.

Product Highlights:

  • 200 watts per channel into 8 ohms
  • 350 watts per channel into 4 ohms
  • selectable stereo (single- or bi-wired), bi-amp (mono) and bridged mono modes
  • bridged mono mode delivers 500 watts x 1 into 8 ohms (800 watts x 1 into 4 ohms)
  • stereo balanced XLR and unbalanced RCA inputs
  • proprietary Class XD amplification incorporates Class A and AB designs for signal purity, low crossover distortion, and improved efficiency
  • 2 toroidal power transformers; 1 for the power amp stage, 1 for input stages and other circuits
  • proprietary Terrapin amplification stages offer improved stereo separation and imaging at low volume levels and consistent sound from all source components
  • total harmonic distortion: 0.005% at 20-20,000 Hz
  • signal-to-noise ratio: greater than 90 dB
  • frequency response: 5-80,000 Hz
  • auto-standby mode detects incoming audio signals for easy integration with a preamp
  • infrared control input, control bus in/out, and 12-volt trigger in/out for integration with external control systems and components
  • all-metal chassis with aluminum front panel to minimize vibration-induced distortion
  • CAP5 proprietary protection system prevents overheating and clipping
  • 16-15/16"W x 5-13/16"H x 15-5/8"D
  • weight: 42.2 lbs.
  • warranty: 3 years
  • Our 60-day money-back guarantee

Wow! Wow! Wow! This amp brings it all to life! I WILL be adding a second!

Jim R, Florida

What's in the Box:

  • Power amplifier
  • 6' AC power cord
  • 38" Mono-RCA cable
  • User Manual (En/Fr/Sp)
  • Quick Start Guide (En/Fr/Sp)
Reviews

Cambridge Audio Azur 851W Reviews

Average Customer Review(s):

(6 Reviews)

Cambridge Audio Azur 851W

Anonymous from Ft Lauderdale, FL on 9/19/2017

Crutchfield Customer Review (What's this?)

I wanted this stuff because when you look at it on the rear end of it on the computer screen you cannot tell the difference of the inputs for the uhd player! Here in the U.S. we have what is called universal inputs for this when you buy the main product such as a computer or a TV. you more less have freedom of choice on the type or brand of printer and screen for the computer. And the type and brand of blue player you want to hook to your TV. This thing I had to argue with every one in your there for a day 1/2. about this ! My Blu-Ray Player cost was a over 400.00 and to convert with their input . By the way you had to buy their converter to do this cost add on was another 200.00 to do this would make it close to what they wanted for their player! To me that is like a CON! So I think i going to talk to BBB. about this and see what they say about all this! No one informed me of this ahead of time when I ordered it. And those approved shipping lables say the back shipping will be still charged on me ! If they do i will call American Express and tell them about all this and they will take them Off!

Pros:

Cons:

Swwweeeeeet amp, but runs very hot

Joe from Fredericksburg, VA on 1/3/2017

This is one of the best sounding amps I've ever heard, period! I would hold it's sound quality up agains a McIntosh or NAD any day. The sound is very clear, clean, precise, open, bright, delicate, warm, accurate, and sweet. In my opinion, at the price, this is one of the best deals in amps today. You can use it as a 2 channel 200/500 watt (8/4 ohms respectively) or as a 500/800 watt monobloc (which is the way I used them, until I had to return them). The connection options are awesome, both balanced/unbalanced inputs, 12v triggers, etc. My plan was to by 2 of them, to be used as monoblocs for my B&W 800 D3 speakers, and then eventually buy another 2, to run a pair of these amps for each of my speakers. The reason I ended up abandoning this plan and returning them was that they just go too dang hot, super hot; hot enough to burn your hand if you touched them. They say their topography is ClassXD, but they sound and act just like pure Class A amps, which are known to run VERY VERY hot. I tried cooling solutions I found on Amazon, but because of their honeycomb skin desing, I couldn't get these fans to provide a channeled airflow to keep them cool. One side of both amps eventually failed, and so I had to return them (I couldn't take the chance of them failing after the return period/warranty ended. My heart was devastated, as I REALLY loved these amps. I ended up with a Bryston 4B3. I wish Crutchfield would sell Bryston products.

Pros: Swwweeeeeet sounding amp, one of the very best sounding amps I've ever heard, plenty of power to burn, handles 4-ohm loads with ease, dynamic, clean, crisp yet delicate sounding. VERY flexible options (stereo, mono, bridge, etc.)

Cons: Runs HOT, very HOT. Did I mention that the amp runs HOT, probably hot enough to fry an egg on, but will certainly burn your hand? I tried external cooling fans, but found nothing that could really keep it comfortably cool.

Best in its price range

Linconln from Brazil on 12/27/2016

This is simply the best power amplifier that I ever had! It has the same impact of Emotiva´s XPA2 for me but with a more pleasant sound. My Monitor Audio Silver 10 were suffering with the Parasound A23 and I simply couldn´t find a position to hear them the way I wanted. Cambridge´s beast unleashed all the qualities of the speakers and the position lost all the matter. It sounds very good even with low volume and gives the urge to raise up the level to feel the impact of bass. Last but not least, it has a beautiful finishing and I spent a lot of time looking at it when I first saw.

Pros: Powerfull Beautiful Noiseless

Cons: It´s hot! 2400 V it´s an unthinkable power consumption value although it is only measured in bridge at 4 ohms for what I´ve read

C.A. 851 W

Cristian G from Miami, FL on 11/8/2015

I have this amplifier hooked up to a hotel rc 1590 ( i needed two pre out's and two sub out's ) with a pair or Martin Logan 60x and the sound is absolutely clean, practically no distortion at high volume and it makes the speakers open at a low volume. The finishing of the product is outstanding. I highly recommend this product to whoever who's into great sound and performance, worth every penny.

Pros:

Cons:

Cambridge 851W

Cambridge 851W from Florida on 10/26/2015

Crutchfield Customer Review (What's this?)

The Cambridge 851W to me is a great amplifier, punchy , with guts, and will beat any other amplifier costing twice or three time as much. Don't take my word for it, please go and purchase one from the guys at Crutchfield, if you don't like it you could returned and they give you your money back.

Pros: Everything.

Cons: None.

851W Kicks A$$!

Jim R from Florida on 3/5/2015

Crutchfield Customer Review (What's this?)

Wow! Wow! Wow! This amp brings it all to life! I WILL be adding a second!

Pros: The clarity is amazing! The power is awesome!

Cons: None

Details

Hands-on research

Product Research

Features

Class XD Amplification: Cambridge Audio's proprietary XD 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. Cambridge Audio's Class XD system operates in both Class A and Class AB mode, dynamically moving the crossover point depending on the audio output volume. Cambridge Audio's Class XD amplification with 12 output transistors per channel combines the near zero crossover distortion of pure Class A with improved efficiency of Class AB at higher volumes, without any compromises in performance.

Stereo & BridgeD Modes: The Cambridge Audio Azur 851W delivers a massive 200 watts x 2 channel into 8 ohms (or 350 watt x 2 channel into 4 ohms) in stereo configuration, but can also be run in bridged mono mode to output 500W x 1 channel into 8 ohms (or 800 watts x 1 channel into 4 ohms). There is a switch on the back of the amp which selects between Stereo or Bridged (mono) mode.

Dual Toroidal Transformers: Separate, high-end transformers for the power amplifier and input and other circuitry ensure audio performance is unaffected by the dramatic current output swings required to drive demanding speakers, by keeping power supplies entirely separate.

Terrapin Impedance Buffering Modules: Cambridge Audio's proprietary modules replace the op-amps commonly found in similar amplifiers. At the critical low level gain stages, these offer far improved stereo separation and imaging.

Balanced & Unbalanced Analog Inputs/Outputs: The Cambridge Audio 851W power amplifier is fitted with both balanced (XLR) and unbalanced (RCA) analog audio inputs to make connection to Cambridge Audio's 851E preamplifier (779851EB, sold separately) or other manufactures preamp (sold separately). XLR is a higher-quality input that can reject noise and interference from equipment with balanced outputs. Both the unbalanced and balanced inputs have loop outputs that can be used with the 851W's Bi-Amp Mono and Bridged-Mono modes to allow two or more 851Ws to be used in a very high-quality audio system.

Note: Only one type of input (balanced or unbalanced) can be used. There is a switch on the back panel of the amp which selects between the balanced or unbalanced inputs.

Binding Post Speaker Outputs: The Cambridge Audio Azur 851W power amplifier is equipped with two sets of gold-plated, binding-post speaker terminals. The speaker terminals can be used in a Normal Stereo, Bi-wire Stereo, Bi-amp Mono, or Bridged Mono configuration. The binding-post terminals will accept bare wire (up to 10AWG), pin-connects, and banana plugs (dual or single). Only connect speakers with a nominal impedance of 4- to 8-ohm.

All-Metal Chassis: The Cambridge Audio 851W power amp features an acoustically damped full-metal chassis with thick brushed aluminum front-panel.

5-Way Protection System: The 851W benefits from the latest version of Cambridge Audio's 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.

  • DC Detection: CAP5 offers loudspeaker protection if the output of the amplifier goes to a high constant voltage (DC).
  • Over Temperature Detection: AP5 includes temperature detection which constantly monitors the heat generated by the output transistors. If the monitored temperature reaches a high level (suitably within the limits of the output devices) the amplifier will automatically switch into a fault mode.
  • Over Voltage Detection: CAP5 offers V/I protection by constantly monitoring the output transistors to keep them working inside their Safe Operating Area (SOA). The SOA is a set of limits given by the output transistor manufacturer to ensure reliability. V/I also protects the amplifier against short-circuits on the speaker terminals during use.
  • Short-Circuit Detection: During power up from Standby, CAP5 performs a check on the loudspeaker terminals to see if a short across the terminals has been accidentally introduced. If the resistance measured across the loudspeaker terminals is too low, the unit will remain in Standby mode until the fault has been removed and power up is re-attempted.
  • Intelligent Clipping Detection: CAP5 has the ability to detect when the amplifier starts to clip or overdrive at its output, which can damage loudspeakers and degrade the sound. Clipping distortion is caused at high volume levels when the output signal briefly goes outside the maximum voltage that the amplifier can provide, causing the tops of the signal to flatten off. When CAP5 detects clipping, the volume will be automatically nudged down until CAP5 detects an undistorted output.

IR Input/Control Bus: The 851W also features a IR Emitter input (3.5mm) which allows modulated IR commands from multi-room systems or IR repeater system to be received by the amplifier. In addition, the 851W features a Control Bus Input and Output (RCA), which allows un-modulated commands from multi-room systems or other components to be received by the amp and loop out to another unit.

Trigger Input/Output: For custom install use or with preamps and with trigger outputs, the 851W can be turned on and off (i.e. brought in and out of Standby mode) by the presence of 5-12V DC at the Trigger input (3.5mm). A trigger input will also produce an internally generated 12V DC trigger output at the Output/Thru connection (3.5mm). Turning the 851W on from the front panel also produces a 12V DC trigger output at the Output/Thru connection. This can be used to turn on/Standby other connected power amplifiers or other equipment if desired

Smart Auto-Standby: Smart Auto-Standby mode (<0.5W) detects incoming audio signals to simplify integration with Cambridge Audio preamplifiers.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

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Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

The reviews I read where very positive. It's individual power supply, and wpc where what I needed to run my sonos Faber speakers. I looked at other amps notable the Rotel 200 wpc, but am hoping that this unit lives up to the reviews of more stage presence and natural sound.[ michael  May 06, 2017 ]
Perfect companion to the 851E Preamp.[ Anthony  Nov 12, 2016 ]

1 question already asked

Thanks for your question. For information on comparing two or more models I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences and help you make the best choice for your system and your budget.[ Kenny  Dec 09, 2016 ]  Staff
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