Hisense shows how two screens are better than one … mostly

Having spent time comparing the new Dual Cell technology to OLED, I have just two things to say: Wow! And, wow, how did they get it so wrong?

Hisense 65SX

Hisense’s Dual Cell technology can produce extra black where it’s needed . . . and sometimes where it’s not needed. 

You spend a great deal of time trying to get two screens in perfect synchronisation when you’re a professional gadget reviewer and trying to do a side-by-side comparison of TVs.

I’ve just spent almost the entire morning fast-forwarding, pausing, rewinding and just fiddling with dozens of shows on two Hisense TVs, trying to get the shows to the exact same spot to compare Hisense’s new “Dual Cell” TV with its older OLED TV, which the Dual Cell technology will be replacing.

And, having spent all that time comparing the two, I have just two things to say: Wow!

And … I only wish Hisense had spent as much time synchronising the two screens in the Dual Cell as I spent synchronising the Dual Cell TV with the OLED one. Because, wow, how did they get it so wrong?

Think of it as wearing two nappies, except for light.

Just how one TV can have two screens that need to be in perfect sync with each other could probably do with some explanation.

Hisense’s Dual Cell technology, which is making its debut in the 65-inch 65SX I’ve been reviewing, is the TV industry’s latest – and I must say most promising – attempt to give ordinary LCD TVs the deep blacks and saturated colours that you get from OLED, without the downsides of OLED (chiefly, image burn-in and reduced longevity).

It does this by sandwiching two screens on top of one another: a regular 4K, full-colour screen and, underneath it, a high-definition (1080p) black-and-white screen, which sort of acts as the light source for the 4K display.

The big problem with LCD TVs, you see, is that LCD technology “leaks” light. The crystals (LCD stands for Liquid Crystal Display) that make up the display aren’t capable of completely blocking the light that’s coming from behind (the so-called backlight), even when they’re supposed to. As a result, parts of an LCD TV picture that should be inky black wind up being off-black, or, worse, a washed-out grey sort-of halo colour if the part of the image that was meant to be black is smack bang up against something quite bright.

TV makers have tried all sorts of methods to prevent blacks washing out and highlights from creating halos, and all of them have big drawbacks.

Full-array local dimming (FALD) is the main approach.

Rather than having just one, big backlight as cheaper TVs have, FALD divides the backlighting into dozens or even hundreds of individually controllable zones and then turns these off or on depending on how dim or bright that part of the picture is.

Hisense 65SX

The woofer below the TV cleverly doubles as ballast for the TV’s weight when it’s sitting on a cabinet rather than mounted on a wall. 

But FALD, though an improvement on other forms of LCD, can still create bizarre and unwanted effects, such as where large, rectangular areas of a screen go completely black when they were supposed to be grey, or supposed to be black but with pin pricks of light in them.

Watching Star Wars on a FALD TV can be most disconcerting. You notice the FALD rectangles flickering on and off and drifting around the screen almost as much as you notice the wooden acting and cheesy dialogue.

But imagine, if you will, that instead of having dozens or even hundreds of backlighting zones, you had 2,073,600 zones. That’s sort of what Hisense’s Dual Cell technology does.

It uses the black-and-white display to mask the light coming off the backlights, so that by the time that light reaches the 4K colour display, it’s already dimmed where it’s supposed to be dimmed, and bright where it’s supposed to be bright.

Creepier still, people get four eyes: two where they should be, and two white patches somewhere else.

Any light leakage is kept to a minimum, because in order for you to see a halo or a washed-out black, that light has to first leak through the mono display and then though the 4K colour display.

Think of it as wearing two nappies, except for light rather than pee.

The result, when the mono display and the 4K display are in perfect sync with each other, is remarkable. Dual Cell is the best LCD technology we’ve seen by a country mile, at least in terms of its ability to deliver inky blacks and highlights without halos.

Side by side with 2018 Hisense OLED TV, watching Star Wars and other content that is great with OLED but troubling for LCD panels, it was often impossible to tell the difference between the two images. It’s remarkable.

Sure, when you go “off axis”, sitting off to the side rather than directly in front of the LCD screen, you start to see a little leakage – but no more than most LCD TVs deliver on axis.

And, sure, the skin tones the TV delivers aren’t quite what you get from more premium brands such as Sony, Samsung and LG, but they have spent years tweaking their picture quality while Dual Cell is brand new.

Despite these things, Dual Cell is pretty amazing. I literally exclaimed “Wow!” the first time I saw it.

But if you fiddle with the settings a little bit and choose some picture mode other than the one the TV came in, things go badly pear-shaped.

I’m not 100 per cent certain what goes wrong, but I’m pretty sure the black-and-white display is getting out of sync with the 4K display, causing mayhem on the screen.

People suddenly have four eyebrows, for instance, or four nostrils: two where they should be, and two dark patches somewhere else on their face, where the black-and-white screen is much dimmer than it should be.

Creepier still, people get four eyes: two where they should be, and two white patches somewhere else, where the black-and-white screen is much brighter than it should be.

And you don’t have to tweak the settings much before the picture goes awry like that.

All I did was change the TV’s “Ultra Smooth Motion” setting to “film” mode – to address the “soap opera effect”, where a show can look like it’s a documentary about the making of the show, rather than the show itself. It usually does the trick but on the Hisense it caused the picture to stutter and blur and become borderline unwatchable.

It wasn’t till I turned Ultra Smooth Motion off altogether that I figured out what was going on. Without it, everyone on the screen had two faces, or was in two places on the screen at the same time.

The way we see it in the Digital Life Labs, only one thing could cause that. Or, two things, really. Two screens, one behind the other physically and temporally.

Maybe Hisense should ship the 65SX with two remote controls, one for the 4K screen and one for the mono screen behind it, so you can pause one of them just a few milliseconds till the other one catches up and everyone’s nostrils are where they should be.

Or maybe you should just forget about it and get an OLED. Trying to get two screens into perfect sync is such a pain.

Hisense 65″ Dual Cell Series SX

Likes Huge progress overcoming LCD’s biggest weaknesses

Dislikes Image can fall apart dramatically, and become unwatchable

Price $3499

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John Davidson

John DavidsonColumnistJohn Davidson is an award-winning columnist, reviewer, and senior writer based in Sydney and in the Digital Life Laboratories, from where he writes about personal technology. Connect with John on Twitter. Email John at jdavidson@afr.com

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