Home theater A-Z: all the key jargon explained

4K (Ultra HD)

The benchmark resolution for TVs today. Four times sharper than Full HD, the standardised 4K resolution is 3840 x 2160 pixels – or 8.3 million pixels across the whole display, whether it’s a 48in or a 70in screen.

8K

The successor to 4K and the future of TV screen resolutions. Only a few sets feature it today – including the crazy expensive Samsung 75Q950TS – and there’s little in the way of 8K content to watch on them. But with 33 million pixels to play with, it’s a real treat for the peepers.

Active speakers

Passive speakers need to be powered by an external amp; active ones have their own amplification, so they only need an audio signal (and electricity).

Acoustic Surface Audio+

Seen in Sony TVs like the brilliant XR-55A90J, Acoustic Surface Audio+ uses actuators to excite the entire surface of a screen, basically turning it into a speaker. Luckily the movement is too small to be visible.

Centre channel

Bass might vibrate your furniture, but the centre channel is a key audio path in any home theater setup. It’s where much of the dialogue is reproduced and should be positioned beneath your TV.

Dimming zones

Screens like the Samsung 75Q950TS divide the LEDs doing the backlighting into many independent zones. That way the brightness of different areas can be controlled on a zone-by-zone basis.

Dolby Atmos

An object-based spatial audio system with overhead as well as front, rear, left and right channels of sound. In the home theater it’s generally achieved by bouncing sound off the ceiling to make you feel truly immersed in audio.

DSP

DSP stands for ‘digital signal processing’. It refers to any tweaks made by home theater kit to the audio signal as its sent through to your speakers. Yamaha’s latest AV receivers, for example, intelligently detect and adjust the weight of different audio effects in the signal.

Dynamic metadata

Allows an HDR TV to optimise its picture brightness on a frame-by-frame basis to ensure you’re always getting the most vibrant and convincing image.

Dolby Vision

An alternative HDR format, seen on TVs, smartphones and tablets. It’s not open-source like HDR10, but it supports dynamic metadata to continuously optimise the picture to the screen and offers greater flexibility for broadcasters.

Dolby Vision IQ

The next stage in Dolby’s Vision HDR standard, Vision IQ tailors a screen’s HDR performance relative to the ambient light in your home theater room using sensors in the screen itself.

DTS:X

An object-based audio alternative to Dolby Atmos, developed by DTS. Capable of creating 3D surround sound using speakers that add a height component for immersive listening.

Dynamic HDR

Standard HDR uses fixed brightness and colour for a whole movie. Dynamic HDR decodes dynamic metadata (see above) to adjust these levels on a frame-by-frame basis, for contrast that better matches the scene. Dolby Vision and HDR10+ are both examples of dynamic HDR formats.

HDMI 2.1

The new connection standard brings a whole host of features that allow a next-gen games console to perform at its absolute best in terms of refresh rate, latency, HDR and more.

HDMI ARC

The inclusion of an Audio Return Channel (ARC) means a television can send sound to a compatible soundbar (for instance) using an HDMI cable rather than, say, a digital optical cable.

HDMI eARC

Enhanced Audio Return Channel offers much better speed and bandwidth over plain ARC. So even a complicated soundbar like this can get all the information it needs down one cable.

HLG

Hybrid Log Gamma is another version of HDR. Co-developed by the BBC and Japanese broadcaster NHK, it’s the favoured format for broadcasting 4K HDR images. It combines standard and high dynamic range images into a single signal, so it can be played on pretty much any TV it’s sent to.

HDR

Dynamic range is the difference between the extremes of brightness and darkness across a display. HDR is high dynamic range, which means brighter brightness, darker darkness and a lot more colours in between the two. The result is a more vivid, realistic picture. For more on HDR, read our dedicated explainer.

HDR10

HDR10 is an open-source HDR format that’s become the industry standard. The 10 refers to the colour depth of 10 bits (resulting in a palette of one billion hues, versus the 16 million of standard dynamic range). If your TV is HDR compatible, it’s almost guaranteed to work with HDR10.

HDR10+

The latest HDR format, which takes HDR10, adds dynamic metadata (see above) and multiplies maximum brightness by four. The result is better contrast and an even more vivid viewing experience.

Horn-loading

A way of targeting and focusing the distribution of sound from a speaker driver by placing it at the back of a horn- shaped enclosure. This guides the soundwaves more directly.

IMAX Enhanced

This certification guarantees the 4K HDR picture and DTS sound of a piece of content are, basically, good enough to pass muster at IMAX. Which is not easy to achieve.

MicroLED

Like OLED, MicroLED uses emissive display technology – but it’s not organic. Instead, it deploys tiny LEDs (three per pixel), which turn themselves on and off as required. So they should offer great black levels, top-notch contrast and off-axis viewing, but with a brighter picture, lower price point and none of the burn-in concerns of OLED. For more on the differences between MicroLED and OLED, read our dedicated feature.

LED

Despite the name, LED displays still use a liquid crystal panel like you’d find in a traditional LCD TV. The difference is the backlight, which in an LED screen uses – you guessed it – light emitting diodes.

OLED

OLED stands for organic light emitting diode. Each pixel in an OLED display can produce its own light, rather than using the classic LCD backlight. Pixels can be turned off completely for perfect black levels. And there’s no light leakage from bright whites, so contrast is outstanding. But brightness can be an issue.

Passive radiator

Sometimes called a ‘drone cone’, a passive radiator is a speaker driver without magnets or a voice-coil. It uses sound pressure alone to boost your bass – and you’ll find a few in most soundbars. Full home theater systems tend to use active subwoofers instead.

QLED

QLED is Samsung’s take on the LED TV. The ‘Q’ stands for ‘quantum dots’. These are microscopic molecules which, when hit by light, emit their own differently coloured light. These dots are contained in a film that’s added to the LCD panel and the result is a much brighter picture, for less than OLED. For more on QLED, check out our dedicated explainer.

Refresh rate

Refresh rate is how many times per second the image on screen refreshes. This is fundamental to smooth motion, especially when viewing fast action: a low number can lead to blurring. The benchmark is 60Hz, which means the image refreshes 60 times every second. For slicker responses, many mid-range sets support native 120Hz, while some top TVs now claim effective rates of 240Hz – although the meaning of the numbers isn’t always consistent across manufacturers.

Upscaling

This means boosting the resolution of source material to match a higher resolution. An 8K home theater screen, for example, has more than 33m individual pixels. If you want to watch content with less pixel info than that (ie: anything), the TV must smartly fill in the gaps to cover its screen. This is usually achieved with clever AI trickery.

Variable refresh rate

Movies have a set frame rate: 24 per second. Games, though, can vary theirs – so to deal with this, a home theater display (TV or projector) must have a variable refresh rate.

• What is Variable Refresh Rate? VRR explained