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Onkyo TX-NR646 review: Powerful, feature-packed receiver amps up the thrills

Powerful, feature-packed receiver amps up the thrills

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Ty Pendlebury

Editor

Ty Pendlebury is a journalism graduate of RMIT Melbourne, and has worked at CNET since 2006. He lives in New York City where he writes about streaming and home audio.

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Steve Guttenberg

Ex-movie theater projectionist Steve Guttenberg has also worked as a high-end audio salesman, and as a record producer. Steve currently reviews audio products for CNET and works as a freelance writer for Stereophile.

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6 min read

It is written in the AV bible that the industry "shalt invent a new doohickey every year that compels the buying public to back its wallets up to the till and empty the contents on new gear." Last year that doohickey was Dolby Atmos; this year it's DTS:X. While neither are terribly compelling yet due to a lack of software, if you're interested in better movie immersion, they're worth investigating.

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8.0

Onkyo TX-NR646

The Good

The fully-loaded Onkyo TX-NR646 delivers cutting-edge technologies such as both Dolby Atmos and DTS-X surround formats, in addition to AirPlay, Wi-Fi and Bluetooth. Its sound quality is excellent for movie replay with exciting sonics and class-leading dynamics. Its superb connectivity includes eight HDMI inputs (one front, seven rear) and two outputs in addition to a phono input.

The Bad

The Onkyo TX-NR646's Dolby Atmos height channel capabilities are limited to only the front-left and -right channels, not the surround height channels, and the receiver is only DTS:X "compatible" until an update is released later in 2015. Its external design is generic and bulky, and the user experience isn't helped by its terrible remote and an ancient menu system.

The Bottom Line

Considering the Onkyo TX-NR646's generous feature set and superlative sonic skills, it's one heck of a value.

The Onkyo TX-NR646 not only offers both formats but also some other useful inclusions, such as improved streaming features and greater connectivity. Onkyo has made some excellent-sounding home cinema receivers in its time, and that tradition continues with the TX-NR646. The receiver can also put forth decent music output too, and nice-to-haves like a turntable input sweeten the deal.

While it's not the best-looking receiver on the market and its user interface is ripped straight from a 1980s RadioShack catalog, it's got enough on the inside to compare well against a strong competitor like the Sony STR-DN1060 . If you don't care about proprietary multiroom audio in your AV receiver and instead want an exciting-sounding AV hub for your system, this Onkyo is a great choice.

Design

Sarah Tew/CNET

Looks and usability are definitely the Onkyo's weak point, but neither is a deal-breaker. That's because AV receivers mostly sit quietly at the bottom of AV racks, requiring little little interaction beyond powering up, switching inputs and adjusting volume. If you want more from your receiver, look elsewhere.

The TX-NR646 has the looks and size of a British bulldog. It measures a standard 17-and-change inches wide, but stands almost 7 inches tall and over a foot deep. The front is generic-looking at best, all bathed in its green LED color scheme. One thing I've always appreciated about the design is the direct input buttons. No more random wheel-of-fortune spinning of a dial -- just press the input you want. That's about the only good point.

Sarah Tew/CNET

If we had a "worst remote control" award, then a receiver would no doubt scoop the pool, and it could easily be an Onkyo. The confusing clicker is bristling with more buttons than the bridge of a nuclear submarine, and the most-used buttons like Menu and Volume +/- are much smaller than those on competing devices. It's simply a poor usability experience in every way.

Sarah Tew/CNET

The menu system is likewise unchanged and ancient in feel, consisting of of white text on a black background. Onkyo is one of the last companies to offer a bare-bones menu in a midlevel receiver. Next year, guys?

Features

While not a completely different beast than last year's model, the TX-NR646 does offer some significant tweaks. The most obvious is the addition of DTS:X, the newest "object-based" surround-sound format. Object-based surround, which also includes the better-established Dolby Atmos format, means better control over the placement of effects for producers, and the addition of "height" speakers for consumers. While high-end receivers offer the full complement of four height channels, "entry-level" receivers like the NR646 have just two, and in this case those are the fronts.

The TX-NR646 is a 5.2.1 (the last figure being height) receiver that has had a modest bump in (stereo) power over last year: 100W versus 95W.

Sarah Tew/CNET

Connectivity has been improved with an extra HDMI port on the back, as well as an extra stereo analog port. This brings the total of HDMI connectors to eight inputs and two outputs, all with HDMI 2.0 capability and HDCP 2.2 support.

Sarah Tew/CNET

The receiver boasts Wi-Fi on board in addition to Ethernet, and now offers Airplay for playback from iOS devices and Mac computers. There's also Spotify Connect, Pandora, SiriusXM Internet Radio, Slacker and TuneIn. Onkyo also has its own an iOS and Android apps that allow digital playback as well as general control.

The receiver boasts a 384kHz/32-bit "Hi-Grade" DAC in addition to DLNA and USB playback with support for most music formats including DSD.

Dolby

This Onkyo is one of the first to announce support for both "object-based" surround formats, but there's still very little software available for either protocol. At the time of this review, a total of just 13 Dolby Atmos encoded Blu-rays are available, a full year after Atmos' consumer introduction. That's a molasses-slow ramp-up, and there's no reason to believe the rate of Atmos released Blu-rays will dramatically rise in the next year or two.

The other object-based immersive audio format, DTS:X is just launching this month, with the release of a sole Blu-ray, " Ex Machina." DTS is mum about how many DTS:X discs would be launched this year.

Setup

Sarah Tew/CNET

Due to the complex demands of Dolby Atmos speaker setup, we decided to use the TX-NR646's AccuEQ Room Acoustic Calibration program to set volume levels for our Pioneer Elite Atmos speakers and subwoofer.

We were happy to note the procedure requires the user to run the entire calibration routine from just one microphone position, which greatly eases setup compared to systems that use multiple locations. The resulting speaker balances were fine, except the subwoofer volume was much too loud, so we manually turned the sub's volume down.

Performance

We started our TX-NR646 auditions with "The Better Angels," a little gem of a film that covers a small patch of time exploring Abraham Lincoln's youth in rural Kentucky and Indiana. The soundtrack's ambient canopy of birds, buzzing insects and wind rustling the trees' leaves was startlingly realistic. With these sounds of nature, the TX-NR646's resolution of quiet detail was exquisite. Switching over to a Sony STR-DN1060 receiver, the sound was perfectly fine but diminished the sense of place we heard from the TX-NR646.

Next, we watched "American Sniper" to see how the TX-NR646's played this film's Dolby Atmos soundtrack. Did Atmos' height channels add anything to the sound that we didn't hear from standard 5.1 surround sound? Yes it did, but the effect is subtle, and the film's spare use of Atmos height channels makes it all too easy to forget that they are actually doing anything.

The intense combat scenes played nice and loud, demonstrating the TX-NR646's abundant power reserves with better dynamic punch than the Sony. The sheer clarity of the Onkyo's mayhem and dialogue were excellent. We tried out the TX-NR646's Phase Matching Bass feature that promises to "suppress phase shift in the midrange to enhance bass sound," but heard no difference whether the feature was turned turned on or off.

Next. we played a few Dolby Atmos promotion demonstration videos designed to show off Atmos, first on the TX-NR646 and then on the STR-DN1060, which lacks Atmos capability. The differences between the two receivers were much more obvious. The STR-DN1050's spatial dimensionality was smaller, more speaker-bound than what we heard from the TX-NR646. Demos are one thing, but the real-world difference between Atmos and standard Dolby TrueHD movies will be subtle. We didn't have any DTS-X encoded films on hand to try a comparison with Dolby Atmos films.

We were initially concerned that the TX-NR646's Atmos processing was limited to just the front-left and -right channels. Would the front speakers' envelopment seamlessly match with the side surround speakers? It turned out that front-to-rear sound balances were very good. And since we had our surround speakers set up a foot higher than our heads' seated height, the sound always came from above. This higher placement strategy for surround speakers has been recommended by Dolby for as long as we can remember. Now, with front-channel-only Atmos systems like this Onkyo, mounting the surround speakers high makes even more sense.

With that in mind, perhaps front-only Atmos left and right speakers will be more than adequate in some rooms, like the relatively compact CNET listening room. This approach also reduces the cost of assembling an Atmos home-theater system, since your current surround speakers may not have to be replaced.

We did one more round of TX-NR646 and STR-DN1050 comparisons, this time with music from the Rolling Stones' 2008 concert "Shine A Light" on Blu-ray. It has a non-Atmos soundtrack, but even so the TX-NR646 came out ahead. Its energy, dynamics and power made the music more exciting, while the STR-DN1060 sounded a bit softer and more bland in comparison.

Connecting Bluetooth to our Samsung Galaxy S4 Active sounded good, with unexpected detail in midrange-oriented tracks. It didn't get screechy or break up with guitars as some implementations can. Swapping to Spotify Connect, however, showed us what we had been missing, with more treble bite and even greater detail.

Conclusion

The Onkyo TX-NR646 is an awfully impressive receiver for the money, and it sounds terrific. It's just as proficient as the Sony STR-DN1060 but sports better dynamics, and its features are skewed toward home cinema. Dolby Atmos and DTS:X are nice extras but not the real reason to buy this model. It gets our recommendation because it makes movies sound good regardless of which proprietary format they're in.

onkyo-tx-nr646-01.jpg
8.0

Onkyo TX-NR646

Score Breakdown

Design 6Features 9Sound 9Value 8
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