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Pierre-Jean Alzieu
Pierre Anzil
Published on October 20, 2011
Translated by Sam McGeever


  • Screen size 37 inches
  • Resolution 1920 x 1080 pixels
  • HD compatibility (1080i/720p) Yes / Yes
  • HD Ready certification Yes
  • Brightness NC
  • Contrast ratio NC
Alongside its CX523 TV, Sony has another LCD TV with CCFL backlighting, this BX420.  It's a rather basic offering, and so doesn't include support for 3D.  The maximum refresh rate is just 50 Hz and there are no motion interpolation filters or online services.

Build Quality and Design

The Sony BX240 is one of the few TVs released this year to still use CCFL backlighting with fluorescent tubes behind the display.  They make the screen a little thicker than TVs that use Edge LED backlighting, and it measures 9 cm from front to back instead of the 3 cm or less we've been getting used to.

There is some good news, though, in the shape of the matte finish on the display.  It might not be as attractive as a glossy sheen, but it does mean your viewing isn't affected by reflections.

It has two HDMI 1.3 inputs, a composite video input, a VGA port and a SCART socket, which isn't a very wide offering.  If you've got a TV decoder, a games console and a DVD player—which isn't that uncommon—then you'll have to keep swapping the HDMI cables.

Apart from the media player, which is accessed via a single USB port, the BX420 doesn't have any other noteworthy features.  Recently, Sony has been improving the media player firmware installed in its TVs, and AVI files no longer pose a problem.  Better still, there's now support for multiple subtitle tracks.  With MP4, MKV and DivX+ video, only audio tracks encoded using AAC are available, and subtitles inside container files aren't recognised either, so you'll need to work with external subtitles.

With so few features on offer, the BX420 has a very simple remote.  The redesign has also changed the look—for the better.  It's now round, rather than flat, at the back, making it easier to hold in the palm of your hand.

Matte finish doesn't suffer from reflections

37BX420 Profile

Inputs and outputs

Ghosting and Input Lag

This graph shows the ghosting time, measured in ms, that the TV takes to entirely remove the previous frame. The shorter the time, the more fluid moving images will appear

The BX420 is certainly not recommended for gaming.  Firstly, it has an input lag of four whole frames, or 66 ms, and secondly, the MVA screen takes around 18.5 ms to remove the previous frame from display, well above our average value of 12 ms.

Image Quality

With the factory settings, this television does no better than average.  The picture is far too garish, with a very strong blue tinge caused by blues at 13000 K instead of the usual value of 6500 K.  Fortunately, most of those problems can be solved by switching to Custom mode.

Good colour reproduction in Custom mode: average deltaE: 1.9

Having made those adjustments, the colour reproduction looked more accurate to us, something our equipment confirmed by recording an average deltaE of 1.9.  This result measures the discrepancy between the colours included in the video source and those actually shown on screen.

Contrast ratio in Custom mode: 3400:1

At 3400:1, the contrast ratio is also excellent.  Blacks look very deep, even in dark environments.  However, the MVA display has narrow viewing angles, scoring just 1.9 out of 5 on our scale.  Lighter areas towards the edge of the screen have a blue tinge.

Ghosting is visible in films during long tracking shots.  You'll also have to put up with a little jerkiness in films, which there's no motion interpolation filter to sort out.



The good news is that this TV doesn't have any problems at all with clouding.  The black bands above and below films aren't pockmarked with light leaking from the edge of the frame as is so often the case with LCD TVs that have Edge LED backlighting.

Audio Quality

The sound produced by the BX420's speakers is pretty powerful, but it could definitely do with being a little more accurate.  The treble and medium are both jumbled and the the bass is far from overwhelming.  Some external speakers or a sound bar would be aworthwhile investment.

Energy Consumption

CCFL backlighting might have the advantage of not creating clouding, but it has the downside of being less energy efficient.  This 37'' TV, for instance, used 90 W while switched on.  That comes to 238 W/m², which is rather a lot compared to the 120 cd/m² that other TVs can manage.  On standby, at less than 1 W, it uses as much power as its competitors. 
Our Readings
Contrast: 3400:1
Black level: 0.06 cd/m²
Gamma quality: 4.6 / 5
deltaE: 1.5
Average discrepancy across display: 11%
Viewing angles: 1.8 / 5
Energy consumption:94 W
Multimedia player: 3.4/5

Find and compare our other readings in our Face-off.

We take these readings using the best settings for watching a movie. Cinema mode is generally the one we use. Wherever possible, we set the white levels at 200 cd/m².

See also: How do we test TVs?


  • Excellent contrast ratio and deep blacks: 3400:1 and 0.06 cd/m²
  • Accurate colour reproduction: average deltaE: 1.9
  • Matte finish doesn't suffer from reflections
  • No clouding on the unit we tested


  • No motion interpolation filter
  • Narrow viewing angles
  • Display is less responsive than average
  • Uses more power than LCD TVs with LED backlighting


The Sony BX420 TV doesn't miss its fourth star by much. Despite a friendly price tag, it has a great picture quality with a high contrast ratio and accurate colour reproduction. The only real problems are the lack of a motion interpolation filter and a relatively unresponsive display.
3 Sony Bravia KDL-37BX420 DigitalVersus 2011-10-20 00:00:00
Compare: Sony Bravia KDL-37BX420 to its competitors
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