February 4, 2010 9:16 AM PST

Panasonic admits plasma TV black level change but says picture quality still 'excellent'

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Panasonic says black level increases are automatic as part of normal operation.

(Credit: Sarah Tew/CNET)

Update March 3, 2010: CNET testing points to the extent of the black level increase in affected plasmas. Click here for details.

In response to complaints reporting a loss in black level performance in its plasma TVs over time, Panasonic has issued a statement.

It admitted that "background brightness will increase," but described the change as "automatic" over the TVs' lifespan and part of normal operation in order to "achieve the optimal picture performance throughout the life of the set."

It also said that newer plasma TVs will include a "more gradual change in Black Level over time," but made no mention of a fix for existing plasma TVs, whose owners first noted the issue at enthusiast Web site AVS forum.

Here's the entire statement as e-mailed to CNET, entitled "Automatic Control of Contrast over Operational Lifetime."

Panasonic Viera plasma HDTVs deliver exceptional picture performance throughout the lifetime of these products. Various elements and material characteristics of all electronic displays change with use over time. In order to achieve the optimal picture performance throughout the life of the set, Panasonic Viera plasma HDTVs incorporate an automatic control which adjusts an internal driving voltage at predetermined intervals of operational hours.
As a result of this automatic voltage adjustment, background brightness will increase from its initial value. After several years of typical use, the internal material characteristics will stabilize and no additional automatic voltage adjustments are required. The Black Level at this stabilized point will yield excellent picture performance.
The newest Viera plasma HDTVs incorporate an improved automatic control which applies the voltage adjustments in smaller increments. This results in a more gradual change in the Black Level over time.

More questions than answers
I first contacted Panasonic seeking comment on January 11 , and the company has not responded until this statement, which was e-mailed to me Wednesday, February 3. Though arguably better than silence, the statement leaves too many major questions unanswered.

I have followed up with Panasonic seeking those answers, asking, among other questions, if/when a fix is planned for current TVs to address owner complaints; at what "predetermined intervals" do the the voltages increase; when do the materials stabilize; what the quantitative difference is between the initial black level and the "stabilized point"; which are the "newest Viera plasma HDTVs" referred to in the statement; and what should owners do who are unsatisfied with the picture quality of their TVs. I'll update this story when I receive a reply.

The big picture for plasma
As I mentioned in the original report, I haven't seen a Panasonic plasma affected by the lighter black levels yet, so it's impossible for me to reply to the big question of whether the loss of black level performance is significant enough to make the TV pale in comparison to its competitors. Many eyewitnesses believe it is, judging from the original thread at AVS forum and from a few of the comments on the report, but other owners are less definitive or report no change.

I began a long-term test using two 2009 Panasonic plasmas in my lab, but it will be at least a month before I can expect to notice any change in black level. Of course, I'll report back when that happens.

I'll also report that since 2005, my main TV at home has been a Panasonic TH-50PHD8UK plasma, and I've never noticed a change in its black level performance. At CNET, we didn't hear of this issue until we read the reports on AVS forum, and to our knowledge, past Panasonic plasmas, as well as models by LG, Pioneer and Samsung, have delivered basically consistent black levels over time.

That's why, despite Panasonic's statement that "all electronic displays change with use over time" and that after said change its sets still have "excellent picture performance," I tend to believe owners who describe the black level increase in the company's latest plasmas as unusual and ultimately detrimental to picture quality.

A quote included in my original report accords perfectly with much of Panasonic's eventual statement, enforcing that belief. In it a respected calibrator who goes by the screen name D-Nice, citing sources within the company, called the too-aggressive voltage increase a "goof" on the part of Panasonic engineering. The closest Panasonic has come to admitting as much is contained in its reference to an improved, more gradual change in new models.

Now what?
My main job at CNET is to provide buying advice regarding TVs, and Panasonic plasmas were one of my go-to recommendations. The 50-inch G10 was the most popular TV on CNET during 2009, and the V10 series earned the only Editors' Choice award I handed out to any flat-panel TV last year. In fact, after I reviewed the 2009 models, my dad bought a TC-P42X1, two of my colleagues at CNET, Matthew Moskovciak and John Falcone, bought TC-P50G10s and another, David Carnoy, bought a TC-P65S1 (we're keeping tabs on the black levels of those sets, too). It's safe to say that many readers of this Web site did the same thing dad, John, Matt and David did: buy a solid-to-excellent HDTV for a good price, and be perfectly happy with the picture quality. Judging from reader reaction, that happiness may be in jeopardy.

Nothing halts a shopper's reach for his wallet better than doubt, so I believe it's in Panasonic's best interest to answer those lingering questions. Until that happens, it's going to be hard for me to recommend the company's TVs without a degree of uncertainty.