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BenQ MX631ST Short Throw Projector Review - Performance

Posted on November 24, 2015 by Art Feierman
BenQ MX631ST Review:  Brightness - Noise - Audio The BenQ MX631ST has a zoom lens with a 1.2:1 zoom ratio and with a specified throw ratio range of 0.9 to 1.08.   For the following measurements and evaluations,  the zoom lens was set at the mid position and the projected image was just under 74 inches wide.


Picture Mode                                                             White Lumens*
Bright 3279
Presentation 2584
sRGB 1731
Cinema 2361


The BenQ MX631ST, like many other single-chip DLP based business and education projectors in this class, have a Brilliant Color feature and uses a clear segment in the color wheel to increase the brightness of whites and lighter shades.  However, this produces an overall less accurate image with the more saturated colors appearing far too dark and muted as compared to the whites and lighter shades.  To evaluate the brightness impact of the Brilliant Color feature I set it to off and then measured the brightness of a 100% white test pattern with the projector operating in Cinema mode.  The lumens output dropped from  2361 lumens with Brilliant Color turned on (as shown in the table) to only 834 lumens with Brilliant Color turned off.  This lower value more closely represents the Color Lumens brightness of the projector in Cinema picture mode.  For more on the topic see the article we have prepared HERE, that covers Color Lumens along with a few other topics.

The reported brightness levels in the above table were with the projector's zoom lens set to it mid-position, with the lamp set to Normal Mode (the brightest mode), and the factory default settings for each picture mode, which included Brilliant Color being turned on.  As noted above, the Color Lumens for this projector is much lower for each of the picture modes, as is typical for many single-chip DLP projectors of this class.

Operating the projector in Eco mode reduced the lumens output by 20%.

I found that lumens output varied very little over the limited 1.2X zoom range of the MX631ST.  Brightness uniformity did vary across the projected image with the left side of the image showing very little drop in brightness as compared to the center of the image, but the brightness fell off on the right side of the image, measuring a worst case 40% drop at the bottom right corner.  This was with the projector table mounted and with no digital keystone correction being used.

I checked the native on/off Contrast Ratio and measured a maximum of near 2,000:1 in the best case, which is certainly better than 3LCD projectors of this class and is competitive with other DLP projectors in the class.

BenQ did not provide compatible 3D glass and the performance of the projector's 3D mode was not tested.

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BenQ specifies the noise produced by the MX631ST as 33 dBA in normal (high) lamp mode and 28 dBA in Eco mode.  These noise levels are not excessive when comparing to competing projectors of this class and certainly less than many projectors rated at around 3000 lumens.

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Audio Performance

The MX631ST has a single 10 watt speaker that is capable of producing reasonably good sound quality.  Certainly adequate for use in most conference rooms or small to perhaps moderate size classrooms.  if you really need higher fidelity or higher volume levels use of an external power speaker(s) is suggested.  Overall, I would rate the overall audio performance a little above average for this class of projector and certainly much better than can be found with smaller pico and pocket projectors.

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