The LG SM8600 is a good UHD IPS TV with decent picture quality, excellent response time, and very low input lag that'll please gamers. It has decent SDR peak brightness and is more suitable for average-lit rooms where blacks don't matter as much; the good reflection handling minimizes distracting reflections. As an IPS panel, the SM8600 has wide viewing angles and is great for wide seating arrangements. Unfortunately, blacks look more like gray in a dark room due to the low contrast ratio and the inefficient local dimming. HDR isn't that great either, as the TV can't get very bright in HDR to display bright highlights as it should.
The LG SM8600 has an excellent design. The stand is made of plastic and supports the TV well. However, the TV wobbles significantly if you nudge it. The back of the TV is made of thin metal and has a mild brushed texture, but has no grooves to guide the cables to the stand's hollow neck. The TV is thin and won't stick out much if wall-mounted. Finally, the build quality is decent and we don't expect you to have any issues with it.
The stand of the TV is plastic and resembles last year's SK8000. Although the stand supports the TV well, its neck has a lot of flex and the TV wobbles significantly if nudged.
Footprint of the 55" TV stand: 33.1" x 9.25".
The back of the TV is plain with a mild brushed texture. It's made of a metal sheet that flexes easily if you gently push it inwards. The stand's neck is hollow (has a removable cover) and you can guide the cables through the slot to help with cable management.
The borders are thin and made of metal. They look good and give the TV a premium feel.
The SM8600 has a decent build quality. It has a metal back which has a little flex, and the stand allows more wobbling than the SK8000. However, the TV feels solid, and the border finish gives it a more premium feel. You shouldn't have any issues with it.
The SM8600 has decent overall picture quality. However, blacks in a dark room look more like gray due to the low contrast ratio, and the local dimming can't help improve that. The TV is more suitable for average lit or dim rooms, as it can't get very bright in SDR. On the upside, it can handle reflections well, so you won't be distracted if the room has a few lights. The gray uniformity is good with minimal dirty screen effect to please demanding sports fans. The TV has a wide color gamut, but it can't get very bright in HDR and thus it can't display HDR content as bright as it should. Finally, the viewing angles are decent and the image remains accurate if you watch from the side. This is great if you have a large room with a wide seating arrangement.
The LG 55SM8600PUA has a mediocre contrast ratio, as expected for a TV with an IPS panel. The contrast ratio does not improve when local dimming is enabled. This is due to the fact that the TV is edge lit and local dimming cannot help in our checkered pattern. This performance is very similar to last year's SK8000.
The LG SM8600 has bad local dimming. It is an edge-lit TV and thus has vertical local dimming zones which can cause issues with local dimming performance. The TV, however, has particularly bad local dimming performance when LED Local Dimming is set to 'High.' In certain scenes, the TV reacts to brightness changes in small areas of the screen by brightening/dimming entire vertical columns, which causes significant blooming; this is very distracting.
Setting LED Local Dimming to 'Medium' makes this a lot milder, although many people will still find this vertical blooming distracting. We recommend you set the LED Local Dimming to 'Medium.'
The local dimming performance is very similar to last year's SK8000, but the SM8600 has a less aggressive performance when LED Local Dimming is set to 'Medium.'
The above video displays the TV's performance with our recommended local dimming setting of 'Medium'.
The SDR peak brightness is decent. it is slightly brighter than last year's SK8000 but it is still more suitable for dim or average-lit rooms.
We measured the peak brightness after calibration, using 'ISF Expert (Dark Room)' Picture Mode, with Backlight set to '100,' LED Local Dimming set to 'Medium,' and Color Temperature set to 'Warm2.'
If you do not care about image accuracy, you can obtain higher brightness levels. We were able to reach 487 nits with the 10% window using the default settings of the 'Vivid' Picture Mode and LED Local Dimming set to 'Medium.'
The HDR peak brightness is mediocre. Although the peak brightness is slightly lower than last year's LG SK8000, the two TVs seem to have different behavior in HDR. The SM8600 seems to be boosting smaller highlights even if it can't sustain this brightness, whereas the SK8000 has a very uniform level of brightness across scenes except for very small highlights that are significantly dimmed.
We measured the peak brightness before calibration, using 'Cinema' Picture Mode, with BackLight set to '100,' LED Local Dimming set to 'Medium,' and Color Temperature set to 'Warm2.'
If you do not care about image accuracy, you can obtain higher brightness levels. We were able to reach 455 nits with the 10% window using default settings of the 'Vivid' Picture Mode.
The LG 55SM8600PUA has decent gray uniformity. The edges of the screen are a little darker than the rest. The center is more uniform, and the minimal dirty screen effect is unlikely to bother sports fans. In darker scenes, the uniformity is better and you hardly notice any distracting blooming.
The LG SM8600 has decent viewing angles as expected for an IPS panel TV. The image remains accurate for wider angles as you move off-center, and the TV is a good choice if you often watch from the side. However, when the viewing angles increase further, the TV loses accuracy as gamma shifts and brightness is diminished. For even wider viewing angles, check out an OLED TV like the LG B8.
The LG 55SM8600PUA has disappointing black uniformity. However, this is expected on IPS panel TVs. When local dimming is disabled, there is visible backlight bleed and blooming. With local dimming enabled and set to 'Medium,' the edges are a little darker but a significant area to the left and to the right of the test cross remains lit. The overall black uniformity performance is better than that of the SK8000.
The LG SM8600 has mediocre accuracy with our pre-calibration settings. There are significant inaccuracies that most people will notice both in the shades of gray and in the colors. The gamma does not track the target very well and thus most scenes are a bit brighter than they should be. The color temperature is significantly warmer than the target of 6500K, and the image has a red-yellowish tint.
After calibration, the SM8600 has almost perfect accuracy. The white balance dE and color dE are both very good which means that most of the inaccuracies were corrected. Any remaining inaccuracies are unnoticeable without the aid of a colorimeter.
The TV features an auto-calibration feature which still requires the use of colorimeter.
You can see our recommended settings here.
The LG 55SM8600PUA upscales 480p content, like DVDs, well without any obvious upscaling artifacts. When compared to other TVs, the SM8600 is performing in the same ballpark as the Samsung Q70R.
720p content, like cable TV, is upscaled well, with no strange artifacts. This performance is in the same ballpark as the LG C9.
The SM8600 has a good wide color gamut. It's a slight improvement over last year's SK8000.
The EOTF is slightly over-brightening some very dark scenes, but, in general, it follows the input stimulus well until it starts a sharp roll off towards the TV's peak brightness. The 'Game' mode EOTF is almost identical as you can see here.
We also measured the tone mapping at 50% stimulus to check if the TV is prioritizing brightness over color accuracy. As we can see from the results for the Rec. 2020 color space, and the results for the DCI-P3 color space, the tone mapping is much better at the 50% stimulus. This means that the TV has better color accuracy at lower brightness levels since the tone mapping is better.
The LG SM8600 has excellent gradient handling. In most real-life content gradients are excellent but there are cases, like the pattern in the photo above, where banding is visible throughout most of the colors and shades. Our test is not run on the picture shown above. It is designed to measure gradient performance in situations that resemble more real-life content, and this is depicted in the results.
If you wish to smooth out gradients, you can enable the Smooth Gradation setting. This setting seems to work well with real-life content but doesn't do anything in our test pattern photo. Enabling Smooth Gradation might cause some loss of fine detail.
This gradient behavior is not new and resembles the behavior we encountered in last year's SK8000.
There is some faint image retention immediately after the long exposure of our test image. However, it does not stay on the screen for long and is hardly noticeable in normal content.
While some IPS panels can have some temporary image retention, this doesn't seem to be permanent as the IPS panel in our long-term test appears to be immune.
The motion handling of the SM8600 is excellent. It has a very fast response time which is great for watching fast action sports or playing video games. The TV uses PWM to dim its backlight at a flicker frequency of 240Hz which might bother some people. The TV's fast response time can make low frame rate content to appear to stutter, which you can remove with the help of the TV's motion interpolation. The SM8600 can display movies free from judder from most sources, including its native apps.
The LG 55SM8600PUA has a very fast response time. There is very little overshoot and the overall performance is very similar to last year's SK8000.
The LG 55SM8600PUA uses Pulse Width Modulation to dim its backlight. The flicker frequency can be as high as 240Hz. Some of the TVs picture modes, that are primarily aimed at movies ('Cinema,' 'ISF Expert (Dark Room),' etc), have 240Hz flicker. However, when TruMotion is enabled, the flicker switches to 120 Hz in these modes.
The other picture modes like 'Game,' 'Standard,' 'Sports,' etc always have 120Hz flicker.
The LG SM8600 has an optional Black Frame Insertion feature that can lower the flicker frequency and make motion look crisper.
To activate this option, enable TruMotion to 'User' and this will immediately make the flicker frequency 120Hz no matter the picture mode. If you set Motion Pro to 'On' then the flicker frequency becomes 60Hz.
Unfortunately, this decreases the picture brightness, and 60Hz flicker can be bothersome to some people.
When you are in 'Game' mode the flicker frequency is always 120Hz. To lower the frequency to 60Hz, you must follow the same procedure as before.
The LG SM8600 can interpolate lower frame-rate content up to 120fps. The TV stops interpolating in very fast scenes to avoid creating too many artifacts. When this happens, the sudden change in frame rate can be noticeable as a sudden "jerk" in motion. To enable motion interpolation, enable the TruMotion setting.
See here for the settings that control the SM8600's motion interpolation feature.
Note that just enabling TruMotion changes the backlight flicker to 120Hz.
The SM8600 has a very fast response time, which makes the image appear to stutter in movies or other lower frame rate content. If stutter bothers you, motion interpolation or the optional black frame insertion feature can help.
The SM8600 is judder-free from most sources. Unfortunately, during our test, the TV was unable to completely remove 24p judder from 60i signals. To remove judder, the Real Cinema option must be enabled in the Picture Option Settings menu.
The LG 55SM8600PUA has a native refresh rate of 120Hz. Unfortunately, it doesn't appear to support any of the variable refresh rate technologies, including FreeSync or the HDMI 2.1 VRR format. We tested this with an Xbox One S, which did support HDMI-Forum VRR on the C9. Although we can't be sure it won't work from an HDMI 2.1 source, we don't expect it to. We will retest this once we have an HDMI 2.1 source.
The LG SM8600 has an outstanding low input lag in most modes and also supports the most common resolutions and refresh rates. All resolutions have proper chroma 4:4:4 when the TV is set in PC mode, except for 1080p @ 120Hz which doesn't. It has a good selection of inputs and supports Dolby Digital and DTS passthrough.
The SM8600 has a very low input lag which is great news for gamers. To get the lowest input lag you must set the TV in 'Game' mode. To get low input lag and proper chroma 4:4:4 just change the input icon to PC. The picture mode does not matter.
The TV supports an Auto Low Latency mode that LG calls 'Instant Game Response,' but it only works with compatible devices like the Xbox One. When 'Instant Game Response' detects that you're playing a game, it switches to 'Game' mode. After that, if you switch to another picture mode, you are still getting low input lag and the only available settings are the 'Game' mode ones. This means that all picture modes can have the same low input lag when 'Instant Game Response' is activated.
See our recommended gaming settings here.
The LG 55SM8600PUA supports the majority of most common resolutions including 1440p, just like the C9.
All supported resolutions can display proper chroma 4:4:4 as long as PC mode is enabled, except the 1080p @ 120Hz which doesn't.
Some of the high bandwidth resolutions, like 4k @ 60Hz + HDR, require the HDMI ULTRA HD Deep Color setting to be enabled for the port in use.
It's unclear if the LG 55SM8600PUA supports HDMI 2.1 or not. At the moment, we can not confirm this either way, as we have no way of sending an HDMI 2.1 signal. We will retest this when we get a device capable of sending such a signal.
Like the 2018 LG OLEDs, the LG SM8600 supports DTS and Dolby Digital passthrough to a standard ARC receiver. It doesn't support eARC as the C9 does.
The sound quality is sub-par. The TV doesn't get very loud, and its bass doesn't have any thump or rumble, but also lacks quite a bit of punch. However, the TV will produce clear and intelligible dialog. For a better sound, it's recommended to add dedicated speakers or a soundbar.
The frequency response is disappointing. LFE (low-frequency extension) is at 151Hz, which is poor. This means that the bass of this TV won't have any thump or rumble, and will lack quite a bit of punch too. The frequency response above the LFE point is decent and relatively well-balanced so it produces clear dialog, but it may lack a bit of airiness. This TV doesn't get loud and doesn't have a room correction system.