Maxent MX-50X3 Plasma Monitor Tests and Calibration

Tests and Calibration

A separate service remote (not provided) is mandatory for calibrating the white balance of this set to D6500. The factory did make one available to me upon request, and its package had a warning that ". . .the service remote. . .is designed to be used by qualified service engineers and technicians." I assume that means that a qualified ISF technician ought to be able to get one; they are not available to a consumer.


To put the MX-50X3 through its paces, I fed it SD and HD signals in analog and digital formats from three set-top boxes, LG's LST3410 (terrestrial/cable), Motorola's DCT5000 (cable), and the recently-discontinued Radio Shack Accurian terrestrial receiver. Test patterns came from AccuPel HDG2000 and Sencore VP403 pattern generators, and a Panasonic RP56 DVD player took care of SD test patterns and charts.

The MX-50X3 runs a little on the "hot" side, when it comes to factory brightness and contrast settings. I turned back both controls to get the best grayscale possible and measured full screen brightness at 23.7fL (foot-Lamberts), using a full screen white test pattern. Small area (window) brightness was measured at 37.7fL.

Using a 16-block checkerboard pattern, I measured contrast at 667:1 average and 764:1 peak in Standard mode, while Cinema mode yielded readings of 591:1 and 660:1. Black levels were pretty low, averaging 0.056fL, which explains the high contrast numbers. Absolute peak contrast (using a white window on a black background) was 2072:1 in Standard mode and 1013:1 in Cinema mode.

I mentioned earlier that a service remote is required to access the RGB controls and fine-tune the white balance. Without it, you'll find the base color temperatures to be about 7700 degrees K (Standard) and 5600 degrees K (Cinema). The former is too cool, and the latter is a bit warm.

After some fiddling in the service menu, I was able to pull the Cinema grayscale to between 6300 and 6500 degrees, a better match to HD and movies transferred to video. Also, color temperature values were more linear across the brightness range than in the factory Cinema setting. Aside from the slightly cool reading at 20 IRE, the total swing in temperature was only 458 degrees across the grayscale. I've seen worse.

The available color gamut covers a good portion of the HDTV (REC709) color space, coming very close to the red and blue coordinates but missing the green coordinates. However, many flat-panel displays have a hard time achieving a deep, saturated green, and in this regard the MX-50X3 does about average when compared to some leading brands of plasma TVs.

How about bandwidth? In this area, the MX-50X3 has problems, as the highest frequency at which it could pass analog 720p luminance and chrominance multiburst patterns was 18.5MHz. With analog 1080i multiburst patterns luminance response clipped to 12.5MHz. Switching to the HDMI input didn't help things all that much; I observed banding at 18.5MHz with 720p and 1080i patterns.