TCL C9K vs IFFALCON U85X

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.

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 well above average in this price segment. This is particularly evident in full-screen, bright scenes. Examples from movies like Life of Pi or the final test sequences from The Meg prove that the TV can maintain the strength and essence of the HDR effect when the entire panel has to "light up," delivering truly satisfying experiences. However, problems begin in high-contrast scenes, where smaller, bright details appear on the screen; the dimming algorithms prioritize deep blacks to such an extent that they can suppress the brightness of small highlights to just 100 nits, drastically reducing the dynamism of the image and depriving us of the true "punch" we expect from HDR standards. However, the question of colors remains a sweetener; 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 color palette, allowing for a rich and vibrant image in most content.

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.

We tested the factory colors in 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 problem that stands out in both SDR and HDR content is improper white balance - an excess of blue and red components gives the image a slight purple tint, which undermines the naturalness of film scenes. However, an even greater challenge is the way the television manages its brightness. Analyzing the gamma curve for the SDR signal, we noticed significant instability: instead of sticking to the reference value of 2.4, the device oscillates around 2.2, only to suddenly experience an unnatural jump to around 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 feature 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. 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 professional calibration of the movie mode, we must admit that the effect is more than satisfactory – the iFFALCON U85X undergoes a true transformation. Color errors in SDR content dropped to a level below 2, making them practically imperceptible to the human eye. We managed to set the white balance almost perfectly, and brightness management (gamma) became nearly exemplary. As a result, with standard quality materials, the television looks simply perfect, and it's hard to find any faults with it.

In the case of HDR signal, the situation has also improved significantly, although here the nature of the device is a bit more pronounced. Color 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 chart (available on the right side of the screen in the filters: 4K HDR, gamma / EOTF) to see what is not immediately visible regarding brightness management by the U85. Although 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 algorithms. Does this disqualify this model for watching HDR content? Absolutely not. It's simply a typical ailment of almost every Mini-LED that has to reconcile high brightness with an attempt to maintain deep black. One just has to be aware of these technical limitations, which are unavoidable in this segment.

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.

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

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

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.

In contrast to budget constructions, which in dynamic sports scenes may resemble a slideshow, the iFFALCON U85X is a heavyweight contender equipped with a panel featuring a native refresh rate of 144Hz. However, it is worth remembering that in the world of movies, series, or sports, we will mostly 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 don't exist in cheaper 60-Hz models.

We manage everything from the "Motion Clarity" menu, where instead of using pre-set, often too aggressive modes, we definitely recommend a custom configuration based on two sliders. The most important of them, reduction of flicker, is responsible for smoothness in films – here, it's best to aim for a value around 4, which will maintain a natural, cinematic character of motion without falling into the artificial "soap opera effect." On the other hand, the first slider, reduction of blur, 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, and annoying 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 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.

iFFALCON U85X is an exceptional device for gamers that has virtually everything you can expect from a modern screen for consoles or PCs. Here we find two fully-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 and with minimal latency. The TV handles high refresh rates at various resolutions without any problem, and a real curiosity is the mode that allows for up to 240Hz when dropping to Full HD quality. The entire system is managed by the Game Bar (a faithful copy from TCL), which allows for instant switching of picture modes, customization of the interface appearance, or even adding a virtual crosshair in the middle of the screen.