TCL C9K vs IFFALCON U85X

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.

iFFALCON U85 handles HDR in a rather dual manner – on one hand, it can surprise with a solid peak brightness of around 650 nits, which places it significantly above average in this price segment. This is particularly evident in bright, full-screen scenes. Examples from movies like Life of Pi or the final test sequences from The Meg prove that the television can maintain the power and essence of the HDR effect when the entire panel needs to “ignite,” providing truly satisfying experiences. However, problems arise in high-contrast scenes, where smaller, bright details appear on the screen; the dimming algorithms prioritise black depth so much that they can crush the brightness of small bright points down to just 100 nits, drastically lowering the image dynamics and depriving us of the real “bite” we expect from HDR standards. However, the question of colours remains a sweetener, as thanks to the use of the PFS phosphor filter (marketed as QLED by the manufacturer), they look very good, achieving nearly 94% coverage of the DCI-P3 colour gamut, which allows for a rich and vivid image in most content.

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.

We tested the factory colours in the iFFALCON U85X model in “Film” mode, which is definitely the most accurate among all available settings, although it is still far from perfect. The main issue that catches the eye in both SDR and HDR content is the improper white balance – an excess of blue and red contributes to a slight purple tint in the image, detracting from the naturalness of the film scenes. An even greater challenge is how the television manages its brightness. Analysing the gamma chart for SDR signal, we noticed significant instability: instead of adhering to the standard value of 2.4, the device oscillates around 2.2, then suddenly makes an unnatural jump to around 3.0. In practice, this leads to confusing effects – large, bright surfaces on the screen appear too dark, while smaller elements are unnecessarily brightened. A similar characteristic can be found in the EOTF curve, which makes the image unpredictable and loses its cinematic authenticity.

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 professional calibration of the movie mode, we must admit that the effect is more than satisfactory – the iFFALCON U85X undergoes a true transformation here. Colour errors in SDR content have dropped to a level below 2, making them practically undetectable to the human eye. We managed to set the white balance almost perfectly, and brightness management (gamma) has become almost exemplary. As a result, with standard quality materials, the television simply looks perfect and it's hard to fault it.

In the case of HDR signal, the situation has also improved significantly, although here the nature of the device is a bit more noticeable. Colour errors have been reduced to around 3, which is an outstanding result in this price range. It's worth taking a look at the EOTF chart (available on the right side of the screen in filters: 4K HDR, gamma / EOTF) to see what is not immediately apparent regarding brightness management by the U85. Though the reference line looks decent, in actual film scenes the television still interprets the signal “in its own way” due to very aggressive local dimming zone algorithms. Does that disqualify this model for watching HDR content? Absolutely not. It’s simply a typical issue with nearly every Mini-LED that has to balance high brightness with the attempt to maintain deep blacks. One just needs to be aware of these technical limitations, which are unavoidable in this segment.

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.

When it comes to scaling images to 4K resolution, the iFFALCON U85X performs solidly. The device effectively boosts low-quality signals, making even older materials look clean and clear on the 4K panel. At extremely low resolutions, such as 480p, you can notice slightly jagged edges (especially on thin lines), but let’s be honest – this is a scenario you'll only encounter while watching very old recordings, so in everyday use, it’s not a real issue.

On the other hand, the digital processing aimed at smoothing tonal transitions performs significantly worse. Although the menu features a function called “Gradual Smoothing”, its effectiveness is at least debatable. In practice, it does not effectively eliminate banding (colour stepping) and, worse yet, can cause more harm than good. This filter can be too aggressive where it shouldn’t be, artificially smoothing out details that shouldn’t be touched, such as the natural texture of the face or the fine details of skin texture. Instead of improving quality, this function can give the image an unnatural, “plastic” look, so it’s best to use it with caution or, preferably: leave it turned off.

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.

Unlike budget constructions that can resemble a slideshow in dynamic sports scenes, the iFFALCON U85X is a heavyweight player equipped with a panel featuring a native refresh rate of 144Hz. It's worth remembering that in the realm of movies, series, or sports, we'll predominantly operate at 120Hz due to the specifics of image enhancement systems. Such a fast panel is excellent news for gamers and sports fans, as it opens the door to advanced motion settings that simply aren't available in cheaper 60Hz models.

Everything is managed from the menu “Motion Clarity”, where instead of using ready-made, often overly aggressive modes, we strongly recommend a custom configuration based on two sliders. The most important of these, Flicker Reduction, is responsible for fluidity in films – here, it's best to aim for a value around 4, which helps maintain the natural, cinematic character of motion without falling into the artificial “soap opera effect.” Meanwhile, the first slider, Motion Blur Reduction, is key to success in sports broadcasts. In this case, it's worth going all out and setting it to maximum, ensuring that the image remains sharp during fast-paced action on the field, while annoying ghosting is eliminated.

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.

iFFALCON U85X is an outstanding piece of gear for gamers that has pretty much everything you could ask for from a modern screen for console or PC. It features two full-fledged HDMI 2.1 ports with a full bandwidth of 48 Gbps, which opens the door to key technologies such as VRR and ALLM, ensuring smooth gameplay without screen tearing and with minimal lag. The TV effortlessly handles high refresh rates at various resolutions, and a real curiosity is the mode that allows for up to 240Hz when dropping down to Full HD quality. Everything is managed by the Game Bar (which is a faithful copy from TCL), allowing for instant switching of picture modes, personalization of the interface appearance, or even adding a virtual crosshair in the middle of the screen.