LG OLED C6H (TANDEM OLED) vs TCL P7L / P79L

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 biggest limitation of the TCL P7L in HDR is simply brightness. The TV does not have much luminance headroom, so strong highlights, the sun or small light sources can't clearly 'pop' out of the picture. As a result, even well-produced HDR material looks fairly restrained and, in terms of dynamics, is closer to good SDR than to what brighter models show. That does not mean the P7L completely fails at HDR. The issue is primarily a lack of backlight power.

Looking at colours, the situation is a little better. The TV covers around 91% of the DCI-P3 gamut and about 68% of the wide BT.2020 colour space, so for this price class the colour range is quite respectable. TCL markets this model as QLED, although the nature of the solution used is closer to backlighting that uses a PFS phosphor than to a classic quantum-dot layer. What matters most to the viewer, however, is the effect: more saturated colours are on offer.

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.

In Film mode the TCL P7L performs quite respectably without major changes to the settings, particularly with ordinary SDR material. White balance is relatively even, though as brightness increases there is a slight rise in red and blue and a touch too little green. This does not, however, produce a strongly visible tint and most colours remain close to their reference points. The Colour Checker confirms this, with a large portion of errors falling below the level that should be particularly noticeable during normal viewing. We have more reservations about the gamma response. In the darkest parts of the image the TV runs it noticeably above the reference value, so some shadow detail can be a little too subdued. The characteristic then calms down and across much of the range it is close to the intended behaviour. As a result SDR generally looks natural, but in dark scenes the P7L can lose some subtlety.

In HDR the factory calibration is less precise. As brightness increases the excess of blue becomes more pronounced, which can make the image look cooler than it should. The number of larger colour deviations also grows, particularly in brighter hues. As for the EOTF curve itself, it is handled fairly conservatively, with the TV showing the image darker than the reference across much of the range. For such an inexpensive model, the factory Film mode settings are not bad.

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.

After calibration the TCL P7L can deliver a genuinely pleasant picture, especially with conventional SDR material. We managed to even out the white balance very well, and the gamma curve now tracks close to the target value of 2.4. This is also reflected in the colour measurements: most errors have fallen noticeably, and in everyday viewing it is hard to point to any obvious inaccuracies. Films, series, YouTube and ordinary broadcast TV therefore look more natural, without unnecessary warmth or a cool tint. For a model in this price bracket the SDR performance is really very good.

With HDR the situation becomes more complicated. Calibration helped improve the white balance and tidy up some deviations, but here the panel's limitations become increasingly apparent. The P7L has relatively low brightness and cannot maintain adequate luminance for more saturated colours, so some errors remain even after careful tuning. In other words, settings can improve the way the TV interprets the signal, but they cannot overcome its physical limits. That is why calibration makes most sense for this model primarily in SDR.

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 this respect the TCL P7L performs surprisingly well, especially for such an inexpensive TV. The banding-reduction feature, which in many budget models does little or nothing, actually manages to improve the picture here. It does not remove all banding entirely, but it can noticeably reduce posterisation and make more challenging gradients look more natural. At this price point that’s a genuinely pleasant surprise. Upscaling itself also performs well. Lower-resolution material is scaled correctly, without over-sharpening or adding artificial outlines around objects. Of course the P7L won’t turn a very poor source into a 4K-quality image, but for regular TV the result is simply solid. For a model in this class there is little to criticise.

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.

The TCL P7L uses a panel with a native 60 Hz refresh rate at 4K resolution, and that's how it should be regarded in everyday use. When watching films the TV mainly offers frame interpolation, so it can smooth motion and reduce the characteristic judder, but it does not deliver the fluidity typical of true 120 Hz panels.

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.

For such an inexpensive TV, the P7L has quite a lot to offer gamers. It has ALLM, VRR, Dolby Vision for gaming, and TCL also includes its Game Bar, which lets you quickly check the key information or change some settings without leaving the game. Not everything is perfect, though, because HGiG doesn’t work here as it should, but at this price point it’s hard to complain about the feature set. The most interesting part starts when you give up 4K. At that resolution the TV runs at up to 60 Hz, but at 1440p and 1080p it can display at 120 Hz. And that’s not just a line in the specs. In fast-paced games that support that frame rate you can really notice the improvement in smoothness, so if you value smoother motion more than maximum image detail, that mode can make a lot of sense. Of course, that doesn’t turn the P7L into a proper 120 Hz TV. Even so, those extra modes are exactly what make the P7L perform very well for gaming.