CX800clipPanasonic’s CX800U 4K Ultra HD LED LCD TV series represents some of those new LED LCD TV models popping up across the industry that fit just below the top-performing 4K Ultra HDTVs, sacrificing high dynamic range (HDR) and some degree of color space capability to hit a slightly more affordable price.

Currently, Panasonic’s 55-inch TC-55CX800 stands as a step-down model from the company’s 55-inch TC-55CX850, which boasts an enhanced phosphor emissivity layer on its full-array LED backlighting system, and is said to produce up to 90-98 percent of the Digital Cinema-P3 color space, used for professional digital theaters. The company said the TC-55CX800, which uses edge-lit LEDs with local dimming, will cover up to 90 percent of the DCI-P3 color space, save you about $600 on the cost of the 55CX850 model and almost $1,600 on the cost of the 65-inch CX850 model that also supports HDR.

Originally ringing in at $2,000, the price of the 55CX800 has been reduced to a special advertised price of $1,400 as this was written.

Although the CX800 model series does not support HDR metadata encoded in forthcoming native 4K HDR software- like the aforementioned 65-inch TC-65CX850 model — it does offer an impressively large color gamut. Black level performance is very good for an LED TV, but the edge-lit LED system is no match for pricier full-array LED models, and the local dimming technology isn’t as effective at controlling light output to localized zones on the screen.

More on the Panasonic TC-55CX800U after the jump:

Still we found overall picture quality on the TC-55CX800U to be quite good for the price. The biggest knock is its off-axis viewing performance, which, like many LED LCD TVs available today, begins to lose color and contrast fidelity after moving just a couple of steps to the left or right of center screen. Similar results are found viewing the screen from low or high angles.

For best results, this model should be placed on a tabletop at direct eye level from a seated position in front of center screen. Viewers seated to the left or right will lose some color saturation and contrast. Those viewing the set mounted at a high angle on a wall will similarly lose some image quality.


One of the big changes in Panasonic’s 2015 Viera TV line is the inclusion of a Firefox operating system, which brings a faster and simpler user experience than the company’s previous generation sets. The Firefox Home button presents a screen with choices for: Live TV, Apps, and Devices.
The Devices menu lists all of the available external sources identified by input jack/card slot, second-screen mirroring and all of the available DLNA devices connected to the wireless home network. The internal Wi-Fi connectivity was quick and easy to set up and DLNA music played back after some manipulation from a connected network attached storage device one floor up.


To simplify the search for particular programs and movies, Panasonic includes the “XUMO” Discover recommendation guide, which gets to know a users’ viewing preferences and makes recommendations of movies, TV shows and video-on-demand offerings that might be of interest to the user from the included streaming networks.

Pressing and holding the home button activates the XUMO recommendations, which in this case offered shows including Fargo, Empire and The Hobbit at start up, but this felt more like advertising than personalized viewing suggestions.

The Apps page, which is also available via a dedicated “apps” button, shows the most popular available streaming services, including: Netflix, Amazon, YouTube, Vudu, and CinemaNow, plus Aol.On, Accuweather, IPTV CC Setting, Viera Link, Calendar and the Firefox browser. An Apps Market is also available to browse through dozens of additional apps and games. No Hulu or HBO Now are provided at this time. Noteworthy for those interested in 4K streaming services, the system supports 4K streaming from Netflix, Amazon and YouTube, but does not yet support M-GO or Ultraflix.

Games available through the Firefox App Store are pretty basic and reminiscent of those you would find on your cellphone, though there are plenty of titles to keep younger kids happy for hours.

The Live TV page on the Home Screen connects only to the TV’s internal tuner, requiring the viewer watching cable or satellite services to switch to the appropriate HDMI input.


The CX800U does a nice job with 4K upconversion of Full HD and 720p HD material, but has some trouble with background noise artifacts in low-light scenes, older grainy movies and broadcast TV programs that were originally shot in analog.

For example, the brighter day lit scenes in Pirates of the Caribbean: At World’s End Blu-ray looked clear and generally free of color blotchiness, but a good bit of background noise was evident in the darker opening scenes of the movie post calibration. Switching on the Video Noise Reduction system to medium helped somewhat, but noise blocking was still evident up close in dark scenes. Processing artifacts, like blurry distant textures and background elements are also more noticeable in older movie titles that have visible film grain.

The set didn’t exhibit much of a soap opera effect from movies and film-based materials, giving film-based content a nice theatrical feel, while video continued to look sharp and alive.

More recently produced Full HD video content is impressively displayed, such as Dolby’s brightly lit “The Art of Flight” Blu-ray offering spectacular ice and snow shots with nice white levels and detail.

p3                                                                                                         P3 Color Space Measurement

2020                                                                                                            BT.2020 Color Space Measurement

Color Performance

As mentioned, the TC-55CX800U is advertised as handling up to 90 percent of the Digital Cinema P3 color space. We measured the set’s native color space against P3 and the gold standard BT.2020 color spaces with the resulting target points and actual points shown in the charts above. The CX800 performance, while strong, is still a little under the P3 space.

4K Ultra HD Resolution

The set’s 4K Ultra HD performance was tested using ISF test patterns, which looked clear and sharp. I streamed the 4K version Hand of God through Amazon offering good quality images, with color and detail that appeared slightly better than it did in 1080p, although the improvement wasn’t significantly dramatic.

3D Viewing

Those who appreciate 3D will find the CX800 supports viewing via passive polarized 3D glasses. This technology gets a performance boost from Ultra HD, providing Full HD resolution to each eye from the split image field. Passive glasses 3D systems offer half that resolution in Full HD 1080p panel applications. Glasses were not provided with the set, but using a standard off-the-shelf pair showed minimal crosstalk with impressive clarity and detail when viewing a 3D Blu-ray copy of Avatar from a central seating position. Crosstalk and blurring increased, however, when viewed from an angle below center screen.


The Super Bright panel of TC-55CX800U put out a nice amount of light in Vivid mode, which is the brightest of the system’s picture presets, and generally used for rooms with high ambient light. In this mode, I measured 165 foot lamberts from an 18 percent white window on a black field. The Vivid mode pumps up both backlight and contrast to 100 percent. The Cinema mode, however, produces the closest color temperature to 6500 Kelvin, ideal for theatrical content in darkened viewing environments. So, I used this mode for calibration purposes, reading 43 foot lamberts off the center white screen, taking the backlight down to 25 percent while contrast was bumped to 98.

Black Level

As stated, Panasonic has done an impressive job improving black levels on its 2015 4K Ultra HD LED LCD models. When viewed from dead center, blacks appeared deep and not washed out, although it does tend to crush out some of the fine detail and color in the blackest segments. This is becoming a bigger issue as TVs supporting HDR take on more prominence at the upper end of the market.

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Adjustment Controls

The CX800 is a calibrator’s dream, with a wide selection of picture adjustment settings including: a full color management system with multiple color-temperature presets for hue, saturation, and luminance of red, green, and blue; and hue and saturation of cyan, magenta, and yellow. The set also supplies two- and 10-point white balance adjustment; normal and native color gamut settings; multiple gamma presets, and 10-point gamma control. All this will help you (or a professional calibrator) set your picture settings perfectly for the room lighting conditions you prefer or are forced to experience when watching TV.


As mentioned above, the Cinema mode preset yielded good grayscale and color standards with an average grayscale error (DeltaE) of 1.8 (errors below 3.0 are considered imperceptible in motion video.) HD color gamut was excellent with DeltaE 2000 errors measuring less than 1.812 (a value of 3.0 or less considered ideal.)

We measured the set using the ISF calibration section of Calman 5 software along with X-Rite i1Pro 2 and SpectraCal C6 spectroradiometers. Test patterns were generated with a DVDO TPG.


Test pattern examinations revealed the CX800U display to be impressively uniform for an edge-lit LCD. The screen showed no pronounced splotches of light causing significant clouding or muddiness on the screen, and no noticeable bleeding at the edges of the screen.

Motion Compensation

Panasonic employs its Image Motion 240 Hz motion compensation circuitry to reduce motion blurring, although the set has a native 120Hz refresh rate, like most 4K TVs in this class. I didn’t find the motion blurring to be a big issue on this set and opted to turn off the added enhancement.



Panasonic’s CX800U models come with two non-backlit remotes, including a traditional long IR variety loaded with all the expected buttons, plus a prominently positioned Netflix button, which is a requirement for the set’s Netflix Certification status.

The second remote is much smaller and Bluetooth-connected with an upwardly curved smile-shaped faceplate and a centrally located touchpad. Buttons are provided for Home, On-Screen Remote, Voice Search, Volume Up/Down, Channel Up/Down, Favorite, Return, Guide, and Menu. Also included are directional arrow keys and four color buttons. The smaller remote also includes a built-in mic and a button to activate it. Simple spoken commands execute basic set functions including: mute, volume up/down, power off, etc.

The CX800 can be controlled with Panasonic’s TV Remote 2 control app for iOS and Android devices. The app offers screens to perform both the IR and Touchpad functions, along with a virtual keyboard and a direct-app launcher that removes the need to go through the TV home screen menu.



The Panasonic TC-55CX800 has an attractive, silver-colored bezel, measuring 0.4 inches on the sides and top of the screen, and 0.6 inches on the bottom. The supplied stand features a matching U-shaped metal base that is stable and easy to install with a couple of screws. The base is centrally located under the screen and provides only two inches of clearance between the bottom of the bezel and the surface of the tabletop. This is ample space for some thin-client cable or satellite TV boxes to be placed behind or under the screen, but too shallow for larger Blu-ray Disc players or DVRs. The stand also juts out six inches in front of the screen. The TC-55CX800U set without stand measures 48.7 x 28.3 x 2.2 inches.



The TV provides a typical assortment of inputs, including three HDMI 2.0 ports with HDCP 2.2 content protection (1 and 2 are placed on the rear facing down and 3 is positioned straight out on the left side of the screen) and three USB ports (all placed on the left side of the screen, and an SD card slot).

An optical audio output, an antenna/cable connection, and an Ethernet port are all placed on the rear with plug access conveniently facing down, to limit interference from protruding cables in wall mounting installations. However, if you plan to wall mount and use legacy equipment, the set’s component/composite video inputs face straight out of the back of the set. For a set of this size and price, having only three HDMI inputs was a little disappointing, compared with many other models in this range that offer at least four.

Sadly, Panasonic did not elect to include the DisplayPort 1.2 input that it included in last year’s 4K TV models. Although, at this point the only real use for it would be to connect with similarly featured PCs.

On-board buttons are offered for: Power, Volume Up/Down, Channel Up/Down, and Input/Menu are placed on the right side of the back of the HDTV.

On-Board Sound

Sound for the CX800U is emitted by two down-firing 10-watt speakers. Panasonic provides three sound mode presets in the menu plus an eight-band equalizer. Controls are available for surround, bass boost, volume leveling, and boundary compensation. The result was acceptable room-filling audio with clear dialog, though it’s no replacement for a good outboard surround sound system or speaker bar.

Bottom Line

Overall, the TC-55CX800 is a very good edge-lit 4K UHD LED TV performer with decent black levels and excellent Rec. 709 color gamut performance.

This model doesn’t deliver HDR, but for an extra $1,600 you can have the TC-65CX850 – the Macdaddy of Panasonic’s 2015 4K UHD LED TV line — offering a larger screen, phosphor-coasted LED backlighting and the ability to receive and display 4K Ultra HD content with HDR. The latter will prove to be a game-changer for 4K Ultra HD picture quality standards going forward, but with no standard for HDR brightness established, it’s hard to judge how any TV will ultimately handle HDR content right now. (Stay tuned).

What does seem certain is that all future TV introductions are going to be measured by HDR ready TVs next year and beyond, so if you expect a new set offering the latest performance standards, you’ll want to look for a different model.

One of the closest competitors in this class of features and performance is Sony’s 55-inch XBR-55X850C, which is available on Amazon at  $1,498. The Sony model will support HDR metadata, although how effectively we don’t know yet because the capability is being added through a forthcoming firmware update.

Another competitor in this price class is the Samsung 55-inch UN55JS7000, which is now available for $1,300, and is part of the company’s SUHD TV series offering Nanocrystal technology for wide color gamut and HDR-compatible playback from an 8-bit panel. (Panasonic did not respond to our queries about the bit-depth of the CX800’s panel). This set also offers good colors and solid upscaling, but like both the Sony and Panasonic models, suffers from diminished contrast and color when viewed about 30 degrees off angle or more.

The TC-55CX800U offers a nice cosmetic design, easy to use smart TV system, good picture quality, passive 3D playback with Full 1080 resolution, and a more affordable price than top-of-the-line HDR models. Unfortunately, unless you know someone who owns a Panasonic TC-55CX800, it’s going to be hard to see a demonstration for yourself. Panasonic has scaled back retail distribution on its 2015 TVs, opting to sell primarily through its own online web store, and a handful of specialty A/V dealers around the country.

The set provides a good, not great, value, alongside other models in this price range, but the picture quality should not disappoint most viewers.

We award the Panasonic TC-55CX800U 3.5 out of 5 hearts.  3.5 out of 5


The TC-55CX800U used for this review was a company loan.

By Greg Tarr


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