Subwoofer Reviews

Connections on the back panel include stereo line level inputs, an XLR balanced input, an XLR passthrough, and an IEC power cord socket. There are six controls on the amplifier: three knobs for Crossover, Phase, and Level and three toggle switches for Crossover (On/Off THX), EQ (Extended/THX), and Power (Auto/Always On). Unfortunately, Monoprice doesn’t provide a PEQ (parametric equalizer) or control via a smartphone app, as can be found on some subs from competitors. I consider a PEQ and app control as nice-to-haves, not have-to-haves. As I stated earlier, the Monolith subwoofers check all the right boxes. But how do they sound? Spoiler alert: awesome!

Not for Girly Men
Unboxing either subwoofer is a two-person job: The 12” weighs just under 100 pounds (98.5, to be exact), and the 15” weighs 128.5 pounds. Then there’s the added weight of the double-boxed shipping container. There are no instructions for unpacking the beast, but it’s best to open the top of the outer box, slowly flip the whole thing over, and lift the outer box off the inner one. Repeat the process to remove the sub from the inner enclosure; your back will thank you. Each sub has spiked rubber feet, so it’s best to use some sliding furniture movers (available at your local hardware store) to position it. Monoprice includes a pair of white gloves in case you want to provide your own white-glove service and keep oily fingerprints off the satinfinish, black ash vinyl.

Given their size, neither of the subs would fit in the preferred front left corner of my room, due to a fireplace hearth and my wall-mounted front left speaker. (I usually put the small-footprint, cylindrical SVS Ultra there.) So I placed each of the Monoliths in Position No. 2, which is along the right side of my room, about a third of the way—where I usually keep my reference Hsu Research sub.

I set up two user profiles—one for the 12” and the other for the 15”—in my Anthem AVM 60 pre/pro and calibrated the speaker output levels using an SPL meter and test tones from a THX calibration disc. As mentioned, you can choose to use either sub sealed by installing the provided port plugs. This will give you the tightest bass, at the expense of some low-frequency extension. Or, given the multi-port design, you can close one of the two ports on the 12” or two of the three ports on the 15”; by doing so, you’ll get the greatest extension at the expense of reducing maximum output. I listened to both subs in this extended mode, as well as with all ports open. For music, I really liked all ports open, but for movies, I preferred the extended mode.

My go-to audio tracks to test subwoofers include Justin Bieber’s “Baby,” Regina Spektor’s “Fidelity,” and Joss Stone’s “Sleep Like a Child.” I moved back and forth between the 12” and the 15” with each of these songs multiple times, and I was surprised at how well the 12” was able to hang with its larger sibling. In a lot of cases, the 12” was a tad tauter, but I’m really splitting hairs between the two subs when it comes to music: Both sound fantastic.

On some bass-intensive rap tracks, such as N.W.A.’s “Dope Man,” the 15” definitely showed that it could dig a little deeper and play louder than the 12”, which foretold what I would hear later with movie soundtracks. Of course, that shouldn’t be a surprise given the 15” sub’s larger enclosure, woofer, and amplifier.

The Ultra HD Blu-ray of Pacific Rim is one of my favorite discs in the new format. Not only does it boast fabulous-looking HDR, but the Dolby Atmos mix is a stellar example of the breed with its ample use of overhead effects and its deep, sub-20-Hz bass content. In the movie, after the Jaeger battles the Kaiju off the coast of Alaska, the Jaeger makes its way to shore while a grandfather and his grandson search for treasure with a metal detector. With the 15”, I could literally feel the approaching giant before I saw him come through the fog thanks to its reproduction of the accompanying low-bass information. The same scene on the 12” didn’t have quite the same visceral impact. Granted, my room approaches 5,000 cubic feet, so it really puts the 12” in a situation beyond its intended application. In most every case, I was able to hear—and feel—either subwoofer deliver movie sound that had ample bass above 20 Hz, such as the dive-bomb scene on the beach in the first part of Dunkirk or the battle in “Blackwater” (season 2, episode 9) from Game of Thrones. Each sub was able to cleanly reproduce articulate bass with good extension down low and plenty of output, although I always got more oomph with the larger sub.

To be fair to the 12” and gauge its performance in a more suitable space, I spent some time with it in my secondary system that’s housed a 1,100-cubic-foot room. In that room it performed marvelously with movies. So this certainly is a case of choosing the proper subwoofer, or quantity of subwoofers, for the environment. I’m sure that dual 12” Monoliths would have performed flawlessly in my larger theater.

Double the Fun
Monoprice has definitely impressed me with their initial offering of THX-certified subwoofers. Each warrants a Top Pick—but if you can swing the extra cash for the 15” model, it would be my preference, especially if you have a large room. One thing worth repeating: In order to receive THX certification, these subs need to meet a low distortion number, which really translates to clean and controlled bass response. I truly enjoyed my time with both of these subs and wouldn’t hesitate to recommend them to a friend, but I would add to this my usual adage: Two is better than one, because, well...there’s never such a thing as too much bass!