Panasonic 65″ AX900U 4K LCD TV Review

Bench Tests

All video testing is done using CalMAN from SpectraCal. The standard targets are the HDTV Rec.709 colorspace with a gamma using the BT.1886 formula. The target for light output is between 35-40 foot-Lamberts which is ideal for a darker room. Measurements are performed using an i1Pro2 spectrometer and a C6 colorimeter. Patterns are APL 18% using a DVDO AVLabTPG. For the P3 color gamut we are using the P3 color points, the D65 white point, and a gamma using BT.1886.

The preset THX mode on the AX900U is very accurate. The only issue with THX mode is that it targets a gamma of 2.2 and not the BT.1886 gamma. BT.1886 can offer better shadow detail with an LCD TV and it what we use for our calibrations. If we changed our target to 2.2 then the THX preset would score even better than it does. The grayscale goes towards red a bit as we near 100% with the gamma at 90% being off as it is too close to 100% luminance. This doesn’t cause a big difference in the dE2000 number so it isn’t an error you’ll really see.

The color checker shows a couple issues in blue but nothing major at all. Luminance levels show no issue, and the only result that causes any question is the uniformity reading. This is really measuring the quality of the backlight, as the panel should be very uniform, but we see issues here. The dE2000 levels for white are relatively high and this is because the center is brighter than the rest of the screen. Since this is the first display we’ve run this on I can’t be certain if this is a good result or a bad result. Just know that ideal would be 0.0 across the screen for error levels.

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CalMAN can calibrate the AX900U directly but I had better results by doing it myself. It takes a bit longer but it produces better results. After calibration the grayscale could be improved with a couple more passes, but the colors are overall improved. The main issue seems to be the gamma changing a bit between calibration and final readings, likely due to the backlighting system. This could be cleaned up even better with more work but the difference is not really noticeable. Honestly the preset THX mode is so close to accurate that only the true purists are going to spend the time and money to calibrate it. If you do calibrate it the colors wind up virtually perfect.

In both cases we see that the contrast ratio is only 1100:1. This is common for an IPS LCD panel. Using the 18% APL patterns and enabling the local dimming produces the same results in measurement. In use the black levels are better looking than this, since 1100:1 is really a dark gray, but it doesn’t measure as well doing the standard method.

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I also measured and calibrated for the P3 color gamut. The AX900U can do 90% of the P3 gamut according to CalMAN which is below the 98% that Panasonic specs claim. It is still well beyond what the Rec.709 gamut can produce. The real issue is that green comes up a bit short while red and blue are both at the targets. Post-calibration the grayscale is practically perfect (showing what could be done in the Rec.709 mode had I spent more time tweaking by hand instead of using the automated routing) and the colors are very good up until 100% saturation. The 100% saturations are the issue since the panel is coming up short of the P3 targets while 90% and below are on-target.

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Aside from the contrast ratio, the Panasonic AX900U measures very well. It doesn’t quite do the full P3 gamut, but it does the HDTV gamut perfectly. Once we have P3 content the AX900U does enough of the gamut that you will still see a noticeable difference compared to the Rec.709 gamut.

Calibration Summary
Measurement Pre-Calibration Post-Calibration
Contrast Ratio: 1105:1 1153:1
White Level: 38.0 ftL 39.5 ftL
Black Level: 0.1177 ftL 0.1172 ftL
Gamma Point: 2.25 2.66
Average Grayscale dE2000: 1.86 2.28
Average Saturations dE2000: 1.98 1.43
Average Color Checker dE2000: 3.27 0.87
Summary: Post-calibration the AX900U is even more accurate but not by a huge amount. If you are OK with a gamma of 2.2 instead of BT.1886 then the THX mode will work just fine for you. What you'll need to calibrate for is the P3 gamut once content that uses that comes out. Colors are basically perfect post-calibration with the grayscale errors only being due to some fluctuations in the gamma from backlighting.