LG OLED C6H (TANDEM OLED) vs Hisense U7S / U77SE

And the biggest advantage of the Tandem OLED panel is most obvious with HDR. The C6H's brightness is simply very high and, in our measurements across most film scenes, hovered around 1,900 to 2,300 nits. That's the kind of level at which bright highlights, the sun or small light sources can look truly spectacular. The scene that impressed us most was the fifth scene from the film The Meg. It's particularly demanding for OLEDs because almost the entire screen is extremely bright. Even so, the C6H reached about 1,650 nits in that scene. By comparison, the standard C6 with a classic WOLED panel managed roughly 600 to 700 nits at the same point. So we're talking about more than double the brightness, and in places the difference approaches three times as much. And that's probably the best example of what Tandem OLED delivers. It's not just a higher score on a small test window. The C6H can maintain very high brightness even when much more of the screen is illuminated. That gives HDR a much wider dynamic range, and in this respect the C6H is considerably closer to flagship OLEDs than to typical mid-range models.

Colours

Tandem OLED also brings improvements in colour. DCI-P3 coverage remains virtually complete at around 99%, while in the much wider BT.2020 colour space we measured about 82–83%. That's roughly 7 percentage points more than the standard C6. In everyday viewing this won't be a difference you notice in every scene, because most films don't use such a wide palette. However, when very highly saturated colours appear, the C6H has noticeably greater capability, especially with reds. Reds benefit the most, becoming deeper and more saturated. It's still not at the level of the best QD-OLED panels or SQD TVs, but for a WOLED panel the result is really very good.

The Hisense U7S has considerable HDR potential, but it can’t make full use of it in every scene. On a test pattern it reaches about 1100 nits, so the backlight is genuinely strong. In our brighter film scenes we measured around 640 to 745 nits. That’s still enough for the sun or bright highlights to have a distinct bloom and to show an advantage over SDR material. When the TV needs to light a larger portion of the image, it handles it quite well.

The problem appears with small lights on a dark background. Each of the 192 zones covers an area considerably larger than a tiny point on the screen. If the TV were to drive such a zone strongly, it would brighten the surrounding area along with the light. Hisense tries to avoid that and dims the whole zone. Blacks look better as a result, but a small bright object that should draw the eye also loses intensity. That’s why in two tougher scenes we recorded only 297 and 154 nits. The difference is large: in one shot HDR can impress, and in the next small highlights are noticeably muted. The U7S therefore prioritises keeping deep blacks, even at the expense of bright details. With this number of zones it’s an understandable compromise, but it’s worth remembering that the peak 1100 nits tells us about the backlight’s capability, not how brightly the TV will show every element of a film.

Colours

Hisense markets the U7S as ULED, but that’s a marketing name; the wider colour gamut here is achieved by a PFS phosphor backlight. In our measurements the TV covered about 91% of the DCI-P3 space and 71% of BT.2020. Those are good results, though a little short of the best screens on the market. The biggest shortfall is in green — the TV doesn’t even reach the DCI-P3 boundary there, so the most intense green hues will be less saturated than they should be. Most colours in HDR films and series still look suitably vivid, however. A positive is the repeatability of the results: gamut coverage on test patterns and in film scenes is practically identical.

Right out of the box the LG C6 is pretty well set up, especially if you select Filmmaker mode. In SDR content the white balance is good, although as brightness increases it starts to lack red slightly. This makes the picture a bit cooler, but not enough to be very noticeable during normal viewing. More is going on in the luminance response. Gamma is a bit low and instead of holding at 2.4 it sits closer to 2.1–2.2 across a large part of the range. In practice the C6 slightly brightens midtones. Shadows are therefore more readable, but the image loses a little depth compared with how it should look in a dark room.

In HDR the situation is a bit more interesting. The start of the grayscale looks very good, but from around 20–30% brightness the white balance starts to drift more strongly. As brightness increases red builds up and blue becomes noticeably lacking. In the brightest parts the difference is already significant and also affects the reproduction of some colours. The EOTF curve itself is handled quite well across most of the range. The C6 only has a tendency to slightly brighten the picture, which we've already seen in our film comparisons. The biggest deviation appears around the brightest sections where the TV starts to adapt the signal to the panel's capabilities.

So the factory Filmmaker setting in HDR is not perfect, but overall performs well. The biggest room for improvement is the white balance, especially at high brightness.

Factory colours on the Hisense U7S are decent, but there are a few things to fix. In SDR the white balance favours red, so the image looks too warm, in places with a slightly pink tint. You can see this on faces and bright, neutral surfaces. Gamma also runs below the target, so the TV brightens the image, especially in darker areas. That makes it easier to see shadow detail, but the scene loses some of its depth.

In HDR the white balance is a bit more even, but not completely neutral, with midtones lacking blue and the brightest parts lacking red. A bigger problem is the way brightness is reproduced. The EOTF curve shows that a large portion of the midtones is boosted, making the image appear brighter than the source material intends. Color Checker measurements also fare worse than in SDR: many errors are around 3 to 4, and individual ones reach as high as 8. Colours can therefore look attractive, but they're not always faithful to what we should be seeing. There’s room for improvement and we’ll see how much can be corrected with calibration.

LG TVs have long responded very well to calibration, and the C6 is no exception. After adjustment, the white balance was set almost perfectly, and most colour errors fell to values below 3, often around 2. In practice this means very accurate colour reproduction in both SDR and HDR. An interesting detail only showed up with the HDR luminance response. On a classic EOTF chart everything looks almost perfect and at first glance it would be hard to fault. Only when we measured the TV’s behaviour using filters based on real film scenes did it emerge that the C6 has a slight tendency to artificially boost image brightness.

It isn’t a huge difference and many people may even see it as a positive, since HDR looks a bit more punchy. From the point of view of fidelity to the source material it’s not ideal, though — some scenes are simply a touch brighter than the filmmaker intended. Interestingly, this is quite atypical for LG. In previous generations, this brand’s TVs usually stuck very closely to the reference picture characteristics after calibration. With the C6 we’re still very close to the standard, but that subtle boost in brightness can indeed be noticed in movies and TV shows.

Calibrating the Hisense U7S did the most for SDR content. We managed to even out the white balance, so the earlier warm tint is gone and whites and greys look neutral. Gamma now sits very close to the reference, so the TV no longer brightens the image unnecessarily and darker scenes have regained depth. Color Checker measurements confirm the improvement: most errors are below 2. For watching regular TV and SDR films, this delivers a really well calibrated picture. Calibration in HDR wasn’t as smooth. The TV lacks an effective way to correct the EOTF curve, so Hisense still interprets the film’s brightness a bit on its own. It brightens parts of the image and, depending on the scene and local dimming, can tone down the brightest elements. That couldn’t be eliminated by calibration. This also shows up in the Color Checker results, where many errors remain around 3–4 and some exceed 7. In SDR the result is therefore very good, but in HDR we have to accept that the TV adds its own interpretation of brightness to the image.

Here the LG C6 has taken a really big step forward. The TV uses the same processor found in the flagship G6, and in terms of image processing the two models are very similar. That's a big plus, because in this area LG's processor this year performs excellently. The 'Smooth Gradation' function works especially well. With heavily compressed material it can effectively hide unsightly tonal banding and artefacts that often appear, for example, in lower-quality streaming. It's best left on the 'Low' setting. That way the improvement is clear, and the TV doesn't yet start to blur fine details. Higher levels smooth the picture more, but can begin to remove some of the natural texture of objects on screen. Upscaling itself also performs very well. Lower-resolution content is properly sharpened, edges look clean, and the processor quite effectively reconstructs fine details. In this respect the C6 is already really close to LG's top TVs and the differences compared with the G6 are small.

The processing of lower-quality material in the Hisense U7S is fairly average. The Pentonic 700 chipset used here doesn't cope particularly well with the effects of heavy compression. There's a "Smooth and Gradient Picture" function in the menu, but its performance leaves a lot to be desired. At the low setting it's hard to see any improvement in tonal transitions, though at least the picture doesn't suffer. Medium and high settings still don't remove visible banding between tones and begin to blur details; in our clips parts of characters' faces even vanished. Interestingly, film grain remains untouched at every level. If you do use this function, stick to the low setting. Its current performance needs refinement, but that's mainly down to the processor used here.

Upscaling to 4K performs much better. Lower-resolution content gains clarity, edges are well reproduced and fine details look sharp. That doesn't mean the TV can recover details that weren't in the recording, but it makes good use of what's provided by the source. Another plus is the lack of edge cropping, even with an SD signal.

The C6H with a Tandem OLED panel can also run at a refresh rate of up to 165 Hz. PC gamers will get the most out of that, of course, because with consoles, films or sport we're still looking at a maximum of 120 Hz. The panel itself performs excellently in motion. OLED pixels respond almost instantly, so even with fast-moving objects you don't see the usual trailing. The picture stays clean both when watching sport and in fast-paced games.

If you prioritise smoothness over motion clarity, TruMotion is available. LG lets you adjust two parameters separately. De-Judder mainly works with films and series shot at 24 fps and reduces their characteristic judder. De-Blur is intended for 50/60 fps content, so it's mainly useful when watching sport or TV.

Motion handling on the Hisense U7S is decent thanks to its 144 Hz refresh rate. For films there's also a motion smoothing option with adjustable judder and blur reduction. You can keep a more cinematic feel to motion or increase smoothness if choppy camera pans bother you. High refresh is also useful for sport and gaming, but unfortunately it doesn't solve the panel's biggest problem.

The issue is pixel response time. Fast-moving objects leave long, distinct trails, as our UFO test shows. It's worst on dark backgrounds, where the trail is particularly pronounced. So motion can be smooth, but the moving object loses sharpness, and that difference on the U7S is fairly easy to spot.

The C6H offers virtually a full gaming feature set. On consoles you can easily use 4K at 120 Hz, while PC users can push the refresh rate up to 165 Hz. The TV also supports VRR from 40 to 165 Hz, ALLM and a correct implementation of HGiG. Dolby Vision is available in game mode too, which remains a big plus for Xbox owners. All the key info can be seen in the Game Bar, which provides quick access to VRR settings and the current signal parameters. The tandem OLED doesn’t change the actual feature set for gamers, but with such high panel brightness HDR games can look even more impressive. Functionally, the C6H is simply a very complete TV for consoles and PC.

The Hisense U7S has plenty to offer gamers. You get two HDMI 2.1 ports and support for 120 Hz in Full HD, 1440p and 4K, so modern consoles’ capabilities are well utilised. When connected to a PC you can use 144 Hz at 4K or switch the resolution to Full HD and run 240 Hz. So there’s a lot of choice, although it’s worth remembering the motion smearing mentioned earlier, which the high refresh rate doesn’t eliminate. VRR and ALLM are present as well. VRR helps keep the picture tear-free when a game’s frame rate changes. ALLM automatically switches the TV into game mode, so you don’t have to go into the menu each time. VRR works from 48 to 240 Hz, with the highest refresh rate available in Full HD. Xbox users can also play in Dolby Vision at 120 Hz. Importantly, that format does not cause significant input lag here. The Game Bar also looks great. It’s clear and attractive, and lets you quickly check what signal the TV is receiving. Handy gaming settings are close to hand too, including shadow brightening. If it’s hard to spot an opponent in a dark game, you can improve visibility without digging through the whole menu.

Our biggest complaint is HGiG. Hisense keeps doing its own tone mapping, which makes setting up HDR on the console confusing. You adjust the checkerboard pattern, and the TV continually alters its appearance. As a result, the point at which the pattern disappears does not correctly indicate the display’s brightness limit, and it’s easy to set the value too high. For this model it’s better to set the target HDR brightness on the console to around 900 to 1000 nits, rather than rely on the configurator.