The first new MartinLogan speaker of the CLX generation, Spire marks a new paradigm for high-performance sound. Crossover engineering derived from the CLX loudspeaker seamlessly blends the high-resolution XStat™ and PoweredForce™ drivers.

Revealing every subtle nuance of recorded sound with unflinching accuracy, Spire's ultra rigid AirFrame and curvilinear XStat electrostatic transducer reveal a magical performance with precision, dynamics and three-dimensional sound staging. Housed within an ultra-rigid, extruded aluminum and composite AirFrame™, Spire's CLS™ (Curvilinear Line Source) XStat™ transducer builds upon the legacy of MartinLogan's 25 year heritage of providing the highest quality electrostatic products.

A Curvilinear Line Source electrostatic transducer.

XStat™ Transducer

Advanced MicroPerf stator technology gives MartinLogan's latest-generation CLS™ electrostatic transducer almost twice as much exposed diaphragm surface as a traditional electrostatic panel of the same size. This dramatic increase in effective radiating area translates to higher efficiency and an even more effortless, unlimited dynamic presentation. The XStat pulls no punches!

But there's more to it than just putting more holes in the stators, which must maintain uniform spacing in front of and behind the diaphragm to exacting tolerances. They cannot flex. XStat's ultra-rigid aluminum AirFrame™ firmly anchors the transducer's working elements – stators and diaphragm – around their periphery, while ClearSpar™ spacers stiffen the assembly further across its width. ClearSpars enable precise, consistent tensioning of the Vacuum Bonded diaphragm without obstructing the floating, see-through look that is the visual hallmark of MartinLogan electrostats.

In the end, a speaker cannot outperform the signal feeding it. MartinLogan's state-of-the-art toroidal transformer and electrical interface engineering ensure an absolutely transparent link from amplifier to electrostatic panel. The result is sound of unparalleled purity, precision, clarity, and openness – the next best thing to no speaker at all.

Parts of a MartinLogan AirFrame


MartinLogan AirFrame.

A) Top Strut
B) Compression Rod
C) Rod Isolator
D) ESL Transducer Isolator
E) Aluminum Side Pillar

AirFrame™ Technology

XStat™ panels are secured to speaker cabinets using MartinLogan's AirFrame technology. AirFrames, manufactured from aerospace-grade billet and extruded aluminum alloy, make the panels extremely rigid without obstructing playable surface area or interfering with their dipole sound radiation. At the same time, they provide electrical and acoustical isolation, minimizing intermodulation distortion caused by vibration and resonance. Overall, AirFrames enhance imaging, low-level sonic detail, accuracy, and efficiency.

Vacuum Bonding

The components of each XStat™ panel – two insulated, high-purity carbon steel stators, plasma-deposited PET diaphragm, and ClearSpar™ spacers – are fused into a cylindrical-section geometry with an aerospace adhesive whose hold strength exceeds that of welding. Our proprietary Vacuum Bonding process ensures uniform diaphragm tensioning and facilitates the extremely tight tolerances necessary for construction of such a precision transducer.

Curvilinear Line Source Electrostatic Panel

One of MartinLogan's original breakthroughs, CLS™ technology has been an essential ingredient of every electrostatic loudspeaker we've produced. Proprietary manufacturing methods enable construction of electrostatic panels as cylindrical sections. Their gentle horizontal curvature solves the problem of obtaining good high-frequency dispersion from a large radiating surface without compromising overall sound quality or reliability.

An aluminum cone woofer.

PoweredForce™ Bass

MartinLogan PoweredForce woofers feature advanced driver and amplification technologies that deliver astonishingly dynamic and articulate bass to as low as 29 Hz. Integrated low-frequency equalization further enhances performance by allowing precise tailoring to individual room acoustics.

Low-Distortion Aluminum-Cone Woofer

By eliminating cone flexure, aluminum diaphragms help our advanced-technology woofers achieve the very low distortion necessary for proper blending with MartinLogan electrostatic panels.

MicroPerf Stators

Although stators are the elements of an electrostatic driver that are supposed to stand still, they carry the audio signals that do the work of propelling the diaphragm back and forth to move air and produce sound. Because the stators sandwich the diaphragm between them, they must be perforated to allow sound to pass through. Yet they must also be rigid enough to remain absolutely stationary despite the strong electrostatic forces pushing and pulling at them during operation.

MartinLogan's MicroPerf design optimizes this tradeoff by reducing the size of the individual holes and using many more of them than in a traditional electrostatic panel. MicroPerf almost doubles effective diaphragm radiating area without compromising structural integrity. The resulting increase in output capability and efficiency allows a panel to be made much smaller without sacrificing performance – or to enjoy a substantial leap in bandwidth and dynamics without growing larger.

Dipole sound radiation.

Dipole Sound Radiation

The sound we hear from a loudspeaker is a combination of direct radiation from it to our ears and reflections off of room surfaces – walls, floor, and ceiling. How our brains integrate all this information is far from simple. Depending on the angle of incidence to the ears and the arrival-time difference between direct and reflected sound, reflections can either blur detail and stereo imaging or enhance the natural impression of depth and openness.

True dipole speakers, such as electrostatic panels, have long been noted for their near-ideal radiation patterns. They send very little sound to the sides, thereby minimizing side-wall reflections with short arrival times that tend to interfere with perception of the direct sound. Their strong rear radiation, however, produces a generous amount of ambience-enriching later-arriving reflections off the wall behind them.

Vojtko™ Crossover

Featuring an advanced proprietary Vojtko™ crossover topology derived from the flagship CLX™ loudspeaker, MartinLogan electronic specialists hand-build each Spire crossover utilizing only the finest of components and construction techniques to assure the cleanest, most precise signal path possible. The resulting precision crossover flawlessly preserves even the smallest subtleties in sound while effortlessly handling the broadest range of dynamics contained within even the most demanding sonic source, whether used in a 2-channel audio system or dedicated home theater.

Portless Enclosure

Although ports are a convenient and cost-effective way of increasing low-frequency output, they rely on resonant energy in a way that impairs bass quality. A good sealed system will exhibit less transient-blurring group delay while maintaining smooth, consistent response regardless of output level or voice-coil temperature. Listen carefully to the sound of a bass drum, and you'll hear the difference.

35-Hz Level Control

Spire backplate showing the 35Hz level control and bi-wire binding posts.

Spire's PoweredForce™ active woofer system enables fine-tuning of the speaker's output in the frequency ranges most commonly and severely affected by room acoustics. The result is bass that is not just deep and powerful, but also smooth, clean, and detailed.

Bi-wirable Toolless Binding Posts

MartinLogan's proprietary toolless binding posts make cable connection and management easy. Two sets are supplied, one connected to the crossover section feeding the electrostatic panel, the other to the section feeding the woofer. When the two are linked using the supplied straps, a conventional single-cable connection can be used. Or you can remove the straps for bi-wiring.

MartinLogan CLS (Curvilinear Line Source) electrostatic transducer.

Custom Feet and Energy Transfer Coupler Spikes

The Spire is supplied with sturdy, 3/8-16 ETC™ spikes, which can be used in place of the standard feet to enhance stability on thick carpets or to create tighter coupling between speaker and floor.

Finish Options

Available in a variety of hand-rubbed wood finishes, MartinLogan Spire™ loudspeakers can be personalized to match any décor.