Review Projector BenQ MX631ST Short Throw

The BenQ MX631ST is a short throw projector intended for use in classrooms or conference rooms.  It is a single chip DLP XGA projector that in its brightest mode is specified to produce 3200 lumens and its lamp is rated to have an unsually long life of up to 10,000 hours, in SmartEco mode.  Even when operated in the full power (i.e, “normal”) mode, the lamp is rated at a fairly long 4,500 hours life.

This is a XGA resolution projector (i.e., 1024 x 768) with a 4 x 3 aspect ratio as is typical for many entry-level business and classroom projectors.  However, since many classrooms and conference rooms are already equipped with 4 x 3 aspect ratio projection screens, the MX631ST is certainly a viable choice when replacing an existing XGA projector.

BenQ describes the MX631ST as follows:

“Designed to deliver crisp, bright, larger-than-life images from a short projection distance, the BenQ MX631ST is ideal for use in places where space is at a premium such as small conference rooms, training rooms and classrooms. With a powerful 3200 ANSI lumens bright image and an impressive 13000:1 contrast ratio, razor sharp image and rich, accurate colors, the MX631ST will help you present your best.

With brightness of 3200 lumens, Projector BenQ MX631ST directly competes against 3LCD and other single chip DLP projectors from a variety of other companies.  In fact, this is one of the most crowded segments of the projector marketplace, and represents what is essentially entry-level for a a relatively bright business or classroom projector.


  • Long lamp life – up to 10,000 hours
  • Short throw design supports placement fairly close to the screen (e.g., 1 screen width)
  • Two HDMI inputs, one support MHL 2.0
  • XGA resolution (1024 x 768) and 4 x 3 Aspect Ratio
  • Built-in 10 watt speaker
  • 3D support compatible with Blu-ray 3D sources
  • Produces relatively high image contrast, for this class of projector

BenQ MX631ST Short Throw Projector – Special Features:  Short Throw, MHL Support, Extensive Eco Support, Long Lamp Life, 3D Support, Compatible with Chromecast and Roku Stick.

Short Throw

Business and classroom projectors in this class typically have zoom lenses with a limited zoom range and the Projector BenQ MX631ST is no exception.  Its 1.2:1 zoom ratio is typical, but this model has a relatively short throw ratio of 0.9 to 1.08 meaning when projecting, for example, an 80 inch wide image the projector can be located as close as 72 inches and as far as 86.4 inches from the screen.  Ideally the projector should be placed a little below the bottom of the screen, when table mounted, or a little above the top of the screen, when ceiling mounted.  Using a short throw projector, such as the MX631ST, can be useful in keeping the light from the projector away from the presenter’s or teacher’s eyes when they are standing toward the front of the room, although not to the extent possible with ultra throw projectors.   The bottom line is a short throw model can be the right choice for may conference room or classroom situations.

MHL Support

MHL is essentially mobile HDMI. The MX631ST supports MHL on its HDMI #2 input.  This allows you to plug in MHL compatible devices such as a Roku stick or a MHL enabled smart phone (however, not tested for this review).   MHL is relatively recent, so it may see a lot more capabilities down the road.  To be effective, since MHL supports video, audio, and command and control, a projector really should have its own sound system and the MX631ST does appear to have these capabilities. MHL allows many people to “cut the cord”.   BenQ specifically says the MHL capabilities of the MX631ST allows you to display pictures, movies and games from MHL enabled Android devices to the big screen

Extensive Eco Support

Projector BenQ MX631ST supports what BenQ calls SmartEco(TM) technlology.  They describe this as:

“…the MX631ST not only offers greater energy savings, but continues to deliver amazing picture quality through this innovative technology. SmartEco mode is designed to use only the exact amount of lamp power a projector needs to deliver the best contrast and brightness performance. This feature enables the MX631ST to deliver uncompromised projection quality with the added benefit of reduced the total cost of ownership by extending the lamp life and lowering power consumption.”

One of energy saving features is when there is no input signal present, the lamp power is reduced to only 30% of full power, thus reducing both energy consumption and extending the lamp life.

Long Lamp Life

BenQ literature says “Within the SmartEco Lamp Saving Technology umbrella, Lamp Care mode takes your dollars further – much further by offering an astonishing lamp life of up to 10,000 hours!”  Now of course you cannot expect that sort of lamp life if you always run the projector in normal power mode, but it does appear the MX631ST should be among the best in terms of lamp life and only seriously outdone by LED and laser based projectors.  BenQ provide a 1 year warranty (or 2000 hours of use) on the original installed lamp while replacement lamps only carry the standard 90 day warranty.

3D Support

Many low cost DLP projectors lack support for the 3D signal format used by Blu-ray Discs, but this is not the case for the MX631ST.  It is spec’ed to support the most popular 3D signal formats, including the frame packing technique used for Blu-ray.  BenQ did not provide 3D glasses with the review unit and I did not evaluate the 3D capabilities of the projector.


  • Sharp display with good focus uniformity, limited only by the projector’s native 1024 x 768 resolution.
  • Short throw may make some installations easier than with projector’s having a mid-throw
  • Relatively quick and easy setup with factory default setup settings appropriate for most users using this as portable projector.
  • Unusually long lamp life, especially when operated in SmartEco mode
  • Supports MHL via HDMI input for connection of MHL capable smart phones and tablets
  • Superior contrast as compared to 3LCD business/education projectors in this same price range
  • Built-in speaker produces adequate volume for most moderate size conference rooms or classrooms


  • Many picture adjustments are greyed out (i.e., not available to the user) when using HDMI inputs, which limits the ability of the user to improve picture accuracy
  • While the manufacturer’s lumen rating was verified, these White Lumens values can be misleading when comparing to other projectors that offer similar white lumens but much higher Color Lumens
  • No microphone input may be a limitation for some business or classroom applications
  • No network based management tools offered which could be an issue for applications where multiple projectors are to be installed (i.e., not simply used as a portable or standalone installation)
  • Remote control has no backlight make is difficult to operate in dim room lighting
  • Brightness uniformity of the projected image was not very good will a brightness fall-off toward the right side, when the projector was table mounted.

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