How we test
Find out how Which? tests LCD and plasma TVs. Which? tests the sound and vision, power consumption and usability of every LCD and plasma TV.
Find out how Which? tests LCD and plasma TVs. Which? tests the sound and vision, power consumption and usability of every LCD and plasma TV.
Which? now tests LCd and plasma TVs almost every month, reviewing 120 a year and covering nearly all the best-selling models – four times as many as in 2005.
Each LCD and plasma TV is put through an extraordinary six-week test - a mixture of expert panel assessments and technical laboratory testing - scrutinising everything from picture and sound quality, to energy efficiency and ease of use.
New test results and reviews of all the latest LCD and plasma TVs will be added to Which? Online every month.
As well as subjecting LCD and plasma TVs to the Which? technical tests, we use an independent expert viewing panel to assess picture quality under the same conditions in a dimmed, tungsten-lit room.
Brightness and contrast levels are set as equally as possible and the LCD and plasma TVs all receive the same-quality picture signal. The same experts take part each time, and we conceal the brand names.
We show a test card and eight different video clips – each helps the experts assess a different aspect of picture quality, eg a moving train helps highlight problems with panning and movement. We also view the LCD and plasma TVs in HD mode via satellite and have now added a test sequence for high-definition DVD players too.
Each image is awarded an individual score, and each LCD and plasma TV an overall picture score. Picture quality accounts for 40% of the overall test score.
The Which? tests use a similar mix of technical measurements and expert opinion to assess each LCD and plasma TV's sound quality.
Our experts listen to, and score, male and female voices, classical music, pop music, jazz and a TV drama under controlled conditions. Benchmark samples from previous Which? tests are used to ensure continuity.
Technical assessments include measuring the characteristic background noise (e.g. a low-level buzzing) and the maximum sound levels from the internal speakers. Sound quality accounts for 20% of the overall score for each LCD and plasma TV.
Is the instruction manual as clear as the picture? Our ease-of-use experts assess each LCD and plasma TV according to a variety of realistic everyday scenarios. Ease of use accounts for 20% of the overall score.
This involves setting-up the TV for the first time, connecting up all the cables and tuning it in. All the LCD and plasma TVs in this review tune themselves, so you don’t have to fiddle around looking for the best reception.
You shouldn’t have to get out the instruction manual to switch the telly on and off, change channel or use the EPG. We make sure everything is as straightforward as it should be.
Assessments include adjustment of picture settings, making recordings via the EPG and setting the child-lock. The design of the on-screen menu systems are crucial.
You’ve checked behind the sofa but still no luck. There’s nothing for it, you’re going to have to use your LCD or plasma TV without the remote control. This nightmare scenario is this basis for our experts’ assessment of the front-panel controls. Common problems we encounter include:
Modern LCD and plasma TVs can be a drain on the environment and on your wallet. Which? tests the power consumption of each LCD and plasma TV in a variety of viewing modes and estimates the annual running costs. TVs that guzzle power are marked down overall.
Which? experts helped establish the latest international standards for measuring LCD and plasma TV energy consumption and we use these as the basis for our tests. Using standardised video footage power consumption readings are taken in 16:9 (widescreen) mode with the TV settings as delivered.
However, we actually exceed the minimum standard and take further readings for each LCD and plasma TV while using a moving test pattern. We also check everything in 4:3 (old box shape) mode and then do the whole test again, using the optimum picture settings as selected by our expert viewing panel. We then take measurements five minutes and two hours after switching into standby.
To assess the efficiency of any power-saving light sensor we take measurements in three typical living-room environments; bright daylight, dimly lit and, for horror movie fans, in the dark.
Our experts have found that adjusting the settings (see ideal settings for each LCD and plasma TV tested) can reduce power usage considerably. Power use accounts for 5% of the total test score.
Which? does a full feature check on each LCD and plasma TV – but goes well beyond just ticking a box for every socket found. Our tests often reveal some hidden functionality and nasty surprises.
For instance, many LCD and plasma Vs come with a digital audio out socket, however digital surround-sound on Freeview is virtually non-existent, so to make use of the socket, surround-sound signals from other pieces of equipment (like DVD players or Sky boxes) have to be channelled through the TV via HDMI. But this handy trick only works on some LCD and plasma TV models.
Scart sockets on widescreen LCD and plasma TVs usually support auto-format switching – eg showing standard (4:3) broadcasts with black bands on either side, so the images aren't stretched out of proportion. We check for this and find some models don’t automatically switch correctly.
When adjusting your LCD or plasma TV for the perfect picture, you may want to tweak the settings differently for Freeview or DVD. Which? tests whether different picture and sound settings can be ‘remembered’ by the tuner, Scart and HDMI sockets.
Features account for 10% of the total test score.
Once we have all our test results in, we evaluate the data to determine the total test score for each LCD and plasma TV. Currently 40% of the total test score is awarded to picture quality, 20% to sound, 20% to ease of use, 10% features, 5% power use and 5% for digital TV features.
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