TCL C9K vs Philips OLED820

As we mentioned regarding black levels and contrast – the C9K can make a huge impression in synthetic tests. Our measurements showed that on a screen 10% filled with white, the television can achieve... 4000 nits of brightness! It sounds out of this world, but – and here's where the pattern unfortunately repeats – the numbers say one thing, and the practical experience says another. In real movie scenes, the situation looks different. In the best-case scenario, when light effects occupy a large part of the image and the local dimming algorithm doesn't have to ponder too much about what to do with thousands of zones, the effect is really quite good. At that point, the C9K can hit around 1500 nits, which delivers a pleasant, intense burst and can indeed leave a positive impression.

The problem arises 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 to as low as 400–500 nits. That's a huge difference from the potential 4000 nits we saw in lab tests. Why does this happen? Most likely, the television is trying to protect the black levels in this way and minimize the halo effect around bright objects. Unfortunately, this comes at the expense of detail – some details simply vanish, 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 the 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 incredible precision, as this is the brightness range in which modern productions are mastered. Of course, there are situations where even the OLED820 has to compromise. Full-screen scenes flooded with white, like those in the film The Meg, can drop brightness to 400–500 nits, which clearly diminishes the effect. This is a characteristic of OLED technology that has not yet been fully eliminated. Despite this limitation, it's hard not to appreciate the HDR in this model – high luminance and a wide coverage of the DCI-P3 colour palette at 99% make the image look simply fantastic.

For colour tests, we once again reached for the Filmmaker mode – a new feature in TCL televisions for 2025. While the direction is a step in the right way, the execution leaves a lot to be desired. The white balance in SDR content turned out to be too warm – there was an excess of red. On the other hand, 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 – brightness management. Regardless of whether we were watching SDR or HDR content, the image tended to wash out the entire scene, giving it an unnatural, almost grotesque character. Therefore, it’s hard to call this a "director's mode" – because no director has ever seen such an image.

The colour reproduction in the factory settings really surprised us, and in a positive way. 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, although there was a slight deficiency in the blue hue, which sometimes gave the image a slightly yellowish tint. However, this is not a drawback that particularly interferes with everyday viewing. A bigger problem arose with the brightness characteristics. The gamma chart clearly deviated from the ideal, as the line was 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 on 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 brightness management also managed to be brought into order in SDR content, and the effect was more than satisfactory. Unfortunately, when we turned on HDR materials, the situation quickly became complicated. No matter how we set the local dimming, the television had a tendency to do what it liked with the image – either it overexposed everything or darkened the darkest parts too much. Just like we saw in the scene from the movie Billy Lynn. Colour-wise, the improvement after calibration makes a great impression, but brightness management in HDR remains the Achilles' heel of the C9K and presents a certain technological limitation.

After calibration, both the Filmmaker mode and the gaming mode improved quite a bit. A slight adjustment of the white balance and enhancement of the brightness characteristics yielded excellent results with SDR content – the image looked nearly perfect, natural, and very close to the reference. For HDR material, the situation was similar; the colours looked fantastic, and it was hard to find fault with anything. However, we did notice a certain characteristic, which we had already pointed out when comparing scenes from the film Billy Lynn. The analysis of the EOTF curve showed that the TV has a slight tendency to dim details in the blacks, meaning that the darkest parts are not always displayed exactly as the director intended. Nevertheless, the effect after calibration is superb, and the OLED820 is emerging as one of the more interesting screens in its class. A little bit of fine-tuning is all that’s needed, and there’s really nothing to worry about.

Digital image processing on the TCL C9K is rather average. The smooth tone transition feature seems to be present, but activating it practically changes nothing – colour bands are still visible, and it can unintentionally highlight elements we’d rather keep hidden, such as object textures. Fortunately, it doesn’t remove film grain, but that’s poor consolation given that the effects are still meagre. It’s therefore hard to recommend using this option.

On the other hand, image scaling presents itself much better. Lower quality materials look quite decent – characters and backgrounds are rendered clearly, although of course, with sources like 576p, the laws of physics cannot be fooled. Occasionally, there’s characteristic edge distortion of objects, but that’s the fault of the source itself, not the algorithm. A plus for not having issues with overscan – the image isn't artificially cropped or enlarged.

Fortunately, the earlier effects of the mentioned posterisation can be quite effectively mitigated. The "distortion reduction" feature set to medium handles unwanted colour banding well, improving the smoothness of tonal transitions. It does sometimes work a bit too aggressively and smooths out some details – such as the minor imperfections of the actors’ skin – but despite that, it can be considered worth using without major compromises. The upscaling in the OLED820 also performs well. The test image with the model is exceptionally soft, sometimes perhaps too much, although this can be remedied with a slight increase in sharpness in the picture menu – that's a matter of individual preference. The absence of overscan issues with very low-resolution content is also commendable, allowing us to not worry about the image being unnecessarily cropped.

Similar to the C8K, the C9K is also a really fast TV – both figuratively and literally. It features 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 image looks very smooth and clear. Additionally, in movies, we get an extra motion smoother called Motion Clarity, which allows you to adjust the smoothness to your own preferences – from cinematic "judder" to almost theatrical smoothness.

Motion fluidity 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 will mainly benefit PC gamers, but even with standard TV sources or consoles, where it operates at 120 Hz, motion is fast, sharp, and simultaneously smooth, without any signs of smearing. This is thanks to the remarkable response time between pixels, which ensures the image maintains clarity in every dynamic scene. The manufacturer has also added their own smoothness enhancer called "Motion Style." In the menu, we find two sliders – the first, responsible for smoothness, allows for the adjustment of the number of artificially added frames in films. This way, we can choose a raw, cinematic character with clearly visible film frames 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.

From a gaming perspective, the TCL C9K is a complete tool. It features two (out of four) full bandwidth 48 Gbps HDMI 2.1 ports, 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 that allows you to quickly check the most important parameters and adjust settings without fumbling through menus. Also, TCL's policy is a plus – the TV isn’t afraid of 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 plenty of freedom.

The Philips OLED820 is one of the most comprehensive TVs for gamers. Onboard, we find practically everything one could expect: two HDMI 2.1 ports with full bandwidth of 48 Gbps (shame there aren't four), Variable Refresh Rate (VRR), Auto Low Latency Mode (ALLM), support for Dolby Vision in games, and a good implementation of the HGiG mode. The TV also handles lower resolutions at 120 Hz without issue, so you can count on great flexibility when choosing different picture modes on your console. Philips also adds a Game Bar – a panel that allows you to change picture modes, add a crosshair, or preview parameters. Although it looks a bit clunky and is less refined than its competitors, it gets the job done. In practice, therefore, the OLED820, in addition to a full set of four HDMI 2.1 connections, offers almost everything a gamer could need.