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Panasonic TX-50CX680B (CX680) 4K UHD TV Review

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Mastering the magic of a bargain

by Phil Hinton Sep 22, 2015

  • SRP: £799.00

    What is the Panasonic TX-50CX680?

    The CX680B from Panasonic is an entry level Ultra HD 4K set with a number of features including Firefox OS smart TV and a high brightness VA panel. The CX680 is very similar to the recently reviewed CX700 in specifications with just a few slight changes design wise, and the CX680 is available from a number of retailers, whereas the CX700 is a Currys only model in the UK. The CX680B is available in 40-, 50- and 55-inch screens sizes and it's the middle size we have in for review.

    As the director intended is the mantra from Panasonic this year and while the CX680 doesn’t have the full 4K Studio Master processing chip of the higher models like the CX802B, it does feature quad-core processing and Studio Master colour as well as 200Hz scanning technology. The LED edge-lit backlight also incorporates Panasonic’s local dimming which, when added to the already decent black levels from the VA panel, promises a better contrast performance. So let’s find out if it’s all as intended.

    Design, Connections & Control

    The design of the TX-50CX680B does differ slightly from its Currys cousin the CX700. The most obvious difference is the stand which is an all-in-one loop on the CX680 and which makes placement on normal TV stands easy. The CX700 only had feet at the far ends of the chassis which ruled it out for placement on both of the TV racks we had available. The CX680 stand works well and although you can’t swivel the screen, it is sturdy and holds the screen firmly in place, unlike the recent Sony TV we had in and panicked about every time we walked past it. Around the screen is a nicely brushed effect bezel which is thin and in keeping with contemporary designs with the Panasonic logo at the bottom which is also unassuming and not in your face or backlit.

    Panasonic TX-50CX680B Design, Connections & Control

    In terms of connections there are enough here to keep most end users happy, although there are only three HDMI slots. All three are 4K 60/50P HDCP2.2 compliant which means they will handle future UHD formats going forward and as the CX680 is not HDR capable it doesn’t require any further updates. HDMI 2 is ARC compliant and there are also three USB slots (2 x 2.0, 1 x 3.0) along with legacy connections such as component and composite and audio connections including a digital out and headphone jack. There is also a wired LAN connector as well as built-in WiFi.

    Controlling the CX680 is a silver coloured Panasonic remote control. If you have ever owned a Panasonic product you will be instantly familiar with the layout and feel of the remote, which sits neatly in the hand and is easy to use. All the important keys are positioned within easy reach of your thumb and our only slight complaint is the positioning of the dedicated Netflix button which is top side of the directional keys and as such, easily pressed by accident. Even with the smart TV Apps the remote is capable of easy navigation and we love the fact that when using the DTV tuner, the directional keys make it easy to channel surf and see instant now and next information. Some other TV manufacturers could learn a trick or two here in terms of ease of use.

    Features & Specs

    The CX680 is an Ultra HD 4K TV at a price point which makes it very affordable for the end user and at the same time adds in the latest must-have features. It has quad-core processing driving the FireFox operating system which runs Panasonic’s Smart TV and Home Screen 2.0 for 2015.

    Just like its cousin the CX700 some of the apps available help to push the TVs 4K Ultra HD credentials with Netflix, Amazon and You Tube all offering 4K content to use on the set. We found that even with an average internet speed the quality of the streams was very good indeed and we didn’t notice any resolution changes during any viewing. The fact that the apps are set up out-of-the-box to deliver 4K content is a massive plus point, especially at this price level.

    The whole smart experience is easy to use and has a nice graphical interface that the whole family will be able to get to grips with. You certainly don’t need to be any kind of expert to set everything up first time and it just all works in an easy to follow manner. The only thing still missing from the CX680 is Freeview Play which has had a few delays now and should be seeing the light in October 2015. We will test it out as soon as it is available.

    As all the HDMI ports are HDCP2.2 compliant you will be relatively future proofed with the TX-50CX680B for new formats such as UHD Blu-ray. The TV is not HDR compatible and therefor is not upgradable, but that technology is still reserved for the higher end TVs and will be for a while yet. As UHD Blu-ray is backwards compatible the lack of HDR support shouldn’t cause too many concerns, not for the next few years anyway. The fact you can pick up a feature packed TV like this one, with 4K apps support and as future proofed as possible, for less that £800 is quite staggering really.

    You can get the full run down of the new Panasonic Smart TV system for 2015 in this review.

    Why would you buy an HD only TV when you can have all this for under £800?

    Picture Settings Out-of-the-Box

    We measured a number of out-of-the-box settings to make sure we identified the most accurate to the standards out of the box. With Panasonic pushing the message of picture quality that matches the director's intent, their picture presets need to get close to the standards for that message to ring true. They will be happy to hear then that with the True Cinema and Warm2 colour temperature settings along with gamma set to 2.2 (for brighter room), they are indeed very close to the standards. You just need to set the brightness, contrast, gamma and backlight for your viewing environment and off you go. In the price vs performance stakes, the out-of-the-box presets are good enough to go against a full professional calibration.
    Panasonic TX-50CX680B Picture Settings Out-of-the-Box
    Panasonic TX-50CX680B Picture Settings Out-of-the-Box

    The greyscale tracking is excellent with DeltaE errors under 3 which mean that most will not see any issues within the image.

    Gamma also tracks well with just a rise at 10% and a slight rise again at 90% which doesn’t make any impact on the picture quality with normal material. There is just a little too much red at the higher end of the track, but this is so slight that yet again, you will not see the effect on screen. So in terms of the greyscale it’s excellent news.

    Moving to the colour gamut we again have good results with just a little under saturation at green and cyan and a slight over saturation at red. However, the luminance results are very good. With the overall DeltaE errors you would be hard pushed to see the effects of the green and cyan within normal viewing material, apart from maybe some sports viewing where you have green pitches, but again, most wouldn't notice.

    Picture Settings Calibrated

    While the charts above don’t look pretty they actually tell experienced users that the onscreen performance is very much acceptable to all but the very fussiest of viewers. Given the price point of this TV and its likely end use we feel that the best out-of-the-box picture settings we have listed above would suit 99% of those likely to purchase this set. We have come a long way in the last 5 years to get to a point where we can say that. However, we also fully test all TVs that we review, so let’s see what the CX680B can do when fully calibrated.
    Panasonic TX-50CX680B Picture Settings Calibrated
    Panasonic TX-50CX680B Picture Settings Calibrated

    Because the out of the box greyscale tracking was so good we just used the 2 point white balance controls to get it tracking perfectly. We hit DeltaE errors under 2 that means we won’t be able to see any errors in the image. We also managed to get the gamma tracking perfectly at 2.2 and if you are going to use the CX680B in darker environments it also tracked just as well at 2.4 when we checked.

    With a full CMS and a wide native panel gamut we had two ways to bring the gamut tracking to Rec.709 standards. We managed to hit all the required points on the CIE and saturation tracking from 25, 50, 75% was also excellent with just a slight undersaturation on red, which wouldn’t be visible to the eye. The calibrated performance was reference in terms of the end results and on screen it made a slight difference, but not a major one over our best out-of-the-box settings, more on that later.

    Picture Settings Video

    Picture Quality

    Out of the Box Performance

    We tested the TX-50CX680B in the usual two rooms we have here. We have a normal living room with two large windows and plenty of light for some of our testing and we also have a completely light controlled cinema room where we can test even further and in more controlled surroundings. We tested with normal DVB broadcast material, SD content from DVD, 1080/24 Blu-ray along with the 4K apps on the TV and native 4K material we have shot ourselves.

    With it using a VA panel we found that the black levels when viewed head on were very good and measured 0.02 cd/m2 with a black raster and the same with an ANSI checker board and we were easily able to reach our standard 120 cd/m2 brightness. In dynamic mode, like the CX700, the peak brightness measured was 450 cd/m2 which is just too bright for any environment in our opinion. The best image quality is with True Cinema picture mode as the other modes introduced or highlighted some weaknesses with the LCD tech used. Viewing angles were good for a VA panel with optimal picture quality to around 30 degrees before wash-out and blue tinted blacks. Direct viewing is important to get the best from this TV and we would recommend careful positioning within your viewing room.

    The CX680 performed at its best with normal ambient light in the room. The backlight was uniform in these conditions with strong black levels, good sharpness and believable skin tones. This is the TV's bread and butter environment and we found ourselves using the set as our everyday work horse. It stayed in situ a lot longer than most TVs in for review and that says something about its quality at the price point. Like with the CX700 we were not overly impressed with the local dimming and in the end switched off Adaptive Backlight and Contrast Control. We found that the VA panel and native blacks were good enough without any help and mixed scene material looked superb for an LCD panel, with just the lowest parts of the shadows missing. Motion is usually an issue with LCD TVs and the CX680 with IFC turned off displayed around 350 lines on our motion test pattern. We avoid Intelligent Frame Creation with all film and drama content and in our case, didn’t find that anything over low for sports material was required. However this is very much a personal preference issue and you should experiment for yourself to see what works for you. With 24p and 4K native material the blur looked normal and as expected for such material, looking natural and as intended.

    As this is an Ultra HD Panel the upscaling performance from HD and some SD content is very important as around 90% of material viewed on this TV will not be 4K. We found that with the best HD and some good quality SD broadcast channels the performance of the video processing was very good at normal viewing distances. Artefacts were kept to a minimum with good SD content and the HD channels didn’t highlight any issues at all. We found the same with 24p HD Blu-ray and other content. With the UHD streaming channels we found that Amazon produced the best quality with some striking detail on offer with content like season one of Bosch.

    The only downside we found with the TX-50CX680B was during use in very dim or blacked out conditions and that’s to be expected with LCD technology. There was some visible light pooling at the bottom corners and we also noticed the backlight structure with certain material in these conditions. None of this was visible in normal viewing conditions with ambient light present. You can introduce and notice these issues if you use higher light output presets like Normal and Dynamic and have settings higher than they should be for best performance. In those instances you are likely to see more and more artefacts and issues with the source material and the LCD technology. Stick to the best settings and all of those issues are mitigated in normal conditions.

    When you sum up the image quality vs the price point the Panasonic is really a massive bargain and offers superb performance at the price point and above. The out-of-the-box settings are also very good with strong blacks, good motion and excellent colours.

    Calibrated Performance

    As with all TVs we test the CX680 was fully calibrated to get the absolute best out of the image. In normal viewing we think that the majority of viewers probably wouldn’t notice a huge difference between the best out-of-the-box settings on this review sample and the calibrated results. The improvements are subtle at best, with colour accuracy for experienced eyes probably looking that little bit better. We don’t however think the improvements given the RRP and the excellent out-of-the-box settings justify the cost of a professional calibration. The CX680 is great value right out of the box.

    In terms of price vs. performance the CX680 punches well above its weight.

    How future-proof is this TV?

    4K Ultra HD Resolution
    HDR Support
    Colour Space (percentage of DCI - 100% best) 50%
    10-bit Panel
    HDMI 2.0a Inputs
    HDCP 2.2 Support
    HEVC Decoding
    4K Streaming Services
    Smart TV Platform
    Picture Accuracy Out-of-the-Box (score out of 10) 9
    What do these mean?

    Sound Quality

    Like its closely related cousin the CX700, the 680 offers reasonable sound quality for the size of the chassis and power available. It never sounds distorted unless turned up way above normal levels and dialogue is always clear and concise. Given the size of the panel unless you are sat dead-on there was also no real stereo separation to be had. Music and other effects are handled in a decent fashion but the overall sound quality will always be bettered by an off board solution, like a sound bar. It’s perfectly reasonable if being used in a normal living room, with normal viewing.

    Input Lag

    Using our Leo Bodnar lag tester we recorded a lag time of 39ms which is probably best described as an average result that will not affect the vast majority of gamers. Be aware that Game Mode on the Panasonic doesn’t affect the lag time, it just changes picture settings.


    OUT OF


    • Excellent out-of-the-box preset with True Cinema
    • Excellent colour reproduction
    • Superb greyscale tracking
    • Good black levels and contrast from VA panel
    • Good motion
    • Good lag input result
    • Superb value for money


    • Some clouding and halos when viewed in completely dark surroundings
    • Netflix button on the remote easy to press accidentally
    • Stay away from other picture presets
    You own this Total 14
    You want this Total 4
    You had this Total 9

    Panasonic TX-50CX680B (CX680) 4K UHD TV Review

    Should I buy one?

    Given that we have only reviewed a couple of HDTVs so far this year gives you an idea of where the market is heading for TVs. The higher priced 4K HDR capable sets certainly dominate the forums chat and there is no surprise in that; our members are always looking for the best picture possible. But then you look at the sub £1000 price point and you don’t expect to get a fully-fledged Ultra HD 4K TV with the latest smart features and UHD Netflix, Amazon and YouTube and HDCP2.2 future proofing. So the mere fact that the CX680 exists and costs just £799 (September 2015) offering all that and more is the biggest surprise.

    The image quality out of the box based on this review set is excellent and offers very close to the standards quality without a professional calibration. The Smart TV features are superb and provide 4K UHD content when it is still hard to find on other formats, and the overall performance vs price and the fact it is available at a number of high street and online retailers makes it a Best Buy in our opinion.

    What are my alternatives?

    Other options at this price point are the Currys only TX-50CX700B from Panasonic which offers an identical level of performance but is restricted to one retailer. You also have the Samsung UE48JU6400 which has a slightly smaller screen size but can be found for £50 less or the slightly more expensive 50-inch UE50JU6800 which is still under £1000.

    The Rundown

    Contrast/Dynamic Range/Black Level


    Screen Uniformity


    Colour Accuracy


    Greyscale Accuracy


    Video Processing


    2D Picture Quality


    Picture Quality Out-Of-The-Box


    Picture Quality Calibrated


    Sound Quality


    Smart Features


    Build Quality


    Ease Of Use


    Value for Money




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