TCL S Series/S405 4k 2018 TV Review

The design of the TCL S405 is quite basic and in line with other TCL TVs such as the US5800 from 2016. It has a wide stand which requires quite a large table but supports the TV well.

Update 3-19-2019: The design of the S425/423/421 models might have some cosmetic differences but we have not reviewed them yet to provide you with more detail.

The stand does a good job of holding the TV steady but is made of plastic. It feels quite cheap but does support the TV well.

Footprint of the 43" TV stand: 7.8" x 30.2"

The rear of the TV is simple, with a metallic top half and plastic body.

Update 11/20/2017: Note that the different sizes of the TV have different VESA mounts. The 49" (49S405) and 55" (55S405) have a 200x200 VESA mount, and the 65" (65S405) has a 300x300 VESA mount.

The borders have an average thickness but look fine. There is a bit of a gap before the beginning of the picture.

The TV has an average thickness when viewed from the side. It will stick out a bit if wall mounted.

The build quality of the S405 is decent. The top half of the back is metal, but the bulk of the TV is plastic (including the borders). This won't present problems during use but doesn't feel as premium as other high end TVs, or even the LeEco Super4.

The TCL S425 / S405 has a very good native contrast ratio for a LED TV. With over a 4000:1, the S405 contrast ratio is over what we consider to be a good value for a TV and will procure deep enough blacks to make dark scene pleasant to watch, especially when the TV is set in a bright room. In comparison, this is a small improvement over the 2016 TCL US5800.

The TCL S405 / S425 does not have a local dimming feature. The video is for reference only.

Plot over time

Disappointing SDR peak brightness, good enough for a moderately lit room but not bright enough for a well lit room. The brightness does remain unchanged no matter the scene shown, which is good. The edges of the screen are slightly dimmer than the center, as seen by the lower real scene brightness. This brightness is very similar to the lower tier TCL S305, but a lot less than the next tier P607.

Plot over time

Bad HDR peak brightness, highlights in HDR will not be shown much brighter than the rest of the scene. The brightness does remain consistent no matter the scene due to the TV's lack of CE dimming, which is good. This brightness is a lot lower than the more expensive TCL P607.

The TCL 4 Series / S Series gray uniformity could be better and a lot of the uniformity problems come from the edge of the screen being a bit darker than the center, especially the corners. There is also a large darker band on the top of the screen with some smaller vertical one that is a bit warmer/dirtier than the rest of the screen. Dirty screen effect is visible when watching some specific content like hockey of football, where there are large panning shots over a uniform surface. For normal content like movies or TV show, dirty screen effect is less of a problem though.

Looking at our 5% test picture, we can see that both sides are a bit brighter than the center, but this is not really a uniformity problem, but more a visual effect due to the narrow viewing angle.

Bad viewing angle, but fairly typical for a TV with a VA panel. Blacks become gray and colors shift when the TV is viewed from even a small angle, while brightness decreases more gradually at an angle. This TV is not well suited for a room where people will be often viewing the TV from the side.

The native black uniformity of the TCL S405 is very good. Looking at the black uniformity test picture, we can see some clouding near the top and bottom edge but luckily, this is really faint and does not really affect our test result and also it did not show up in dark scene while looking at regular video content. Note that here, the black level of the test picture doesn't look that deep, but here the test is evaluating the uniformity of the screen and not the black level.

The reflection handling of the TCL S Series is okay. It has a semi-gloss finish which causes reflections to appear larger, diffused across the screen. This does help to reduce their intensity slightly though. For an average room it's ok, but in a bright room, the reflections are distracting.

Out of the box, the TCL S405 / S425 accuracy is impressive and for most people, even enthusiasts, it would be very hard to notice the little inaccuracies. Overall, the colors are tracking their target pretty well and the white balance and gamma too, which is pretty good. At this level of accuracy, a calibration would not be needed and could be used as is in most case.

After calibration, the TCL S405 is one of the most accurate TV we ever reviewed. At this level of accuracy, most imperfections are not even noticeable. Since the TV was already very accurate out of the box, the calibration was done in a breeze and no real issues came up during the process.

Like other TCL TVs, the calibration is only possible via the mobile apps and is one of the easiest methods available from all the major brand of TV we have worked with. The 11 points white balance control and the color space control are fairly responsive and procure a very easy way to do the calibration.

You can see our recommended settings here.

Upscaling of low-quality content such as DVDs is good. As with other TCL TVs, the image isn't too soft and details are preserved.

720p sources such as cable are upscaled well. Details remain clear.

1080p content such as Blu-rays look sharp and detailed.

No issues can be seen with native 4k content.

Update 02/26/2018: We have received reports that the 49" model of the S405 (49S405) has a different panel, which displays a crosshatching like effect which is visible from up-close (see here). This appears to be similar to the P607 (visible in the pixels photo here)

Narrow color gamut, only good enough for SDR content. The true color gamut is shown by the maximum red, green and blue in the Rec 2020 gamut picture. All other colors in the Rec 2020 picture, and all the P3 colors are shown horribly undersaturated, likely because the TV is prioritizing brightness over color accuracy because the TV is so dim. These tests were done at 75% brightness stimulus; shown here and here are tests done at a dimmer 50% stimulus that have much better accuracy. Most colors in HDR content will be at a dim stimulus and have decent accuracy, but very bright colors will have poor accuracy.

The TV's EOTF follows the HDR PQ curve fairly closely until 50% stimulus grey, where it rolls off very early to ease the transition to the TV's low peak brightness. This test was done with the 'Gamma' set to '2.0' in the TV's advanced picture settings in the Roku app; at the default 'Gamma' of '2.2' the EOTF was dimmer than the PQ curve, shown here, and shown here with 'Game Mode' enabled. Users can change this 'Gamma' setting to suit the brightness of their room.

Disappointing color volume. The TV's color gamut narrows significantly when showing very dark saturated colors, which is visible in both color volumes. The color gamut remains full for bright saturated Rec 2020 colors, but the gamut narrows significantly when showing bright P3 colors, likely due to the TV's tone mapping prioritizing brightness over color accuracy because the TV is so dim.

The TCL S425 / S405 can display our test gradient very smoothly and without any banding normally seen on 8-bit panels. Some little imperfection can be seen on the dark green and toward the end of the dark grayscale, but this is very minimal. Banding in HDR movies was not a problem and the performance is very good overall.

No image retention could be detected on the TCL S405 and this is in line with other TVs that use VA panels.

We don't expect VA panels to experience permanent image retention, as the VA panel in our long-term test appears immune.

The response time is great, resulting in only a short trail following fast-moving objects. This is a noticeable improvement over TCL 4K TVs from 2016, the US5800 and UP130, and is better than the S305 from 2017.

The TV uses PWM at 120Hz to dim the backlight, starting at 100/100 backlight setting. Lowering the setting shortens the duty cycle, while amplitude remains constant. Backlight PWM results in duplications following fast-moving objects, visible in the motion blur box.

Unfortunately the S405 has no option to reduce its flicker frequency to 60 Hz, although its 120 Hz PWM backlight does help somewhat to make motion look clearer.

The S405 is unable to produce motion interpolation, so fans of the soap opera effect could be disappointed.

The TCL S405 / S425 is good at displaying content smoothly, without stutter. After each transition completes with 24p content, the frame remains static for only ~27ms. This produces a smoother image as the response time helps to blur the transition between frames.

Like the 2017 TCL P607 and 2016 TCL US5800, the S405 can only display without judder 24p movies when they are played from 24 sources like DVDs or Blu-rays. 24p Movies playing from 60p/60i sources like cable or satellite boxes will have some judder.

There is not specific feature or option needed to be turn on to remove judder from 24p movies on 24p sources, as the TV detect and display them correctly.

The S405 has a 60Hz panel without support for more advanced features such as FreeSync.

Update 05/06/2019: The S405 now supports Auto Low Latency Mode, and will automatically enable 'Game Mode' when you start playing a game on a supported device. We tested it with an Xbox One S.

Update 07/18/2017: The TV only shows 4:4:4 color properly when in 'PC mode'. For most sources this is accomplished by changing the input's icon to 'Computer'. For a PC, if the TV detects a PC as its source it forces PC mode, and this cannot be avoided except by intercepting the AVI infoframes sent from the PC. The 4:4:4 input lag measurements were in error, but all input lag measurements have now been updated (essentially unchanged).

Excellent low input lag, good enough for even competitive gamers. All picture modes have the same low input lag when the 'Game Mode' setting is on, and 4:4:4 color is displayed properly in all modes. This input lag is very similar to the higher tier TCL P607.

Most resolutions are supported. 4k @ 60 Hz is only supported when the HDMI input used is set to HDMI 2.0 in the TV's settings. 4:4:4 color is displayed properly in all picture modes.

The TV's 4:2:0 color support is inconsistent. 4:2:0 isn't displayed properly from some sources, such as a PC (whites turn pink, scanlines), while our HDR Blu-ray player had no such issue. This inconsistency could be a problem for 4k @ 60 Hz sources that only support HDMI 1.4, as 4:2:0 is needed for these sources to remain within the bandwidth cap of HDMI 1.4.

Update 07/18/2017: The TV only shows 4:4:4 color properly when in 'PC mode'. Sharpness also has no effect in PC mode, even though the slider can still be changed. For most sources PC mode is activated by changing the input's icon to 'Computer'. For a PC, if the TV detects a PC as its source it forces PC mode, and this cannot be avoided except by intercepting the AVI infoframes sent from the PC. Changing the input's icon does not avoid this forced PC mode. This behavior was not known during initial testing, leading to the incorrect assumption that 4:4:4 color is displayed properly in all modes.