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Acer K138ST Projector Review – Special Features

Posted on December 15, 2017 by Nikki Zelinger

Acer K138ST Projector Review – Special Features: LED Light Engine, Gaming, 3D Capable, Bluetooth Enabled, Wireless Networking

LED Light Engine

This is a common trait of pocket projectors. The LED light engine lasts up to 30,000 hours in ECO mode, 20,000 at full power. That’s a far cry from most lamp-based projectors of today, which claim between 3,000 and 8,000 hours running at full power, with considerable dimming happening within the first thousands of hours. Not so with LED light engines – you’ll be running this puppy for thousands upon thousands of hours before you start to see it dim. In fact, you’ll be getting your next projector well before you even approach the claimed light engine life, even running at full power.

Some quick perspective here. Running the Acer K138ST at full power for 40 hours a week for a year would bring you to a mere 2,080 hours. You’d have to run it for just under 10 years to reach the 20,000 hour mark. I highly doubt that you will be satisfied with the same projector (and with 720p resolution) for ten years, especially considering that we are well on our way to 8K resolution, and true 4K projectors have just dropped to below $5,000 with the release of Sony’s VPL-VW285ES this year. You will definitely be upgrading well before you even have to think about the light engine going out.

Gaming on the Acer K138ST

This projector’s got game! I won't go into much detail here, as I talk at length about the Acer K138ST's gaming capabilities on the Performance Page later in this review. Suffice it to say that the K138ST has some of the lowest input lag available, better than most $1000+ projectors, leagues better than its own competitors in the same price rang - even better than my own Epson Home Cinema 5040UB, which costs $2,699. Consider that a definite plus for this pocket projector!

For those of you that don't know, input lag refers to the time it takes for the signal to go from your gaming unit to the display (projector), and is measured in milliseconds. Really excellent input lag falls below 30ms, where this projector measured, while 50 ms is merely acceptable. Anything above 50 ms is truly ugly - the longer the delay, the more frames behind you will be. This Acer performed remarkably well in terms of input lag, so check out the Display Input Lag section later in this review for more information (and clarity) as well as screenshots of gaming on the Acer K138ST.

3D Capable

The Acer K138ST has 3D capabilities! This is really cool to see on such a low-priced projector, especially in the pocket projector class. I find it interesting that this little guy has 3D, while many of the newer 4K UHD projectors do not (manufacturers claim there’s “no 4K standard for 3D” – a lame excuse, by our estimate). Still, the K138ST has a low lumen count for projecting 3D, as 3D eats up about two thirds of the projector’s brightness. Yikes! That gives you roughly 266 lumens to work with. That’s quite dim, so you can expect that you will only be watching 3D at night in a fully darkened room.

The Acer uses active shutter 3D glasses with 3D DLP Link. This allows you to purchase 3D DLP Link Active Shutter Glasses from Acer or any other brand using this technology. You can find these for around $20, give or take, depending on where you look. Do not get passive or polarized glasses “to save money.” They don’t work with this technology. That said, 3D was entertaining on this projector, albeit dim. I don’t own any 3D content (I borrowed Gravity from Art), but I know that children and families particularly like 3D movies, so as long as you’ve got that darkened room, you shouldn’t have any problems with watching 3D.

Bluetooth Enabled

Besides having that incredibly low input lag, the Bluetooth capability is my favorite feature on the Acer K138ST. I'm always hollering about using external speakers in my reviews, since you really can't get excellent audio quality from built-in speakers on projectors at any price point. Sure, some are better than others, but all really lack that robust bass we all know and love.

Hooking up external speakers to a projector so small may seem like overkill to some, since most of those speakers are at least the size of the thing and then some. Most Bluetooth speakers are tiny, like this Acer, but are capable of some truly great sound. Over the summer my friends and I used one of those little Beats by Dre Bluetooth speakers (the tube-shaped one) for music by the pool and it was not lacking in bass.

Pair one of those with the Acer K138ST, and you've got yourself a portable home theater! Better sound and portability isn't all that Bluetooth has got going for it - since the Acer is a short throw, its placement will likely be in the middle of the room (in front of your seating area), and wired external speakers would have a bunch of dangly bits all around, hanging about in an unsightly manner. Bluetooth gives placement flexibility of the speaker, and without the tripping hazard.

Wireless Networking

There are two ways in which one can wirelessly project using the Acer K138ST: WirelessCAST and the WirelessHD Kit. Both are optional, meaning they are not included with the projector. The concept is the same on both devices – plug it in, and you can project content from your device wirelessly. There is a key difference between the two, so whichever one you choose will be dependent on your needs, as neither is “better” than the other.

The WirelessCAST dongle allows for wireless projection from PCs and Macs. If you are running Windows XP, you can project video without audio, but Vista, and 7/8 all can project video with audio. It supports Mac OS X 10.8 or higher, iOS 7 and higher, Android 4.0+, and both iPad and Android tablets. The closest thing the WirelessCAST dongle relates to is Chromecast, though it is not a streaming stick in that you can’t stream Netflix or other services from the device. Oh well – that’s not what it’s for anyway.

The WirelessHD Kit is more for the “cord cutters” among us – those who do not desire cables strewn about everywhere. Since the K138ST is a short throw, it will likely sit in front of your seating area, making it an awkward position for your gaming systems and Blu-ray players. With the WirelessHD Kit, you can place those devices anywhere you want in the room with no regard for where the projector lives. Nice. It comes with a transmitter that connects to your image source via HDMI, and a receiver to plug into your HDMI port on the projector. The signal is wirelessly transmitted between the two devices. The WirelessHD Kit is capable of transmitting video and audio from a computer with an HDMI port.

So, it really comes down to this – will you be using the wireless capability of the Acer K138ST to project videos and such from your phone or tablet, or just the computer? If so, go with the roughly $200 WirelessCAST dongle. If you’re just trying to wirelessly project from a gaming or Blu-ray device, or from a computer, go with the $199 WirelessHD Kit. I had a maddeningly difficult time finding that WirelessCAST dongle though – it doesn’t appear to be on the Acer store website, nor could I find it in any online store that wasn’t dealing in South African Rand. I found it on Amazon for $220 plus $35 shipping, and on a UK site for £68.71, which works out to about $92 plus 20% VAT and an £8.99 ($12) shipping fee. By comparison, the WirelessHD Kit is beyond easy to find. It’s everywhere. So weird.

Naturally, I did not have the Acer WirelessCAST to test (who does?), but I did have the WirelessHD Kit from when I reviewed the Acer H7550ST, a $999 DLP projector. It worked just as well with the K138ST. Once inserted into the HDMI port on the projector’s back panel, the HDMI option is replaced with the “WirelessHD” option within its source menu. The kit comes with a User Manual to make the process quick and easy. My PlayStation 4 is pretty much installed on the shelf behind the couch, hooked up to my Epson HC5040UB via a 4K splitter, and is a total pain to move to test these short throw projectors, so I rather appreciated the placement flexibility offered by the WirelessHD Kit.

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