TCL C9K vs Philips OLED820

As we mentioned with black 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 is capable of squeezing out… 4000 nits of brightness! It sounds astronomical, but – and here, unfortunately, the pattern repeats – the numbers say one thing, and practice says another. In real movie scenes, the situation looks different. At best, when the light effects occupy a large part of the image and the local dimming algorithm does not have to think too hard about what to do with thousands of zones – the effect is really good. At that point, the C9K can reach around 1500 nits, which provides a pleasant, intense flash and can indeed make a positive impression.

The problem starts with smaller elements – such as stars in the sky, the moon, or single reflections. That’s when the proverbial cat comes out of the bag: the algorithms are not yet refined, and brightness drops to even 400–500 nits. That’s a huge difference compared to the potential 4000 nits we saw in laboratory tests. Why does this happen? Most likely, the television is trying to protect the blacks in this way and minimize the halo effect around bright objects. Unfortunately, this comes at the cost of details – 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 that we find in its biggest competitors – LG C5 or Samsung S90F. This means we can count on truly solid performance. This year, mid-range OLED panels are capable of exceeding the threshold of a thousand nits, and the model tested reaches around 1300 nits in some films. This is an outstanding result that allows for an extremely precise depiction of the director's vision, as contemporary productions are mastered in such brightness ranges. Of course, there are situations where even the OLED820 has to compromise. Full-screen scenes flooded with white, like those in the movie The Meg, can drop brightness to 400–500 nits, which clearly weakens the effect. This is a characteristic of OLED technology that has not yet been fully eliminated. Despite this limitation, it is hard not to appreciate the HDR in this model – high luminance and wide coverage of the DCI-P3 color gamut at 99% make the picture simply look great.

For color tests, as always, we reached for the Filmmaker mode – a new feature in TCL TVs for 2025. And while 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. On the other hand, in HDR, it went in the opposite direction: the image became excessively blue. The Colour Checker test revealed quite a few color errors 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 blow out the entire scene, giving it an unnatural, even grotesque character. It's hard to call this a "director-created" mode – because the director has certainly never seen such an image.

The color 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 color. The white balance was relatively accurate, though with a slight lack in the blue hue, which sometimes gave the image a slightly yellowish tint. However, this is not a flaw that particularly interferes with everyday viewing. A larger problem arose with the brightness characteristic. The gamma chart clearly deviated from the ideal, with the line being below the expected values, causing the image to be overly brightened, and the colors 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. Colors finally started to look the way they should, and the overall presentation was incomparably better than in the factory settings. In other words – it’s worth taking a moment to improve this, as the gain is truly significant. The gamma responsible for managing brightness was also brought into order in SDR content, and the effect was more than satisfying. 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 dimmed the darkest parts too much. Exactly as we saw in the scene from the movie Billy Lynn. So, the color improvement after calibration makes a great impression, but brightness management in HDR remains the Achilles' heel of C9K and presents a certain technological limitation.

After calibration, both the Filmmaker mode and the game mode gained quite a lot. A slight adjustment of the white balance and an improvement in brightness characteristics resulted in excellent outcomes for SDR content – the image looked almost perfect, natural and very close to the reference. In the case of HDR materials, the situation was similar; the colors looked stunning and it was hard to find anything to criticize. However, we noticed a certain feature that we had already pointed out when comparing scenes from the movie Billy Lynn. An analysis of the EOTF curve revealed that the television has a slight tendency to dim details in the blacks, which means that the darkest sections are not always displayed exactly as the director intended. Nevertheless, the effect after calibration is remarkable, and the OLED820 stands out as one of the more interesting screens in its class. It just needs a little bit of fine-tuning, and there's really nothing to be afraid of.

Digital image processing in TCL C9K is quite mediocre. The tonal smoothing feature seems to be present, but turning it on practically changes nothing – color bands are still visible, and it can unintentionally highlight elements we would prefer to hide, such as textures of objects. Fortunately, it doesn’t remove film grain, but that’s small comfort since the effects are still poor. Therefore, it's hard to recommend using this option.

On the other hand, image scaling performs much better. Lower quality materials look quite decent – characters and backgrounds are presented clearly, although, of course, with sources at 576p, physics cannot be fooled. Sometimes, characteristic aliasing on objects appears, but that’s the fault of the source itself, not the algorithm. A plus for not having issues with overscan – the image is not artificially cropped or enlarged.

Fortunately, the earlier effects of the aforementioned posterization can be quite effectively mitigated. The "distortion reduction" feature set to medium handles unwanted color banding, improving the smoothness of tonal transitions. It does happen, however, that it works a bit too aggressively and smooths out some details – such as minor skin imperfections of the actors – but despite this, 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 even too much so, although this can be alleviated by slightly increasing the sharpness in the picture menu – it’s a matter of personal preference. The lack 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.

Like the C8K, the C9K is also a really fast television – both figuratively and literally. It features a 4K panel with a refresh rate of 144 Hz, and at lower resolutions, the display can even ramp up to 288 Hz. This speed translates into practice – when watching sports or playing games, the image looks very smooth and clear. Additionally, in films, we get an extra motion smoother called Motion Clarity, which allows us to adjust the fluidity to our own preferences – from the cinematic "judder" frame 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 television sources or consoles, where 120 Hz is used, the motion is fast, sharp, and simultaneously smooth, without traces of ghosting. This is thanks to the outstanding response time between pixels, which ensures the image retains clarity in every dynamic scene. The manufacturer has also added its own smoothing feature called "Motion Style." In the menu, we find two sliders – the first, responsible for fluidity, allows us to adjust the amount of artificially added frames in movies. This way, we can choose a raw, cinematic character with a clearly visible film frame or a more theatrical image with smooth motion. The second slider is for reducing blurring, especially 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 key technologies work: VRR (variable refresh rate) and ALLM (automatic low latency mode). Additionally, the manufacturer added a really intuitive Game Bar, which allows you to quickly preview the most important parameters and adjust settings without digging through the menu. Also, TCL's policy is a plus – the TV is not 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 wide freedom.

Philips OLED820 is one of the most complete televisions for gamers. It practically has everything you could expect: two HDMI 2.1 ports with full bandwidth of 48 Gbps (too bad 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 also handles lower resolutions at 120 Hz without any issues, so you can count on great flexibility when choosing different picture modes on the console. Philips also adds Game Bar – a panel that allows you to change picture modes, add a crosshair, or view parameters. Although it looks quite clunky and is less polished than that of the competition, it serves its purpose. In practice, therefore, the OLED820, besides having a full set of four HDMI 2.1 ports, offers almost everything a gamer might need.