4K TV Reviews

Full-On/Full-Off Contrast Ratio: 17,500:1

Measurements were taken with a DVDO AVLab TPG 4K generator, X-Rite i1Pro2 Enhanced spectroradiometer, Klein K10-A colorimeter, and SpectraCal CalMan 3 calibration software.

Pre-calibration measurements were of the Pro2 preset with default settings. Post-calibration, in Pro2 with the Adaptive Backlight Control set to Max, black level measured 0.0022 foot-lamberts and peak brightness measured 38.5 ft-L, for a contrast ratio of 17,500:1. With Adaptive Backlight Control set to Off, black level measured 0.051 ft-L for a contrast ratio of 774.5 ft-L.

Average Delta E for pre-cal grayscale was an excellent 1.6, with a high of 2.8 at 70 IRE (70% brightness). Calibration improved this to a near-perfect 0.8, with the 10 IRE window measuring 2.1 and all others below 1.0. (Delta E is a figure of merit that indicates how closely a display adheres to the Rec. 709 HD color standard. Levels below 3 are considered visibly indistinguishable from perfect.)

Delta E for pre-cal color gamut averaged 1.0, also superb out-of-box accuracy, with blue the farthest from alignment at 2.4. Calibration improved this to 0.6.

Pre-calibration gamma averaged 2.32 with the 2.2 preset engaged. Calibration resulted in average gamma of 2.16 using the 2.3 preset.

Viewing angle was about the best I’ve seen for an LCD thanks to the Panasonic’s IPS (in-plane switching) panel type, with no fading of contrast or color-shifting visible at even 50 to 60 degrees off axis. There was some minor streaking of the backlight visible in the same area on full-field gray patterns that I attributed to the repeated rough handling and extensive travel of my heavily-used sample; this was not visible in program material and I dismissed it as a defect in my specific unit. Some very subtle haloing around lines of LED clusters behind the screen could also be detected with test patterns, but this was also not visible with real content.

The TC-65AX900U passed our processing tests except for 2:2 cadence tests for SD and HD, and the chroma and luma resolution tests for 1080i HD signals (it passed both for 1080p). The cadence results are typical and largely meaningless, as is the chroma resolution result. The luma test result is more unusual, but I saw nothing to suggest any issues with HD broadcasts, the only 1080i signals most people will ever watch.—RS