TCL A400 PRO vs LG OLED B6

The TCL A400 Pro is a moderately bright TV. Its peak brightness reaches around 600 nits. That level already allows for a real HDR effect, and in many films it does produce a noticeably more attractive picture than in SDR. However, it is not a level that overwhelms with sheer brightness. The A400 Pro therefore isn’t one of those TVs that ‘attack’ the viewer with a powerful flash in every eye-catching scene. The biggest limitation is seen with small bright elements on a dark background. Because of fairly aggressive local dimming control, the TV can significantly reduce their brightness, in extreme cases even to around 100 nits. This means that small lights, sparks, stars or individual highlights can be much less visible than they should be. It’s worth adding, however, that this isn’t without reason. The A400 Pro does this to maintain as deep a black level as possible and to limit the halo effect around bright objects. So it’s an intentional compromise: the TV more often opts for deeper blacks rather than maximally bright, point-like highlights. On one hand this can be understood, especially given the limited number of dimming zones, but on the other you should be aware that the HDR effect won’t always be as strong as the peak brightness alone might suggest.

On the plus side, the colours are a strength. The PFS LED filter used here, marketed by the manufacturer as QLED, allows for suitably saturated colours. Coverage of the DCI-P3 gamut measured around 94%, and BT.2020 around 74%, which is a solid result for this class.

The 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 the new, budget OLED SE panel from LG Display. In practice it simply gives a bit more headroom and makes HDR look fuller in many scenes than on last year’s lower‑end OLEDs. That does not mean the B6 has no limitations. In very bright shots, when a large part of the screen is strongly lit, brightness can fall below 400 nits. This behaviour is typical for OLED TVs, especially in this segment, and that’s where you see the biggest difference compared with more expensive models. Even so, we judge the B6’s results as genuinely solid. It’s still not a TV for breaking brightness records, but the HDR effect is strong enough that films truly feel like a step up from ordinary SDR. Colour gamut Using the OLED SE panel has had a slight impact on wide colour gamut coverage. Compared with last year’s model the results have fallen by a few percentage points. It covers roughly 96% of DCI‑P3 and about 71% of BT.2020. That doesn’t mean the colours on the LG B6 are weak. In most films and series they look lively, 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 stems from the WOLED panel structure. Besides red, green and blue subpixels it also uses a white subpixel, which helps to boost brightness. However, this comes at a price. At very high luminance some colour is effectively 'diluted' by the white light, so the saturation of certain colours can be slightly lower. In everyday use this isn’t a major issue, but in the most demanding scenes you can notice it.

As standard, we performed colour measurements in the best‑tuned Filmmaker Mode, the mode that is designed to be closest to the creators' intentions. The A400 Pro of course also offers other picture modes, but in practice these come with considerably larger colour errors and interfere more with the character of the image. Therefore we will not deal with them in detail in this part of the test. So how does the out‑of‑the‑box colour reproduction fare? In short: really very good. Actually, looking at our measurement results, downright excellent. Both the white balance and the luminance response were set surprisingly precisely. The errors were so small that during measurements we genuinely rubbed our eyes in amazement. Such good factory settings do not happen often, even in TVs operating in Filmmaker Mode. All the more credit is due to TCL, because the A400 Pro right out of the box can deliver an image very close to how the source material should look. The results were so good that one could easily think someone had already given this unit extra attention and tried to calibrate it.

Our nitpicking really comes down to just one thing. In SDR content the image was slightly brighter than the dark‑room reference intends, because the factory gamma was set closer to 2.3 than to 2.4. This is not a large error and most viewers will probably not even notice it.

It should, however, be noted that we are talking about our specific test sample. With factory colours there can always be some variation between units, production batches or screen sizes. We do not assume, therefore, that every A400 Pro will look identical straight out of the box.

We tested the LG B6 in Filmmaker Mode, the best picture setting available straight out of the box. ISF modes produce very similar results, but in our tests we always stick to Filmmaker Mode for better comparison with other TVs. Each of them is, in any case, a much better starting point than Vivid or Eco mode, where the picture is heavily boosted and noticeably less natural. On SDR material the factory settings perform really well. Colour errors are small, the gamma response is correct, and the picture during normal viewing looks natural and does not feel overly "pumped up". It's a bit worse with HDR. When such content is played you quickly see that the white balance hasn't been set perfectly. Too much blue and red gives the image a slightly pink tint. This is also confirmed by colour gamut measurements and the ColorChecker, where samples clearly shift in that direction. It's not a flaw that completely spoils the picture, but it is noticeable with HDR films. Therefore anyone who wants the most faithful image should consider calibration, which we cover further on in the review.

Despite its superb factory calibration, we couldn't resist checking how the TCL A400 Pro would respond to professional calibration. Since the starting point was so good, we were all the more curious whether there was anything more to be had from the TV. And here we must boast: we managed to reduce our unit's colour errors to absurdly low levels. Measurements below a value of 1 are not something you see every day, even in very good TVs. Such results are more commonly associated with professional reference monitors than with a lifestyle TV for the living room. In terms of white balance and colour reproduction the A400 Pro therefore simply performed exceptionally well after calibration. The only gripe we have after closer analysis relates to the luminance behaviour. The TV adjusts luminance depending on the content being displayed and quite often the picture is slightly darker than the reference calls for. This is most likely due to the way the Mini-LED backlight and local dimming algorithms operate in this model. However, this does not spoil the overall impression, because in terms of colour accuracy alone the calibrated A400 Pro showed a level that was really hard to expect.

During calibration, we concentrated mainly on HDR content, because that's where the factory settings needed the most correction. We did not, however, neglect SDR mode, which after adjustment was brought almost to perfection. Colours are very accurate, and brightness is controlled as it should be. The biggest improvement in HDR came from fixing the white balance. Removing the excess red and blue eliminated the pinkish tint, and the image became much more natural. Skin tones, whites and all colours that had previously shifted towards pink 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. So the LG B6 can deliver a very accurate picture, particularly for the manufacturer's entry-level OLED model.

Digital image processing is, unfortunately, one of the weaker points of the TCL A400 Pro. That does not mean the TV performs badly, but it is hard to call it anything clearly above average. The upscaling itself is adequate: edges are smoothed fairly well, the picture does not look overly sharp or "pixelated", and lower-quality content can be watched without much discomfort. At the same time, the overall image is slightly soft and lacks the precision offered by the best image processors in more expensive TVs.

Much worse, however, is how it handles tonal transitions caused by strong signal compression. TCL has equipped the A400 Pro with a "Gradual Smoothing" feature that, in theory, should limit visible colour banding and artifacts in lower-quality material. In practice, though, 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 is best to leave this feature off. The A400 Pro copes decently with basic image scaling, but if you often watch heavily compressed content with noticeable posterisation, this model will not be among the best choices.

The LG B6 handles lower-quality material very well. This is largely thanks to effective digital image processing, which can mask some of the source’s imperfections without overly smoothing the whole scene. The "Smooth Gradation" function proves particularly useful. It noticeably reduces posterisation, especially in dark parts of the image. The safest choice remains the Low or Medium setting. The function still effectively smooths out unsightly tonal banding, but does not yet interfere too much with fine details. Purists can of course leave it switched off. Upscaling to 4K also performs very well. Full HD and 720p material retain a good amount of detail, and the image is neither overly sharpened nor heavily blurred. Some limitations only become apparent with very poor sources below 720p, where the smallest text and fine elements are not always perfectly sharp, but this applies to almost every other TV on the market.

The TCL A400 Pro is equipped with a 144 Hz panel, but in practice we are most interested in its behaviour at 120 Hz. That is the frequency most consoles are limited to today, as well as many sports broadcasts and high-frame-rate content. At that rate the TV performs quite well. The sharpness of moving objects is really good, especially after properly configuring the motion smoothing. The "Motion Clarity" function is responsible for improving smoothness. Its settings include two sliders that let you tailor how the motion smoothing operates to your preferences, separately for lower and higher frame-rate material. This makes it possible to achieve both a more cinematic look and a noticeably smoother picture. Those who do not want to fiddle with manual configuration can use presets such as low, medium, high, cinema or nature.

One of the biggest advantages of OLED panels is the very fast pixel response time. This keeps the picture sharp and free of the visible smearing often seen on LCD TVs. However, there is a downside. During slow camera pans motion can look choppier than on LCD screens, where some of that effect is naturally masked by the slower panel. Fortunately, on the LG B6 this can be easily mitigated using the TruMotion system. With the motion smoothing set correctly you can achieve smoother motion without giving the picture an exaggerated soap opera effect.

In terms of features for gamers the TCL A400 Pro performs brilliantly. The TV has practically everything you can expect from a gaming TV today: support for 4K at high refresh rates, VRR, ALLM, correct implementation of HDR formats in games including Dolby Vision, and HGiG. That means it works well with both next-generation consoles and a PC. Another plus is the presence of the Game Bar, a special panel with the most important settings for gamers. From it you can quickly check basic information about the signal, refresh rate or active features, and also adjust the appearance and behaviour of some settings to suit your preferences. This solution 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 connectors out of the four available, and one of them also serves as eARC. In practice this means that if someone wants to connect two next-generation consoles and a soundbar, they may run into some limitations. In that scenario you will have to either swap devices or use additional equipment, such as an AV receiver or a soundbar with HDMI inputs. Even so, it is hard not to rate the A400 Pro very highly as a TV for gamers. The gaming feature set here is truly powerful.

LG OLED B6 has plenty to offer gamers; it’s simply a complete base for PS5, Xbox Series X/S or a capable PC. It has four full-size HDMI 2.1 ports with 48 Gbps bandwidth, so you can avoid irritating cable swapping when connecting several newer devices at once. It offers a full suite of synchronization technologies, from standard VRR to G-Sync and FreeSync. The screen synchronises the refresh rate seamlessly with the frame output from the console or graphics card. Of course it includes ALLM: the B6 automatically recognises when a game is running and immediately reduces latency to a minimum. HDR support is also excellent. The TV supports Dolby Vision, and a correctly implemented HGiG standard means that, after initial calibration in the console settings, the image won’t suffer from blown-out highlights or lost detail in bright areas. The cherry on the cake is the Game Bar. Instead of digging through the full menu during gameplay, a single click is enough to adjust shadow visibility, tweak selected parameters or simply check the current display mode. All of this makes the LG B6 an excellent choice for gamers.