TCL C9K vs LG OLED B6

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.

LG B6 is a moderately bright OLED. After calibration it reaches around 800 nits, roughly 200 nits more than last year's B5. That's down to LG Display's new budget OLED SE panel. In practice this simply provides a bit more headroom and makes HDR look fuller in many scenes than on last year's lower-end OLEDs. That doesn't mean the B6 has no limitations. In very bright shots, when a large part of the screen is brightly lit, brightness can fall below 400 nits. This behaviour is typical of OLED TVs (especially in this segment), and it's then you see the biggest difference compared with pricier models. All the same, we rate the B6's results as really solid. It's still not a TV built to break brightness records, but the HDR effect is strong enough that films really feel like a step up from ordinary SDR picture.

Colour gamut

Using the OLED SE panel has had some impact on wide colour-gamut coverage. Compared with last year's model the figures have dropped by a few percentage points. DCI-P3 reaches about 96%, and BT.2020 around 71%. That doesn't mean the colours on the LG B6 are weak. In most films and TV series they look vivid, well saturated and simply pleasing to the eye. You only notice the difference in very bright, highly colourful scenes. Then colours lose some intensity compared with QD-OLED panels. This is due to the WOLED panel structure. In addition to the red, green and blue subpixels it also uses a white subpixel that helps boost brightness. This comes at a cost: at very high luminance some of the colour is effectively 'diluted' by the white light, so saturation of some hues can be slightly lower. Day-to-day it's not a big problem, but you can see it in the most demanding scenes.

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 LG B6 in Filmmaker Mode, the best picture setting available straight out of the box. ISF modes give very similar results, but in our tests we always stick to Filmmaker Mode for better comparison with other TVs. Each of them is a far better starting point than Vivid or Eco, where the picture is heavily boosted and noticeably less natural. For SDR content the factory settings perform really well. Colour errors are small, gamma behaves correctly, and the picture looks natural during regular viewing and does not seem overly enhanced.

It's a bit worse with HDR. Once you start playing that kind of content it's quickly apparent the white balance isn't perfectly set. Too much blue and red makes the image take on a slightly pink tint. Colour gamut measurements and the ColorChecker confirm this, with samples clearly shifting in that direction. It's not a defect that completely ruins the picture, but you can notice it with HDR films. So anyone who wants the most faithful image should consider calibration, which we cover later in the review.

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.

During calibration we focused mainly on HDR material, because that’s where the factory settings needed the most correction. We didn’t neglect SDR, though. After tuning it was brought almost to perfection. Colours are very accurate and brightness is controlled as it should be. The biggest change in HDR came from improving the white balance. After removing excess red and blue the pinkish tint disappeared and the image became much more natural. Skin tones, whites and all colours that had previously leaned towards pink improved. After calibration most errors fell below Delta E 2-3, the threshold at which an average viewer stops noticing differences with the naked eye. So the LG B6 can produce a very accurate picture, especially for the manufacturer’s entry-level OLED model.

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.

LG B6 copes very well with lower-quality material. Much of that is down to effective digital image processing, which can mask some source imperfections without excessively smoothing the whole scene. The "Smooth Gradation" feature proves particularly useful. It lets you noticeably reduce posterization mentioned earlier, especially in dark parts of the image. The safest choice is to set it to Low or Medium. The feature still effectively smooths out harsh tonal transitions, but doesn't yet interfere too much with fine details. Die-hard purists can of course leave it off. Upscaling to 4K also performs very well. Full HD and 720p content retain a fair amount of detail, and the image is neither overly sharpened nor heavily blurred. Some limitations are only noticeable with very poor sources below 720p, where the smallest text and fine elements aren't always perfectly sharp, but this is true for almost every other TV on the market.

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.

One of the biggest advantages of OLED panels is their very fast pixel response time. That keeps the picture sharp and prevents visible smearing that often appears on LCD TVs. It does have a downside, though. During slow camera pans motion can look a bit choppier than on LCD screens, where the slower panel naturally masks some of that effect. Fortunately, on the LG B6 this is easy to tame with TruMotion. With the motion smoothing set correctly you can get smoother motion without giving the picture an exaggerated soap-opera effect.

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.

LG OLED B6 has plenty going for gamers; it's a complete base for the PS5, Xbox Series X/S or a solid PC. It comes with four full-size HDMI 2.1 ports with 48 Gb/s bandwidth, so you can forget about annoying cable swapping when you want to connect several newer devices at once. We get a full package of sync technologies, from classic VRR to G-Sync and FreeSync. The panel effortlessly syncs its refresh rate to the frame pacing produced by your console or graphics card. Of course ALLM is present: the B6 automatically recognises when a game is running and immediately cuts latency to a minimum. HDR support is also excellent. The TV supports Dolby Vision, and a correctly implemented HGiG means that after an initial calibration in the console settings the picture won't suffer from blown-out whites or lost detail in bright areas. The icing on the cake is the Game Bar. Instead of digging through the full menu mid-game, a single click lets you correct shadow visibility, tweak chosen parameters or simply check the display's current mode. All of this makes the LG B6 a great choice for gamers.