TCL C9K vs IFFALCON U85X

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.

iFFALCON U85 handles HDR in a rather twofold manner – on one hand, it can surprise with solid peak brightness of around 650 nits, which places it well above average in this price segment. This is especially evident in bright, full-screen scenes. Examples from films such as Life of Pi or the final test sequences from The Meg prove that the television can maintain the power and essence of HDR effect when the entire panel needs to "ignite," delivering truly satisfying experiences. However, problems arise in high-contrast scenes, where smaller, bright details appear on the screen; the dimming algorithms prioritize black depth to such an extent that they can stifle the brightness of small light points to just 100 nits, which drastically reduces image dynamics and deprives us of the true "bite" we expect from HDR standards. On a brighter note, however, the colours remain impressive, as the use of the PFS phosphor filter (marketed as QLED by the manufacturer) showcases them very well, achieving nearly 94% coverage of the DCI-P3 colour palette, allowing for a vibrant and rich image in most content.

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.

We tested the factory colours on the iFFALCON U85X model in 'Film' mode, which is definitely the most reliable among all available settings, although it is still far from perfect. The main issue that stands out in both SDR and HDR content is the incorrect white balance – an excess of blue and red components gives the image a slight purple tint, which disrupts the naturalness of the film scenes. An even greater challenge is the way the television manages its brightness. Analyzing the gamma chart for the SDR signal, we noticed significant instability: instead of adhering to the standard value of 2.4, the device oscillates around 2.2, only to suddenly make an unnatural jump towards 3.0. In practice, this leads to confusing effects – large, bright areas 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 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 professional calibration of the movie mode, we must admit that the result is more than satisfactory – the iFFALCON U85X undergoes a true transformation. Colour errors in SDR content have dropped to a level below 2, which makes them virtually imperceptible to the human eye. We have managed to set the white balance almost perfectly, and brightness management (gamma) has become nearly exemplary. As a result, with standard quality materials, the television simply looks perfect and it is difficult to fault it.

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

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.

When it comes to upscaling the image to 4K resolution, the iFFALCON U85X performs well. The device efficiently enhances low-quality signals, making even older materials look clean and clear on the 4K panel. At extremely low resolutions, such as 480p, one can notice slightly jagged edges (especially on fine lines), but let's be honest – this is a scenario that you will encounter only when watching very old recordings, so in everyday use, it is not a real problem.

Much worse is the digital processing aimed at smoothing tonal transitions. Although in the menu we find the “Gradual Smoothing” function, its effectiveness is at least questionable. In practice, it does not effectively eliminate banding (colour banding), and worse, it can cause more harm than good. This filter can be too aggressive in areas where it shouldn’t, artificially smoothing details that should not be altered, such as the natural texture of the face or fine details of skin texture. Instead of improving quality, this function can give the image an unnatural, “plastic” appearance, so it is best to use it with great caution or, preferably, leave it switched off.

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.

In contrast to budget constructions, which in dynamic sports scenes can resemble a slideshow, the iFFALCON U85X is a heavyweight contender equipped with a panel that has a native refresh rate of 144Hz. However, it is worth noting that in the world of films, series, or sports, we will primarily operate at 120Hz due to the specifics of how image enhancement systems function. Such a fast panel is excellent news for gamers and sports fans as it opens the door to advanced motion settings that simply do not exist in cheaper 60Hz models.

We manage everything from the menu “Motion Clarity”, where instead of using pre-set, often overly aggressive modes, we definitely recommend our own configuration based on two sliders. The most important of these, motion blur reduction, is responsible for fluidity in films – here, it’s best to aim for a value of around 4, which will maintain a natural, cinematic character of motion without falling into the artificial “soap opera effect.” Meanwhile, the first slider, motion blur reduction, is the key to success in sports broadcasts. In this case, it’s worth going all out and setting it to maximum, ensuring that the image during fast actions on the field remains sharp, while troublesome trailing is eliminated.

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.

iFFALCON U85X is an outstanding piece of equipment for gamers that has just about everything one can expect from a modern screen for consoles or PCs. We find here two full-fledged HDMI 2.1 ports with full bandwidth of 48 Gbps, which opens the door to key technologies such as VRR and ALLM, ensuring smooth gameplay without tearing the image and with minimal latency. The television handles high refresh rates in various resolutions without any problems, and a real curiosity is the mode that allows for achieving up to 240Hz when dropping down to Full HD quality. The whole thing is managed by the Game Bar (which is a faithful copy from TCL), allowing for instant switching of picture modes, customising the interface appearance, or even adding a virtual crosshair in the middle of the screen.