Cambridge Audio was founded with a aim of producing the very best sound quality. Stephen Dawson looks at the company’s latest home theatre receiver to see if has reached its goal.

Cambridge Audio is an oddity. And I say that in the best possible way. It comes out of the UK high fidelity revolution of the 1980s when lots of new brands striving to produce the very best sound were appearing, some of them prospering. While their products were often wonderful, the prices were all too often prohibitively high.

Cambridge Audio joined the field in terms of quality, but added another important feature: affordability. Since then, as new forms of digital audio have appeared, Cambridge Audio has remained at the leading edge with a range of DACs and audio streaming devices that are consistently well regarded and are still marked by remarkably reasonable prices.

What it is
At its heart, Cambridge Audio remains an audiophile company, so you can expect something special from its top-of-the-line Azur 751R home theatre receiver.

This receiver is in large part about its amplifiers. There has been no skimping here. The seven amps are each rated at up to 200W per channel into 6Ω, and 170W into 8Ω, with two channels driven. Even with all seven running at once they top out, according to Cambridge Audio, at 120W per channel. And while a surprising number of receivers fussily specify 6Ω as the minimum nominal impedance for connected speakers, the manual for this one invites you to go as low as 4Ω.

It’s also about good old fashioned build quality. When I review a receiver the first thing I do is put it on my desk, on its side, so I can count up all the connections for the specs table. That exposes the bottom. The bottom of this receiver was covered with a metal plate, as they generally are, with slots for air cooling. But usually these plates are thin pressed steel. Knock them with a knuckle and there’s, well, a bit of a tinny response. Not this one. I tapped it and the sound was that of solidity. The panel looks to be about 1.6mm thick. It won’t ring or rattle.

That build is carried through. The unit weighs a claimed 17.4kg, although that seemed to understate matters. My calibrated scales put it at 18.1kg. Contributing to that weight is a whopping great toroidal transformer, rated at some 1,600W.

The receiver comes with six HDMI inputs (one on the front) and far more analogue connections – and digital audio ones as well – than is the norm these days. You even get extensive support for S-Video.

Kind of, anyway. Despite the thorough set of inputs, and the inclusion of all three forms of analogue video output for the second zone, there are no analogue video monitor outputs for the main zone. Just the composite and S-Video outputs for recording. If you have an old analogue video device that you want to watch in the main room, then you will rely on the receiver to convert its output to HDMI format.

There are also lots of control connections, with more than enough to make an installer happy. A credit card sized Zone 2 remote is provided. The main remote is an elegantly slim metallic finished unit that while seeming to have relatively few keys nevertheless always had the right one to hand. Note, though, that the key with the lamp icon is to control the brightness of the receiver’s front panel display, not to backlight the remote control keys.

Control and Power

With the exception of the built in AM/FM tuner, this unit is for providing control over your system and power to its speakers, but not to act as a signal source. So you will not find a regular USB socket for plugging in a memory device full of music files. Nor will you find an Ethernet port for streaming internet or local network content. Cambridge Audio sells other devices for doing those kinds of things. You plug them – or similar devices from other brands – into this unit to amplify their output.

But what it does have is a USB Type B connection. This is the type of connection with a squarish plug/socket with two of the corners rounded off that you’d see on a printer or a scanner, not the flat type seen on computers (and lots of other home theatre receivers). Plug your computer into this and your computer is, to this receiver, just another audio source device. So the receiver converts its audio output into high quality analogue audio.

To your computer the receiver looks like a regular USB audio device, and you can use it as such. But it’s well worth consulting the Cambridge Audio website and reading the ‘Guide to Bit Perfect USB Audio’ available there. This shows you the way to stream sound all the way to 192kHz, 24 bits, from your computer (PC or Mac) to this receiver for pretty much the ultimate in computer sound. A free driver is provided there to allow this.

The receiver incorporates high quality 192kHzm, 24 bit Cirrus Logic digital to analogue converters to get the best out of high bitrate audio. In addition it upsamples lower frequency digital signals to 192kHz.

Performance
I sensed from the manual layout that Cambridge Audio includes the Audyssey 2EQ system for automatic calibration and EQ is bit of a reluctant concession to those who don’t want to do the manual setup. Nevertheless it’s there and it’s useful. Importantly, while this implementation includes Audyssey Dynamic Volume and Dynamic EQ processors, should you want them, it doesn’t apply them automatically as too many receivers do. The default is off, which is the correct thing for a receiver with a focus on audiophile performance. Those processes do considerable damage to sound.

The on screen menus put up by the receiver are very basic white text over a blue background with a resolution of 576p. There are no video overlays, so there’s no on-screen indication of volume changes and such. Nonetheless the unit includes competent video scaling and progressive scan conversion using Anchor Bay Technologies’ ABT2010 scaler. You can specify an output resolution and have the receiver do a fine job of scaling up your video sources (typically to 1080p) and a respectable job of deinterlacing them.

There are a number of control settings for the video, dealing with colour, aspect ratio and such. Omitted, unfortunately, is fine control over the deinterlacing. The automatic film/video cadence detector was okay, but far from perfect, being tricked by my more difficult test clips into treating film-sourced material as video-sourced, and thereby generating visible artefacts.

But one excellent feature of the receiver is that this scaling function can be set independently for each input, so you can have it do a decent job on the output from your PVR, while letting your Blu-ray player’s higher quality signal through without alteration.

Speaking of passing through signals, the unit worked fine with 3D, but I could not get my 4K upscaling Blu-ray player to deliver its output at that resolution through this receiver.

Conclusion
In the end, this receiver is all about the sound. And that it delivered in abundance and to the highest quality. The control it exercised over my large, low impedance loudspeakers was first class, and it drove them to thunderous levels without triggering its own internal cooling fan.

If you want an all in one network receiver – available from many brands, and most of which do a fine job – then you’d probably best look elsewhere. But if you want lots of high quality sound, give the Cambridge Audio Azure 751R receiver a go.