TCL A400 PRO vs LG OLED B6

The TCL A400 Pro is a moderately bright TV. Its peak brightness reaches about 600 nits. That level already allows for a real HDR effect and in many movies it does produce a noticeably more attractive picture than SDR. However, it is not a level that overwhelms by brightness alone. The A400 Pro is not one of those TVs that "attack" the viewer with a powerful flash in every dramatic scene. The biggest limitation is visible with small bright elements on a dark background. Due to rather aggressive control of the dimming zones, the TV can significantly reduce their brightness — in extreme cases down to around 100 nits. That means small lights, sparks, stars, or single highlights can be much less visible than they should be. That said, this is not done without reason. The A400 Pro does this to keep blacks as deep as possible and to limit haloing around bright objects. It's a deliberate compromise: the TV more often chooses deeper blacks over maximally bright, point-like highlights. On one hand this is understandable, especially with a limited number of dimming zones, but on the other hand you should be aware that the HDR effect will not always be as strong as the peak brightness alone would suggest.

On the plus side, the colors are worth noting. The PFS LED filter used here, marketed by the manufacturer as QLED, produces suitably saturated colors. Our measurements showed about 94% coverage of the DCI-P3 gamut and about 74% of BT.2020, which is a solid result for this class.

The LG B6 is a moderately bright OLED. After calibration it reaches about 800 nits, roughly 200 nits more than last year’s B5. That’s thanks to the new budget OLED SE panel from LG Display. In practice it simply gives a bit more headroom and makes HDR in many scenes look fuller than on last year’s lower-tier OLEDs. That doesn’t mean the B6 has no limits. In very bright shots, when a large part of the screen is strongly lit, brightness can drop below 400 nits. This behavior is typical for OLED TVs (especially those from this segment) and that’s when you see the biggest difference versus more expensive models. All things considered, we rate the B6’s results as really solid. It’s still not a TV for breaking brightness records, but the HDR effect is strong enough that you can really feel the step up from ordinary SDR in films.

Color gamut

Using the OLED SE panel has slightly affected wide color gamut coverage. Compared with last year’s model, results fell by a few percentage points. DCI-P3 reaches about 96%, and BT.2020 around 71%. That doesn’t mean the colors on the LG B6 are weak. In most movies and series they look lively, well saturated and simply pleasing to the eye. You only notice a difference in very bright, highly colorful scenes. Then colors lose some intensity compared with QD-OLED panels. This comes from the WOLED panel construction. Besides red, green and blue subpixels it also uses a white subpixel that helps boost brightness. It comes at a cost: at very high luminance some color is effectively “diluted” by the white light, so saturation of some colors can be slightly lower. In everyday use this isn’t a big issue, but you can notice it in the most demanding scenes.

As standard, we carried out color measurements in the best-calibrated mode, Filmmaker Mode, the one that is supposed to be closest to the creators’ intent. The A400 Pro, of course, also offers other picture modes, but in practice they suffer from much larger color errors and alter the image character more strongly. We won’t go into those modes in detail in this part of the test. So how does the factory color reproduction perform? In short: really very well. In fact, looking at our measurement results, it’s excellent. Both the white balance and the luminance response were set surprisingly precisely. The errors were so small that during testing we genuinely rubbed our eyes in disbelief. Such good out-of-the-box settings don’t happen often, even in TVs operating in Filmmaker Mode. All the more reason to praise TCL, because the A400 Pro right out of the box can produce an image very close to how the source material should look. The results were so good that you could easily think someone had already paid extra attention to that unit and tried to calibrate it.

Our nitpicking really comes down to just one thing. In SDR content the image was slightly brighter than the reference for a dark room, because the factory gamma was set closer to 2.3 than to 2.4. It’s not a big error and most viewers probably won’t even notice it.

However, it should be noted that we’re talking about our specific review sample. With factory colors there can always be some variation between units, production batches, or screen sizes. So we don’t assume that every A400 Pro will look identical straight out of the box.

We tested the LG B6 in Filmmaker Mode, which is the best picture setting available right out of the box. ISF modes deliver very similar results, but in our tests we always stick to Filmmaker Mode for better comparison with other TVs. Each of those modes is, after all, a much better starting point than Vivid or Eco mode, where the picture is heavily boosted and noticeably less natural. With SDR content, the factory settings perform really well. Color errors are small, gamma behaves properly, and the image looks natural during ordinary viewing and does not seem overly "pumped up." It's a bit worse with HDR. When you play that kind of content you can quickly see that the white balance hasn't been set perfectly. Too much blue and red causes the image to shift toward a slightly pink tint. This is also confirmed by measurements of the color gamut and the ColorChecker, where samples clearly drift in that direction. It's not a flaw that completely ruins the picture, but you can notice it in HDR films. So people who care about the most faithful image should consider the calibration we describe later in the review.

Despite its excellent factory tuning, we couldn't resist checking how the TCL A400 Pro would respond to a professional calibration. Since the starting point was so good, we were even more curious whether we could squeeze even more out of this TV. And here we have to boast: we managed to bring our unit to absurdly low color errors. Results below 1 are something you don't see every day, even on very good TVs. Such results are more often associated with professional reference monitors than with a lifestyle TV for the living room. In terms of white balance and color reproduction, the A400 Pro after calibration simply performed outstandingly. The only thing we can pick at after a deeper analysis concerns the brightness behavior. The TV can manipulate luminance levels depending on the content being displayed, and quite often the image is a bit darker than it should be according to the standard. This most likely stems from the way the Mini-LED backlight and local dimming algorithms work in this model. However, that doesn't spoil the overall impression, because in terms of color precision alone the A400 Pro after calibration reached a level we really didn't expect.

During calibration we focused primarily on HDR content, because that's where the factory settings required the biggest corrections. We didn't neglect SDR mode, though, which after adjustment was brought almost to perfection. Colors are very accurate and brightness is handled as it should be. The biggest improvement in HDR came from correcting the white balance. After removing the excess red and blue, the pinkish tint disappeared and the image became much more natural. Skin tones, whites and all colors that had been shifting toward magenta improved. After calibration most errors fell below a Delta E of 2–3, the threshold at which the average viewer stops noticing differences with the naked eye. The LG B6 can therefore deliver a very accurate image, especially for the manufacturer's entry-level OLED model.

Digital video processing is unfortunately one of the weaker points of the TCL A400 Pro. That doesn't mean the TV performs badly, but it's hard to call it anything clearly above standard. The upscaling itself is adequate: edges are smoothed fairly well, the image doesn't look overly sharp or pixelated, and lower-quality content can be watched without major discomfort. At the same time the overall look is slightly soft and it lacks the precision that the best image processors in more expensive TVs can deliver.

Much worse, however, is its handling of tonal transitions caused by heavy compression. TCL equipped the A400 Pro with a "Gradual Smoothing" feature that in theory should reduce visible color banding and artifacts in lower-quality content. In practice its effectiveness is very limited. It does not improve tonal transitions in any noticeable way, and at higher settings it can also smooth out image details, giving the picture an artificial, slightly blurred character. For that reason we think it's best to leave this feature off. The A400 Pro handles basic image scaling decently, but if you often watch heavily compressed content with visible posterization, this model won't be one of the best choices.

The LG B6 handles lower-quality sources very well. Much of the credit goes to effective digital image processing, which can mask some source imperfections without overly smoothing the whole scene. The feature "Smooth Gradation" proves particularly useful. It can significantly reduce posterization, which we mentioned earlier, especially in darker areas of the image. The safest choice remains Low or Medium. The function still effectively smooths harsh tonal transitions, but does not yet interfere too much with fine details. The most dedicated purists can, of course, leave it off. Upscaling to 4K also performs very well. Full HD and 720p content retain a good amount of detail, and the image is neither overly sharpened nor excessively blurred. Some limitations become noticeable only with very poor sources below 720p, where the smallest subtitles and fine elements are not always perfectly sharp, but this is true for almost every other TV on the market.

The TCL A400 Pro is equipped with a 144 Hz panel, but in practice we're most interested in how it performs at 120 Hz. That's the refresh rate used by most consoles today, as well as many sports broadcasts and high-frame-rate content. In this range the TV performs quite well. Motion clarity is really good, especially after properly configuring the motion smoothing. The "Motion Clarity" feature improves smoothness. Its settings include two sliders that let you tailor the motion smoothing to your preferences — separately for lower- and higher-frame-rate material. That way you can achieve either a more cinematic look or a noticeably smoother picture. If you don't want to tweak settings manually, you can use presets such as low, medium, high, cinema, or nature.

One of the biggest advantages of OLED panels is their very fast pixel response time. This keeps the image sharp and prevents the visible smearing that often appears on LCD TVs. However, there is a downside. During slow camera pans, motion can look more choppy than on LCD screens, where the slower panel naturally masks some of that effect. Fortunately, on the LG B6 you can easily soften this with TruMotion. With the motion smoothing properly adjusted, you can achieve smoother motion without giving the picture an excessive soap-opera effect.

When it comes to features for gamers, the TCL A400 Pro performs excellently. The TV has practically everything you can expect from a gaming TV today: 4K support at high refresh rates, VRR, ALLM, correct implementation of HDR formats in games, including Dolby Vision, and HGiG. Because of that it works well with both next-gen consoles and PCs. Another plus is the inclusion of a Game Bar, a special panel with the most important settings for gamers. From it you can quickly check basic signal information, refresh rate, and active features, and also adjust the look and behavior of some settings to your own preferences. This is a solution that may not change picture quality by itself, but it greatly improves the convenience of using the TV while gaming.

The only thing to complain about is the number of full HDMI 2.1 ports. The A400 Pro has only two such ports out of four, and one of them also functions as eARC. In practice this means that if someone wants to connect two next-gen consoles and a soundbar, they may hit some limitations. In that scenario you'll have to either swap devices or use extra equipment, for example an AV receiver or a soundbar with HDMI inputs. Despite this, it's hard not to rate the A400 Pro very highly as a gaming TV. The gaming feature set here is really powerful.

LG OLED B6 offers a powerful set of advantages for gamers; it's simply a complete platform for PS5, Xbox Series X/S, or a solid PC. It has four full-size HDMI 2.1 ports with 48 Gbps bandwidth, so you can skip the annoying cable swapping when you want to connect several newer devices at once. We get the full suite of sync technologies – from classic VRR to G-Sync and FreeSync. The screen seamlessly matches the refresh rate to the frame output produced by the console or graphics card. Of course ALLM is included: the B6 automatically detects a running game and immediately cuts input lag to a minimum. HDR handling is also excellent. The TV supports Dolby Vision, and a properly implemented HGiG standard means that after an initial calibration in the console settings the picture won’t suffer from blown-out highlights or lost detail in bright areas. The cherry on top is the Game Bar. Instead of digging through the full menu during gameplay, one click lets you adjust shadow visibility, tweak selected settings, or simply check the display’s current operating mode. All of this makes the LG B6 a great choice for gamers.