TCL C855 vs TCL C6K

The TCL C855 delivers a highly varied HDR effect. At times, the television truly excels, while at other moments, it appears reminiscent of a low-end model equipped with FALD backlighting. Inconsistency is frequently found with this brand, so it didn’t come as a surprise. The first and last scenes, which feature large light elements, are nothing short of spectacular, boasting brightness levels of 1470 and 1820 nits, respectively. Such brightness can make viewers squint their eyes, allowing them to feel the extraordinary dynamism of the scene. It genuinely immerses the audience, creating a sensation of being inside the movie itself. However, the situation shifts dramatically when small or subtle elements with high luminance appear against a dark background. In these instances, the TCL C855 significantly reduces brightness to levels as low as 240 nits to mitigate halo effects. This reduction is disappointing, as it can make the movie appear as if it was not filmed in HDR. Despite these shortcomings, the HDR effect on the TCL C855 enhances the viewing experience during dynamic scenes, making it feel more engaging and allowing the viewer to feel part of the action. Even with smaller high-luminance elements, the television retains details without excessive dimming. Additionally, the TCL C855 adjusts image brightness according to scenes with rich detail, further enhancing viewing comfort.

TCL C6K is a moderately bright TV that can showcase its full potential under the best cinematic conditions – the maximum brightness is around 600 nits. In scenes with large, intense light sources, the HDR effect can be really satisfying, providing a sense of cinematic brilliance. However, it should be noted that when managing the backlighting zones, there are situations where some elements become dimmed and sometimes can even become barely visible. It is clear that there is a lack of proper algorithm optimization here, although looking at the technical parameters in this price range, the design itself performs very well.

The best factory mode for the TCL C855 is the "Film" setting, and all our tests were conducted using this mode. However, like many predefined modes, it has flaws that should be addressed to achieve an image closer to the producer's original vision. In our examination of the colour characteristics for both SDR and HDR materials, issues were found.

Focusing first on SDR content, there is a noticeable dominance of green in the white balance, which leads to an unpleasant greenish tint across the entire image. The gamma chart, crucial for image contrast, shows a significant deviation from the reference line marked at 2.4. Initially, there is a pronounced spike in the measured value, resulting in an over-contrasted image where details can merge into a dark blob. This condition persists for nearly 20% of the chart before it dips below the reference line, causing the image to brighten and resulting in a substantial drop in contrast.

In HDR materials, the factory mode performs somewhat better; the white balance appears more balanced overall, although the green tint resurfaces in the latter half of the spectrum. When we look at the Electro-Optical Transfer Function (EOTF) curve—unlike gamma, which reflects contrast—we identify two main errors: the darkest scenes are too dark, while the brightest ones become overexposed. This discrepancy was evident in our review of the scene from the movie "Pan," further illustrating the TCL C855's HDR performance issues.

This year's TCL televisions feature a Filmmaker mode, and it must be admitted that it is definitely the best choice straight out of the box. This is the mode we recommend for everyday watching of movies and series. Unfortunately, as is often the case, the best doesn't mean perfect. In the case of SDR content, the image was too warm because the red was strongly emphasized in the white balance. On the other hand, with HDR content, we had the opposite impression – the image became cooler than it should have been due to excess blue. Additionally, the brightness characteristic sometimes led to highlights being blown out. In practice, this resulted in quite noticeable color test inaccuracies that are hard to accept in a mode advertised as "by the creators."

TCL, like most manufacturers, offers advanced calibration tools within its televisions. These include both 2-point and 20-point adjustments for grayscale, as well as a comprehensive colour management system. As a result, we achieved impressive results in SDR materials, bringing the image significantly closer to the reference standard. We successfully eliminated both the green tint and the gamma issue, although a slight "kink" at the very beginning of the gamma curve still persists.

In contrast, the situation with HDR materials was less favourable, as the TCL C855 did not allow for precise modelling. We were only able to make minor adjustments to the EOTF curve while significantly enhancing the overall colour accuracy. This limitation suggests that while calibration tools are effective, they may require further refinement for optimal HDR performance.

Thanks to the white balance correction, it was possible to significantly reduce the C6K's tendency to distort colors, which resulted in a very good final outcome. After calibration, we will no longer observe the effect of excessive warming of scenes in SDR or overly cooling the image in HDR. However, it is worth taking a closer look at the brightness characteristics. In SDR content, there are few complaints – the image looks really good, especially in older movies, TV shows, or materials from YouTube. This is much worse for HDR content. Analysis of the EOTF curve suggests that everything is fine, but in practice (EOTF in films), the limitations of the construction become apparent. The TV tends to overly brighten the smallest parts of the frame, and in other situations, it can dim the entire scene too much. The effect of calibration is therefore evident, and in terms of color, the C6K has gained quite a lot, but certain limitations arising from local dimming and, in fact, its management by the C6K simply cannot be overcome.

Once again, we will take a look at the function of smoothing tonal transitions, but this time also image scaling. The latter is particularly important when watching materials of lower quality, such as some television programs or older films. We will focus on the function responsible for tonal transitions. Interestingly, just like in the scenes from the previous test where it performed excellently and smoothed out practically all the inconsistencies, here it had issues. Using the menu responsible for the operation of this function, we found that no setting—even the strongest—was helpful.

Image scaling in TCL C855 is defined as one of the best we have had the opportunity to test so far. The image is sharp, but in a way that could be described as natural to our eye. Even small, fine branches do not have jagged edges, and there is no white halo around figures, a characteristic of weaker scaling systems.

The TCL C6K performs quite well in terms of scaling. Lower quality materials look acceptable, and the lack of overscan issues means that the image is displayed in full, without cropping. However, one cannot expect miracles – content of very low quality will not gain new life here, as the image processor has its limitations. On thin lines or details, the characteristic tearing is visible, which reveals the absence of advanced image enhancement algorithms. It is also a pity that the C6K lacks the feature for smoothing tonal transitions – in older films or video materials, color banding can be noticeable and may be bothersome during long viewing sessions.

The maximum refresh rate you can set on the TCL C855 is 144 Hz. Naturally, this is only possible after connecting the TCL C855 TV to a very powerful PC. Otherwise, we will be operating at a maximum refresh rate of 120 Hz, which is recommended if we want to watch primarily sports or materials with a lot of motion dynamics. For those who require high image fluidity, the manufacturer has implemented a multi-stage motion smoother. It is divided into two separate sliders which control the sharpness of moving images (Motion Blur Reduction) and flicker (Flicker Reduction). Both sliders can be adjusted from 0 to 10, with each level affecting the degree of fluidity, so everyone can find their sweet spot. We present a setting that allows for slight smoothing without the soap opera effect. The matrix of the TCL C855 features a very good response time. This is particularly important since VA panels often struggle with the so-called ghosting effect, where a black halo can be observed behind a fast-moving object. where a black halo can be observed behind a fast-moving object.

TCL C6K features a 144 Hz panel, which is a significant advantage in this price range. This is an important step forward compared to the previous model C655 PRO, which offered only 60 Hz at 4K. The difference is especially noticeable when watching sports or playing games – the ball, athletes, or fast action in a game are displayed more clearly and without losing details. An interesting fact is also the ability of the panel to operate at 240 Hz, which the manufacturer does not mention in official materials. We will return to this topic when discussing the game mode for PC.

TCL also added a feature for movie watchers: "Motion Clarity," which allows you to adjust the image to your preferences using two simple sliders. You can keep the movie frame visible or opt for a very smooth, almost theatrical effect. This way, everyone can find settings tailored to their taste.

The TCL C855 TV has fully-featured HDMI 2.1 ports, boasting a full bandwidth of 48 Gb/s. During our testing, we confirmed the seamless operation of all functions included in this connection standard. As highlighted, all checkboxes are illuminated in green, a feature that will undoubtedly be appreciated by gamers, whether on consoles or those using the TV as a computer monitor. Additionally, the TCL C855 supports both AMD FreeSync and NVIDIA's G-Sync, which can be easily activated in the graphics card settings. Those with powerful configurations can feed a 144 Hz signal to the C855, which handles this effortlessly. It is also worth noting the implementation of the HGIG mode, which can be excessively bright due to the shortcomings of the "Game" mode, making proper configuration on the screen challenging. Fortunately, the TV excels with the Dolby Vision format.

TCL, as one of the pioneering manufacturers, has equipped its televisions with a special GameBar, allowing for extensive adjustment of settings "on the fly" without the need to exit the game. This feature includes options like an additional crosshair grid, black level correction, and settings designed for individuals with disabilities. The image showcases the next generation of this solution.

In summary, the TCL C855 TV is an ideal choice for those seeking a screen for all forms of electronic gaming. With comprehensive features supporting such entertainment, it provides an extremely engaging experience. It is also important to emphasise that it maintains very low input lag, regardless of the selected settings, including when using the Dolby Vision HDR format.

The TCL C6K is a TV that can confidently be called equipment designed for gamers. Here we have 4K at 144 Hz, VRR support, automatic game mode (ALLM), and Dolby Vision Gaming. Additionally, there's a practical Game Bar, a panel with the most important settings readily available – useful when we want to quickly change something during gameplay (e.g., screen aspect ratio: Yes, that’s possible!). The wide VRR range, reaching up to 240 Hz, deserves attention. However, this is mainly an option for PC gamers who drop below the native 4K resolution. Then the TV can spread its wings and show additional smoothness, especially in fast-paced e-sports titles. In the case of consoles, we stick to the classic limit of 120 Hz, but the possibilities are still quite broad. The only drawback is a slight ghosting that can sometimes be seen in dynamic scenes. Other than that, the C6K offers everything gamers expect from a TV.