PRODUCT REVIEW: JULY 2008
SONY XEL-1 OLED TV
Sony’s XEL-1 is like no TV you’ve ever seen before. Does it measure up to its $2,500 price tag?
Many HDTVexpert.com readers have probably heard of organic light-emitting diodes (OLEDs) by now. Numerous companies have been working on them for over 20 years, ever since the first OLED was discovered (some say by accident) at Kodak in 1987.
Organic light-emitting diodes are extremely simple in structure. Each diode element consists of two electrodes (anode and cathode) and an organic film layer that separates them. When the number of electrons being emitted equal the number of “holes” in the opposite electrode, the organic material lights up and emits photons.
The organic material itself is formed using two competing processes — small molecule, developed by Kodak, and dispersed polymer, first invented at Cambridge University and taken privately by spin-off CDT (recently acquired by Sumimoto Chemical of Japan). All OLED display manufacturers license one or the other of these two processes.
Figure 1. Sony’s XEL-1 makes some eye-catching pictures.
Sony was one of the companies doing intensive research into OLEDs early on, and they’ve shown small OLED displays at past Society for Information Display conferences that had excellent color and contrast and wide viewing angles — all attributes of emissive display technologies, which OLEDs are.
Because OLEDs promise high display performance with thin form factors and low power consumption, they are considered to be the “next big thing” in display technology. However, there are numerous manufacturing issues that must first be resolved, such as brightness uniformity, current consumption, and differential aging of OLED materials.
Sony’s bid to bring the XEL-1 to market last fall seemed like a big gamble at the time. The suggested retail price of $2,500 (about $227 per diagonal inch) suggested that OLED yields were low, making the pricing of this product comparable to that of 42-inch plasma monitors from a decade ago.
Given the disparities in life to half-brightness of different OLED colors (blue OLEDs can drop to half-brightness in as little as 10,000 hours) and the inability of other major OLED manufacturers like Kodak, DuPont, LG Display, and Samsung to get their products to market, are you taking a big chance by purchasing one of these sets? Only time will tell…
OUT OF THE BOX
There’s not much to the XEL-1. As a TV, it’s pretty Spartan in appearance (or, should I say minimalist?). The styling is nice and the certainly is thin (about 3 millimeters). It sits at the end of a rigid support arm that extends out at an angle from the base, which is where you’ll find all of the connections and controls. The screen itself tilts front and back a total of 70 degrees, so you can select your optimal viewing angle.
The base, which is surprisingly heavy, is where the speaker system is located. The rear panel connectors are also minimal, with two HDMI 1.3 inputs for external video and audio sources, a single RF connector for analog and digital TV signals, and a USB connector that’s labeled “for service only” unless the optional Bravia DMex module is connected. There’s also a side-mounted 1/8” mini stereo jack for headphones.
Perhaps the most significant thing about the XEL-1 is that it’s the first TV I’ve tested in recent years that has no analog video input connections whatsoever — no composite, no S-video, not even a component connection. It’s HDMI all the way, or nothing.
Figure 2a. Yes, it really is that thin!
Figure 2b. There’s not much in the way of AV connections.
The top of the base contains several buttons for operating the XEL-1. They include a Home button (sort of the central location for all menus and something Sony calls XMB, or Xross Media Bar), Input selection, Volume Up/Down, and Channel Up/Down.
The supplied remote is also super-thin, but it has large buttons (hooray!) that are easy to find in a darkened room. In addition to Volume and Channel controls (set off by themselves), there are four silver buttons for Options (menu adjustments), Input (HDMI1/2 or TV), Return, and Favorites (pre-selected channels). You can also jump directly to sub menus with the Picture and Sound buttons.
The Wide button lets you choose between three different aspect ratios – Full, Wide Zoom, and Zoom. Full is used to show 4:3 and 16:9 content in their native aspect ratios, while Zoom fills the width of the screen with 4:3 content and Wide Zoom is good for filling the screen with letterboxed 4:3 programs.
There’s not too much to adjust in the Picture menu. Basically, you get the Big 5 settings, plus four different color temperatures (Cool, Neutral, Warm 1, and Warm 2). You’ll also find three steps each (plus off) of analog and MPEG noise reduction, three steps of black levels enhancement (contrast expansion), three different and unidentified gamma settings, and a Clear White function that boosts contrast at the high end.
Like other Sony products, the XEL-1 supports the xvYCC extended color gamut, and you can switch that mode on and off from the Picture menu. Of course, you’d need video content encoded in xvYCC in the first place, of which there is exactly none right now (and isn’t likely to be any time soon).
The Audio menu lets you trim treble, bass, balance, surround (S-Force front surround is used), a sound booster for expanded dynamic range, and Steady Sound, a compander for use with low overall volume levels to boost low-level audio.
One warning that caught my eye pertained to image burn-in. Like any other emissive display, OLEDs can experience differential aging over time from continuous display of bright, contrasty material, such as network bugs, screen crawls, and logos.
Here’s what the XEL-1 owner’s manual says about it:
Image Retention — Due to the characteristics of the material used in an OLED screen for its high-precision image, permanent image retention may occur if still images are displayed in the same position on the screen continuously, or repeatedly over extended periods.
Images that may cause image retention: Wide screen sources with black bars at top and bottom (Letterboxed Image), 4:3 screen sources with black bars at the left and right, non-moving images such as photo, game sources, on-screen tickers such as those used for news and headlines, on-screen menus, program guides, channel numbers, etc. of connected equipment such as a set-top box, video recorder, disc player, etc.
So there you have it. Of course, Sony hasn’t mentioned anything about differential color aging during normal operation. The jury’s still out on that one, and it will be interesting to see what posts come up in the next few months about the XEL-1 and any shifts in color over sustained period of use.
ON THE TEST BENCH
I gave the XEL-1 a pretty thorough workout. Of course, measuring screen brightness and contrast becomes problematic when your test instruments are ¼ the size of the entire screen! Nevertheless, I was able to log the key parameters using ColorFacts 7.5 and a Spyder 3 sensor, using text patterns from DisplayMate.
I usually open this section with the preface, “…after calibration for best grayscale image…” but first had to figure out if I could even accomplish that with the XEL-1, given the limited functionality of the user Picture menu.
After experimentation, I determined the best color balance and most consistent color temperature tracking was seen with lower brightness levels (120-130 nits). At the start, I measured nearly 200 nits from the display in Vivid mode, a number that doesn’t drop substantially in Standard mode. Instead, I selected Custom mode and dialed brightness and contrast back until I hit the magic number (120 nits is about 35 foot-Lamberts and plenty bright enough for normal viewing).
Figure 3. Gamma performance is excellent in any picture mode.
Figure 4. The most consistent color temperature tracking happens
around 120–130 nits of brightness.
Brightness uniformity varied by 30% across the screen, most notably to the lower center of the screen from the left and right side. Color temperature (not adjustable from the user menu) varied by 270 degrees across the screen, which is excellent performance for any display. (I logged it at 6280K at center screen.)
Gamma performance is remarkably consistent with any of the picture settings. I could not get the display to crush whites at any point — the gamma curve just kept climbing at 100% white in each test. What did vary was color temperature, though. Apparently there’s more “blue” in the mix with brighter images, as seen in the two color temperature histograms below (Figures 5 and 6).
Figure 5. This RGB histogram shows too much blue in the mix at higher brightness levels…
Figure 6. …while RGB levels are much closer in value at lower brightness levels.
You’ve probably noticed that I haven’t mentioned contrast measurements yet. That’s because my measuring equipment wasn’t sensitive enough to handle the super-low blacks from this OLED TV. “Black” is just about that — black with virtually no quiescent signal present at all. Once I started to see readings below .05 nits, I gave up. Suffice it to say that average (ANSI) contrast is well over 10,000:1 and peak contrast could exceed 100,000:1. The blacks are indeed that low.
The last step was to measure the XEL-1’s color gamut. I expected it to be wider than a conventional CRT, but was still surprised when I saw the results shown in Figure 7. The plotted gamut compares favorably with that of LCD, LCoS, and 3-chip DLP projectors, particularly in the green channel. Figure 8 shows the same gamut compared to the P3 gamut for digital cinema.
Turning the color gamut menu setting to Wide didn’t make much difference with respect to red, green, and blue coordinates, but shifted yellow, cyan, and magenta considerably, as seen in Figure 9. This would be the best setting to view a digital intermediate (DI) file, although the green locus is still inaccurate.
Figure 7. Here’s the XEL-1’s plotted color gamut, measured against the BT.709 HDTV color space.
Figure 8. And here’s the same gamut compared to the P3 digital cinema space.
Figure 9. Selecting Wide color space mode only shifts the yellow, blue, and magenta coordinates. The size of the XEL-1’s color gamut is about the same overall.
VIDEO QUALITY
The XEL-1 has a tough job working with most video signals because of its oddball ¼-HD resolution of 960x540 pixels. Oddly, a 4:3 standard-definition video program would have a nominal resolution of 720x480 pixels, resulting in minimal scaling. In fact, digital SDTV programs do look pretty crisp on the XEL-1 (analog signals are a bit softer).
HD content is also extremely crisp, although you will see some scaling artifacts like “twitter” with both 720p and 1080i programming. 720p needs to be compressed about 25%, while 1080i shows are packed down 50% in both axes. For my tests, I used the Realta HQV DVDs (both red laser and Blu-ray) to check out deinterlacing and 3:2 detection, and found the XEL-1 to be a decent performer in both regards.
The Super Speedway 3:2 clip took about ½ second to lock up each time — slower than some HDTVs, but acceptable. I saw similar results with the video and film resolution loss tests from the BD version, with the XEL-1 needing ½ to 1 second to recognize and correct for the cadence.
The film and video resolution loss tests also showed plenty of banding in higher-frequency multiburst tests, but that was due to the display’s lower resolution and not any problems with “bobbing” between 1080i frames — the XEL-1 weaves interlaced video to progressive scan quite nicely.
In terms of color quality, you’ll want to cut back on image brightness to the levels I suggested (start with Picture at 80 and brightness at 60 in Warm 2 mode) and you’ll love the flesh tones, pastels, and warm yellows you’ll get. Sony has already announced a professional version of the XEL-1 (HDVF-EL100) for attachment to studio and remote video cameras, so they’re on to something in terms of display accuracy.
CONCLUSION
Sony’s XEL-1 is a bold statement and a significant advance in TV technology, although its size is too small and its price too steep for all but the most diehard early adopters. $2500 is a price more likely to be paid by professional video production houses and broadcast networks, and that’s where I think the real niche for this product lies.
That said, you’d be hard-pressed to see this image quality on an LCD monitor. The black levels simply blow LCDs away and are as good as the best Pioneer KURO plasmas — maybe even better! Recall that Sony’s past CES demos of OLED monitors included not only 11-inch models, but also a 27-inch product at well. That (and Samsung’s 31-incher) is what I’m waiting for…
Power consumption: In a 2-hour test, the XEL-1 drew an average of 24 watts of power while displaying HDTV programming in Custom mode.
