Monolith by Monoprice THX Certified Ultra Dolby Atmos speakers review: High-end home-theater audio on a budget

Price When Reviewed

THX-465T towers: $1,998 (pair); TH-365C center: $499; THX 365T mini-towers: $998 (pair). Total cost as reviewed: $3,495

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Monoprice shook up the industry in the early days of HDMI with its high-performance but inexpensive HDMI cables. Indeed, that’s how I was introduced to the brand. But cables are one thing, audio components and loudspeakers are another. When Monoprice launched its Monolith brand of premium home audio components, I expected low-cost products with mundane performance. Boy, was I wrong.

My preconceived notions were obliterated when I reviewed the $1,499 Monoprice Monolith 7 power amplifier. That monster put the world on notice that Monoprice had set its sights on being a high-performance, high-value competitor in the home theater and audiophile markets. I’ve since reviewed several Monoprice products, including its THX-certified balanced headphone amplifier, featuring THX’s superb AAA technology.

Well, Monoprice has done it again with its Monolith line of THX Certified line of speakers and subwoofers. This review focuses on a collection of the company’s THX Certified Ultra Dolby Atmos-enabled speakers.

Dolby Labs

What are Dolby Atmos-enabled speakers?

If you’re not familiar with Dolby Atmos-enabled speakers, here’s a brief primer. Immersive audio—such as Dolby Atmos, DTS:X, and Auro 3D—uses audio height cues to create a three-dimensional soundscape. You can read our more in-depth explanation of immersive audio at the preceding link.

Traditionally, these height cues are emitted from speakers mounted in, on, or hanging from your ceiling. For situations where those installations are impractical or impossible, Dolby Laboratories, came up with a concept they call Dolby Atmos-enabled speakers. This class of loudspeaker has an angled, upfiring driver mounted in the top of the speaker cabinet that bounces these height cues off your ceiling, so that they ricochet back down to your listening position. Your ears—and your brain—perceive the sound as originating from the ceiling, just as if there was an actual speaker mounted there.

Dolby says for optimal performance, the ceiling should be flat (not angled or vaulted), with a height between 7.5 and 14 feet and made of an “acoustically reflective material” such as drywall, plaster, or hardwood. Acoustic ceiling tiles or other sound-absorbing material won’t work. Take a look at Dolby’s Atmos setup guide for more details.

The Monolith speaker lineup

The Monoprice Monolith THX Certified Ultra Dolby Atmos-enabled speakers reviewed here include a pair of THX-465T tower speakers ($1,998 per pair), the THX-365C center channel ($499), and a pair of THX-365T mini-tower speakers ($998 per pair). That’s a complete THX Certified Ultra Dolby Atmos-enabled speaker system for just $3,495.

The Monolith THX-465T tower speaker is a front-ported design, with a 1-inch silk dome tweeter with a Neodymium magnet and copper shorting ring. The tweeter is mounted above a 2-inch cloth dome midrange driver with a Neodymium magnet and aluminum shorting ring. Four 6.5-inch, long-throw fiber pulp cone woofers with NBR surrounds and aluminum shorting rings round out the driver configuration. The high-density fiberboard cabinet tapers at the back to give you a visual sensation that the massive speaker is smaller than its 55-inch height.

Theo Nicolakis / IDG

The tower speakers are relatively easy to drive, with a sensitivity of 89.5dB; but do yourself a favor and avoid using low-quality amplifier or A/V receiver. These speakers have an impedance of 4 Ohms and will reward you in spades when paired with something like Monoprice’s excellent Monolith amplifiers. Frequency response with the front port plugged is 45Hz to 24kHz. With the port unplugged, you’ll get usable bass down around 29Hz.

The THX-365C center channel speaker has the same tweeter and midrange as the THX-465T tower, plus two 6.5-inch long pulp paper cone drivers on either side. The 26.4-pound center channel has a frequency response of 65Hz to 24kHz. Be warned, this is no puny center channel. Its 9.7 x 22.9 x 10.8 (HxWxD) dimensions won’t fit into some entertainment consoles, and you definitely won’t want to set it on a piece of furniture in front of your TV.

The THX-365T mini-tower speaker bears the same drivers and frequency response as the center channel but in a vertical arrangement. The front tower and rear surround speakers have upfiring drivers consisting of a 0.6-inch silk dome tweeter and a 5.25-inch long fiber pulp cone.

What does THX Certified Ultra mean?

Monoprice is looking to establish credibility with home theater and audio enthusiasts by adopting THX technologies and pursuing THX certification for its products. THX certification ensures that an audio product meets strict specifications for accurate frequency response, the ability to achieve certain volume levels without distortion, and good off-axis response without comb filtering. Based on these variables, speakers are then rated for their ability to perform optimally in a given room size or volume. The speaker must then pass rigorous testing, and the final manufactured product is re-tested to ensure that it maintains the established benchmarks in production.

In this case, Monoprice’s tower, mini-tower, and center channel speakers are all THX Certified Ultra, which means that they are certified for delivering a cinematic experience in rooms up to 3,000 cubic feet in size and with a viewing distance up to about 12 feet from the screen. THX Certified Select and THX Certified Compact are designations for smaller home theaters, while THX Certified Dominus is the designation for very large home theaters (up to 6,500 cubic feet, with viewing distance of around 20 feet from the display). You can read more about THX Certified speakers at THX’s website.

Theo Nicolakis / IDG

Unboxing and build quality

My review setup consisted of a 5.0.4 configuration. The first number represents the total number of floor-level speakers (the front-firing aspects of the THX-465T, THX-365C, and THX-365T), the second is the number of subwoofers (not included in this evaluation, hence the “0”), and the third figure is the total number of height channels (the upfiring aspects of the THX-465T and THX-365T).

Unboxing this Monolith collection deserves discussion. First off, the THX-465T tower speaker package is huge and heavy. Unpacking this speaker is a two-person job. Monoprice provides you with a pair of white gloves to set up and handle the speakers—a nice touch. While the white gloves give the THX-465T Tower an air of premium audio, they also gave off an Ikea-esque vibe, because I needed to assemble the base of each speaker—and Ikea at least provides the hex key needed for the job. Meanwhile, the box containing each THX-365T mini-tower speaker is so large and heavy that I at first thought there was a pair of speakers inside. These are serious speakers.

The black veneer is the only thing that disappointed me at unboxing. It’s neither a high-gloss piano black nor is it a high-quality wood-grain veneer. You can find high-quality finishes on other speakers in this price range, but not here. What’s worse is that Monolith veneer has a vinyl-plastic textured feel to it. If this is an area where Monoprice chose to cut costs, then they made the right decision. You don’t see the speaker’s finish with the lights turned down.

Theo Nicolakis / IDG

The tower speakers come with spikes for securing the speakers to carpeted floors and screw-on rubber feet for hardwood or concrete floors. The mini-towers have inexpensive stick-on feet to prevent marring. The bottom of the center channel speaker comes with a large, foam pad that is intended to protect fine cabinet surfaces. It will also prevent any sliding of the center channel once you’ve selected its optimum location.

Setup and listening tests

Think of your speakers, room, and listening position within the room as an instrument that must be tuned for optimal performance. People who buy expensive speakers and just slap them up against a wall miss so much potential performance. I always tune speakers with two-channel music first to find the best location for speaker placement. In this case, I also tested their placement relative to the performance of the Dolby height channels, using the superb Dolby Atmos audio mixes from Mad Max: Fury Road, Dune, and X-Men: Age of Apocalypse to gauge the effect of the 3D sound field. I ended up placing the main speakers about three feet from the front wall and approximately 12 feet from the main listening position.

I designated Denon’s flagship AVR-X8500HA 8K AV receiver as the control center of the Monolith setup. Source devices included an Oppo UDP-205, a Roon Nucleus server, and a 2^nd-gen AppleTV 4K. Music sources included Dolby Atmos music tracks streamed with Apple Music, Tidal streams played via Roon, and local high-res music files.

I calibrated the Monolith setup on the Denon X8500HA using Audyssey’s new $199 MultEQ-X calibration software. I performed independent calibrations with the THX-465T towers open-ported and plugged. I played musical selections with Audyssey and without it in Pure Direct mode. All movies had Audyssey engaged.

The first thing you’ll notice about these Monolith speakers is the beautifully massive soundstage and image they cast. It’s intoxicating and brings whatever you’re playing to life. You simply cannot get such an enveloping, life-like sensation from music or movies from a puny soundbar or smaller speakers; smart speakers won’t even get into the parking lot, much less the door.

With two-channel music, the THX-465T tower speakers etched a detailed, phantom center image with vocals dead center between the two speakers. The presentation was slightly relaxed with a solid, detailed soundstage.

One of my favorite listening sessions was with the O Zone Percussion Group’s album, La Bamba. This is a must-have demo disc. The recording is incredibly lifelike, but the track “Jazz Variants” is my favorite. The Monolith’s dynamics with the xylophone and drums exploded into the room. Kick drums punched me in the gut. The presentation was precise and holographic.

I danced around musical genres such as R&B, rock, and classical, from Concrete Blonde to Adele and Alicia Keys to Copeland’s “Appalachian Spring,” the Monolith welcomed them all in stride.

The Monolith setup did an outstanding job with lossy audio on TV shows and streaming services such as Netflix, HBO Max, and Amazon Prime. But it was Dolby Atmos movies on 4K Ultra HD Blu-ray where the setup really shined.

Theo Nicolakis / IDG

Mad Max: Fury Road on 4K Ultra HD Blu-ray is a Dolby Atmos demo disc for the ages. It’s a non-stop sonic assault on your senses from the start.  The Monolith speakers just disappeared. The walls in my room were almost non-existent, leaving me with the sensation of only a three-dimensional sense of space in which the voices Max hears in his head danced around my room as if in an eery, ethereal realm. While there was a sensation of some overhead layer, the discrete, detailed sounds that I know are there were smeared. Instead of the audio objects being crisp and precise in space and time over my head as they would be with discrete in-ceiling speakers, the audio objects hovered lower and less distinct—consistent with my experience with other Dolby Atmos-enabled speakers.

With the towers playing full-range and the front port unplugged, the Monolith setup did yeoman’s work delivering a satisfying low end. The Monoprice Monolith setup dug deep into the growl of engine roars and thrust the bombastic chaos of Furiosa’s rig in the midst of the desert storm with whirling F5 hurricanes into my living space. If you’re looking for a setup that can play well without a sub, the Monolith is a satisfying solution.

The THX-365C center channel is a showstopper. It never called attention to itself, blending beautifully with its counterparts; yet it stood out by rendering dialogue clearly and intelligibly almost without exception. Best of all, the center channel has an extremely wide and consistent off-axis performance. Whether you’re dead-center or relegated to the far end of the couch, you won’t have any problem understanding what’s happening on screen.

Theo Nicolakis / IDG

If you don’t have Denis Villeneuve’s Dune (Part 1) in your Atmos collection, go buy it now. It’s another immersive audio masterpiece on 4K Ultra HD Blu-ray. The Atmos mix lights up at the first note and the speakers never release their grip. The Denon-Monolith one-two punch was awe inspiring. The Monolith excelled at conjuring up the desertscape of Arakis against the backdrop of Hans Zimmer’s eerie, otherworldly score.

When Paul and his mother escape into the ornithopter pursued by Harkonnens, I was transported inside the cockpit. Alerts blared all around me. I heard and felt the ornithopter’s frame stress and creak as it encountered the increasing fury of the desert storm. Now this is home theater!

At this price point, the Monoprice Monolith THX Certified Ultra speakers proved themselves to be high-value overachievers perfect for immersive, home theater applications. That’s not to say they are perfect.

Comparing the Monolith to the much more expensive Revel Ultima2 Salon (an admittedly unfair comparison), I noted a hint of boxiness in the Monolith’s sound, which is not atypical at this price point. Comparatively speaking, I also noted that the Monolith at times had difficulty rendering complex musical layers crisply and coherently. Here and there I found them to be more bombastic than refined, veiled as opposed to transparent.

Monoprice hits a high note

Monoprice’s THX Certified Ultra, Dolby Atmos-enabled, speakers hit a price/performance high note. Their overall sonic performance, build quality, 5-year warranty, and 30-day in home trial make them exceptionally appealing. If you’re looking to save a few dollars, run the tower speakers full range for an incredibly satisfying home-theater experience. Pair them with one of Monoprice’s indomitable THX Certified subwoofers and you’ll unleash a cinematic onslaught that will leave friends and family awestruck. Apart from my minor quibble about the speakers’ pedestrian veneer, if you’re looking to dive headlong into the home theater hobby or looking to make an upgrade from an entry-level setup, you simply can’t go wrong with the Monoprice Monolith. Just be sure to make an equally strong commitment into a high–quality A/V receiver (or separate components) to maximize your investment and enjoyment.