September 2009

MartinLogan Summit X Loudspeakers

Category: Innovation in Design


Associated Equipment

Loudspeakers -- MartinLogan Vantage, Summit

Power amplifier -- Halcro MC50

Preamplifier -- NuForce P-9

Source -- Marantz DV-9600 SACD/CD/DVD-A/V player

Interconnects -- Synergistic Research Tesla Apex and Precision Reference

Speaker cables -- Synergistic Research Tesla Apex

Power cords -- Synergistic Research Tesla Hologram A and D, Precision AC

Power conditioners -- Synergistic Research PowerCell, PS Audio Noise Harvesters, DIY parallel filter

Accessories -- DIY isolation amp stands, Bright Star Audio and Black Diamond Racing isolation devices, Shakti stones, Synergistic Research TeslaPlex AC outlet, Acoustic Revive CB-1DB Receptacle Base Plate and CFRP-1F Carbon Fiber Outlet Plate, Mapleshade Silclear contact enhancer

Reviewers' Choice LogoI am a longtime electrostatic-speaker junkie who has owned several MartinLogan models, including my current Vantages. When SoundStage! publisher Doug Schneider asked if I was interested in reviewing the new Summit X ($13,995 USD per pair), which replaces MartinLogan’s Summit, we both knew it was an offer I couldn’t refuse.

In a world in which ultra-high-end speakers can cost upward of $100,000/pair, $14,000 for a presumably world-class brace of speakers could, by some, be considered pretty reasonable. But $14,000 is a lot of money even in the best of economic times, and for most people these days -- especially if you’re a working stiff like me -- it’s far more.

Before receiving the Xs, I wondered if they would take me significantly closer to the promised land of electrostatic nirvana than I had ever been. A short while later, two familiarly tall, slender MartinLogan boxes arrived at my door. As they say in the world of sports, this review was on.

eXploring the Summit X

The Summit X is a hybrid loudspeaker: an electrostatic panel paired with two 10" dynamic woofers, each powered by their own 200W amplifier. The most advanced hybrid in MartinLogan’s lineup, the X is eclipsed in stature and price by only two models of the company’s CLX line of full-range electrostatic speakers, both of which cost over $20,000/pair. As discussed below, the X is jam-packed with technology, any discussion of which requires the negotiation of what seems a record-breaking number of trademarked names.

The first thing anyone will notice about the X is its transparent XStat panel, which rises from the woofer cabinet. This panel, gently convex in MartinLogan’s Curvilinear Line Source (CLS) shape, is responsible for reproducing all of the audioband down to the crossover to the woofers, at 270Hz. According to ML, the CLS shape reduces sidewall reflections, and thus minimizes unwanted interactions with such things as ceilings, floors, and walls, while minimizing late arrival time.

The XStat panel’s frame, which ML calls the AirFrame, is manufactured from aerospace-grade billet and extruded aluminum alloy. Extremely rigid, it provides electrical and acoustical isolation that don’t interfere with its ability to radiate sound in dipole fashion, which tends to cancel out sounds at the edges of the speakers, further reducing sidewall reflections. A proprietary vacuum-bonding process ensures the uniform tensioning of the AirFrame and makes possible the precise tolerances to which they must be made.

This panel comprises two large exterior steel stators, an almost weightless diaphragm of Mylar-like film coated with a conductive material, and ClearSpar spacers that keep the stators from touching the diaphragm. They’re fused with an aerospace adhesive whose strength exceeds that of welding. The stators sandwich the diaphragm and remain stationary while the speaker is in operation. They also transfer to the diaphragm the source signal, which, as described below, directs the diaphragm’s movements back and forth to create the sound.

To permit sound to pass through them, the stators are perforated. In developing their MicroPerf technology, MartinLogan has reduced the size of the perforations and increased their number over the company’s earlier models. This not only nearly doubles the diaphragm’s radiating area and, ML claims, allows the Summit X to attain significant improvements in performance, it also makes possible a speaker about half the size of the company’s earlier behemoths.

When the Summit X is operating, its diaphragm holds a fixed positive charge. A transformer changes the power from an amplifier into two high-voltage signals that are then sent to the stators in opposite polarity: one positive, one negative. As the amplifier signal changes, the polarity of the stators flips between front and back, causing the diaphragm to be rapidly pushed and pulled between the stators. This "push-pull" design is said to cause the diaphragm to precisely and rapidly follow any changes in the signal.

The X’s two dynamic Controlled Dispersion PoweredForce woofers have 10" aluminum cones. One woofer fires forward, from the front panel, and the other downward, through the base. According to ML, these woofers extend the X’s response to as low as 24Hz, territory typically claimed only by freestanding subwoofers. The woofers are enclosed in their own sealed cabinet.

The X uses ML’s newly designed, hand-built Vojtko crossover, based on technology trickled down from the CLX line. As discussed below, this crossover must facilitate the integration of the outputs of the electrostatic panels and the dynamic woofers. The longstanding problem in pairing these two types of transducers is that the panels are so much faster than the woofers that their outputs don’t integrate with each other well enough to produce a seamless melding of upper and lower frequencies. Over the years, MartinLogan has made steady progress in solving this problem.

A peek at the rear of the X’s cabinet reveals 25 and 50Hz low-frequency equalization controls. These allow the speakers to be tailored to accommodate individual room acoustics. The listener can raise or lower the speaker’s feet to adjust the speaker’s controlled vertical dispersion, or tilt the X from -1 to +11 degrees from the vertical.

Finally, "just because it’s cool" (per ML’s website), each Summit X has no fewer than three lights. One illuminates the rear controls, another the blue MartinLogan logo, and the third casts the X’s spike-raised underbelly in a piercing white glow that resembles something you’d see illuminating the underchassis of a low-rider. But if glowing speakers aren’t your thing, any or all of the lights can be turned off.

Setup: X marks the spot

Unpacking the Xes was much easier than I’d imagined it would be. And as each speaker weighs only 75 pounds, I was able to set them up myself.

The Xes are a bit larger than my Vantages; I was concerned that the former would be too large for my medium-sized room (12’ x 22’) and thus sound boomy. One nice thing about the active woofers is that if you do run into this problem, you can always decrease the woofers’ output by adjusting the 25 and 50Hz controls. It didn’t take me long to get these settings where I needed them. Of course, the right settings for these controls will be different for every room.

As with many speakers, placement of the Xes was critical. After much experimentation, and taking into consideration the narrowness of my room, I wound up placing the speakers 7’ apart, and my listening chair about 8’ from their midpoint. And, because electrostatics often require lots of breathing room, I positioned them about 2’ from the front and sidewalls.

I used about 30 degrees of toe-in -- any more and the Xes sounded a bit too bright, much less and the soundstage became diffuse. Because I tend to slouch down in my chair when listening to music, I adjusted the rake of the speakers to tilt back only about 3 degrees.

I fed the Xes a steady solid-state diet courtesy my Halcro MC50, a 200Wpc switching amplifier. Note that the active woofers, which have their own 200W amps, make the X a speaker much easier to drive than some of ML’s earlier models; they don’t necessarily need as powerful an amp as many might think. Nonetheless, you’ll likely not want to pair them with an ultra-low-power girly-man amp.

Performance: X is for X-ray

First up was Paul van Dyk’s Global (CD, Gmbh & Co. KG 9201-2). The electronic nature and grinding beat of van Dyk’s progressive house music make it an album that most would not choose to audition electrostatic speakers, but there’s more to Global than its addictive rhythmic pulse. Present in the mix are sweeping synthesizer riffs, luxuriant melodies, and sexy female vocals.

Listening to any track on Global demonstrated that the Summit Xes could move more than enough air in the lower octaves to reasonably rock my house. More than that, the X unmistakably had that MartinLogan signature sound: clear and open, masterfully layering the various synthesized sounds and flushing out their alluring midrange warmth. Call it a magical transparency and immediacy that few conventional dynamic speakers -- and none that I’ve heard at or near this price -- can match. To my surprise, I found that the X displayed a significantly warmer tonal balance than I was used to hearing from ML’s prior offerings.

But after listening for a bit, it was time to move on. While electronic music will benefit from a pair of well-designed speakers, it won’t fully demonstrate those speakers’ ability to, among other things, render the inner detail, complex tonalities, and elaborate harmonic structures produced by acoustic instruments.

So out came a parade of acoustic challenges. In the Tuba Mirum of Mozart’s Requiem, as performed by Sir Charles Mackerras and the Scottish Chamber Orchestra (CD, Linn CDK 211), the opening trombone displayed remarkably good pitch definition and texture, and astounding resonance. "Poem of Chinese Drum," from Yim Hok-Man’s Master of Chinese Percussion (HDCD, Lim K2HD 033), had low-level clarity and coherence as well as window-rattling depth. The string bass on Jorma Kaukonen’s Blue Country Heart (SACD/CD, Columbia CS 86394) was tight, with no sign of overhang.

This is not to say that I can’t think of a number of speakers that provide comparable low-end performance. But it’s the X’s extraordinary realization of the midrange and highs that draw the masses.

Throughout the Mozart Requiem, the Summit X rendered the voices of soprano Susan Gritton, mezzo-soprano Catherine Wyn-Rogers, and tenor Timothy Robinson with silkiness and immediacy. Even the voices of individual members of the Scottish Chamber Chorus were exposed. "The Sweetest Taboo," from The Best of Sade (CD, Epic EK 66686), presented Sade’s voice with a sublime warmth and delicacy that highlighted her sultry, erotic phrasing. Numerous tracks from Shirley Horn’s You Won’t Forget Me (CD, Verve 847 482-2) unmasked heretofore hidden inflections of voice that would impress even her casual fans. Indeed, time after time, the Xes delivered voices that were more detailed, open, and colorless than I’d previously heard in my listening room.

A midrange of this quality would be enough for some speakers to call it a day. But for the Summit X, such skill did not come at the expense of top-end performance. Instead, everything from percussion to bowed instruments was marked by a distinctively clean airiness. The playful opening cymbal strokes in Steely Dan’s "Deacon Blues," from A Decade of Steely Dan (CD, MCA MCAD-11553), threw a bewildering amount of microdynamic data at the Xes that they deftly sorted through, disclosing subtleties of the initial impact of stick on cymbal that are often lost among the ringing waves of energized brass. The Xes also masterfully reproduced the resulting delicate sheen that hovered almost weightlessly over the soundstage, ending only when the last metallic reverberation had been revealed. The protracted, ultra-high-frequency "money notes" in Catalani’s "Ebben? . . . Ne andrņ lontana," from Galina Gorchakova’s Italian Opera Arias, with conductor Constantine Orbelian and the Russian Philharmonic (SACD, Delos DS 3286), were spine-chilling, and so extended they’d no doubt unnerve all but the very best dynamic tweeters.

I heard no sharp, screechy, or collapsed highs, or upper-level grain or harshness, from the Summit X -- unless such defects were present on the recording. Indeed, the X picked up not only everything on each of my recordings, but also any extraneous noise generated by my electronics. Accordingly, a high-quality, low-noise amplifier and well-recorded source material are absolutely essential.

Other strengths of the Summit X were in dynamic range, soundstaging, and transient delivery. The dynamic range was often startling and didn’t seem the least bit constrained, as some claim can occur with curved electrostatic panels. The Xes’ mammoth soundstage can be described only as "electrostatic"-large, and contained focused images that rooted themselves deep beyond my room’s front wall. On several occasions I closed my eyes and pointed to the locations of the various instruments that I was hearing. When I then opened my eyes, I often found myself pointing not at the speakers, but at some other place in the soundstage. Transient speed was so fast as to render useless any comparison to speakers with dynamic drivers.

But the perfect speaker has yet to be made. One area of the Summit X that could be improved is its off-axis performance. MartinLogan says that the Xes’ limited sweet spot is the unavoidable byproduct of a design choice that, as indicated above, controls dispersion by focusing radiated sound into a limited horizontal path. Nonetheless, I found that, for optimal tonality, detail, and imaging, I would be disinclined to invite more than one other person to join me for a serious listening session -- and even that might be pushing it, unless we occasionally traded seats. However, I found that the farther I sat from the Summit Xes, the larger the sweet spot was, with only marginal tradeoffs in detail and tone.

And while I’ll opt for transparency and finesse over brute force any day of the week, the Summit X lacked the sheer weight that some of the larger dynamic-driver speakers can bring to the upper bass and midrange. The strings in the Mozart Requiem were exquisite -- silky, detailed, and surrounded by what seemed physically measurable gobs of air. The Xes also artfully exposed the leading transient edges of each pizzicato pluck. However, the MLs didn’t possess the inner density I’ve heard from the meatiest dynamic speakers. You say you want a Ferrari that can accommodate your family of seven and your dog?

Comparison: V and S vs. X

I compared the Summit X to MartinLogan’s own Vantage. At $5695/pair, the Vantage is more speaker than most listeners will ever need. Nonetheless, in moving up to the Summit X, the moneyed audiophile will experience weighty gains in just about every audiophile criterion, not least of which is musicality. Buyers of the X should know that it’s far less forgiving than the Vantage, in part because it’s more revealing. That the X is better than the Vantage shouldn’t surprise -- at two-and-a-half times the price, it should be.

Far more intriguing to me was to compare the Summit X with the model it replaces -- the Summit itself ($9995/pair), a speaker I’d considered buying a few years ago, until financial reality set in. While preparing to write this review, I visited a friend who has a pair of Summits in order to refresh my recollections of their sound.

Right off the bat I realized that, in the X’s high and midrange regions, MartinLogan has made great strides. The X sounded immensely more lush, airy, and open than the Summit. The Xes also presented more detail and a larger, more solid soundstage. In fact, above the crossover point, the X seemed to produce a substantial reworking of the Summit’s sound, which was somewhat more cool and closed-in, more dull and removed.

I found the bass performances of the X and Summit to be more or less on a par. Well, not exactly -- the Summit’s low-level detail, extension, and accuracy turned out to be very comparable to that of the X, but the X handily outperformed the Summit in the integration of the outputs of the woofers and electrostatic panel.

According to MartinLogan, their Vojtko crossover tightly aligns the phase at the crossover point, thus providing dispersion in the low end that, as with the output of the electrostatic panel, minimizes sidewall reflections. The Summit X woofers are thus said to operate more like the panels than in previous ML models, resulting in a more seamless transition to the upper bass.

Regardless of how the Vojtko crossover works, the improved integration of the drivers’ outputs is a significant accomplishment. While there’s still room for improvement, the blend in the Summit X is much smoother than in the Summit. Of course, as stated above, the perfect speaker does not exist; the art of speaker design always entails making the best selection among many compromises.

Conclusion: electrostatic Xuberance

The Summit X is the latest step in MartinLogan’s ongoing quest for electrostatic perfection. They’ve improved on the technology’s stunning strengths -- transparency, speed, immediacy, midrange presence, soundstaging -- while minimizing its shortcomings, particularly in the integration of the outputs of the woofers and upper-range panels. When these speakers make their special magic, they’ll likely astound and emotionally move even the most experienced and hardened audiophile.

I find the Summit X just too addictive to live without. I’m putting my money where my mouth is and buying the review pair to serve as my new reference loudspeakers. I may never reach the promised land of Audio Nirvana, electrostatic or otherwise, but thanks to MartinLogan, I’m going to enjoy the journey.

. . . Howard Kneller

MartinLogan Summit X Loudspeakers
Price: $13,995 USD per pair.
Warranty: Five years parts and labor.

MartinLogan, Ltd.
2101 Delaware
Lawrence, KS 66046
Phone: (785) 749-0133
Fax: (785) 749-5320