Panasonic's Black Eye

It's been a bad week for Panasonic. A report of suddenly rising black levels in its 2008 and '09 plasmas gained some serious traction throughout the A/V community over the past few days, even though it's been brewing since July 31, 2009, when AVS Forum member Orta (who I assume is male) posted that his TC-P50G10 doubled its black level literally overnight, with measurements to prove it. As you might imagine, this led to a flurry of concern, to which Panasonic finally responded with this official statement:

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.

Okay, so Panasonic plasmas are programmed to increase the "background brightness" (i.e., black level) to compensate for normal aging in the first few years of normal use, after which it should stabilize. But are they really supposed to suddenly double the black level at some point? If so—or even if the increment is supposed to be smaller than that—can the firmware be updated to minimize this effect? Maybe not—according to a cnet report, Bob Perry, a senior VP at Panasonic, says that the TVs work as designed, so there's nothing to fix.

This leads me to wonder if a programmed increase of driving voltage and thus black level over time is common practice among all plasma manufacturers. According to one of my tech contacts at Samsung, he's not aware that his company's plasmas change their level over time. I've also asked LG the same question about its plasmas, but I didn't receive a response by the time I posted this blog.

I applaud AVS Forum member Bdemers for collecting and graphing data about this issue from other members; the graph is reproduced above with permission. I question the absolute precision of these measurements, since most seem to have been taken with relatively inexpensive colorimeters that are probably not accurate at very low light levels, and the conditions under which the measurements were taken are probably inconsistent from one user to the next. But assuming that the measurements of each TV were taken with the same device under the same conditions, the results are valuable as a relative indication of how a given set's black level behaves over time.

As you can see in the graph, the black level of most entries did rise over time. But notice that, in at least one case, the black level did not rise, which corresponds to reports from some Panasonic owners of no visible increase in black level after hundreds of even thousands of hours of use.

This whole thing is particularly troubling to me as a reviewer, since I don't normally have the opportunity to test any TV over a long period of time. Even worse, the problem seems to be inconsistent, so I might or might not see it even if I could run a review unit for hundreds or thousands of hours. All I can do is report what I find, both good and bad, while setting up and watching each TV during the time I have with it.

Clearly, there are anecdotal indications that Panasonic plasmas increase their black level over time—the company even admits it—but there's no proof that it's universally problematic. I tend to think that a sudden doubling of black level is an isolated defect, not an endemic problem, since not all Panasonic owners report it. Also, while the AVS data are interesting, they do not form a statistically significant sample, and AVS members are more likely than the general public to notice and report even a slight increase in black level.

So for now, I'm not going to renounce my overall opinion that Panasonic plasmas are among the best you can buy today. However, I'm also going to keep an eye on this evolving story, and I'll report any significant developments. If you've seen rising black levels in your Panasonic plasma—or not—please let your fellow UAV readers and me know by posting a comment here.

Share | |
brock5's picture

Eyes are the most sensitive part of our body and all Eye disease are equally capable of harming the eyes, as they are very delicate

Joe's picture

Hi Scott, I have been reading about this myself. You are absolutely right that the meters are questionable, and the sample size is small. Furthermore the questionable meter means that some people posting small black level gains are surely seeing the noise in the meter. But I think that is beside the real point. Panasonic has admitted that the sets are designed to do this, and they have not told us the amount they are designed to increase. This is in addition to any black level increase (or peak light decrease) that would occur as a result of normal wear and tear, negatively affecting performance. If I was a Panasonic owner I would be several levels beyond furious. If I was a reviewer I would be angry that Panasonic had not bothered to mention this particular "design feature" while they were busy hyping the other 300 useless bells and whistles they add to every set. Pressure needs to be kept on Panasonic until they make a full disclosure. Let's hope they have learned from To

Joe's picture


David Vaughn's picture

I'll be calibrating a friends new Panasonic plasma soon and will take and store black level measurements with an i1pro meter. I'll keep an eye on his set and see if the same thing happens with it.

Oscar Worthy, DDS's picture

Pioneer Elite, why did you have to go away?!? My father just purchased a 65inch Panasonic V10. The set looks great now, hope it stays that way. We'll see. I feel a little bad, since I talked him into it. I hope this type of feature isn't built into Porsches---you start with 400 horsepower, and then as the engine ages, the central electronics will automatically adjust so that 25 peak horsepower are removed every 7000 miles; for your own safety and enjoyment of course. It will settle around 200 horsepower, which still gives great performance to Average Joe, just not what you remember having. Time to buy a new Porsche. Plasmas future was already shakey, this may be the dagger unfortunately. Please keep us informed on the gossip you hear about this within the professional community, Scott.

Scott Wilkinson's picture

David, what is the lowest light level that meter will reliably measure?

kelsci's picture

What we all do not know here is whether this phenomena happens to all plasma televisions as well.

Scott Wilkinson's picture

Kelsci, you're right, we don't know if this happens in all plasmas. As I said in the main blog text, I asked Samsung and LG if their plasmas do it; my tech contact at Samsung said he thinks theirs don't, but he wasn't completely sure, and I haven't heard back from LG yet. I'll continue to pursue this question until I get a definitive answer.

David Vaughn's picture

Scott, Measurement range: 0.2 to 300 cd/m2 Not as low as a Minolta, but it's much more affordable :) David

Scott Wilkinson's picture

So the low end is 0.06 fL...lower than I thought it would be, but way higher than the AVS data, most of which was taken with meters much like yours.

David Vaughn's picture

Scott, True enough, but it does provide a baseline. I can get consistent readings at low light levels although I'm sure they aren't as accurate as a Minolta, they can at least have a data point to work with. David

Scott Wilkinson's picture

Yes, as I said in the main text, the absolute numbers in the AVS data are probably not accurate, but they do reveal a relative trend over time among most of the samples measured by AVS members. I look forward to the results you obtain from your friend's Panasonic plasma after a few hundred hours of use.

KidHorn's picture

I have a 50g10 and I haven't measured the black levels precisely, but the black level has clearly risen. As a matter of fact you can see the black level jump up when turning on the TV. The image is very dark and after a second or two, it becomes more grey. My hunch is the TV adjusts the voltage a second or two after the TV is turned on. The problem is really noticeable when watching a dark scene with a small amount of ambient lighting in the room. I used to be able to make out some decent details in the dark areas and now it all looks like a dark grey blob.

Michael's picture

The meter most often used in the AVS chart is i1 LT/D2. It's relatively inexpensive but pretty good at measuring low luminance levels. In fact, it's much better than i1-pro which is five times more expensive and better at other things besides black level readings. Ask any professional calibrators and they will tell you the same thing.

Scott Wilkinson's picture

Michael, that's very interesting. Can the LT/D2 accurately measure down to 0.005 fL, an order of magnitude lower than the i1 Pro? What is its specified lower limit?

Michael's picture

Yes, it can measure 0.005 ftL. It may be off by +- 0.001 or maybe just a tad more so I'd give some margin to each data point still. Please note that Tom Hoffman in that chart is a pro and many others are enthusiasts who know what they are doing with their meters. Also, pre-rise black levels have been very consistent with the expected levels cited by D-Nice (another famous pro who alerted the AVS members with the inside info about the black rise).

Scott Wilkinson's picture

So it seems that much of the AVS data is more accurate than I supposed. Good to know...thanks!

David Vaughn's picture

I have a LT as well, so I'll measure the lowest levels with that meter. I'll take a read of the thread at AVS as well in order to perform the same tests they are using. David

Dennis's picture

Scott -- from AVS black rise thread, a poster questions D-Nice: Do you know if Pioneer, Samsung or LG use the same type of approach to increase voltage in a timed basis, as the panel ages, the way Panasonic does, and if they do, have people noticed the sort of loss of black levels, to the same degree that is happening with those Panasonic units? D-Nice's reply: All plasmas have to adjust their pixel voltage levels over time. However, what is going on with the 11/12G Panasonics is exclusive to Panasonic.Other PDPs are capable of adjusting the voltage levels without harming the idle luminance. I don't know the exact hours for the voltage changes. My comment: it's not the voltage change that's the issue, but how Panny has programmed/dealt w/idle luminance -- hence the rise in black levels. This alone should cause you to NOT recommend Panny sets until they "come clean" and fix what has been marketed as deep blacks. Sure, get deep blacks for a few mos. Gone before the warranty expi

Oscar Worthy, DDS's picture

The troubling fact is that picky viewers---meaning anyone reading this magazine, clearly noticed this tendency. Certainly UltimateAV will be reviewing the upcoming VT series of plasmas from Panasonic. Hopefully, this issue can be more extensively discussed with Panasonic representatives well versed in the operational parameters of their line. From what I've gathered, it appears the baseline black levels on these new units are remarkable, as the Pioneer patents for PDP are now owned by Panasonic. I have several collegues that have Elite plasmas, and this clearly visible issue has never surfaced for them over several years of use. It would be beneficial if Panasonic, to clear their rep, would allow you long term, real world use of a set for a few thousand hours like the automotive magazines frequently do. Panasonic has stated that the adjustment is more subtle on the new line. It seems the only way to clear the air.

The Audio Dufus's picture

The leading high-end dealer in my city has had many complaints from recent Panasonic plasma buyers, some wishing to return their sets. Graciously, they have accomodated these clients by allowing an exchange. The returns have not been motivated by performance, but on the fears generated via the web. The dealer discussed the issue with Panasonic and was given the same stock answer---the warranty will not be extended. Also, they related that all Plasma displays increase idle luminance voltage with aging of the sets phosphors. The Kuros had such a deep idle luminance that they just have more room to play with. The new VT plasmas incorporate this electronic idle level. The lead salesman has had the V series unit on display since it's release, amassing more hours use than most home use and has seen no alteration in black levels for any units. Really, can changes of thousandths of a foot Lambert be seen by the naked eye, or only Minoltas? It may be much ado about nothing.

Eric's picture

I've seen no noticeable change in black levels on my 65" V10 plasma after 285 hours. But still, this problem has me very worried about my purchase. The black levels were never as good as I initially expected but I've gotten over that, and now with the threat of the blacks increasing, I'm getting worried again. My picture is fantastic and I've already recommended Panasonic TVs to my friends with two buying G10s. Now I am looking like a fool.

David C's picture

With all the options now out there to consumers, how the heck does a novice like me just go into a showroom and say I want _____ TV, and know it is the best? I guess what I am getting at is, of all the sets you have reveiwed and seen straight out of the box, what, in your opinion, does the best job out of the box without needing additional calibration? I don't have the tools to do it myself nor do I have the money or local resources available to professionally calibrate it. I have respect for THX, should that be the key to looking for the new set also? Everything is changing so fast its impossible to say 1 size fits all but I just want the right inputs and the best picture. Why... why does it have to be so bloody complicated out of the box?

Scott Wilkinson's picture

David, I feel your pain! It is indeed a complicated A/V world. Most TVs look very bad right out of the box because they are in their "vivid" or "dynamic" mode. However, the first time you power up a TV with an Energy Star rating, it asks if it's going to be in a home or retail environment, and selecting "home" improves the picture quality quite a bit. Otherwise, select the "Movie" or "Cinema" picture mode and you'll be in the ballpark; use a setup disc like HD Basics or HD Benchmark to set the basic picture controls to get even closer. THX certification is not perfect, but it does get closer than many non-THX TVs can manage without a full calibration.

Nathan's picture

"This whole thing is particularly troubling to me as a reviewer, since I don't normally have the opportunity to test any TV over a long period of time. Even worse, the problem seems to be inconsistent, so I might or might not see it even if I could run a review unit for hundreds or thousands of hours." ....Now you know how automotive reviewers must feel!

cortisone interaction celebrex's picture

Hi piplviagra

Ray's picture

Could this issue just be a poor marketing decision that backfired ?(to boost brightness so the Vieras "are able to compete" with the newer, brighter LCD TVs?) After performing a firmware upgrade on a 54G10 in late 2009, the black level became immediately noticeably lighter and not as pleasant as it was with the original factory firmware (circa mid 2009). The recent Mar ch/Apr il 2010 G10 firmware update listed as Version TV 0190-2010 Status 1 01014-50217 Status 3 0.8.6 seems to have "restored" the black level to a similar value when the set was new. A color calibration run with the AVIA DVD confirmed the White and Black levels are now dead on, as are the Color and Tint. The picture looks amazing (again).

Ray's picture

Unless you earn your living trying to install multi walls of plasma TVs with "matched" dark level sets or live your life measuring the black level of your plasma TV, this issue has been blown out of proportion and it's not a big deal. More interestingly, average people can't even tell the difference. The black level change "scaring the hell out of paranoid buyers" is very small when compared to the change that occurs when switching from video setting modes from THX to Vivid, to Game, etc. Now, if you are one of those who are never satisfied, then shoot yourself on the foot and get an LCD TV.

jon86868's picture

I just purchased a runco xp 50 ortherwise known as a ucaled panny. The tech did mention that voltage regulation does occur over time not black level. How does this effect caliberate tv. I have just gotten out of a rear project sony I'm use to use. To bad blck levels. I have wish to return to such days.

Enter your Sound & Vision username.
Enter the password that accompanies your username.