MartinLogan Depth powered subwoofer Page 2
Once level-matched and equalized, the MartinLogan Depth moved lots of air, generated clean, powerful subwoofer bass with extremely deep extension, and blended with my Quad speakers (footnote 2). More important, it did not change the pitch, timbre, or quality of midrange and upper-midrange musical tones. Its servo suppressed any upper harmonics, something that power-packed baby subs without servo control have been unable to do in my huge listening room.
Furthermore, the Depth passed my most stringent torture test, "Assault on Ryan's House," from the Patriot Games soundtrack (CD, RCA 66051-2). This track, having the lowest-frequency energy of any CD in my collection, quickly identifies subwoofers deficient in amplifier power or driver extension. The Depth played the track with no sign of distortion or stress. The bass remained clean, deep, and solid, with no spurious noises to indicate that the three woofers were in difficulty.
The Depth's speed and ability to render dynamics with suddenness and explosiveness added to the impact of most bass passages. This quality, coupled with a lack of the single-note emphasis often found in lesser subwoofers, added to the sound's realism and smoothness.
On other music, the Depth demonstrated transient fidelity and an absence of overhang, and delivered kick drums with authority and slam. The ML blended well with the Quad ESL-989s, to produce a satisfactory integration of midbass and lower bass. The deepest bass notes were produced with precision, giving the low frequencies a taut, rhythmic quality. For example, the bass notes on Mary Gauthier's Filth and Fire (CD, SIG 1273) were more taut and solid with the Depth in the system as opposed to no sub at all. The midbass emphasis common among woofers in full-range speakers was totally absent from the Depth, rendering a cleaner, better defined impression of the midbass and above.
The Depth resolved complex deep-bass passages involving several instruments. Some sections of Philip Glass's score for Martin Scorsese's Tibetan epic, Kundun (CD, Nonesuch 79460-2), were greatly helped by the MartinLogan, which resolved the mix of the drone of the Tibetan horns, synthesizer, contrabassoon, and the voices of the Gyuto monks of the Drukpa order. The heartbeat that opens Pink Floyd's "Speak to Me," from the SACD remastering of their Dark Side of the Moon (Capitol SACD-82136-2), exhibited all of the features I listen for: the sound must crescendo, grow more rich, and increase in volume until it rattles objects in the room. For the first time, I heard the heartbeat return, below the swirl of music at the end of the selection, then reappear in the next track, "Time," below the pumping, "oil-can" sound that I had previously thought was the "real" bass line.
The Depth delivered complex subterranean bass notes without obscuring the characteristic sound of the instrument being depicted. Thus, the Depth didn't distort or overload on the complex upper tones and extremely raucous vibrations of David Hudson's close-miked didgeridoo during "Rainforest Wonder," from his Didgeridoo Spirit (CD, Indigenous Australia IA2003D).
In contemporary recordings, the synthesizer has become one of the main sources of subwoofer bass. The Depth added tremendous emotional weight, suspense, and energy to film soundtracks that make use of this instrument. Suspense was pumped up in the "Attempt on the Royals," from Patriot Games. More interest and suspense were heard with the Depth playing during the deep, ghostly, vibrating footsteps that open the Casper soundtrack (CD, MCA MCAD-11240); the low, ominous, foreboding rumblings of "Caravan Moves Out," from Kundun; and the thundering, shuddering dinosaur footsteps on "The Carnotaur Attack," from Dinosaur (CD, Walt Disney 50086 06727).
The Depth allowed the Quads to best handle dynamic bass peaks in my huge listening room when the high-pass filter was set to 80Hz. For example, the synthesized, system-busting opening of Emmylou Harris's "Deeper Wells," from Spyboy (CD, Eminent EM-25001-2), didn't bring the system to its knees. Run with its high-pass filter protecting the Quad panels, the Depth was able to keep the synthesizer separate from the bass guitar during this tumultuous passage, something that most of my full-range speakers—and certainly the unassisted Quad ESL-989s—aren't able to do.
Other pedal-to-the-metal synthesizer passages were handled with equal aplomb, including Don Dorsey's "Ascent," followed immediately by the Introduction of Strauss's Also sprach Zarathustra, from Time Warp (CD, Telarc CD-80106); and Morton Subotnick's The Wild Bull, a powerful, room-shaking composition for the synthesizer built by Donald Buchala at the San Francisco Tape Music Center (LP, Nonesuch H-71208).
The Depth had one weakness. In both options—with and without high-pass filter—it was always "present" sonically. Larger and more expensive subwoofers, when adjusted carefully to my listening room, can "disappear"—ie, the bass notes still appear to come from the main speakers, but with a wider, deeper soundstage and an absence of midbass emphasis. By contrast, the Depth's deep bass remained localized at the corner where it sat, possibly as a result of the unit's low-pass filter allowing through some upper-frequency energy. While the Depth increased the Quads' dynamic range and produced a clearer, more definite impression of the upper-midbass to midrange frequencies, it didn't blend as well with the Quads as, say, the Velodyne DD-18, and didn't improve the depth and width of the soundstage to the extent that other, more expensive subwoofers have done.
The MartinLogan Depth upset one of my longstanding prejudices. I'd been convinced that a subwoofer good enough to move a decent amount of air in my large listening room had to be big and expensive. Deep, shuddering pedal notes from pipe organs—notes that produce "room lock"—had previously been the domain of 3' cubes weighing more than 125 lbs.
Not so with the Depth. Somehow, MartinLogan has persuaded three small 8" drivers and an analog servo unit in a hexagonal cabinet to do the same job for less than $1800. This baby servo sub could move air, create pith-perfect bass, and blend well with such top-quality audiophile speakers as the Quad ESL-989 electrostatics.
I may, as my wife claims, be weird. I may love weird music. But the MartinLogan Depth's ability to reproduce bass is anything but weird. It can give any audiophile or home-theater owner the ability to enjoy powerful, tuneful, pitch-accurate bass in a standard or even large listening room. And that's from a small, easily installed hexagonal box that won't bust your back or your budget. Good work, MartinLogan, in delivering such impactful bass from the small, cost-effective, but mighty Depth.
Footnote 1: I'm sure neither manufacturer will be totally pleased that I borrowed a system from one of them to review the other's product. Still, the DD-18 calibrator showed me how important having such a tool is for properly matching any subwoofer to my rather challenging room. Those with smaller rooms—as most of you reading this article probably have—should be able to manage the Depth's setup without all the extra gear.—Larry Greenhill
Footnote 2: This may be due, in no small part to the fact that the Quad 989 has more bass extension than any previous Quad—it puts out lots of musical energy down to 40Hz. That permits an easier blend with an aftermarket sub.—Larry Greenhill