cx400stockphotoPanasonic’s late-year introduction of the TC-55CX400U 4K UHD LED LCD TV came as a surprise on a number of levels, as the company moved from providing a high-performance product lineup of 4K UHD LED TVs most of the year to offering a couple of “value” lines intended to offer a basic feature set, with good picture performance, at an affordable price point.

First, the new value TVs were a step down from earlier Panasonic 2015 4K LED LCD TV models in features and performance, and came just prior to the holidays when the company’s step-up sets were already out-of-stock on Panasonic’s website. Those flashier offerings included innovative technologies such as the flagship model’s close to DCI-P3 advanced color gamut specs enabled by an unusual blue phosphor LED coating. In contrast, for under $1,000 (or $1,060 on the Panasonic online store as this was posted), the new TC-55CX400 offers a very basic feature set without the wide color gamut and high dynamic range bells and whistles, a limited smart TV platform, but offering a picture with pretty accurate colors within the Rec. 709 color space required for 4K UHD TVs.

Read more of our review of Panasonic’s “value” 4K UHD TC-55CX400 after the jump:

The next surprise was Panasonic’s introduction timing, coming just two days prior to Black Friday, when the company also revealed that it was opening up distribution on the new TVs to a range of retailers for the first time that year. This, after the company spent most of 2015 selling its better performing TVs almost exclusively through its online shop on

The third surprise was Panasonic’s announcement that the new value TVs were designed with “pre-optimized default settings eliminating the need to spend time calibrating picture color gamut, white balance or anything else.” In fact, Panasonic eliminated some very basic picture controls like back light and gamma adjustments making it impossible to do a thorough calibration, as you can with most of the company’s step-up units. The CX420 and CX400 series models do, however, include moderately effective white balance and color management system controls, but without gamma and back light controls setting them gets to be tricky.

Panasonic said the target audience for the 55CX400 is someone who just wants to take their TV out of the box, set it up and forget about it. So it pre-adjusted gamma and back light settings in “home mode” to the conditions of an “average living room,” optimized the color and white points to as close to the CIE 1931 Rec. 709 as possible, and removed more sophisticated and complex settings that the average user isn’t going to understand or bother with. More on this later.

Like all of the Panasonic value TV series released in December, the CX400 is a good basic 4K Ultra HDTV. It was designed to hit an affordable price point at the holidays and pre-Super Bowl selling periods. You’ll get 3840×2160 pixel resolution, but at this screen size and without the wider color gamut and dynamic range, you’ll have to decide for yourself if you can actually see the benefits of that extra detail alone over what’s available on a traditional Full HD 1080p display. Most people can’t.

But here’s the rub: If a basic 55-inch TV is what you want, you are going to have a harder time finding a good one with Full HD 1080p resolution because top line manufacturers are scaling them back in their lineups. There simply isn’t enough money to be made from them any longer, when you can get a 4K UHD model for about the same price that a comparably sized Full HD version was selling for a year ago.

Panasonic’s 55-inch TC-55CX400 ($999.99) is part of a series of models that also includes: the 50-inch TC-50CX400 ($799.99 suggested retail), which has a native 60Hz refresh rate (120Hz effective); and the 65-inch TC-65CX400U ($1,499.99), which has a native 120Hz refresh rate.

Like the 65-inch model the TC-55CX400 has a native 120Hz refresh rate for smooth motion images.

The company also introduced a CX420 series, which basically has a different cosmetic look, with lighter colored bezel trim and other embellishments, where the CX400 models use black bezels.
All of the new CX400 and CX420 models have direct-lit LED LCD panels with native 3840×2160 pixel resolution.


precal cx400u          This is how the TC-55CX400 measured out of the box. Colors were close to hitting all marks.
As with most TVs today, the Panasonic TC-55CX400 has a setup process that asks the user if the TV is going in the home or in a store. Selecting home use puts the TV into “standard” mode, which reduces the brightness settings found in dynamic mode, generally used for bright showroom floors or in brightly lit rooms, like sunrooms. Standard mode sets the screen for use in a room with an above average amount of ambient light during the day.

We found, however, that after selecting home use, switching the picture settings to “cinema mode” for use in a dimly lit room and adjusting the color temperature setting to “warm” achieves a close to 2.1 gamma setting desirable for this viewing environment. Simple enough.

From here, however, calibration got a little trickier, as we were shocked to find the CX400 lacks back light and gamma controls, which makes accurately adjusting the brightness, contrast and gamma to the room lighting conditions difficult, if not impossible. Panasonic said it has pre-calibrated these settings to optimal settings, but without a spectroradiometer to measure light coming off the screen this does not take into account a wide range of room lighting variables. We were surprised to see this from Panasonic, since previously, only cheap no-name brands omitted back light controls.

If you’ve read our buyer’s beware article on TV back lights you’ll know the importance of having a back light control on an LED LCD TV. Plasma displays, which Panasonic once specialized in, did not have backlights and didn’t offer the control.

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Normally, when a set lacks a back light control, the contrast control is adjusted down to achieve a panel brightness of 42-50 foot lamberts. This is typically ideal for dim rooms, and lower is better for dark rooms. But the pre-selected calibration settings for all of the TV’s picture modes, including the cinema mode we selected, pinned contrast at “full” (59 foot lamberts), which as it turns out, is the correct setting for white pluge of 235 without clipping (anything showing above white shades of 236 and higher). So, lowering the contrast setting more than one or two clicks throws off the white pluge setting and clips peak white. To avoid this contrast cannot be effectively dialed down.

The brightness setting that controls black level can be dialed down, and the blacks on this set aren’t too bad for the price point. The space walk sequences in the Orbit Blu-ray Disc showed acceptable blacks for the deep space backdrop. It wasn’t noticeably washed out or gray looking.

As with most Panasonic TVs, the color point matching for Rec. 709 color gamut were not too far off right out of the box. The preset gamma curve was close although the color temperature at “warm” was slightly below 6500K in our test. Unfortunately, there weren’t too many tools we could draw on to correct this.

Even with the color management system and white balance tools we weren’t able to hit the color points dead on, especially with red, blue and magenta. The Cinema mode preset yielded good acceptable grayscale and color standards for an entry level TV, with an average grayscale error (DeltaE) of 2.8 (errors below 3.0 are considered not noticeable in motion video.) But the delta E error for white exceeded 7, where anything below 5 is considered optimal. Again this isn’t too bad for an entry level “value” 4K TV.

Viewing Angle

One of the key problems we found when we reviewed Panasonic’s step-up TC-55CX800 model earlier was a pronounced shift in contrast ratio and color when moving even a few steps to the left or right of dead center. We found this fall-off to be less of an issue with the TC-55CX400. We could move more than three to four feet off dead center before we started seeing the contrast and color starting to degrade. There was a somewhat more noticeable vertical shift, however, when moving from a seated to standing position, which should be taken into consideration when wall-mounting the set.


We noticed some uniformity issues on gray and black screens. Black screens in particular showed noticeable hot spots around the left and right edges of the screen, making it difficult to read some black pluge charts, but overall mottling wasn’t too bad and hardly noticeable with a moving picture on the screen.


The CX400U models come with a non-back-lit remote, of the traditional long IR variety. The remote features the typical channel-tuning buttons, plus a prominent centrally located Netflix button. The remote is long, but the weight is well distributed to fit comfortably in the hand.


Another striking departure in the TC-55CX400 from step-up 2015 Panasonic models is the somewhat pedestrian smart TV system. Where Panasonic’s step-up TVs employ an elaborate FireFox operating system, which brings a faster and simpler user experience, the CX400 and CX420 models have a basic wireless connectivity system that carries only the Netflix, YouTube, Pandora, Vudu, AccuWeather and Toon Goggles apps. The Netflix, YouTube and Toon Goggles apps support streaming compatible 4K UHD movies to the TV. But users will not find such popular service apps as: Amazon Prime Instant Video, M-Go, Spotify, and Hulu.


As mentioned earlier, the TC-55CX400 has 120Hz native refresh rate, which helps to reduce blurring in fast moving objects and smooths out judder in images. Panasonic uses a “Motion Estimation Motion Compensation system, which produces a very noticeable soap opera effect, when switched to full. Soap opera effect is an overall smoothing of an image to the degree that the picture takes on an unrealistic live video (or soap opera) look that can shatter the illusion created by film, even if the original source was film based. Some people like this effect, others find it distracting and not up to the intention of the original filmmaker. We found we had to switch the MEMC completely off to get rid of it, which introduces some judder and image noise in the picture, but this is the lesser of two evils.


The TC-55CX400 did a good job of limiting reflected images on the screen either from overhead lighting or objects positioned in front of the set.


The TC-55CX400 has a thin-bezel design with a black bezel border around the picture measuring one-half inch wide. The set comes with a pair of sleek matte silver feet that mount to the back of the set approximately four inches from each side. The TV measures 48.9×3.26×28.6 inches without stand and can be easily wall mounted.

Power Consumption

Unlike most manufacturers of value-priced TVs, Panasonic designed the TC-55CX400 for optimal performance in the home and not for hitting Energy Star numbers. While the set lists a $40 energy consumption estimate, it does not carry the Energy Star logo.


For the most part the TC-55CX400U presented realistic colors that were not over saturated. Panasonic’s pre-calibration settings came close to hitting most of the color and white points on the CIE1931 color space chart for the Rec. 709 color gamut.


The TV provides a typical assortment of inputs for this price range, including three HDMI 2.0 inputs with HDCP 2.2 content protection (1 and 2 are placed on the rear facing down and 3 is found on the left side of the screen facing straight out); two USB ports (one placed on the left side of the screen and one on the rear facing downward. An optical audio output, an antenna/cable connection, and an Ethernet port are all placed on the rear and conveniently facing down, to limit interference with wall mounting installations. A component/composite video input is placed on the left side of the TV with lead running straight out of the side.

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

Video Processing

Video processing in the TV was acceptable, although we did notice significant analog noise with noise reduction switched off on up converted content running the QDEO Blu-ray HD Video Evaluation test disc. The artifacts were appreciably reduced with noise reduction switched to medium. Running the opening sequences to the Pirates of the Caribbean: At World’s End from the Blu-ray showed a good bit of background noise in the darker scenes post calibration with noise reduction off. Switching it to medium helped somewhat, but noise was still evident up close. Processing artifacts, like blurry distant textures and background elements are also noticeable running older movie titles, with visible film grain.

The test sequences on the QDEO disc for 3:2 pulldown (which is also known as 2:3 pulldown) test exhibited some jerky motion on pans with some noticeable judder with the motion estimation motion compensation (MEMC) system turned off to lessen the soap opera effect. So using the function will require a tradeoff of artifacts.

We found some banding artifacts haloing bright central objects, like the sun in the sky, but not overtly noticeably. In fact, this set handled banding better than some competitive step-up 4K sets we’ve seen costing significantly more.

On-Board Sound

Sound for the CX400U is emitted by two 8-watt speakers that do a serviceable job at filling the room with clear understandable dialog. Panasonic provides three sound mode presets in the menu plus and a custom setting. Controls are available for surround, and auto volume leveling. Like most thin-frame TVs however, the overall effect is a little tinny and weak. To get a truly immersive theater experience, an investment in a good quality sound bar or surround-sound system is strongly encouraged.

Overall Impressions

In developing the TC-55CX400 Panasonic focused on offering good picture quality to a price-focused customer, and did a pretty good job. Colors compare favorably with some step-up competitive models costing hundreds more, although the set doesn’t provide all of the tools you’d expect to adjust the picture to particular lighting conditions in every viewing application.

Panasonic pre-adjusted the calibration pre-sets to accommodate typical living rooms (in standard mode) or dark viewing rooms (in cinema mode), trusting that people looking for an expensive TV aren’t going to care too much about getting the calibration adjustments just right.

Over all, the lack of important calibration settings, problems with video processing and motion compensation, and some mottled uniformity make it tough for this set to compete with most step-up “mid-fi” 4K UHD models. Also, the $899 selling price at some participating retailers is a little high compared with some other competitive models in this class — like the 120Hz 4K UHD Hisense 55H7B costing $200 less and providing 4 HDMI inputs. That model also consumes an estimated $21 per year in electricity according to its Energy Guide sticker, and that’s almost half as much as the TC-55CX400.

But the Panasonic brand name adds significant weight and should assure this model will keep viewers satisfied for many years to come. The TC-55CX400 also makes a great addition as a secondary room TV or a set to give to junior heading off to college.
HD Guru awards the Panasonic TC-55CX400 three out of five hearts.3 out of 5


The Panasonic TC-55CX400U used for this review was a company loan.

By Greg Tarr


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