Samsung S90H (QD-OLED) vs LG OLED C6H (TANDEM OLED)

The Samsung S90H is a genuinely bright TV for the mid-range OLED segment. In synthetic tests its peak brightness reached around 1650 nits. That’s an impressive result in this class, roughly 50% higher than what we have seen from previous models in this price bracket. Most importantly, these tests translate directly to real video material. In four out of five film clips we tested, the S90H’s brightness ranged between 1300 and 1500 nits. That headroom allows it to reproduce most HDR films with very high dynamic range and without obvious compromises, especially in material mastered to 1000–1500 nits. In practice light effects, reflections and explosions have the appropriate punch, and the picture does not appear dimmed. Of course, on full-screen very bright scenes the result is naturally lower and drops to around 900 nits. This is a direct result of the OLED panel’s protection systems working to prevent overload. Even in this scenario there is little to complain about. Those 900 nits across the whole screen is still a very high level, ensuring excellent dynamic range in HDR content.

Colour has always been a major strength of QD-OLED TVs, and the S90H is no exception. The DCI-P3 colour space we measured reached a full 100% (actually 99.9%), while coverage of the much wider BT.2020 gamut hit about 89%. That’s an excellent result, enabling very saturated and vivid colours in HDR content. It’s worth emphasising that QD-OLED’s advantage over WOLED panels is not limited to palette coverage alone. In practice it’s mainly visible in the higher brightness of saturated colours, that is in a greater colour volume. As a result, intense reds, greens and blues in HDR look more vibrant and more striking.

And it is with HDR that the Tandem OLED panel shows its greatest advantage. The C6H’s brightness is simply very high and in our measurements it hovered around 1900–2300 nits in most film scenes. That’s already a level at which bright highlights, the sun or small light sources can look truly spectacular. The biggest impression, however, was made by the fifth scene from the film The Meg. It is exceptionally demanding for OLEDs because almost the entire screen is very bright. Even so, the C6H reached about 1650 nits in that scene. By comparison, the regular C6 with a classic WOLED panel recorded around 600–700 nits at the same point. So we’re talking about more than double the brightness, and in places the difference even approaches three times. And that is probably the best example of what Tandem OLED delivers here. It’s not just a higher result on a small test patch. The C6H can maintain very high brightness even when much more of the screen is lit. As a result HDR has significantly greater dynamism, and in this respect the C6H is much closer to flagship OLEDs than to typical mid-range models.

Colours

Tandem OLED also brings an improvement in colours. DCI-P3 coverage remains practically complete at about 99%, while in the much wider BT.2020 colour space we measured around 82–83%. That’s roughly seven percentage points more than the regular C6. In everyday use this won’t be a difference visible in every scene, because most films do not use such a wide gamut. However, when very highly saturated colours appear, the C6H already has noticeably greater capability, especially in reds. Reds benefit the most, becoming deeper and more saturated. This still isn’t at the level of the best QD-OLED panels or SQD TVs, but for a WOLED panel the performance is really very good.

The next stage of the test was to check how the S90H handles colour reproduction without any calibration. As always, we carried out the measurements in Filmmaker Mode, the best factory picture preset. And here Samsung really deserves praise. The factory tuning is at a very high level, and a few years ago this was not one of its strong points. The average colour error (Delta E) remained around 3, which is below the level at which most people can notice any inaccuracies. Only in the brightest shades of grey did the values slightly approach 4, but even then it's hard to regard this as a real problem while watching. For out-of-the-box settings, the result is simply excellent.

Straight out of the box the LG C6 is fairly well set up, especially if you select the Filmmaker mode. In SDR content the white balance is decent, although as brightness increases it shows a slight deficiency in red. The image therefore becomes a little cooler, but not enough for the difference to be very noticeable during normal viewing. More is happening in the brightness response. Gamma is a bit low and, instead of holding at 2.4, it sits closer to 2.1–2.2 across much of the range. In practice the C6 slightly brightens midtones. Shadow detail is therefore more readable, but the picture loses some depth compared with how it should look in a darkened room.

In HDR the situation is a bit more interesting. The lower end of the greyscale performs very well, but from roughly 20–30% brightness the white balance starts to drift increasingly. As brightness rises there is more red, while blue becomes noticeably deficient. In the brightest scenes the difference is already substantial and also affects the reproduction of some colours. The EOTF itself is, however, fairly well tracked across most of the range. The C6 merely tends to slightly brighten the image, which we already saw in our film comparisons. The largest deviation appears in the very brightest areas, where the TV begins to adapt the signal to the panel’s capabilities.

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

All right, but you know we wouldn't be ourselves if we didn't also check how far we could push the S90H after professional calibration. And there was no big surprise. Since the factory settings were already very good, there wasn't much room for improvement. Even so, we managed to refine the picture to near perfection. After calibration the mean colour reproduction errors fell below the threshold of perception, with Delta E values under 2 for both SDR and HDR material. We also improved the brightness response, so the image more faithfully reflects the creators' intent and maintains appropriate tonality across the whole luminance range. After professional calibration the S90H therefore becomes a display very close to reference.

Will the difference be spectacular for everyone? Not necessarily. The factory settings already deliver a very high level, so in everyday viewing some people may not notice a dramatic jump. Much also depends on the individual unit. Our sample was very well tuned straight out of the box, but that doesn't mean every S90H will perform at the same level. Even identical models can differ from each other in terms of factory calibration. That's exactly why professional calibration makes sense: it allows a specific unit to be brought to the highest possible accuracy, rather than relying on a bit of luck when buying.

LG TVs have long been very receptive to calibration and the C6 is no exception. After adjustment the white balance could be set almost perfectly, and most colour errors fell below 3, often even down to around 2. In practice this means very accurate colour reproduction in both SDR and HDR. An interesting detail only emerged when we looked at the HDR luminance response. On a classic EOTF plot everything looks almost ideal and at first glance it would be hard to find fault. Only when we measured the TV's behaviour on filters based on real film scenes did it become apparent that the C6 has a slight tendency to artificially boost image brightness.

It is not a huge difference and many people may even welcome it because HDR looks a bit more striking as a result. From the point of view of fidelity to the source material this is not ideal behaviour though – some scenes are simply a touch brighter than the filmmaker intended. Interestingly, this is rather unusual for LG. In previous generations the brand's TVs typically stuck closely to the reference picture characteristic after calibration. With the C6 we are still very close to the standard, but this subtle brightness 'boost' can indeed be noticed in films and series.

In this respect Samsung has changed practically nothing compared with last year’s model, which is actually quite good news. The feature responsible for smoothing tonal transitions still very effectively limits the posterisation effect. However, you should remember that it works rather aggressively, because besides the artefacts themselves it can also remove film grain and slightly soften fine image detail. As always, this is therefore a matter of compromise and personal preference. If you want the most faithful reproduction of the source material possible, we recommend leaving this function turned off.

There is also little to be said about upscaling in terms of revolution. The S90H uses the same proprietary NQ4 Gen3 image processor as its predecessor, so scaling quality has remained practically unchanged. The TV handles lower-resolution material well, effectively improving its sharpness. However, the overscan problem has still not been solved. With some older material, especially archival recordings, it may happen that a portion of the image at the edges is cropped. It’s a minor flaw, but a shame Samsung has left this issue unchanged for another year running.

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 considerable plus, because this year's LG processor excels in that area. The "Smooth Gradation" function works particularly well. With heavily compressed footage it can effectively hide ugly banding and artefacts that often occur, for instance in lower-quality streaming. It's best to leave it on the "Low" setting. Then the improvement is noticeable, while the TV does not yet start to blur fine detail. Higher levels smooth the picture more, but can already remove some of the natural texture of objects on screen. Upscaling itself also performs very well. Lower-resolution material is sharpened correctly, edges look clean, and the processor quite effectively reconstructs fine detail. In this respect the C6 is already very close to LG's best TVs and the differences compared with the G6 are small.

In terms of motion handling the S90H delivers a very high level. A new feature here is a panel with a refresh rate of up to 165 Hz, although in practice that will mainly benefit PC gamers. Films, series and sports broadcasts do not use such high refresh rates, so when watching them the difference compared with the standard 120 Hz will not be noticeable. That said, thanks to the OLED panel's lightning-fast response time motion is very clean and the picture does not suffer from the motion blur typical of many LCDs. Samsung has equipped the television with extensive motion-smoothness settings. You get two sliders: judder reduction and blur reduction, which let you easily tailor the picture's character to your own preferences. You can easily achieve a very smooth image when watching sport, but you can just as well preserve a more cinematic feel at the typical 24 frames per second. It all depends on which effect you prefer.

The C6H with a Tandem OLED panel can also operate at refresh rates of up to 165 Hz. PC gamers will naturally get the most out of this, because for consoles, films or sport we're still looking at a maximum of 120 Hz. The panel itself is excellent when it comes to motion. OLED pixels respond virtually instantly, so even with fast-moving objects you don't see the typical motion blur. The picture remains clean whether you're watching sport or playing 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 helps reduce the judder that's characteristic of them. De-Blur, meanwhile, is intended for 50/60 fps content, so it's particularly useful when watching sport or television.

From the outset the Samsung S90H feels like a TV designed with gamers in mind, and it's easy to see why. The manufacturer has equipped it with almost everything you could expect from a modern gaming screen. You get as many as four full-bandwidth HDMI 2.1 ports, support for ALLM and VRR, and very high refresh rates. There's also a clear Game Bar that lets you instantly check key picture parameters or change settings without leaving the game. Another very welcome improvement is the HGiG behaviour. Last year it could cause quite a few problems, but on the S90H it works exactly as it should.

Samsung's ace up its sleeve remains its proprietary Game Motion Plus mode. The feature works similarly to the motion smoothing used for films: it improves animation smoothness in games while keeping input lag at a very reasonable level. For titles running at 30 or 60 fps, with the right settings input lag did not exceed 40 ms in our tests. That's a very good result, especially since with many manufacturers enabling similar features results in delays several times higher. Game Motion Plus does not, of course, replace Dolby Vision Gaming, as it's a completely different type of feature, but overall it's a gaming addition that many players may find more noticeable. Smoother motion in 30/60 fps games often makes a bigger difference than HDR itself (which, incidentally, is often poorly implemented in games).

The C6H offers practically the full suite of gaming features. 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 proper implementation of HGiG. Dolby Vision is also available in game mode, which remains a major advantage for Xbox owners. All key information can be viewed in the Game Bar, which provides quick access to VRR settings and the current signal’s parameters. The OLED implementation therefore does not alter the feature set available to gamers, but with such high panel brightness HDR games can make an even stronger impression. Functionally, the C6H is simply a very complete TV for console and PC gaming.