Editors' Note 04/30/2009: This product has been discontinued, but CNET is continually reviewing current LED-backlit LCD TVs.
Editors' Note 04/29/2008: The rating on this review has been modified from 8.3 to 8.0 due to changes in the competitive marketplace.
Among that tiny segment of the population that cares about the latest HDTV technology, and the even tinier segment that can afford it, the introduction of Samsung's 81 series of flat-panel LCDs is kind of like early Christmas. The first widely distributed LCD HDTVs to incorporate LED backlights--Sony sold a few Qualia 005s a couple years ago at $8,000 to $15,000 a pop--the Samsungs promise amazing black levels, claiming a contrast ratio spec of 500,000:1. The subject of this review, the 46-inch LN-T4681F, does indeed offer the amazing ability to basically disappear in a dark room when displaying a dark scene. That's a tremendous accomplishment for any display, but in the end it's not quite enough to earn our highest praise, because the TV's poor off-angle performance and shiny screen hobble its real-world picture quality in the face of stiff competition, especially given its premium price point. Those issues aside, there's no doubt the Samsung LN-T4681F will make videophiles who can afford it grin with pleasure every time the screen fades to black.
Leave it to Samsung to put together yet another ultrasleek HDTV. The LN-T4681F continues the company's trend of clothing its panels entirely in glossy black, although this model takes things a step further with a few noteworthy accents. The most noticeable consists of a pair of vertical clear acrylic strips running along either edge of the panel. Cupped to deflect sound from the side-mounted speakers into the room, they also serve to support another pair of vertical strips, these made of solid dark gray material that seems a bit out of place among all that gloss.
The overall effect, especially considering the rather wide expanse of glossy black frame between the screen and the clear strips, is of a very wide HDTV; an effect that's further enhanced by the relatively narrow top and bottom sections of the frame around the screen. All told, the LN-T4681F measures 48.4 by 29.6 by 12.6 inches and weighs about 77 pounds including the swivel stand; sans stand, it measures 48.4 by 27 by 4.4 inches and weighs 66 pounds.
Unfortunately the LN-T4681F is saddled with the same shiny screen we complained about during our review of the LN-T4665F. While it catches the eye on the sales floor and lets you check your hair, those benefits are outweighed by its distracting reflectivity under normal room lighting (see Performance).
Samsung's remote is almost the same as last year, and we generally found that the slender wand was easy to operate. Only the keys for volume, channel, and device control (the universal clicker can command four other pieces of gear) are illuminated, but that's better than most TV remotes, which skip backlighting altogether. All of the buttons are nicely separated and differentiated, with the exception of the secondary controls clustered at the clicker's base, which kind of blend together. We'd like to see dedicated buttons for each input, although because the set automatically senses and skips inactive inputs, cycling between sources is less arduous than usual. The menu system is easy to navigate, and we appreciated the text explanations that accompanied the selections.
The reason the Samsung LN-T4681F costs significantly more than any LCD TV at its screen size has to do with its backlight. On flat-panel LCDs, the backlight is what powers the picture, and it's generally made of cold-cathode fluorescents (CCFL). Using light-emitting diodes (LED) instead supposedly improves color reproduction over standard LCDs and cuts power consumption somewhat, but by far the most important improvement comes in the form of black-level performance. That's because individual sections of the backlight can be turned off independently and completely, a process Samsung calls "local dimming." As a result, black parts of the picture, such as the void of space or letterbox bars, actually look black instead of the darker gray typical of many flat-panel displays. See Performance for details.
Although many LCD HDTVs this year offer a 120Hz refresh rate, the LN-T4681F refreshes its image at the standard 60Hz. In comparison, the less-expensive, non-LED-backlit LN-T71F series refreshes at 120Hz. We haven't seen many benefits of 120Hz by itself, although we have seen some marked improvements caused by antijudder technology, which the 81F also lacks. The set does include a feature called "LED Motion Plus," which, according to Samsung, cycles the LED backlight in eight horizontal sections, once every frame in sync with the LCD, to avoid illuminating LCDs when they're turning off, and thus eliminating "a majority of visible image lag." That sounds well and good, but we encountered a quirk with this feature that discouraged us from engaging it, although this quirk is eliminated with the latest firmware.
Other picture adjustments abound on the LN-T4681F. We liked the ability to adjust the three picture modes independently for each input, allowing us to customize each source with three different groups of picture settings. Only Movie mode allows full adjustment, however, so we recommend using it for the most demanding viewing conditions.
In addition to the five presets for color temperature, there's a full set of detailed color temperature controls. Labeled "white balance," they offer both gain and offset adjustments for red, green, and blue, which allows more advanced users to really zero in the set's grayscale. The My Color control, on the other hand, doesn't seem to do much of anything helpful, so we left it in the default positions. The selection of secondary picture controls includes items labeled "black level," which affects shadow detail; dynamic contrast, which adjusts black level on the fly; gamma, which affects the rate of progression from dark to light; and a selection for color gamut, which controls the range of colors the display can reproduce.
We appreciated the solid collection of aspect ratio controls, which include four choices for HD sources. Just Scan is our favorite because it introduces no overscan and does not scale 1080i or 1080p sources, preserving the dot-by-dot match to the TV's native pixels. Standard-def sources allow four choices, as well, including two zoom modes you can adjust vertically to see subtitles or obscure tickers, for example. The Samsung also has a picture-in-picture function that allows it to display two programs at once.
The setup menu controls include, among other items, the energy-saving function of the LN-T46681F. You can choose from four different energy saver modes, which limit peak light output (backlight intensity) to conserve power. As promised, even at full strength the LED backlight does consume less energy than most traditional CCFL backlights we've tested, and the "local dimming" function has the added benefit of cutting power consumption during darker scenes--much like a plasma (see The Basics of TV power for details). The LN-T4681F consumed just a bit less power (about $2 per year) than the former champ, the 46-inch Sony KDL-46S3000 in its default setting. See the Juice Box for complete details.
Like many 2007 HDTVs, the Samsung LN-T4681F offers three HDMI inputs, as opposed to just two, and all are HDMI 1.3-compatible, for what it's worth. Two are on the back, while a third can be found in a recessed bay along the panel's left side. The Samsung's commendable connectivity continues by including a pair of component-video inputs; an AV input with S-Video and composite video; two RF inputs for cable and antenna; and a VGA-style RGB input for computers. That recessed bay offers an additional AV input with S-Video and composite video, a headphone jack, and a USB port that can interface with thumb drives to display photos (JPEG only) and play music (MP3 only).
It's not a stretch to call the Samsung LN-T4681F's picture quality a breakthrough. For anyone sitting in the sweet spot in front of the set, watching in a dark room, it delivers better overall picture quality--namely black levels and color accuracy--than any HDTV we've tested so far. What prevents it from earning our highest praise is its performance to people sitting to either side of the sweet spot and, to a lesser extent, viewing the TV with the room lights on.