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Cambridge Audio Azur 851E

Stereo preamplifier (Black)

Item # 779851EB

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Our take on the Cambridge Audio Azur 851E

The purpose of audiophile equipment is always the same: to reproduce music as accurately as possible without introducing any sound that wasn't there to begin with. Cambridge Audio has long taken this mission seriously with their highly regarded amplifiers. Their Azur 851E preamp moves them one large step closer to this ideal. Every aspect of this preamp's construction is designed for accurate playback with an absolute minimum of distortion and noise.

Taking aim at perfection

The purpose of audiophile equipment is always the same: to reproduce music as accurately as possible without introducing any sound that wasn't there to begin with. Cambridge Audio has long taken this mission seriously with their highly regarded amplifiers. Their Azur 851E preamp moves them one large step closer to this ideal. Every aspect of this preamp's construction is designed for accurate playback with an absolute minimum of distortion and noise.

Cambridge Audio Azur 851E preamplifier and 851W power amp (not included)

Together with the 851W power amp (top - not included), the Azur 851E preamp delivers impeccable musical accuracy with minimal distortion (shown in Black).

Old and new features

Some of the 851E's features will look familiar to audiophiles, such as the oversized toroidal transformer, balanced XLR connections, and the all-metal chassis. But there are some interesting developments that add to this preamp's impeccable performance. A new solid-state volume controller offers precise linear control while not introducing distortion into the analog source signal. This not only keeps the signal pure, it also offers more accurate balance between the left and right channels at low volumes.

Building a better preamp stage

Another key reason for this preamp's clean sound is the proprietary Terrapin amplification stage. Rather than use standard op-amp chips, Cambridge Audio developed their own amp circuit that offers improved stereo separation and imaging at low volume levels. The Terrapin circuitry also employs an impedance buffering module, which separates the incoming source signal from the amplifier stage. This buffer minimizes the effect that varying output impedances among connected sources can have on an amplifier's performance. That means you can connect up to eight source components to the 851E while maintaining its sonic clarity and astonishingly low distortion.

A few more perks

While purity of sound is the purpose of the 851E, Cambridge Audio managed to sneak in a few cool features without compromising Job #1. There's a front-panel display which allows you to customize the names of your source components. There's also a subwoofer output with selectable full-range or as a 200 Hz low-pass operation for flexible bass management. In addition to the many connections for source components, the 851E offers advanced control features and connections like 12-volt trigger and IR jacks. Of course, the easiest way to achieve seamless integration is to pair this preamp with Cambridge Audio's Azur 851W power amp, for a dynamic duo that will scale sonic heights without breaking a sweat.

Product Highlights:

  • connect up to 8 source components at a time
    • 3 pairs of balanced XLR inputs
    • 7 pairs of unbalanced stereo RCA inputs
    • stereo RCA record input/output
  • stereo balanced XLR and unbalanced RCA preamp outputs
  • total harmonic distortion: less than 0.00057% @ 20,000 Hz
  • signal-to-noise ratio: less than 110 dB
  • advanced solid-state volume controller offers precise fine tuning with accurate channel balance even at low volume
  • proprietary Terrapin amplification stages offer improved stereo separation and imaging at low volume levels and consistent sound from all source components
  • large toroidal power transformer for clean, stable power
  • front-panel LCD display with custom naming for source inputs
  • sub preamp output for connecting a powered subwoofer
    • adjustable for full-range output or 200 Hz low-pass filter
  • infrared control input, RS-232 port, control bus in/out, and 12-volt trigger in/out for use with external controllers and components
  • bass and treble tone controls
  • 1/4" headphone jack
  • all-metal chassis with brushed aluminum front panel to minimize vibration-induced distortion
  • frequency response: 10-100,000 Hz
  • remote control
  • 16-15/16"W x 4-1/2"H x 16-1/16"D
  • weight: 17.9 lbs.
  • warranty: 3 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Pre-amplifier
  • 6' AC power cord
  • IR remote control (RC-8/SM)
  • 3 "AAA" batteries
  • 38" Mono-RCA cable
  • User Manual (En/Fr/Sp)
  • Quick Start Guide (En/Fr/Sp)

Hands-on research

Features and Specs

Signal to Noise Ratio Not Given
THD 0%
Number of Inputs
USB Connections None
Ethernet Connections None
Phono Inputs None
Preamp Outputs 5
Network Streaming Services N/A
Bluetooth No
AirPlay Compatible None
Width (inches) 16-15/16
Height (inches) 4-1/2
Depth (inches) 16-1/16
Weight (pounds) 17.9
Parts Warranty 3 Years
Labor Warranty 3 Years

Product Research


Low Distortion: Every component within the Cambridge Audio Azur 851E pre-amplifier is designed not to interfere with the audio signal input and output, meaning that harmonic distortion and noise are so low that they're almost impossible to measure.

Solid State Volume Control: The Cambridge Audio Azur 851E pre-amplifier employs a solid state volume control that offers precise control, retains channel balance accurately at low levels, and offers truly linear performance; all without introducing any distortion to the precious analog source signal. While the volume control itself is digital, the signal remains completely analog.

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

Full Metal Chassis + Toroidal Power Supply: The 851E pre-amplifier features an acoustically damped, low resonance full-metal chassis with a thick, brushed aluminum front-panel. The 851E also uses a large toroidal transformer to deliver exceptional reliability and perfect performance every time.

Balanced and Unbalanced Analog Inputs: The Cambridge Audio Azur 851E pre-amplifier is fitted with both balanced and unbalanced analog audio inputs.

  • Balanced XLR Inputs: The 851E  pre-amplifier features three sets of balanced XLR inputs to connect high-resolution CD and SACD players. XLR is a higher-quality input that can reject noise and interference from equipment with balanced outputs.
  • Unbalanced RCA Inputs: The Cambridge Audio 851E is fitted with eight pair of gold-plated analog audio unbalanced inputs (RCA) to connect your external audio sources; such as your Blu-ray/DVD player, AM/FM tuner, CD/SACD player, or Network Player.
Note: The pre-amplifier's Inputs 1, 2, and 3 feature both XLR and RCA inputs; only one type of connector can be used at a time for an input.

Balanced and Unbalanced Analog Outputs: The Cambridge Audio 851E offers a variety of balanced and unbalance analog audio outputs.

  • Preamp Outputs: The Cambridge Audio 851E is equipped with a set of balanced XLR preamp outputs, as well as a set of RCA preamp outputs to connect the pre-amp to Cambridge Audio's 851W power amp (779851WB, sold separately) or other external power amplifier (sold separately).
  • Sub Out: The 851E is fitted with a mono-RCA subwoofer output to connect a powered subwoofer for added bass. This output can have either a full-range, unfiltered frequency response or a 200Hz low pass filter can be applied.
  • Record Output: One of the pre-amp's stereo RCA inputs is a "Record In" and is paired with a "Record Out" which also consists of stereo RCA connectors. This allows you to connect to a CD recorder, MiniDisc recorder, or tape recorder.
  • Headphone Output: The 851E pre-amplifier offers a front-panel 1/4" headphone output to connect a set of headphones for private listening. When headphones are connected, the output to loudspeakers is muted. Use headphones with an impedance of between 32 and 600 ohms.

Audio Settings: The 851E pre-amplifier offers a variety of audio adjustments to tailor your music.

  • Tone Control: The 851E has independent Bass (10Hz) and Treble (20kHz) controls. The Bass can be adjust from -10 to +10dB, while the Treble can be adjusted from -7.5 to +7.5dB. Balance control allows you to adjust the relative output levels of the left and right speaker channels.  The Bass, Treble, and  Balance controls only effects the preamp outputs; it does not effect the record outputs.  Direct mode gives the audio signal a more direct path, bypassing the bass and treble control circuits for the purest possible sound quality.
  • Gain: The relative levels of the inputs can be adjusted by gain trim. This allows each to be adjusted so that each sounds the same in terms of average loudness when you switch between them. In addition, any input of the 851E is able to be set for fixed gain. Whenever this input is selected the gain will automatically go to this value and will not be adjustable by the volume control. This can be useful with sources that have their own built in volume control.

Front-Panel LCD: The 851E has a front-panel display that shows the current status and allows you to access the 851E' system settings menu. Here you can adjust the listening settings of the amplifier to personal preference. The menu system is easy to navigate and control from the remote or pre-amplifier. You can adjust the brightness of the display.

Remote Control: The 851E is supplied with an IR remote control that wirelessly operates this pre-amplifier, as well as other Cambridge Audio 851 series products and Stream Magic gear (sold separately).

IR Input/Control Bus: The 851E 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 pre-amplifier. The 851E also 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 pre-amp and loop out to another unit.

Trigger In/Out: For custom install use, the 851E 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 or by turning the 851E on from the remote/front panel will also produce an internally generated 12V DC trigger output at the Trigger Out 1 and 2 connections (3.5mm). This can be used to turn on/ Standby a connected 851W power amplifier if desired.

RS232 Port: The integrated amp's RS232 port is used for control of the 851E in custom install situations from an external controller. A full protocol is available for the 851E on Cambridge Audio's website.

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.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

Great Specs[ William C.  Dec 19, 2016 ]
Excellent preamp, I don't think you can go wrong with this device is the perfect companion to the Cambridge 851W Amplifier.[ Anthony  Nov 12, 2016 ]
Read good reviews, already have Cambridge CXN Network player, which I love.[ S  Aug 12, 2016 ]