This 55-inch 1080p TV doesn't ace its exams, but compared to the rest of the class, it's ahead of the curve. For $999, the AS680U delivers an inviting, user-friendly smart platform and solid picture quality.
Heavy & industrial
Aesthetically speaking, the AS680U is an unassuming television. The 55-inch panel rests on top of a heavy, rectangular steel stand that slots into the back of the TV with all of the grace of an industrial assembly line. If you examine the stand from the back, the exposed screws are not handsome. That said, there's something to be said for the stand's simplicity when viewed from the front.
On the back of the TV you'll find an L-shaped cutout harboring 3 HDMI ports, an ethernet jack, a digital audio output, shared component/composite inputs, and a coaxial connector.
The AS680U ships with two remote controls: a standard, no-frills remote, and a "Smart Touch" remote, which features a touchpad and voice recognition. Both of them work for every menu across the board, but the Smart Touch remote's circular touchpad makes using the TV's browser and smart platform much easier. There's no tactile feedback when tapping the center of the pad, however, so selecting menu items and typing is a frustrating experience more often than not. There are certain tasks that are easier with one remote than they are with the other, so I felt inclined to bounce back and forth between the two. Individual mileage may vary, of course.
We test TVs before and after calibrating them to determine how their default, out-of-the-box performance compares to reference standards. Exactly how closely a given TV can perform to standards is limited by the number of calibration controls offered in its software. For our calibration purposes, the AS680U features 2- and 10-point white balance controls, primary and secondary color adjustments, and gamma control.
I began in the AS680U's "Cinema" mode and set the color temperature to "Warm2." I left the gamma at 2.4, boosted the backlight to 51, and made finer adjustments to the TV's grayscale via its white balance controls.
Televisions produce black, white, and gray by combining red, green, and blue sub-pixels. We measure a TV's grayscale to determine how evenly these primary colors are emphasized. Color pollution occurs if there's an over- or under-emphasis of one or more sub-pixel. If a TV comes equipped with white balance controls, we can make attempts to fix these errors.
The errors themselves are measured in DeltaE across a grayscale that starts in the TV's deepest black (0 IRE) and ends in its reference white (100 IRE). We hope for an out-of-the-box DeltaE of 3 or less.
The AS680U performed terrifically in this area, averaging a DeltaE of 1.93 before calibration. After some fine-tuning it started to look even better, finishing off with an average of 0.61.
Upon further inspection, we can see that the cause for the initial reading of 1.93 can be attributed to the AS680U's over-emphasis of blue, particularly in the brighter regions of its grayscale.
Smart & somewhat savvy
Other than its big screen, the inclusion of Panasonic's 2014 smart platform (dubbed Smart Viera) is one of the things that vaults the AS680U into the mid-to-high-range class it occupies. The platform's main menu is split up into a customizable, easy-to-use grid. The inclusion of a remote with a touch pad makes navigation that much easier, particularly when using the internet browser.
If you already stream content via Apple TV, Roku, or a gaming console, Smart Viera might be a bit redundant. That said, the platform offers a fair share of gizmos to people who might be new to the world of smart content.
In the picture customization department, the AS680U is decent, but those hoping to do some extensive calibration might want to seek other avenues. Panasonic has outfitted the AS680U with detailed color management controls, but the white balance options are limited to 2- and 10-point customization.
Spending time with the AS680U proved to be a user-friendly endeavor with minimal head-scratching and eye-rolling. Between the apps that ship with the TV and the myriad options available through the Smart Viera app store, users looking to bring the web into their living room will be satisfied.
A solid performer with some blemishes
The AS680U packs a mean punch in the performance department, but not without a few flaws. First, the positives: deep, inky-black shadows and an accurate color palette.
I measured a terrific black level, a foundation for a picture rich with detail. And, aside from a blue tinge, the AS680U produces a satisfying array of properly saturated colors. In fact, when watching a movie side-by-side with our reference TV, the slight blue tint was the only distinguishing factor between each picture from a color standpoint.
After seeing countless TVs struggle to produce accurate color, it's always refreshing to experience content the way it was meant to be seen. This is particularly important for movies or shows that rely heavily on highly-stylized color filters in order to convey tone.
Panasonic has described the TV's refresh rate as "240Hz native" and, with the amount of times this is mentioned on the packaging, it wants to make sure you don't miss it. In practice, however, the AS680U's motion performance isn't as fluid as advertised. I spent a while with an action movie and went back and forth between being marginally impressed with the TV's ability to render motion and disappointed in how things were shaking out. Sequences involving quick camera pans and handheld shots were jittery, which makes it difficult to orient yourself within a scene.
The AS680U does feature a motion smoothing setting which cleans up some of the choppiness, but as is the case with most of these types of features, it removes all of the cinematic quality of whatever you happen to be watching. Even the lowest setting makes the picture look artificially rendered.
55-inch screens are built for group viewings, so viewing angle is particularly important when assessing a TV of this size. Unfortunately, the AS680U's picture does not hold up at even slightly off-center angles. For more on its narrow viewing angle, check out the Science page.
There's a wide range of audio equalization options built into the AS680U; an oft-neglected feature, even for higher-end TVs. The built-in speakers are adequate, albeit a little light on bass.
Contrast ratio describes a display's reference white divided by it's deepest black level. We consider black level the cornerstone of a TV's picture quality. Without rich, deep black levels, a good amount of detail in the picture is compromised.
We use an ANSI checkerboard to measure both black level and reference white. Although readings tend to be more favorable in 100% black and 100% white screens, we feel that the ANSI checkerboard is more representative of what's actually on the screen at any given time. After all, there's not too many instances in which viewers find themselves watching a white or black screen for an extended period of time.
The AS680U has an average reference white of 101 cd/m2 , but a better-than-average black level of 0.035 cd/m2 .
Our viewing angle test measures the maximum off-angle that viewers can watch a TV from before the picture degrades to less than 50% of its original quality.
Generally speaking, LED TVs struggle in this area (rest in peace, plasma). The AS680U is no exception to this rule, unfortunately. I measured a total viewing angle of 34°, or ±17° to either side of the screen. It's not great, but then again, it's par for the course for most of the AS680U's competitors.
A worthy competitor
The AS680U is a respectable performer with a satisfying, well-built smart platform. If you're able to pick it up for the online price of $999, you're locking down a great TV at a phenomenal price.
From a performance standpoint it certainly has its flaws, but it's occupying a place in the market that lacks competitive televisions at similar prices. That said, for roughly the same amount of money, you could upgrade to the 60-inch Vizio M602i-B3, which also features a smart platform and packs a great picture.
When dealing with color, television manufacturers strive to meet a set of international standards known as Rec. 709. This document outlines the precise saturation, luminance, and hue of a TV's primary and secondary colors.
The AS680U is an interesting case. Its out-of-the-box color measurements were decent, but could stand to have been improved. Despite the inclusion of a color management system within the TV's menu software, however, I was unable to correct the majority of the color points with any significance. It's simply a very stubborn TV.
That said, it's out-of-the-box test results are nothing to scoff at.
Gamma describes how quickly (or slowly) a TV jumps out of black (0 IRE) and into various shades of gray. If there's an uneven distribution of luminance at any of these stages, you might notice muddy, highly-segregated regions within the picture. The effect resembles a gradient with not enough information between each step. We calibrate our TVs for a gamma of 2.4, which is ideal for a room with little or no ambient lighting.
The AS680U produced a fantastic gamma sum of 2.43 out-of-the-box. Post-calibration results were even better: The TV arrived at a gamma of exactly 2.4.
Meet the testers
Senior Staff Writer@Reviewed
Michael Desjardin graduated from Emerson College after having studied media production and screenwriting. He specializes in tech for Reviewed, but also loves film criticism, weird ambient music, cooking, and food in general.See all of Michael Desjardin's reviews
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