Choosing an HD TV is a tricky business these days. Walk into your local TV shop and you’ll be bombarded with jargon and specifications, not to mention all the features including media playback, smart internet portals and, of course, 3D.
Another decision you have to make is whether to opt for an LED or plasma screen. Here, we’ll explain the differences between the two, their pros and cons and which is likely to be the best choice for you.
See also: what is an OLED TV?
LED TVs explained
Let’s start by clearing up the LED vs LCD confusion. Pretty much all manufacturers call their TVs ‘LED’ nowadays, even though they’re actually LCD TVs. What changed, compared to LCD TVs from a few years ago, was the way the LCD panel was lit.
Old LCD TVs had fluorescent tubes, much like those you’d find in an office or garage, but on a much smaller scale. They use a lot of power and, as with many types of light, have been superseded by the energy-efficient LEDs.
Technically, then, manufacturers shouldn’t really call their TVs ‘LED’ since they never called them ‘fluorescent’ or ‘cold cathode’ before. But that’s the way it is. We’ll adopt this nomenclature to keep things simple.
There are two basic types of LED TV: those that are lit from the edge of the screen by a strip of LEDs, and those which have a grid of LEDs behind the entire panel (sometimes called direct lit). Unless you’re paying top dollar, it’s rare to find LED back-lighting. It’s much more common for LED TVs to be ‘edge lit’.
Pros of LED TVs
Edge lighting has the benefit of allowing manufacturers to make their TVs super thin and, although it sounds contrary, edge lighting can lead to a brighter, more consistent-looking image than an LED-backlit set.
LED TVs can produce a wide range of colours (also called the gamut), with some manufacturers (Sony, for example) employing some cunning technologies such as quantum dots and blue LEDs to deliver hard-to-reproduce reds, greens and blues. It means that TVs such as Sony’s KDL-40W905A deliver a very lifelike image with vibrant, vivid hues.
LEDs, as we’ve said, don’t use much power, so even a 42-inch set might use as little as 40 or 50 watts. The exact power usage will depend on the image being displayed, the power of the amplifier and other things including Wi-Fi. LED TVs, though, are by far the cheapest of any kind of TV to run.
LEDs can be very bright, which means it’s never usually a problem to see the action, even if your room is flooded with sunlight. It also helps to overcome the reflective coatings that manufacturers seem all too keen to put on their TVs at the moment.
Cons of LED TVs
Where LED TVs struggle is creating deep blacks. Despite what manufacturers may tell you, it isn’t possible to perform local dimming in the same way that direct-lit LED TVs can. In other words, the whole picture can be dimmed, but not small portions.
This dimming – which is generally called dynamic contrast in the menus – is often distracting as the electronics can be slow to respond to scene changes in the programme you’re watching. When moving from a bright, outdoor scene to a dark, indoor one the fraction-too-late drop in brightness and subsequent delayed increase when returning to a bright scene can become annoying.
Backlight unevenness can also be a problem with LED TVs. Typically you’ll notice this in dark scenes where it could be brighter along the edge where the LEDs are located, or in the corners.
Another issue of LED TVs (because of their LCD panels) is narrow viewing angles. Viewing angles depend on the type of LCD panel used. LED TVs with poor viewing angles typically lose saturation when viewed from the side (or simply not square-on) but colours might change completely or invert.
Plasma TVs explained
Unlike LCD TVs, whose pixels are lit by LEDs shining through filters, plasma TVs have a three individually lit plasma chambers for each pixel (one each for red, green and blue). When current is applied, the gases inside the cells form a plasma and glow.
Plasma is a relatively old technology and as the current used to form the plasma is mostly given off as infrared heat, they use a lot more electricity than LED TVs. Of the few manufacturers still making plasma TVs, most are ramping down production – Panasonic has already said it wants to pull out and concentrate on LED. Samsung and LG also produce plasma TVs.
Pros of Plasma TVs
The biggest advantage of plasma in most people’s eyes is the excellent black levels. Since each cell is lit individually, a plasma TV can produce a black image (or small areas of black) by applying no current to those cells. By contrast – no pun intended – LED TVs look much greyer. Even direct-lit LED TVs aren’t lit per-pixel, so cannot match a plasma TV for black levels.
Again, plasma TVs inherently produce more even brightness levels across the screen, and since there’s no need for dynamic contrast, there are no distracting shifts in brightness when scenes change.
Similarly, because each cell is self-lit, viewing angles tend to be much better than the vast majority of LED TVs. You can sit 45- or even 80-degrees off centre and still see the same rich colours as you would if you were sitting directly in front of the set.
Plasma TVs have a fast response time compared to LCD TVs where the liquid crystals have to physically move. It means fast-moving objects look sharper, and also means reduced ghosting (cross-talk or double-imaging) when watching 3D content.
Cons of Plasma TVs
Plasma suffers from a lack of peak brightness, so while blacks are deep, whites aren’t generally as bright as on the best LED TVs. It isn’t usually a problem, except on particularly sunny days when it might be hard to see what’s going on.
Because of the way an image is generated, some people are susceptible to plasma flicker. This is especially noticeable on brighter images, where the screen appears to shimmer or flicker like an old CRT monitor.
High power consumption is another problem. Although modern plasma TVs are more efficient, they still use several times more power than an equivalent-size LED TV.
Image retention used to be a big problem with plasma panels, but it’s not such an issue today. When there’s a static image or panel (such as a channel logo or HUD in a game you play regularly) the image ‘burns in’ and is displayed even when the logo or block of colour has gone from the video source. Subtly moving the entire image is a trick manufacturers use to try to avoid the problem, but the effects are worst on a brand new panel, so it’s worth being careful to avoid watching channels (BBC News, say) for long periods in the first month or so.
Which is best: LED or Plasma?
The decision between the two technologies is largely down to your preferences, since neither is a clear winner over the other.
If you want the best image quality, in both 2D and 3D, and aren’t bothered about the electricity cost, a plasma could be the way to go. It’s also a good choice if you – for some reason – can’t sit directly in front of your TV, thanks to the wide viewing angles.
If running costs, thinness and brightness are more important, an LED TV will appeal.
Don’t forget to read our TV reviews before you buy one!