Introduction and features
As if the TV buying world wasn't already complicated enough, it turns out we're entering another period of alternative standards and expanded options. Now you don't just have to choose between HD resolution and UHD resolution for your next TV; you also have to decide if you want high dynamic range and wide colour gamut technologies alongside the UHD/4K resolution.
The Panasonic 55DX650 sits in the middle of this new three-tier TV world. Which is to say – if you've already lost count – that it offers a native 4K resolution, but doesn't stretch to high dynamic range support.
Obviously it's a shame on one level that the 55DX650 doesn't do HDR, given how amazing HDR can look when it's done well. But then experience suggests that it's pretty unlikely that a screen as affordable as the 55DX650 would have been able to do HDR well…
Design
The home for the 55DX650's UHD screen is very attractive. Its slender frame combines a see-through top layer and a cool grey lower layer to create an eye-catching, almost three-dimensional design effect, while its legs can be mounted with either their curved ends or their straight ends to the fore.
This is hardly customisation on the level you get with high-end brands like Loewe or Bang & Olufsen, but frankly, at this price point I'll take any flexibility I can get. Plus, handily, the legs actually look pretty attractive, whichever way round you mount them.
Shifting attention to the 55DX650's rear, the set sports a solid rather than spectacular set of connections. Three HDMIs will provide the main port of call for most external sources – although you should note that only two of these HDMIs are equipped with HDCP 2.2 anti-piracy protocols, and the capability to play 4K at up to 60 frames a second.
Connectivity
When it comes to multimedia support you're looking at a pair of USBs (many higher-end TVs offer three now), and streaming from DLNA-enabled devices on your network. In an ideal world the 55DX650 would also support Bluetooth, and join some of its Panasonic brethren in carrying an SD card slot for direct playback from the memory cards now used in the majority of digital cameras and camcorders; but for £849, an ideal world was never really an option.
Looking at the 55DX650's screen technology, the news is distinctly mixed. On the upside it backs up its native Ultra HD resolution with direct LED lighting – something that experience shows generally leads to superior contrast performance. It's also a 'Bright Panel', offering slightly enhanced light levels and a wider colour spectrum than basic LCD panels.
Panel problems
The bad news is that it uses an IPS type of LCD panel, rather than the more reliable 'VA' type.
The problem with IPS panels traditionally is that while they deliver slightly better effective viewing angles than VA panels (handy if it's hard for your whole family to always sit directly opposite the screen), this slightly improved viewing angle comes at the expense of good black colour reproduction.
I guess all we can do is hope that the direct LED lighting system, together with Panasonic's usually strong light control systems, will have what it takes to counter the usual IPS contrast issues.
Talking of picture processing, the 55DX650 enjoys a decently powerful quad-core 'brain', but doesn't benefit from the proven quality of Panasonic's new Studio HCX processing platform. Nor does it benefit from 3D playback – you'll need to step up to the Panasonic DX750 series if you want that.
Smart features
Getting back to the good news, the 55DX650's smart TV system delivers a potent combination of the Firefox TV OS and Freeview Play. The latter provides access to the four main UK catch-up TV platforms, either via dedicated apps or a listings system that lets you scroll back seven days as well as forwards – this really is an excellent way of bringing the worlds of live TV and on-demand streamed TV together in a more or less seamless way.
Firefox is not, perhaps, the most app-rich smart TV OS in town – but I'd argue that it doesn't need to be. Smart TV operating systems always work best, it seems to me, when they focus on and prioritise the sort of apps that actually deliver features useful to TVs – predominantly, video streaming platforms and content finding/management utilities.
Plus, Firefox uses a colourful, straightforward and ultra-customisable interface that's second only to LG's super-slick webOS platform when it comes to good old-fashioned usability.
Picture quality and performance
The main question here is whether the 55DX650's combination of direct LED lighting and Panasonic picture know-how can counter the picture quality issues inherent to the IPS panel at its heart. And the short answer, sadly, is that it can't.
As soon as you watch any dark movie or TV scenes it becomes blatantly obvious that the screen can't deliver anything close to a natural, deep black colour, leaving such scenes looking greyed over, flat and distractingly unnatural. The greyness hides some shadow details in dark areas too, making them look hollow and unconvincing.
Compare and contrast
If you want to see just how poor by modern standards the 55DX650's native black level performance is, turn off the TV's Adaptive Backlight feature and leave the backlight set to the sort of default levels most of the TV's picture presets recommend. The degree of low-contrast greyness infiltrating the pictures at these settings is painful by 2016 standards.
The only way to make the black level performance in any way workable is to push the Adaptive Backlight feature to its very highest setting, and to greatly reduce the TV's backlight setting. I personally felt I had to reduce the backlight to barely a third of its maximum value before the pervasive greyness became suitably subdued.
Dark destroyer
I guess it's good news that the TV has the tools to provide at least some solution to its inherent contrast woes. However, before you say "that's okay then" and move along, it's worth reflecting that removing more than 60% of the brightness from the picture leaves you with a picture which isn't very, well, bright. This denies colours the pop and vibrancy I like to see even on affordable LCD TVs these days, as well as worsening the issues with lost shadow detail.
There's another issue too. Namely that running the Adaptive Backlight on its highest level can cause some pretty distracting moments of brightness shifting as the brightness of the image content changes.
The 55DX650's problems with black level reproduction don't only affect blacks, unfortunately. The pervasive greyness also lies across colours, reducing their intensity and naturalism, especially – though not exclusively – during dark scenes. Plus, as noted earlier, having to remove so much brightness from the picture to boost black levels leaves colours looking rather muted and flat by 2016 standards.
A few good points
At this stage I ought to point out that the 55DX650 is not all bad. For starters, while colours lack punch once you've adjusted the image to account for the black level problems, they do also look surprisingly refined, with plenty of finesse in the way even the smallest tone or shading differences are resolved. There's an impressively balanced feel to the colour palette too, which ensures no tones look too dominant.
The 55DX650 also does a respectable job of delivering on its native UHD resolution. With native UHD sources there's a clear boost in clarity and detail over HD, despite the screen's affordability. Even more surprising for the money is the quality of the upscaling processing used to convert HD sources to the screen's UHD resolution. This processing is clever enough to add detail without exaggerating source noise or compromising colour tones, resulting in upscaled images that wouldn't look out of place on a 4K TV costing twice as much.
Upscaling standard definition content turns out to be a bit of a stretch – but the same can be said, in truth, of pretty much every 4K TV.
Motion and gaming
Contributing to the 55DX650's sense of sharpness is some good motion reproduction for such an affordable big-screen 4K TV. Movement in the image and camera pans aren't immune to judder and blur, but it's pretty low in intensity compared to much of the similarly-priced competition.
The 55DX650 may appeal to video gamers, meanwhile, thanks to an admirably low input lag reading of around 30ms. This amounts to barely a frame of delay in the time it takes the screen to render images, which shouldn't be enough to cause too many deaths in fast-response games. Before gamers get too excited, though, I would say that the screen's contrast issues don't make games that feature lots of dark nooks and crannies particularly enjoyable.
There are times – essentially when you're watching bright content in a fairly bright room, since ambient light does a good job of reducing the native contrast issues – when the 55DX650's strengths win the day. Unfortunately, though, it's the various problems associated with the TV's IPS LCD panel that crop up regularly and aggressively enough to become its defining feature.
Usability
When it comes to day-to-day use the 55DX650 is a doddle to use, thanks to the attractive, logical and customisable design of the Firefox TV interface. The remote control is reasonably easy to learn your way around too, despite being more laden with buttons than many of today's TV handsets.
You do need to put some up-front effort in with Firefox TV to customise its home page to suit your needs, though, and if you're anything like me you may find yourself regularly paying frustrating visits to the picture set-up menus to try and better solve the screen's backlight problems.
Sound
Despite its fairly slender and stylish design – which doesn't feature any forward-firing speakers – the 55DX650 sounds pretty respectable. It can go loud without the chassis rattling or the speakers crackling or dropping out, it delivers good treble detailing without sounding harsh or dominant, and it even manages a bit of bass without that bass sounding thuddy, or causing voices to sound muddy.
The key audio mid-range that invariably gets the most hammer with a TV audio system sounds open and clean, and even manages to shift up a couple of gears to embrace action scenes when required.
Verdict
Panasonic has got seriously aggressive on pricing for its 2016 TV range, a move epitomised by the relatively measly £850 price tag attached to the 55-inch UHD-resolution TX-55DX650. The set's shelf appeal is enhanced, moreover, by an attractive design and one of the best smart TV systems around. It's even got direct LED lighting – another unexpectedly premium feature for such an affordable TV.
Getting a 55-inch 4K TV from a respected brand for just £850 looks like a great deal on paper, despite the lack of any HDR support. Unfortunately, though, while there are some redeeming features, and the Firefox OS continues to impress, the 55DX650's sub-par picture quality ultimately means it's much less of a bargain than it first appears.
We liked
The 55DX650's design is pretty, airy and even supports a degree of customisation in the way it lets you decide which way round you attach its legs. It sounds good for such a slim TV too, and its Firefox operating system is excellent, as its HD upscaling processing. It's also aggressively priced for a 55-inch 4K TV.
We disliked
Panasonic's decision to use an IPS type of panel inside the 55DX650 proves predictably unhelpful, leading to pictures that really lack contrast compared with the sort of images we've now come to expect from LCD TVs. You have to take a lot of brightness out of images to counter the contrast issues too, while the adaptive backlight system can cause noticeable brightness instability when running at the high level you really need to use it at.
Verdict
Despite an eye-catching design, aggressive price, some decent picture processing and an excellent smart TV system, the 55DX650 is ultimately a disappointment. The bottom line is that no amount of peripheral features and attractions – not even the use of a direct backlight array – can disguise the inherent weaknesses of the IPS panel at the 55DX650's core.
