Vizio P652ui-B2 (P Series) 4K LED TV Review
Vizio's P Series is the perfect choice for building your home theater on a budget.
Behind The Screens
The Vizio P652ui-B2 is an admirable performer with a few minor-but-definite flaws. This TV's full-array backlight with local dimming provides excellent minimum luminance and reference white levels, and reduces common issues with lamp uniformity. Vizio's pixel tuning helps maintain similarities in halation and loading (white falloff), ensuring that varying APLs emit similar luminances.
Because it wields a VA (vertical alignment) LCD panel, the P652ui-B2 doesn't present with the widest viewing angle, but it's similar to competing 4K TVs in that regard. This unit's biggest flaw is in terms of color production: it struggles a bit to fully saturate red, green, and blue, with minor hue discrepancies in secondary colors in the Calibrated Dark picture mode.
In a menu called "Picture Mode Management," the P652ui-B2 features an expansive control called Color Tuner that allows access to 2- and 11-point grayscale controls, a full 18-step Color Management System, a gamma slider, and a few test patterns. In conjunction with our CS-200 chroma meter and the CalMan 5 software, I worked in the Calibrated Dark picture mode to tune the P652ui-B2 to ideal home theater standards: a gamma curve of about 2.4, and a reference white of about 40 fL.
Throughout the Science Page, you'll see side-by-side charts documenting the performance of the P652ui-B2's out-of-the-box calibration (as found) and my calibrated results side-by-side. Below are details of the P652ui-B2's picture settings in the Calibrated Dark picture mode and my final settings. Note: I turned off all processing effects during the calibration session.
Thanks to its full-array backlight with local dimming, the Vizio P652ui-B2 is capable of a very commendable contrast ratio. Using the standard ANSi checkerboard pattern in the Calibrated Dark default settings, I measured a minimum luminance of 0.02 cd/m2 and a reference white of 120.70 cd/m2, for a total contrast ratio of 6035:1. This is almost exactly the same result as Sony's X950B flagship.
Uniformity refers to how even the output of a TV's backlight LEDs are. Excessive or underwhelming luminance can cause streaking or hot spots in the picture, especially in very dark/shadowy scenes. While we've yet to implement an objective test for backlight uniformity, it's something that's only a problem when directly perceptible, making it easy to document subjectively or with photos.
I checked the P652ui-B2's backlight uniformity by viewing 50, 40, 30, 20, and 10 IRE full-field white patterns, and photographed each result. At 40 and 50 IRE (mid-tone luminances), small vertical interruptions in the panel's light are slightly visible, but get harder to see into the lower shadow tones. There were certainly no major uniformity problems on our sample unit. Note that at 5 IRE and below, full-field screens automatically dim and turn off.
Because it has a VA (vertical alignment) panel, which arranges liquid crystals in such a way that they block light well at the cost of horizontal (and vertical) viewing, the P652ui-B2 does not have a very good viewing angle. It's comparable to edge-lit TVs in this regard, and performed notably worse than the Sony X950B, another full-array 4K television. I measured a total viewing angle of 41°, or ±20.5° from the center to either side of the screen.
The P652ui-B2 struggles to entirely saturate its red, green, and blue primary colors to the full ideal degree as documented in the ITU's Rec. 709 guidebook. Unlike many other 4K TVs, this Vizio doesn't allow the user to select between a calibrated and a wider (native) color space, and content suffers from slight undersaturation as a result. The Calibrated and Calibrated Dark picture modes are both pre-set to these slightly undersaturated versions of Rec. 709. It isn't a major problem, but it may fall short in the future when content is created at higher levels of color saturation.
Grayscale & RGB Balance
The ideal result for visible error within grayscale elements (expressed as a collective called DeltaE) is 3 or less. Prior to calibration, the P652ui-B2 tested with a total DeltaE of 6.4, which isn't egregious, but is obviously more error than we'd like to see. Using the TV's 2- and 11-point white balance controls, I found it very easy to line up the TV's RGB emphasis and achieve a DeltaE of 0.59.
We can tell where this error stems from when taking a closer look at how the P652ui-B2 emphasizes red, green, and blue within the grayscale. Ideal emphasis puts red, green, and blue equally at about 100% of the signal from 10-100 IRE, but by default the P652ui-B2 over-emphasizes red and blue at the expense of green. It was easy enough to line up the emphasis to an almost perfect result, however.
Gamma refers to the mid-tone luminance of a display, or how quickly it adds luminance at each IRE step out of black towards reference white. Vizio claims that the Calibrated Dark picture mode adheres to a gamma of 2.2, and while the out-of-the-box result was 2.17 (which is close), the points themselves do not follow a straight line: in actuality, this gamma is closer to 1.8 as it grows bright out of black much too quickly.
Other than a single hiccup at 90 IRE (the peak level for most broadcast content), calibrating the P652ui-B2 to a gamma closer to 2.4—the dark room ideal—was relatively easy. I ended with a gamma of 2.38.
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