Monoprice Monolith M518HT THX 5.1 Home Theater Review

Monoprice Monolith M518HT

Monoprice Monolith M518HT THX 5.1

3.5/5

To be honest, I have mixed feelings about these speakers. The subwoofer is most certainly the strong link in this set, offering good bass response. However, the weak link, in my opinion, are the satellites, which are not easy to mount using traditional mounting hardware, and do not have quite the frequency response I expect from speakers that carry the THX certification.

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When Monoprice announced that they had released Monoprice Monolith M518HT, a set of compact home theater speakers, and that they were THX-certified, I was eager to give them a try. The set arrived in a large and rather heavy box, with 5 satellite speakers measuring roughly as a 6-inch cube (6” x 6.3” x 5.9”) weighing 4.2 pounds each and an 8” downfiring subwoofer measuring approx. 12.5” x 13.5” x 13.5” and weighing 19.8 pounds. All of the speakers have a flat black finish, and the satellites have an optional fabric grill.

Monoprice Monolith M518HT Front
Monoprice Monolith M518HT Rear
Monoprice Monolith M518HT front

At first glance, I was a bit disappointed in the lack of mounting screw holes in the satellites. Monoprice has included a keyhole mount on the rear. There appears to be a threaded screw hole on the bottom of the speaker, but I was unable to use that to attach these to my existing wall mounts in my living room. That made the placement of surrounds rather difficult, so I decided my first test would be to use just the subwoofer and three of the satellites as my front L-C-R speakers. The Monoprice Monolith M518HT subwoofer was set to all of the THX default settings. After running the Audyssey calibration program on my Denon AVR-X2400H receiver, the crossovers for all three satellites were detected as 80Hz each. I then adjusted the levels using an SPL meter. I ran the speakers through the usual paces, with all of my usual demo material (Apocalypse Now, Raiders of the Lost Ark, Toy Matinee DVD-Audio, Blue Man Group: Complex DVD-Audio), and did find that these had slightly better performance than my older Polk TS100 bookshelf and CS10 center speakers. The first and most important thing I noticed right off the bat was a cleaner and clearer center channel. The subwoofer also provided a bit more bass compared to the OSD PS10 subwoofer I usually have installed in my living room. So far, so good, and I was somewhat pleased with the performance of the subwoofer and front three speakers.

It was now time to place all six speakers to the test in my home office, usually decked out with Energy CB-10 bookshelf pairs, Energy CB-5 center, and Onkyo SKH-410 Dolby Atmos upfiring speakers in the front, Energy CC-5 bookshelf pairs as my surrounds, and a Polk PSW111 subwoofer. I replaced all of the Energy speakers and the Polk subwoofer with the Monolith satellites and sub. I ran the Audyssey calibration on my Denon AVR-S930H receiver, and this is where things got a bit weird. Audyssey detected different crossovers for each set of speakers. Left and right fronts were 120Hz, center was 90Hz, and surrounds were 60Hz – all five speakers are identical – and the Onkyo Dolby Atmos speakers at 200Hz. I ran Audyssey several more times, and received the same results. I then sampled my usual demo material and found that overall the sound was a bit hollow. I adjusted the crossovers to 80Hz for the Monoprice Monolith M518HT, and the sound improved somewhat, but was still rather hollow, but bass response, especially LFE effects, were rather impressive.

To be honest, I have mixed feelings about these speakers. The subwoofer is most certainly the strong link in this set, offering good bass response. However, the weak link, in my opinion, are the satellites, which are not easy to mount using traditional mounting hardware, and do not have quite the frequency response I expect from speakers that carry the THX certification. Also, the lack of a true and dedicated center speaker was a bit of a head-scratcher. Still, for $799.99 direct from Monoprice, the set is a good option for those looking for a matching entry-level 5.1 speaker setup. The Monoprice Monolith M518HT THX-Certified 5.1 Channel Home Theater speaker set can be purchased directly from the Amazon link below.

Todd Erwin has been a reviewer at Home Theater Forum since 2008. His love of movies began as a young child, first showing Super 8 movies in his backyard during the summer to friends and neighbors at age 10. He also received his first movie camera that year, a hand-crank Wollensak 8mm with three fixed lenses. In 1980, he graduated to "talkies" with his award-winning short The Ape-Man, followed by the cult favorite The Adventures of Terrific Man two years later. Other films include Myth or Fact: The Talbert Terror and Warren's Revenge (which is currently being restored). In addition to movie reviews, Todd has written many articles for Home Theater Forum centering mostly on streaming as well as an occasional hardware review, is the host of his own video podcast Streaming News & Views on YouTube and is a frequent guest on the Home Theater United podcast.

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JohnRice

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I guess I don't know why cubes would need a "dedicated" center speaker. Usually that's just because it's horizontally aligned instead of vertical. With cubes, there's no need. Am I missing something?

And the wonky crossovers from auto calibration seems like a fault with Audyssey rather than the speakers.

The lack of a 1/4-20 thread on the back does seem baffling.
 

Todd Erwin

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I guess I don't know why cubes would need a "dedicated" center speaker. Usually that's just because it's horizontally aligned instead of vertical. With cubes, there's no need. Am I missing something?
I guess I'm just used to a center speaker looking like a center speaker.
And the wonky crossovers from auto calibration seems like a fault with Audyssey rather than the speakers.
Possibly, but when I re-installed my Energy speakers today, they all registered with crossovers at 90Hz.
 
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