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 deliver a noticeably more appealing picture than in SDR. However, it’s not a level that dazzles by brightness alone. The A400 Pro is not one of those TVs that bombard the viewer with a powerful flash in every dramatic scene. The biggest limitation is visible with small bright elements on a dark background. Because of fairly aggressive zone control, 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. It should be added, though, that this isn’t done without reason. The A400 Pro does this to keep black levels as deep as possible and to limit the halo effect around bright objects. It’s a deliberate compromise: the TV more often opts for deeper blacks rather than maximising point highlights. On the one hand this is understandable, especially given a 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, delivers suitably saturated colours. Our measurements showed about 94% coverage of the DCI-P3 gamut and around 74% of BT.2020, which is a solid result for this class.

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.

As usual, we carried out colour measurements in the best‑tuned picture mode, Filmmaker Mode, the one intended to be closest to the creators’ intentions. The A400 Pro, of course, also offers other picture modes, but in practice they show much larger colour errors and interfere more with the image character. So we won’t cover them in detail in this part of the review. How does the factory colour reproduction fare? In short: really very well. In fact, looking at our measurements, it’s excellent. Both the white balance and the luminance response were set surprisingly precisely. The errors were so small that during the measurements we genuinely rubbed our eyes in surprise. Such good factory settings don’t happen often, even in televisions running Filmmaker Mode. All the more reason to praise TCL, because the A400 Pro straight out of the box can produce an image very close to how the source material should look. The results were so good you could easily think someone had already given this unit extra attention and tried to calibrate it. Our one bit of nitpicking comes down to a single issue. In SDR material the image was slightly brighter than the reference for a dark room, because the factory gamma was set closer to 2.3 than 2.4. It’s not a large error and most viewers probably won’t even notice it. We should note, however, that we are talking about our specific test unit. There can always be some variation in factory colour between individual units, production batches or screen sizes. We do not assume 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 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.

Despite the outstanding factory tuning, we couldn't resist checking how the TCL A400 Pro would respond to professional calibration. With such a strong starting point, we were especially curious whether we could squeeze even more from this TV. And here we have to boast: we managed to bring our sample to absurdly low colour errors. Results below 1 are something you don't see every day, even on very good TVs. Such outcomes are more often 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 after calibration simply excelled. The only thing we can pick on after closer analysis concerns the brightness response. The TV can vary the luminance level depending on the content being displayed, and quite often the picture is a little darker than it should be according to the reference. This most likely stems from the way the Mini-LED backlight and the local dimming algorithms work in this model. That said, it doesn't ruin the overall impression, because in terms of colour precision the A400 Pro after calibration reached a level that was genuinely hard to expect.

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 is unfortunately one of the weaker points of the TCL A400 Pro. That does not mean the TV performs badly, but it’s hard to call it anything clearly above standard. The upscaling itself is acceptable: edges are fairly well smoothed, the picture does not look overly sharp or “pixelated”, and lower-quality material can be watched without major discomfort. At the same time the overall image has a slightly soft character and you don’t see the kind of precision that the best image processors in more expensive TVs can offer.

Handling of tonal transitions caused by heavy compression is much worse. TCL equipped the A400 Pro with a “Gradual Smoothing” feature that in theory should reduce visible colour banding and artefacts in lower-quality material. In practice, however, its effectiveness is very limited. It does not improve tonal transitions in any noticeable way, and at higher settings it can further smooth image detail, giving it an artificial, slightly blurred character. For that reason we think it’s best to leave this feature off. The A400 Pro copes decently with basic image scaling, but if you often watch heavily compressed material with visible posterisation, this model will not be one of the best choices.

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.

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 most consoles, as well as many sports broadcasts and high-motion sources, are limited to today. In that range the TV performs quite well. Motion clarity is really good, especially after properly configuring the motion smoothing. The 'Motion Clarity' function improves smoothness. Its settings include two sliders that let you tailor the motion smoothing to your preferences, separately for low-frame-rate and high-frame-rate content. This allows you to achieve either a more cinematic look or a noticeably smoother image. If you don't want to fiddle with manual configuration, you can use built-in presets such as Low, Medium, High, Cinema or Nature.

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.

In terms of gaming features the TCL A400 Pro performs brilliantly. The TV has practically everything you’d 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‑gen consoles and PCs. Another plus is the inclusion of a Game Bar, a dedicated 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 customise the appearance and behaviour of some settings to your preferences. It’s 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 criticise 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 serves as eARC. In practice this means that if you want to connect two next‑gen consoles and a soundbar you may run into some limitations. In that scenario you’ll need to either swap devices or use extra equipment, such as an AV receiver or a soundbar with HDMI inputs. Even so, it’s hard not to rate the A400 Pro very highly as a gaming TV. The gaming feature set here is genuinely powerful.

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.