TCL C9K vs Philips OLED820

As we mentioned with black and contrast – the C9K makes a huge impression in synthetic tests. Our measurements showed that on a screen 10% filled with white, the television is capable of squeezing out... 4000 nits of brightness! It sounds cosmic, but – and here unfortunately the pattern repeats – the numbers say one thing, and practice another. In real film scenes, the situation looks different. In the best case, when the light effects occupy a large part of the image and the local dimming algorithm doesn't have to think too hard about what to do with thousands of zones – the result is really quite good. At that point, the C9K can reach about 1500 nits, which provides a pleasant, intense flash and can indeed make a positive impression.

The problem begins with smaller elements – such as stars in the sky, the moon, or individual reflections. That's when the proverbial cat comes out of the bag: the algorithms are not yet refined, and brightness drops even to 400–500 nits. This is a huge difference compared to the potential of 4000 nits that we saw in laboratory tests. Why does this happen? Most likely, the television tries to protect the black and minimise the halo effect around bright objects. Unfortunately, this comes at the cost of details – some of the intricate details simply disappear, and the scene loses its nature.

When it comes to HDR quality, the Philips OLED820 uses the same class of WOLED panel found in its biggest rivals – the LG C5 and Samsung S90F. This means we can expect really solid results. This year, mid-range OLED panels can exceed the threshold of a thousand nits, and the tested model reaches around 1300 nits in some films. This is an outstanding result, allowing the director's vision to be conveyed with immense precision, as this is the brightness range in which contemporary productions are mastered. Of course, there are situations where even the OLED820 has to compromise. Full-screen scenes filled with white, like those in the film The Meg, can drop brightness to 400–500 nits, which clearly weakens the effect. This is a characteristic of OLED technology that has yet to be fully eliminated. Despite this limitation, it is hard not to appreciate the HDR in this model – high luminance and a wide DCI-P3 colour gamut coverage of 99% make the image simply look fantastic.

For colour tests, we once again reached for the Filmmaker mode – a new feature in TCL televisions for 2025. And although the direction itself is a step in the right direction, the execution leaves much to be desired. The white balance in SDR content turned out to be too warm – there was an excess of red. Conversely, in HDR, it swung in the opposite direction: the image became excessively blue. The Colour Checker test revealed quite a few colour inaccuracies that were noticeable to the naked eye. An even bigger problem turned out to be what we mentioned above – managing brightness. Regardless of whether we were watching SDR or HDR content, the image had a tendency to blow out the entire scene, giving it an unnatural, almost grotesque character. Therefore, it is hard to call this a 'director’s mode' – because the director surely has never seen such an image.

The colour reproduction in the factory settings really surprised us, and positively so. The Philips OLED820, switched to Filmmaker mode, immediately showed that it was quite well tuned in terms of colour. The white balance was relatively accurate, though there was a slight deficiency in the blue hue, which occasionally gave the image a slightly yellowish tint. However, this is not a flaw that particularly detracts from everyday viewing. A bigger issue arose with the brightness characteristics. The gamma curve clearly deviated from the ideal, with the line below the expected values, causing the image to be excessively brightened, and the colours looked as if they were covered with a light milky filter. This effect was also noticeable in tests using the Colour Checker pattern, where more pronounced errors appeared.

After calibration, we finally managed to tame the white balance – and it immediately translated into a more natural image. Colours finally started to look as they should, and the overall presentation was incomparably better than with the factory settings. In other words – it’s worth taking a moment to improve this, as the gain is really significant. The gamma responsible for managing brightness was also brought under control in SDR content, and the effect was more than satisfactory. Unfortunately, when we switched on the HDR material, the situation quickly became complicated. No matter how we set the local dimming, the television had a tendency to do what it pleased with the image – either overexposing the whole picture or dimming the darkest parts too much. Just like we saw in the scene from the film Billy Lynn. Colour-wise, the improvement after calibration makes a great impression, but managing brightness in HDR remains the Achilles' heel of the C9K and constitutes a technological limitation.

After calibration, both the Filmmaker mode and the gaming mode gained a lot. A slight adjustment of the white balance and an improvement in brightness characteristics produced excellent results in SDR content – the image looked almost perfect, natural, and very close to reference. In the case of HDR materials, the situation was similar, the colours were presented wonderfully, and it was hard to find anything to criticise. However, we noticed a certain feature, which we already pointed out when comparing scenes from the film Billy Lynn. The analysis of the EOTF curve showed that the television has a slight tendency to dim details in the blacks, so the darkest parts are not always displayed exactly as intended by the director. Nevertheless, the effect after calibration is stunning, and the OLED820 is emerging as one of the more interesting screens in its class. It just needs a little pampering, and there really is nothing to worry about.

The digital image processing in TCL C9K is rather mediocre. The tone transition smoothing feature is supposedly present, but activating it hardly makes any difference – colour banding is still visible, and it can inadvertently highlight elements we would prefer to hide, such as textures of objects. Fortunately, it does not remove film grain, but that's scant consolation considering the effects are still poor. Thus, it's hard to recommend using this option.

On the other hand, image scaling performs significantly better. Lower quality materials look quite decent – characters and backgrounds are represented clearly, although of course, with sources like 576p, the limitations of the physics cannot be disguised. Sometimes, there's characteristic aliasing of objects, but that's due to the source itself, not the algorithm. A plus for the fact that there are no overscan issues – the image is neither artificially cropped nor enlarged.

Fortunately, the earlier effects of the mentioned posterisation can be quite effectively mitigated. The "distortion reduction" function set to a medium level deals with unwanted colour banding, improving the smoothness of tonal transitions. It does happen that it works a bit too aggressively and also smooths out some details – such as minor skin imperfections of the actors – but nevertheless, it can be considered worth using without substantial compromises. The upscaling in the OLED820 also performs quite well. The test image with the model is exceptionally soft, sometimes even too much so, although this can be rectified by slightly boosting the sharpness in the picture menu – this is really a matter of individual preference. The absence of overscan issues with very low-resolution content is also commendable, meaning we don't have to worry that the image will be unnecessarily cropped.

Similar to the C8K, the C9K is also a really fast television – both figuratively and literally. On board, we have a 4K panel with a refresh rate of 144 Hz, and at lower resolutions, the panel can even ramp up to 288 Hz. Such speed translates into practice – while watching sports or playing games, the picture looks very smooth and clear. Additionally, in films, we get an extra motion smoothing feature called Motion Clarity, which allows you to adjust the smoothness to your own preferences – from the cinematic "stuttering" of frames to nearly theatrical smoothness.

The fluidity of motion is an area where OLEDs always shine, and the Philips OLED820 confirms this rule. The panel itself offers a refresh rate of 144 Hz, which primarily benefits PC gamers, but even with standard television sources or consoles, where it operates at 120 Hz, the motion is fast, sharp and simultaneously smooth, without signs of blurring. This is thanks to the remarkable response time between pixels, which maintains image clarity in every dynamic scene. The manufacturer has also added its own smoother called "Motion Style". In the menu, we find two sliders – the first, responsible for fluidity, allows adjustments to the number of artificially added frames in films. This way, we can choose a raw, cinematic character with a distinctly visible film frame or a more theatrical image with smooth motion. The second slider is for motion blur reduction, particularly useful in sports broadcasts. Here, we definitely recommend setting it to the maximum value, as the effect is truly excellent.

For gaming, the TCL C9K is a complete tool. Here we have two (out of four) HDMI 2.1 ports with full bandwidth of 48 Gbps, so all the key technologies work: VRR (Variable Refresh Rate) and ALLM (Auto Low Latency Mode). Additionally, the manufacturer has included a really intuitive Game Bar, which allows you to quickly check the most important parameters and adjust settings without rummaging through the menu. Also worth noting is TCL's policy – the television does not shy away from any HDR formats, even in game mode. Whether it's HGiG or Dolby Vision for the Xbox Series S/X console – everything works as it should, giving the player a wide range of freedom.

The Philips OLED820 is one of the most complete televisions for gamers. On board, we find practically everything one could expect: two HDMI 2.1 ports with full bandwidth of 48 Gbps (it's a shame there aren't four), variable refresh rate VRR, automatic game mode ALLM, support for Dolby Vision in games, and a good implementation of the HGiG mode. The television handles lower resolutions at 120 Hz with ease, so one can count on considerable flexibility when choosing different picture modes on the console. Philips also includes a Game Bar – a panel that allows changing picture modes, adding a crosshair, or previewing parameters. Although it looks rather clunky and is less polished than that of the competition, it does its job. In practice, therefore, the OLED820, in addition to a full set of four HDMI 2.1 ports, offers nearly everything a gamer could need.