There has been some controversy about increases in the black levels of Panasonic’s 2009 plasmas as they age. They reportedly push higher than the level observed when the set is new. The increases apparently occur quite abruptly at certain time thresholds. Since we’re talking about changes that occur after hundreds of hours of use and not the dozens usually involved in a review, I didn’t observe any such effect in my evaluation of the TC-P50G20. I put 100 hours on this set before I performed the measurements and calibration, and perhaps 50 more hours before I’d finished the review.

Panasonic has admitted that it designed an automatic feature that increases the panel drive voltage into its 2009 and 2010 plasmas. It is designed to compensate for the subtle loss of panel brightness that’s inevitable over time. This could explain the increase in black level. Panasonic has also noted that while this automatic drive voltage feature is still present in the 2010 sets, it has now been made more gradual and thus less conspicuous. THX certified some of the 2009 Panasonic plasmas in question, as well as the TC-P50G20. It’s aware that this feature exists and has stated the following: “We evaluate product stability during the course of our testing process and are currently evaluating new testing procedures to address longer-term product aging and any resulting shifts in picture quality.”

Panasonic has extended our loan on the TC-P50G20 so that we can continue to test its black level and contrast ratio over time. We will report our findings at a future date both online at HomeTheaterMag.com and in these pages. It is our preference here at Home Theater that any such programmed increase, if present, be made optional for the user, at least in the THX and perhaps Custom Picture modes, unless serious technical issues preclude that option. THX states that, to its knowledge, the automatic drive voltage is not defeated on 2009 and 2010 Panasonic plasmas when the THX mode is engaged.

Nevertheless, even if this Panasonic’s black level doubles with time (which we don’t expect), it would likely still offer black levels that are superior to its competition. The TC-P50G20 will remain a Top Pick as our long-term testing continues.—TJN