Reviews of Attainable Hi-Fi & Home-Theater Equipment

Reviews of Attainable Hi-Fi & Home-Theater Equipment

Sonus Faber describes itself as an “Artisan of Sound,” and a glance at their website reveals how much effort they put into physically crafting their loudspeakers -- from their least expensive speaker all the way up to the Aida ($130,000/pair, all prices USD). When, in June of 2019, I reviewed their Sonetto Wall speaker ($1199 each), the high-gloss black finish of my review samples was so seamless that each speaker looked as if carved from a block of solid ebony.

With speakers retailing in six figures, Sonus Faber is one of the most exclusive speaker brands around. But unlike most such boutique speaker manufacturers, they also make home-theater models -- center-channel and surround speakers -- to match their main-speaker models, including their Gravis line of five subwoofers. Sonus Faber sent me a sample of the central Gravis model, the III ($2995 each). As I found out through my audition, it has the looks and performance to fit in nicely with their Sonetto and Olympica Nova speaker lines.

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At 16.3”H x 15.7”W x 19.5”D and 58.8 pounds, the Gravis III is, for me, a subwoofer of the “right” size and weight. In that it’s unlike my Paradigm Servo-15 V2, which I find a bit unwieldy at 20.2”H x 18.2”W x 21.5”D and 114 pounds. As soon as I touched the Gravis III, I knew it was something special. Rather than the black paint found on most subs, the Gravis III, V, and VI are covered in gorgeous black leather. And the corner edges are rounded, not sharp. Under the leather, the cabinet walls are made of 1.25”-thick high-density fiberboard (HDF), extensively braced inside. The Gravis III’s wooden top panel can be ordered in one of three hand-applied finishes: matte Wenge or Walnut, or gloss Piano Black. My sample had the Wenge finish, which was as beautiful as any fine furniture I’ve seen. A small Sonus Faber logo medallion is subtly inset at the center of the top panel.

The Gravis III is a sealed-box, powered subwoofer. Its forward-firing 10” driver is hidden behind a cloth grille secured with solid metal posts -- no worries that they’ll snap off like the more common plastic variety. The driver’s long-throw cone comprises a core of honeycombed Nomex sandwiched by outer layers of woven fiberglass. The result is a very stiff cone that resists flexure due to the high forces to which any subwoofer driver is subjected, and its wide rubber surround permits excursions of as much as 1” with no flexure, Sonus Faber claims. The Gravis III’s amplifier is specified to output 600W RMS and peaks of 900W; because it operates in class-AB, not the class-D of most subwoofer amps, there’s a good-size heatsink on the rear panel.

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Also on that rear panel are a pair of unbalanced line inputs (RCA), a balanced line input (XLR), and a four-pole Neutrik speakON connector. There are also an Ethernet jack to permit operation of the Gravis III by third-party controllers, a USB port for diagnostics and servicing, a Volume knob, and a Coupling button, for pairing the sub with Sonus Faber’s optional wireless subwoofer Transmitter ($399). The Gravis III has one of the most minimal control sets I’ve seen on a subwoofer.

All other controls are found on an app, Gravis Sub Control, that can be downloaded from the Sonus Faber website to any iPad, iPhone, or Android device. In the app, which communicates with the Gravis III via Bluetooth, are the controls usually found on a sub’s rear panel: variable phase, low-pass filter, and volume. Also included are preset EQ modes labeled Audiophile, Cinema, Night, and Streaming, and the ability to fine-tune the auto on/off threshold, and equalize the sub’s output with parametric equalization. This equalizer has eight points you can adjust for frequency, bandwidth, and gain. Of particular interest is the app’s Auto EQ function. With this, you first use your smartphone’s microphone to take a nearfield measurement of a frequency sweep (200-20Hz) generated by the app, then a farfield measurement of the same sweep at your listening seat. It took me only a few seconds to take both measurements.


My listening room measures 23’L x 16’W x 8’H, and my gear is at one end of one long wall. I set up the Gravis III in the spot usually occupied by subwoofers: the front right corner. When I took the nearfield measurement of the Auto EQ sweep in the Gravis Sub Control app through my iPhone 8, it showed that the Gravis III had solid output down to 25Hz, confirming the -6dB point specified by Sonus Faber. Another good sign that this was a serious subwoofer was that my wife could feel the floor shake in the room above my listening room as I measured the frequency sweeps. The farfield measurement at my listening seat revealed a suckout at around 80Hz -- Auto EQ generated a plot that indicated, in green, a correction curve that would compensate for this. The final, corrected curve measured remarkably flat from 25 to 200Hz. Although Gravis Sub Control is a great addition to the Gravis III, I had a few problems with the app: When it saves the EQ setting, you can’t then return to it; the plot also disappears if you’re out of the Gravis III’s Bluetooth range; and the farfield response varies wildly if you move the phone even a little bit. Perhaps if the app could take and average multiple farfield measurements, the correction curve would be more consistent.

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I also set up Sonus Faber’s Sonetto Wall speakers, driven by my Anthem MRX 720 A/V receiver. The speakers were hung on the wall using the included double bracket, a clever device with one bracket that attaches to a wall and another that attaches to the speaker, the two brackets joined at a hinge that lets you angle the speaker to optimize the imaging. The only drawback of using the bracket is that the Sonetto Wall then isn’t flush with the wall, but juts out a few inches; however, the bracket is invisible when the speaker is viewed from the front -- the Sonetto Walls look as if they’re floating in space. The speakers were about 12’ from my listening seat and 8’ apart. One compromise I had to make, due to my room configuration, was that their tweeters ended up a foot higher than my ears when I sit down to listen. I played music through the Anthem MRX 720 via the DTS Play-Fi app on my iPad, with Anthem Room Correction and my reference Paradigm subwoofer turned off.


I scoured my BD collection to find a movie suitable for testing this subwoofer, and came up with Jurassic World. Like the other films in the dinosaur franchise, this one has many scenes full of loud, low sounds -- as in chapter 6, when an immense Mosasaurus (they could be 59’ long and weigh 15 tons) leaps from the water to snap up a great white shark. Through the Gravis III, the subterranean bass in this scene was loud enough to shake my walls and ceiling tiles. In the climactic fight scene between the Tyrannosaurus rex and the genetically engineered Indominus rex, their heavy foot stomps pounded through my room, rattling my lighting fixtures. The Gravis III gave me all the bass output I needed in my room for such LFE effects, and more. In fact, I was surprised at such terrific performance from a relatively small subwoofer with a single 10” woofer. Its combination of huge amp and high-excursion driver paid off.

One reason for having a subwoofer is to underline the tension a film’s soundtrack can inspire. Throughout the film Doctor Sleep, the sound of a beating heart followed by eerie music ramps up the suspense. Through the Gravis III, that heartbeat was loud and tight, as it should be. Ported subs often produce high output that’s compromised by bass overhang -- what sounds like a slower response to the LFE signal that results in bass sounds droning on and on. I heard none of this from the sealed-box Gravis III -- its response was always fast and tight.

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Another great test of a subwoofer is the opening credits of Blade Runner 2049. The music builds throughout, and ends with an extreme close-up of an eye. The sequence is terrific for setting up this film as something to be reckoned with. The heavy LFE effects and music rattled my walls through the Gravis III. Later, when replicant K (Ryan Gosling) tries to bring in runaway replicant Sapper Morton (Dave Bautista), a fight ensues. Through the Gravis III, the dynamic impacts of their punches were so great that I could physically feel each one in my own body. When the characters burst through a wall, the sound of their bodies hitting the floor was represented by a loud, realistic thud that, again, I could feel with my entire body, not just hear with my ears.

Having satisfied myself as to the Gravis III’s performance with films, I switched to music, curious to hear how the Sonus sub would blend with the output of a pair of minimonitors. I hooked up my MartinLogan Motion 4i’s -- small speakers only 12”H, with a specified frequency response that goes down to only 70Hz. I set the Gravis Sub Control app to its Audiophile EQ preset. I then ran Anthem Room Correction (ARC) on this combo of speakers and subwoofer, to better blend their outputs at and around the crossover frequency.

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As I listening to stereo recordings of music, the blend of the MartinLogan Motion 4i’s and Gravis III was perfect, with the tight bass I’ve already raved about hearing with movies. For example, when I listened to “Train Song” from Temptation, Holly Cole’s album of Tom Waits covers (16-bit/44.1kHz FLAC, Alert), I could hear every note of David Piltch’s intricate double-bass playing. Each note was distinct in pitch through the Gravis III, not a mush of tones. Another great example was Aaron Copland’s Fanfare for the Common Man, with Eiji Oue conducting the Minnesota Orchestra (16/44.1 FLAC, Reference). With the Gravis III in my system, the percussion came through loud and clear, with a lot of impact. The timpani sounded particularly tight and forceful.


I compared the Gravis III with my everyday reference subwoofer, Paradigm’s Servo-15 V2 ($2200, discontinued). The big Paradigm has a 15” driver, weighs almost twice as much as the Sonus Faber, and its class-D amp puts out 1200W RMS -- twice the Gravis III’s RMS output. But the Servo-15 V2 was designed in the mid-2000s -- it lacks a smartphone app for setup.

Playing some of the jazz I favor, I heard little difference between the two subwoofers. Both are sealed designs, and the bass from both was tight, the transients fast. As I listened to “Code Cool,” from Patricia Barber’s Smash (24/192 FLAC, Concord Jazz/Mobile Fidelity Sound Lab/HDtracks), Larry Kohut’s double bass and Jon Deitemyer’s drums had the same dynamic impact through both subs. But the Servo-15 V2’s 15” cone had an advantage with recordings of pipe organ, such as Jean Guillou’s performance of his own transcription of Mussorgsky’s Pictures at an Exhibition (16/44.1 FLAC, Dorian). In track 11, Promenade, the Gravis III couldn’t match the visceral feel of the Servo-15 V2 -- hardly surprising, given the difference in driver size. Remember, the Gravis III’s specified -6dB point is 25Hz -- but this CD’s bass goes down to 20Hz.

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But for home theater, most LFE-channel activity is from 30Hz up, precisely the range in which the Gravis III excelled. With the Paradigm Servo-15 V2 I can get louder reproduction of LFE-channel info, but I tend to turn it down -- that big sub can overwhelm my 24’L x 14’W x 8.5’H room. The Gravis III proved an ideal subwoofer for a room of this size, with still enough power to shake the walls.


Sonus Faber’s Gravis III is a terrific subwoofer that provided me with endless enjoyment as I listened to music or watched movies. It went as low as 25Hz in my room, and was particularly adept with sound effects through movies’ LFE channels. And I liked the fact that its output could be seamlessly blended with that of a pair of minimonitors. Sonus Faber’s app is another nice touch, and made it easy to set up the Gravis III from my listening seat. And for those lucky enough to own Sonus Faber Sonetto or Olympica speakers, not only is the Gravis III’s sound good enough to mate well with those models -- so are its beautiful finishes.

. . . Vince Hanada

Associated Equipment

  • A/V receiver -- Anthem MRX 720
  • Speakers -- MartinLogan Motion 4i, Sonus Faber Sonetto Wall
  • Subwoofer -- Paradigm Servo-15 V2
  • Sources -- DTS Play-Fi streaming app through Anthem MRX 720 AVR
  • Interconnects -- Analysis Plus Super Sub
  • Speaker cables -- Analysis Plus Blue Oval

Sonus Faber Gravis III Subwoofer
Price: $2995 USD.
Warranty: Five years parts and labor.

Sonus Faber SPA
Via Antonia Meucci 10
36057 Arcugnano (VI)
Phone: (39) 0444-288788