Audiophiles and videophiles can be a little obsessive, endlessly analyzing and assessing various aspects of their favourite gear. The Internet magnifies that tendency, because it makes it easy for 'philes to share their observations - and obsessions.

A recent example involves Panasonic's 2009 plasmas. Last summer, some knowledgeable posters on AVS Forum began discussing a sudden increase in the black levels of certain Panasonic plasma TVs. TVs that had delivered very deep blacks when new now produced blacks that looked greyish. Included in these posts were careful measurements and photographs documenting the change. The story has been picked up by various technology Websites, notably CNET and Ultimate AV.

Panasonic acknowledges the issue. Responding to a CNET inquiry in early February, the company said that the TVs' firmware includes "an automatic control that adjusts the internal driving voltage at preset intervals of operational hours." The intent is to maintain reliable performance and optimal picture quality as the TV ages. The first automatic adjustment occurs after somewhere between 300 and 350 hours of operation. There are other adjustments at later intervals, until the TV is completely stabilized, after about three years of typical use.

Panasonic agrees that the adjustments affect visible black level, but maintains that even after the adjustments are complete, the televisions still deliver excellent performance. These assurances have not been enough to pacify concerned owners of these TVs. In early February, a group of them launched a class-action lawsuit against Panasonic in the U.S. Panasonic's stance is that the TVs work as designed, and so there is "nothing to fix." Panasonic's Canadian subsidiary says it has had service requests on this issue. The change in black level cannot be altered by adjustments to brightness or other controls, or any other kind of calibration.

I reviewed one of the affected televisions last summer. I liked the Panasonic TC-P50V10 well enough to name it (and other models in the series) as one of my Gear of the Year picks for 2009. That television is still in my home theatre, and has accumulated enough hours for it to have had at least one automatic voltage adjustment. In day-to-day viewing (as opposed to reviewing), I have not noticed any increase in black level. But most of my viewing is done in a room with subdued lighting, rather than a completely dark room. After following the story, I was curious to see whether black levels had changed.

Unlike the AVS Forum posters, I hadn't measured Minimum Luminance Level of the TV - the amount of light it produces when the picture is completely black; nor had I photographed the screen on a black picture. But I had taken detailed notes of my viewing impressions on a variety of Blu-ray Discs and recorded HDTV shows. Referring to my notes, I played the same or similar discs (the recorded shows were long gone).

My conclusions: whatever changes in black level have occurred, they are not visible except in a very dark (pitch-black or close) room. Even with subdued room lighting, I don't think they are visible. Nor are the changes in black level apparent with bright program material. At night, with all the lights turned off, it seemed to me that blacks weren't quite as deep on some content. The black bars above and below the picture in dark sections of wide-aspect-ratio movies like Casino Royale were a little greyer than I remembered. I had the same impression in other programs with predominantly dark content, including rolling credits against a black background. But other high-contrast HD content with dark elements on the screen, such as the Shallow Seas episode of Planet Earth, looked every bit as wonderful as I remembered, and as I had recorded in my notes.

I can understand that serious videophiles who do all their viewing in darkened rooms, who seek a truly cinematic experience, and who have invested in one of these TVs after careful research might feel kind of ticked. But most viewers will be delighted even with the shifted black levels.

In the end, there is a time to obsess and a time to enjoy. This controversy has not made me reconsider my choice of the V10 plasma as a Gear of the Year pick, nor has it detracted from my enjoyment of this set whenever I watch it.

Article Tags:  panasonic, plasma, black,level, brightness, minimum, luminance, adjustment, v10, AVS, forum, voltage, automatic, videophile