TCL 6 Series/R646 2021 QLED TV Review

The TCL 6 Series/R646 is a new TV in TCL's 6 Series Mini LED QLED lineup. The TCL 6 Series/R635 2020 QLED is in the same lineup, and the main difference is that the R646 has Google TV, and the R635 uses Roku. There's also the R648, which is an 8k model that uses Roku. This TV mainly competes with the Hisense U8G, but you can also find the Sony X85J and the Vizio P Series Quantum 2021 in the same price range.

This TV looks similar to the TCL 6 Series/R635 2020 QLED as it has a silver bottom bezel and the same back panel, but there are a few tweaks. This TV uses different feet that have a more premium feel, and the Google speaker sticks out at the bottom.

The TCL R646 features new metal feet that don't take up as much space as those on the TCL 6 Series/R635 2020 QLED. They support the TV well, and there's minimal wobble. There's 3.5 inches from the table to the bottom of the screen, and even with a soundbar placed in front, we could still use the remote and voice control properly.

Footprint of the 55 inch TV: 40.35" x 12.48"

The back is entirely plastic, with a glossy top and textured bottom where the inputs are. There are vents on top of the textured section for airflow. Each of the feet have flaps that you can use for cable management.

This is a bulky TV that won't sit flush against a wall because the bottom part near the inputs sticks out.

It has good build quality, and it feels very similar to the TCL 6 Series/R635 2020 QLED. It's well-put-together, and it feels sturdy for the most part. The feet are good, as there's almost no wobble. However, the plastic on the back flexes quite easily, and it's noticeable with both the glossy top and the textured bottom.

It has an outstanding native contrast ratio. It displays deep blacks, and the local dimming feature helps it achieve high contrast with our checkerboard test pattern. Keep in mind that contrast can vary between units.

Note: As explained in the Local Dimming section, the local dimming feature doesn't seem to improve the picture quality too much in real scenes. We're measuring a high contrast with the checkerboard test pattern, but it's not entirely representative of the performance in real content.

The SDR brightness is fantastic, so glare shouldn't be an issue in most bright rooms. It gets brightest with small highlights, as seen in the 10% and 25% windows, and even though brightness varies a bit between scenes, it shouldn't be too distracting.

We tested the SDR brightness after calibration in the 'Movie' Picture Mode with Brightness and Contrast at their max, Local Contrast on 'Low', the Color Temperature set to 'Warm -5', and Gamma on '2.2'.

You can achieve a slightly brighter image by setting Local Contrast to 'High' and Color Temperature to 'Cool 4'. We measured 1,180 cd/m² in the 25% window using these settings, but this comes at the cost of losing image accuracy.

The TCL 6 Series/R646 has a decent full-array local dimming feature. It has Mini LED backlighting like the TCL 6 Series/R635 2020 QLED, but it's an improvement overall. There are 128 zones on the 55 inch model, and the larger sizes may have more. Overall, it helps improve the contrast with our checkerboard pattern, but it doesn't seem as good as other TVs in improving the overall picture quality in dark scenes. There isn't much black crush because it seems that it raises the black level in scenes with bright objects, and it's almost as if the local dimming feature isn't doing enough. However, there's not much blooming around bright objects as the zones average out the black level. Subtitles also look good.

Uniformity is good, and you don't lose many details in scenes like a star field. Fast-moving objects transition between the zones well, and even though you may notice the transitions more with our pattern, it's not as noticeable in real content.

We recommend setting the local dimming, called Local Contrast, to 'Low' because the 'High' setting is more aggressive, resulting in too much black crush and blooming. However, with some real content, the difference is minimal, so you should choose whichever setting you prefer. We also measured the contrast in SDR and HDR with both settings:

• SDR Contrast
• Low: 19,300:1
• High: 15,692:1
• HDR Contrast
• Low: 18,952:1
• High: 18,766:1

However, these measurements are high and don't reflect entirely its performance with real content.

The local dimming in Game Mode is decent, and it performs the same as out of Game Mode. Once again, we recommend setting Local Contrast to 'Low'.

The TCL 6 Series has impressive HDR peak brightness. It doesn't get much brighter than in SDR, but it's still enough to make highlights stand out in HDR. We verified the real scene brightness to make sure the measurement was correct, and it was. The EOTF follows the target PQ curve nearly perfectly until the slow roll off at the peak brightness, so you don't lose too many details in bright scenes.

We measured it using the 'Movie' HDR Picture Mode with the Brightness and Contrast at their max, Local Contrast on 'Low', and Color Temperature on 'Warm -5'. There are two settings called Micro Contrast and Black Stretch that are meant to optimize the contrast and brightness, and we measured our checkerboard pattern with them, and they don't make much of a difference, if any.

If you find the image too dim, use the same settings as above, but with Dynamic Tone Mapping enabled and the Gamma set to '1.8'. This results in a much brighter EOTF, but it doesn't change the peak brightness.

The HDR brightness in Game Mode is excellent. It scores 0.1 better than outside of Game Mode because the real scene highlight is slightly brighter, but the visible difference is minimal. We tested it using the same settings as outside of Game Mode.

The gray uniformity is good. There aren't many visible issues here, except for some darker edges, but it's hard to tell. Uniformity is better in near-dark scenes. Keep in mind that uniformity can vary between units.

The black uniformity is good. Without local dimming, there's backlight bleed in the corners, and the local dimming feature helps eliminate that issue. With local dimming, you can see how it doesn't deliver perfect blacks, but there's less blooming than on the TCL 6 Series/R635 2020 QLED.

The TCL 6 Series 2021 has narrow viewing angles, which is expected from a VA panel. The image looks inaccurate if you're viewing it from the sides.

The reflection handling is excellent, and it's much better than the TCL 6 Series/R635 2020 QLED. It does a much better job at absorbing light, so combined with the high peak brightness, visibility shouldn't be an issue.

The TCL 55R646 has good out-of-the-box accuracy, but this can vary between units. Most colors are only slightly inaccurate, and the color temperature is close to the 6500K target. However, white balance is off, which affects the shades of gray, and gamma doesn't follow the 2.2 target well, so most scenes are darker than they should be.

The accuracy after calibration is fantastic. Color accuracy and the color temperature improved, and the white balance is much better too. Gamma is perfect for most scenes, but some really bright scenes are a bit too dark.

See our recommended settings here.

Unfortunately, the TCL 6 Series 2021 doesn't properly display 480p content. When we try to display an 852x480 resolution with a 16:9 aspect ratio from our PC, it upscales it to an 800x600 resolution with a 4:3 aspect ratio. We tried to change the Aspect Ratio settings on the TV, but everything looked off. The above image is a crop, but you can see the original with the black bars here. You can also see what the 4:3 image looks like here.

Fortunately, there aren't any issues with 720p content, like from cable boxes.

It upscales 1080p content nearly as good as native 4k content.

This TV displays native 4k content perfectly as there aren't any issues.

This 4k TV can't display an 8k signal.

This TV uses a BGR subpixel layout, which can affect how text is displayed when using the TV as a PC monitor. You can read about it here.

This TV has a great color gamut for HDR content. It has fantastic coverage of the commonly-used DCI P3 color space, and tone mapping is good, too, so colors look accurate. Coverage of the wider Rec. 2020 is more limited, but it's still decent.

The color volume is good. Thanks to its high peak brightness, it displays bright colors well, but it can't display extremely dark colors like an OLED because it doesn't have a near-infinite contrast.

Update 10/19/2021: We retook the gradient photo on an uncalibrated HDMI port, as the calibration appears to have caused a few flaws in the original photo. It didn't result in any changes to our results, but the photo is more consistent with our other reviews.

The TCL R646 has good gradient handling, and it's a significant improvement over the TCL 6 Series/R635 2020 QLED. There's obvious banding in the test pattern with the darker shads of each color, but it only seems to be happening at certain steps and not in between. Setting Gradation Clear to 'Low' or 'High' helps improve the banding in the test pattern and real content, but that comes at the cost of losing details.

Unfortunately, there are some signs of temporary image retention after displaying a high-contrast static image, but most of it disappears quickly. However, this can also vary between units, so your experience may be different.

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

The TCL R646 has a great overall response time. There's overshoot in most transitions, but the 0-100% transition is slow, resulting in black smearing, which is typical of VA panels.

The TCL R646 uses pulse-width modulation (PWM) to dim its backlight in any picture mode. It flickers at all backlight levels, including at its max. However, the flicker frequency is so high that most people won't notice it.

There's an optional backlight strobing feature, commonly known as black frame insertion. It only flickers at 120Hz and it creates noticeable image duplication, but it doesn't dim the screen much. Our BFI scoring is based on the flicker frequency,

There's a motion interpolation feature to interpolate 30 fps and 60 fps content up to 120 fps. It's not bad overall, but it still creates artifacts in fast-moving scenes. We tried to measure the flicker frequency with the motion interpolation feature, but there's so much noise we couldn't measure it properly.

Due to the quick response time, there's some stutter with lower-frame rate content because each frame holds on for longer. Enabling the motion interpolation feature can help reduce this.

It automatically removes 24p judder from any source, and no extra setting is needed.

It has variable refresh rate support to reduce screen tearing. TCL doesn't specify which formats it supports, but we confirmed with our Radeon PC that it supports FreeSync. VRR also works with the Xbox Series X, but because the Xbox supports both HDMI Forum VRR and FreeSync, there's no way to know which one is working and if it supports HDMI Forum VRR or not. It's also unclear when VRR is working because no prompt pops up on the TV, but we confirmed with the pendulum test video and in games that VRR works.

The TCL 6 Series/R646 has very low input lag in Game Mode. It's an improvement from the TCL 6 Series/R635 2020 QLED, and you shouldn't notice any delay when gaming. We had issues with our VRR input lag testing because the HDMI Forum VRR may have been active, so our results were a bit more inconsistent than normal, which is done with FreeSync. However, the results are still in line with what we expect.

The TCL 6 Series supports any resolution up to 4k @ 120Hz, as long as you set the HDMI Mode to 'HDMI 2.1' to reach the full bandwidth. It displays proper chroma 4:4:4 with 1080p and 4k signals at 60Hz, but it can't do it with any other signal. It accepts a 4k @ 120Hz signal in 10 or 12-bit color depth with chroma 4:4:4, but it doesn't properly display chroma 4:4:4 because text looks a bit fuzzier than what we would expect.

Update 10/19/2021: We've received a few requests to check for resolution halving in certain games. We tried it with Destiny 2 on an Xbox Series X and didn't notice any signs of resolution issues; 4k @ 120Hz is displayed properly.

This TV supports any signal from the Xbox Series X and PS5 up to 4k @ 120Hz. As mentioned in the Variable Refresh Rate section, no VRR signal shows up on the screen when it's working.

The HDMI 2.1 ports support full bandwidth HDMI 2.1, as we confirmed with the CRU. HDMI 1 and 2 support 4k @ 120Hz signals with up to 12-bit color depth and chroma 4:4:4, meaning it supports up to 48 Gbps, which is the maximum allowed under the HDMI 2.1 bandwidth.

The Composite In input needs an adapter, but it doesn't come with one.

This TV supports eARC, allowing you to pass DTS:X and Dolby Atmos audio formats to a compatible receiver using a single HDMI connection. During our testing, our receiver wasn't properly playing the Dolby Atmos audio file, but the Dolby Atmos logo popped up on the TV. This is likely an issue on our end, and we expect it to work for most people. Since TCL advertises the Dolby Atmos support, we list it as 'Yes', but if you experience the same issue, let us know.

The frequency response is decent. It's similar to the TCL 6 Series/R635 2020 QLED, but it gets louder and has a bit higher deviation, but the sound profile is still well-balanced. It has decent bass, but it's still nothing like a dedicated subwoofer.

The distortion performance is great. Even at the max volume, there's hardly any distortion. However, this depends on the content and not everyone may hear it.

Unlike the TCL 6 Series/R635 2020 QLED, the TCL 6 Series/R646 comes with Google TV. TCL uses its own implementation of Google TV, so the settings menu is different than on Sony and Hisense TVs. It may take some time to get used to, but menu navigation feels very smooth.

We read reports of people experience a ton of bugs with the Google TV. We didn't notice any, but if you do let us know.

There are ads on the home page, but we couldn't get a photo of them during testing because they pop in and out, and they're not always there.

The Google Play App store has a massive selection of apps available to download.

The remote is new and is rather simplistic. It has a few shortcut buttons, and the navigation buttons may seem unclear at first as to what they do. There's a built-in mic for voice control, and you can ask it to change inputs, open apps, and search for content, but you can't ask it to change settings.

There's a built-in mic in front of the TV that you can use for the Google Assistant feature, as long as the TV is on.

The power button is on the back of the TV on the right, and you can change inputs with it too. There's the switch to turn the built-in mic on and off above it.

• Remote control (with 2x AAA batteries)
• Power cord
• User guide