Although I’m in awe of the vast array of ultra-expensive audio gear reviewed at the SoundStage! Network’s websites, I’m one of the more pragmatic reviewers. I obsess about gear as much as the other reviewers, but I don’t spend vast amounts of money on audio and home-theater equipment. I try to allocate my funds where it will make a significant difference, and to keep my components as long as I can. So when I see a DAC for $10,000, I shake my head: “That’s insane!”
But a company like Cambridge Audio, based in London, England, really impresses me. Cambridge’s line is chock-full of Vince-friendly gear -- from $600 DACs to a line of integrated amps that tops out at $2000, Cambridge is the definition of sensible in the audio lexicon. On their website, the consistent theme is one of sound quality and value. According to Cambridge’s business model, value comes from keeping their R&D in London and their manufacturing in China, where they can maintain high quality at a fraction of the price of manufacture in Europe or elsewhere.
Here I review the Azur 751R upsampling receiver -- “upsampling” giving a hint of the audio engineering that has gone into this model. Although not cheap at $2999 USD, the Azur 751R promises good value and emphasizes sound quality, something you don’t see in mass-market brands.
Although the Azur 751R is a sophisticated piece of home-theater equipment, you wouldn’t know it from its modest size: It measures 16.9”W x 5.9”H x 16.5”D and weighs 38.3 pounds. If you’re a neat freak, the 751R is not for you -- all of its many buttons are out in the open. The advantage of that is ease of use -- no guessing which knob or button does what. In the middle of the faceplate is a blue display; to the right of that is a large volume-control knob, and below it is a line of buttons for directly accessing your sources. Running along the bottom of the front panel are the On/Off button, DSP mode selection, and buttons to operate the tuner, Zone 2 selection, and picture adjust. Near the On/Off button is a jack for the headphone output, which incorporates Dolby Headphone, which creates up to 7.1 channels through any pair of headphones. On the right side are inputs for HDMI, left and right analog audio, composite and S-video, optical digital, and a line-level MP3 jack.
Around back are five HDMI v1.4 inputs and two outputs -- a nice touch, as most receivers have only one HDMI output. If you have many digital devices, Cambridge Audio looks after you with nine digital inputs: four optical, five coaxial. They also supply two optical and two coaxial digital outputs, which are rarely seen in A/V receivers. A USB type-B socket is included for streaming music from an HTPC or laptop computer. Seven pairs of RCA jacks are provided for analog sources -- more than enough for most home-theater systems. The Azur 751R also accommodates, with two subwoofer outputs, the growing trend of using dual subs. However, these outputs are identical and can’t be individually set, as you can do with some receivers these days. There are seven pairs of color-coded speaker binding posts, and Zone 2 has component-video output as well as a subwoofer output.
A cooling fan dominates the rear panel, though I never heard it running. This may have been due to the X-Tract heatsink tunnel working so well; it runs inside the 751R from near the front to the back. Hot air is exhausted from the tunnel by the thermostatically triggered fan.
The remote control is familiar Cambridge Audio fare: silver and classy, but even slimmer than the one that accompanies the Stream Magic 6. As much as I love this remote’s looks, it has a disadvantage for home-theater use: its buttons aren’t backlit, which makes it harder to use in a darkened room. Thankfully, the big, circular navigation button is also where you find the volume control, the most frequently used control, thus minimizing fumbling.
Inside, the Azur 751R’s quality of construction is higher than that found in run-of-the-mill receivers. Visible are the toroidal transformer and large capacitors that make it possible for the 751R to meet its power-output specification of 120Wpc, all seven channels driven. Another feature is Cambridge’s Adaptive Time Filtering (ATF) upsampling technology, which is included in the company’s more expensive models. ATF upsamples all digital audio sent to the 751R to 24-bits/192kHz. Many audiophiles shy away from upsampling, as it can sometimes muck up the sound. Cambridge’s proprietary Anagram Technologies ATF upsampling purportedly solves these issues by using polynomial curves to more accurately reproduce the analog waveform, resulting in higher resolution with less smearing of detail.
All DSP chores are handled by three chips: two 32-bit Texas Instruments Aureus DA788 chips for surround-sound decoding and post-processing, and a 40-bit Analog Devices SP-21261 chip for ATF upsampling. Surround-sound decoding is up to current standards, and includes Dolby True HD and DTS-HD Master Audio. The Azur 751R also includes a feature rarely seen in A/V receivers: DTS remapping, which can support nonstandard surround-speaker arrays, such as height speakers, with a single-channel rear surround speaker. To convert digital signals to analog, the 751R uses a Cirrus Logic CS43122 24/192 DAC for the front left and right channels, and a CS52526 IC for the surround channels. For video scaling and deinterlacing, the 751R uses Anchor Bay’s venerable ABT2010 chip.
I experienced a few minor disappointments in setting up the Cambridge Audio Azur 751R. First, the onscreen display is very basic, with no pictures at all. (The font looks like Courier.) Second, the auto-calibration and setup software is Audyssey 2EQ, which gives results inferior to those from Audyssey MultEQ XT or MultEQ XT32. Audyssey 2EQ asks for only three calibration positions, in contrast to the six to eight positions of MultEQ XT or MultEQ XT32. Another negative is that HDMI switching (from one source to another) takes a long time to complete. The video took forever to lock on even when I switched from the onscreen display to a Blu-ray source. Finally, the OSD doesn’t show the volume level as you adjust it; with my equipment stacked in a rack behind me, I had to constantly look back to check the volume level as I adjusted it.
Those nits picked, setting up the Azur 751R was relatively straightforward. When you plug the calibration microphone into a jack at the left of the front panel, the Audyssey calibration screen pops up. I let Audyssey 2EQ whip its three rounds of test tones through my speakers; the distances and levels were set accurately, as were the crossover points and levels.
When using the Azur 751R receiver to watch movies, I encourage you to turn off the Audyssey 2EQ room correction. With it on, I had mixed results: It sounded fine with certain Blu-rays, odd with others. For example, when I played the DTS-HD Master Audio 7.1-channel soundtrack of Will Ferrell’s basketball comedy Semi-Pro, the center-channel level was so low, and there was so much reverb through the other speakers, that I had to strain to hear the dialogue. Everything seemed to be taking place in a large, cavernous space. When I turned Audyssey off, everything sounded as it should.
In fact, it sounded glorious. Dialogue was easy to follow, and I didn’t miss a single joke (which would have been a crime -- I’m a huge Will Ferrell fan). With small speakers, such as Definitive Technology’s ProCinema1000, bass was properly redirected to my subwoofers, which let through the full-force impact of the crowd’s roar. With 120Wpc on tap, the Azur 751R had enough power to play movies as loudly as I wanted to hear them, without clipping or distorting in my 2700-cubic-foot room. Nor did the 751R have any problem keeping up with the loud, frenetic pace of heavy action movies, such as when I cranked up the opening shoot-out and chase of Quantum of Solace, and Alicia Keys’s “Another Way to Die,” which plays over the opening credits. The highs of this soundtrack can get a bit bright and screechy through some underpowered mass-market receivers, but not so with the Azur 751R -- it sounded smooth and airy, similar to other Cambridge Audio components I’ve auditioned. In fact, it ranked up there with the best receivers I’ve heard from any company.
My Oppo BDP-95 Blu-ray player has the highly regarded Marvell Qdeo video-processing chip; consequently, using the Anchor Bay chip in the Azur 751R would be redundant and possibly detrimental. Fortunately, the Azur 751R’s bypass video mode is a true bypass. It doesn’t muck up the video by, say, altering black levels, as I’ve seen many A/V receivers do. Blu-rays looked stellar through the Oppo-Cambridge combo. When I used the 751R with lower-resolution sources, such as satellite TV, and let the Anchor Bay chip do its thing, the deinterlacing and scaling were first-rate.
With Cambridge Audio’s philosophy of sound quality first, I was anxious to hear how the Azur 751R would handle two-channel, music-only recordings. The 751R has an analog stereo direct mode with absolutely no processing -- you can be assured that CDs and analog audio sources won’t be subjected to unnecessary A/D conversions. This made for a great match with my Cambridge Audio Stream Magic 6, which upsamples to 24/384. For this reason, I preferred to connect the Stream Magic to the Azur 751R through the analog rather than digital outputs. Another cool benefit to using these components together was that I could use the 751R’s Control Bus RCA jacks, which allows its volume to be controlled through the iOS app on my iPod Touch.
One of my favorite CDs is Holly Cole’s album of Tom Waits songs, Temptation (16/44.1 FLAC, Alert), which I’ve burned to my NAS for playback through the Stream Magic 6. To test a product’s imaging abilities, I like to use “I Don’t Wanna Grow Up” -- Cole’s voice should appear solidly and precisely between the front left and right speakers. Through the Azur 751R, that’s just where it was throughout the song, the piano and bass slightly behind her. “Tango ’Til They’re Sore” is good for assessing bass response -- there are lots of deep double-bass notes. Playing this track through both the Definitive Technology ProCinema1000 speakers with subwoofer, and Definitive Technology BP8060STs on their own, none of the bass depth was missing, and bass notes had both pitch and definition -- a hard feat for any two-channel gear, let alone a receiver.
For higher-resolution recordings, I linked the USB jack on the rear of the Azur 751R to my laptop computer, which runs Windows 7 and JRiver Media Center 17. Playing 24/192 files was easy with Cambridge Audio’s USB 2.0 driver installed. The Azur 751R played such tracks as “Don’t Know Why,” from Norah Jones’s Come Away with Me (24/192 FLAC, Blue Note/HDtracks), flawlessly without cutting out. However, when I compared this to the sound of the same file, downsampled to 24/96, through my Stream Magic 6 (which doesn’t play 24/192 tracks cleanly), I preferred the lower resolution -- it had a wider dynamic range and airier highs. I attribute this to the higher upsampling and better DACs in the Stream Magic 6.
Over the last few years my system has included a number of different receivers and processors, including Cambridge Audio’s own Azur 650R (now discontinued) and the Anthem MRX 500, both of which retailed for around $1500. Although both have long since departed my system, they and the Azur 751R all emphasize audio over home-theater performance. The Azur 751R has been updated in many respects over the 650R: more HDMI inputs, Audyssey auto-calibration, Anchor Bay video scaler, a USB input, and ATF upsampling. Believe it or not, the 650R’s OSD is even more primitive than the 751R’s. With all of these enhancements, the Azur 751R is a worthy upgrade over the 650R. And though I praised the Azur 650R’s sound, I can’t imagine that it sounded better than the Azur 751R.
The biggest selling feature of the Anthem MRX 500 is the inclusion of Anthem Room Correction (ARC). ARC is definitely better than Audyssey 2EQ in the Azur 751R, and works flawlessly for both music and movies. Additionally, the MRX 500 has a very nice OSD that displays the volume setting onscreen as it’s being adjusted. From what I recall of the Anthem’s sound quality, I have to give the nod to the MRX 500 with ARC invoked over the Azur 751R. With the Anthem, bass response was especially even-keeled throughout my listening room. However, the sweetness of the Azur 751R’s highs can’t be overlooked. It would be best to audition both receivers to hear which you prefer.
The final comparison was with my reference system, which includes Integra’s DHC-80.3 preamplifier-processor ($2600) and DTA-70.1 nine-channel amplifier ($1800). Given the price discrepancy, you’d think the Integra would slay the Azur 751R. Not so fast -- with two-channel audio, the Cambridge sounded better. This was due to Cambridge’s ATF upsampling and the 751R’s pure analog direct mode. The Integra DHC-80.3’s direct mode isn’t truly direct -- it includes an A/D conversion. As well, channel-to-channel level differences were always an issue. When I tweaked the settings in the Integra, the sound quality approached but did not surpass the Azur 751R’s. Even so, I had to play around with the Integra’s settings quite a bit before it sounded right; the Azur 751R sounded great right out of the box.
When I listened to Amber Rubarth’s Sessions from the 17th Ward (24/96 FLAC, Chesky/HDtracks), “A Kiss to Build a Dream On” gave a good sense of space, with Rubarth’s voice in the middle and Tim Snider’s violin in the right channel. Through the Azur 751R, the sense of realism, of being in the recording venue with the musicians, was greater than with the Integra DHC-80.3. Of course, the Integra excels at home-theater performance, with its THX Ultra2 modes, Marvell Qdeo video processor, Audyssey MultEQ XT32 room correction incorporating dual subwoofers, etc. If home theater is more your thing, the Integra combo is better suited to that than the Azur 751R.
I found it difficult to put the Cambridge Audio Azur 751R in the proper context. On the one hand, at $2999, it’s one of the costlier A/V receivers out there, competing in the same price bracket with receivers that have all the latest features, such as a built-in streamer, Audyssey MultEQ XT32, 4K video scaling, iPod app control, and 11 channels of surround sound. However, Cambridge Audio invested their design time in the Azur 751R where they think it matters most -- in the sound quality. You can’t argue with that. With this in mind, this receiver is best suited to those whose hearts belong to two-channel music; and those who want to watch movies but are willing to give up some of the home-theater extras that can degrade sound quality. If that describes you, this is your receiver!
. . . Vince Hanada
- Preamplifier-processor -- Integra DHC-80.3
- Amplifier -- Integra DTA-70.1
- Speakers -- Definitive Technology BP8060ST, Definitive Technology CS8060HD center channel, Definitive Technology Mythos Gem surround speakers, Definitive Technology ProCinema1000
- Sources -- Oppo BDP-95 Blu-ray player, Cambridge Audio Stream Magic 6, Acer Timeline 1810T laptop running Windows 7 and JRiver Media Center 17
- Cables -- Analysis Plus Blue Oval in-wall speaker cable, Analysis Plus Super Sub interconnects
Cambridge Audio Azur 751R A/V Receiver
Price: $2999 USD.
Warranty: Three years parts and labor.
Gallery Court, Hankey Place
London SE1 4BB
North American distributors:
Audio Plus Services (US)
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
Phone: (800) 663-9352, (450) 585-0098
Fax: (866) 656-0686
313 Marion Street
Le Gardeur, Quebec J5Z 4W8
Phone: (866) 271-5689, (450) 585-0098
Fax: (866) 656-0686