Martin Logan “Source” Hybrid-Electrostatic Loudspeaker

Throughout the late 1980s and early 1990s, the MartinLogan Curvilinear Line Source (CLS) full-range electrostatic was my reference loudspeaker, and although I’ve since gone on to other things, the CLS remains one of the purest and most transparent transducers I’ve heard. This was a speaker that made the old cliché about opening a window on the orchestra come true— everything in earshot of the CLS was clear and distinct and incredibly finely detailed. The trouble was it was also a bit bleached, thin, and cool. The CLS’s extraordinary transparency came at the cost of suckout in the bass and the power range of the lower mids. Although this balance seemed to increase resolution (rather in the way a spare pen-and-ink drawing can look more finely detailed than a lush oil painting of the same subject), it also reduced lifelike density of tone color, body, and sock. The problem with timbres, coupled with the CLS’s inability to reproduce powerful dynamics in the low end, is one reason why Martin Logan eventually abandoned its full-range ’stat for the ’stat/cone hybrids that are its specialty.1 However, while the weight and color of cones do solve timbre problems, as well as adding oomph in the bass, hybrids come with their own price in coherence. Let’s face it: A cone is a cone and a ’stat is a ’stat, and whenever the twain have met in the past, there has always been an audible seam between them. To me trading off leanish coherence for rich incoherence has always seemed a poor deal. So, while looking forward to hearing MartinLogan’s latest—the $1995 Source electrostatic hybrid—I also suspected that the mating of cone and ’stat wouldn’t be my sonic dream-date. Boy, was I wrong.

Might as well get this out of the way: The Source is the most impressive hybrid loudspeaker I’ve auditioned—an astonishingly successful blend of what I once thought were essentially incompatible technologies—and, with a couple of provisos (see below), one of the two most lifelike full-range loudspeakers I’ve heard for under-$2k. What makes the Source’s success even more astonishing, over and above its quite affordable price, is the way it boxes other audio verities squarely on their ears. For instance, the Source doesn’t just use an 8″ cone; it uses an 8″ paper cone in a ported box that, while serviceable, is—how shall I put this?—less-than-Magico quality. On top of this, it crosses its cone over to the electrostatic panel at 470Hz—just a little above middle A, the note the oboe sounds when the orchestra tunes up. All of which makes the Source not only a surprise but also a bit of a miracle.

better than ten years, but it is now obvious that, while I was sleeping, a good deal of ingenious engineering work was being done out there on the prairies of Lawrence, Kansas. For one thing, ML’s electrostatic panel, though still “curved” to improve horizontal dispersion and off-axis listening (though it doesn’t really improve either much), is now framed in aircraft-grade aluminum-alloy rather than good old pine, increasing the rigidity of the panels and shielding them more effectively from resonances generated by the movement of the electrostat’s diaphragm and the cone woofer. For another, the panels themselves have been updated. The ultra-low-mass PET (polyethylene terathylate) diaphragms are now coated with an electro-conductive material that is said to adhere better and improve impedance characteristics, while the stators have been made stiffer and their perforations smaller and more numerous, roughly doubling the area of exposed diaphragm and, thereby, increasing output and efficiency. For a third, the latest crossovers are superior. MartinLogan has developed a proprietary crossover topology, called (for reasons not immediately apparent) “Vojtko,” that is said to lower distortion and provide more seamless driver integration—and call me Vojtko if it doesn’t do just that very thing.

How does the Source sound? In a word, terrific. This is one very quick, very high resolution, surprisingly robust, wideband, and coherent loudspeaker, capable of making select voices and instruments sound as you-are-there “real” as some multi-thousand-dollar Big Boys. If you haven’t heard a MartinLogan electrostat in awhile, you kind of forget just how astonishingly lifelike they can be. Despite the fact that all ’stats use the same basic drive system, panels from different companies sound as substantially different as dynamic loudspeakers from different companies. Logans are fast, fast, fast—and transparent, as in “clear, pure, uncolored.” Hearing plucked guitars or violins played back on CLSes always made everything else, even other ’stats, sound slightly stuck in the mud. It’s no different with the Source. Only the Source is far more realistically dense in tone color and far more full-bodied and three-dimensional than the old CLS.

You would think the addition of a cone woofer (and cone-woofer enclosure) would slow down transients, but it doesn’t—or at least it doesn’t to my ear. Plucked strings—like those of Joan Baez’s guitar or Nadia Salerno-Sonnenberg’s fiddle—still have the kind of “snap” that’ll put a smile on your face: They’re just that much quicker, more immediate, and more lifelike than what you hear through cones, even great cones like those of the Magico Mini II. The nice part is that, as noted, this speed now comes with greatly improved tone color, so you don’t just hear the snap of the string; you also hear the resonance of the guitar or violin body. Indeed, while not as luscious or as dense in color as the timbres of, oh, a Gamut L-3, the Source’s tone colors are still pretty damn luscious.

And that resolution! A friend of mine, a good listener, compared these things, justly, to giant headphones—they have that kind of upfront, super-clear, super-detailed, super-immediate presentation. Little things that get swallowed by the mass and inertia of cone drivers—like the trailing edge of the tiny grace note on the piano that launches the Lutoslawski Concerto for Orchestra [EMI] or, as I mentioned in my review of the fabulous TW Acustic Raven AC-3 turntable, the glistening “finish” that the plucked harps add to the doublebass pizzicatos in the Passacaglia of this same great concerto—are reproduced with magical clarity. Voices, like Joan Baez’s on “House Carpenter” [Vanguard] or John Shirley- Quirk’s on Lutoslawski’s Les Espaces du Sommeil [Sony Classical], are reproduced with so much more detail about the way the vocalist is shepherding his breath or expending it that the sense of hearing actual singers singing is greatly increased.

On top of this, the Source has very good bass. No, it’s not a Mini II in the bottom octaves (and certainly not an MBL 101 E), but it’s a good deal more than respectable down into the low 40Hz range. Those bass and harp pizzicatos on the Lutoslawski, the powerful Fender ostinatos on Chris Isaak’s “Dangerous Game” [Reprise], the big pedaled chords of Brooks Smith’s Steinway on the Kreutzer Sonata (and just as remarkably, the sound of Smith letting up on the sostenuto pedal) are fast, clean, detailed, and full-bodied. If the bass is a smidgen “slower” (oops, there’s that “s” word again) than the electrostatic midrange and treble—and it probably is—it didn’t bother me. In other words (and unlike every other hybrid loudspeaker I’ve heard) I wasn’t plagued by the thought that I was listening to two different and incompatible drivers. Where I think you do hear the difference in the cone bass— and perhaps its enclosure—and the electrostatic panel is in soundstaging, at which the Source is no world-beater. Whether it’s the narrower more beamy dispersion of the line-source ’stat or the higher distortion of the woofer or the resonance of the woofer’s enclosure, the Source doesn’t image much “outside the box.” It images beautifully “between the boxes,” but it is consistently “forward sounding,” and its stage is consistently more restricted, less expansive, and less deep than that of, say, the Focal/JMlab 1007Be or, frankly, the $550 Magneplanar MMG. To this extent, you do hear the Source as a sound source.