MartinLogan Theos

Floor-standing speaker (High-gloss Piano Black)

  • MartinLogan Theos

    High-gloss Piano Black

  • MartinLogan Theos

    Back (High-gloss Piano Black)

  • MartinLogan Theos

    CLS (Curvilinear Line Source) electrostatic transducer panel

  • MartinLogan Theos

    Side view (High-gloss Piano Black)


Our take on the MartinLogan Theos

by Dave Bar

Floor-standing speakers — still standing tall

Sure, floor-standing tower speakers buck the industry trend toward smaller, visually inconspicuous speakers, but they're hard to beat if great sound is your primary goal. Tower speakers produce powerful sound with excellent bass, making them a great choice for serious music lovers and for folks who want high-impact home theater.

Light up your listening room

When MartinLogan recently visited to show off a pair of their Theos electrostatic floor-standing speakers, they lit up our cavernous, notoriously speaker-unfriendly product training room with sound that simply blew us away. And they did it using a moderately priced receiver that never even broke a sweat! Rock, Jazz, and acoustic music unfolded from the Theos' tall, sleek panels with a sense of immediacy and presence that felt as if the musicians were sitting there in the room. Our takeaway: you don't need a rack full of uber-expensive components or a fancy, dedicated listening room to enjoy fantastic sound with these speakers.

The secret to transparent sound

Unlike speakers that use domes and cones to reproduce treble and midrange, the Theos features an ultra-thin polymer film, or diaphragm, suspended between two electrically charged, perforated steel plates. The diaphragm's ultra-low mass allows it to move very efficiently back and forth between the plates thousands of times a second in response to the music signal, creating enticingly transparent, low-distortion sound. The panel is visually transparent, too, so it makes an unforgettable impression when seen in person.

Throwing a curve into the equation

Martin Logan Theos loudspeaker

Controlling a speaker's sound dispersion in a room is crucial to creating realistic sound. MartinLogan's signature 30º curved electrostatic panels allow for ideal dispersion in your home listening environment and minimize reflected sound off of the side walls that can muddy detail and stereo imaging. This design helps take the room out of the sonic equation.  

Less crossover equals better sound

Even the best crossovers can add distortions that negatively impact sound quality. The Theos' hybrid design uses its electrostatic panel to operate all the way from the highest audible frequencies down through the crucial midrange (where our ears are most sensitive) to 425 Hz without a crossover for the purest possible music reproduction. A high-excursion 8" aluminum cone woofer takes over from there, seamlessly blending in to provide taut, precise bass that rounds out the speaker's low-end end response.

Sonic refinement with a beautiful finish

From its hand-built cabinet with a gorgeous, hand-rubbed finish to its custom, bi-wire capable binding posts and heavy-duty floor spikes, the Theos exudes quality. Adding further to its refined sound is a precision hand-built crossover network with point-to-point wiring and premium parts. Inside and out, the Theos is one beautiful speaker that can complement virtually any listening room.

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  • 44" x 9-3/16" XSTAT™ CLS™ (Curvilinear Line Source) electrostatic transducer for wide sound dispersion, excellent clarity, and low distortion
  • 8" cast basket high-excursion aluminum cone woofer (reproduces frequencies below 425 Hz)
  • bass-reflex (ported) woofer enclosure
  • external low-voltage DC power supply (included) requires AC outlet connection to energize electrostatic panel
  • hand-built Vojtko™ crossover network with precision point-to-point wiring, polypropylene capacitors, massive air-core coils, and a custom wound E-I core transformer
  • frequency response: 43-23,000 Hz (±3dB)
  • sensitivity: 90 dB
  • impedance: 4 ohms
  • recommended amplifier power: 20-400 watts
  • High-gloss Piano Black finish
  • adjustable feet and floor spikes
  • custom 5-way bi-wire tool-less binding posts
  • 10-3/4"W x 59-3/8"H x 19-1/8"D
  • weight: 43 lbs.
  • warranty: 5 years (with product registration)
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Enclosure Bass Reflex
Finish Wood veneer
Color Gloss Black
Tweeter E-ST
Tweeter Size (inches) 9.2x44
Midrange Size (inches) N/A
Woofer Size (inches) 8
Woofer Composition Aluminum
Woofer Surround Butyl Rubber
Built-in Powered Sub No
Video-Shielded No
Connector Type Binding post
Bi-amp Inputs Yes
Parts Warranty 5 Yrs w/ Registration
Labor Warranty 5 Yrs w/ Registration
Power Range 20-400
Frequency Response 43-23k Hz
Sensitivity 90 dB
Impedance (Ohms) 4
Amplifier Power ---
Height (inches) 59-5/16
Width (inches) 10-3/4
Depth (inches) 19-1/8
Weight 43 lbs
Product Research
What's in the box?

Download owner's manual

  • Floor-standing hybrid electrostatic loudspeaker
  • AC power adapter (w/ attached 10' DC cord)
  • 4 Spiked feet
  • User's Manual (En/Fr)
  • Product Registration Card

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.


Electrostatic Technology (How it Works): Where traditional loudspeaker technology incorporate cones, domes, diaphragms, and ribbons that are moved with magnetism, electrostatic loudspeakers employ charged electrons attracting and repelling each other. An electrostatic transducer consists of three pieces; stators, the diaphragm, and spacers. The diaphragm is what actually moves to excite the air and create music. The stator's job is to remain stationary and to provide a reference point for the moving diaphragm. The spacers provide the diaphragm with a fixed distance in which to move between the stators. As your amplifier sends music signals to an electrostatic speaker, these signals are changed into two high-voltage signals that are equal in strength but opposite in polarity. These high voltage signals are then applied to the stators. The resulting electrostatic field, created by the opposing high voltage on the stators, works simultaneously with and against the diaphragm, consequently moving it back and forth, producing music. This technique is known as push-pull operation and is a major contributor to the sonic purity of the electrostatic concept due to its exceptional linearity and low distortion.

Hybrid Electrostatic Speaker: The MartinLogan Theos is a hybrid electrostatic loudspeaker that features a XStat CLS electrostatic transducer panel, an optimized Vojtko crossover, and a passive 8" woofer. Electrostatic panels are perfect for reproducing high, midrange, and midbass frequencies. However, both the size and the power requirements of deep bass frequencies are best served by traditional cone woofers. A phase and amplitude optimized Vojtko crossover (425Hz) ensures a seamless transition between the two sound reproduction philosophies. As a result, this speaker offers the best performance for high, mid, and low frequencies.

XStat CLS Transducer:  The MartinLogan Theos features a 9.2" (w) x 44" (h) XStat CLS Transducer. This new XStat transducer builds upon the legacy of MartinLogan's electrostatic heritage with the incorporation of a myriad of technology and design innovations including CLS, MicroPerf, Generation 2 Diaphragms, ClearSpars, Vacuum Bonding, and AirFrame technology. Through rigorous testing, this curvilinear electrostatic panel has proven itself to be one of the most durable and reliable transducers available today. Fabricated from a custom tool punched high-grade steel, the patented panel is then coated with a special polymer that is applied via a proprietary electrostatic bonding process. This panel assembly houses a membrane just 0.0005" thick. Ruggedly constructed and insulated, the panel is rated to easily handle 20 to 400 watts of power.

  • CLS (Curvilinear Line Source): MartinLogan engineers discovered a simple solution to achieve a smooth pattern of dispersion from a smaller electrostatic transducer without degrading sound quality. By curving the horizontal plane of the electrostatic transducer, a controlled 30° horizontal dispersion pattern could be achieved, yet the purity of the almost massless electrostatic diaphragm remained uncompromised.
  • Generation 2 Diaphragm: The diaphragm used in the Theos XStat transducer employs an extremely sophisticated conductive coating applied to the polymer surface at an atomic level using a plasma bonding process. A proprietary compound is driven into the surface of the polymer film in an oxygen free argon chamber. This process allows extremely uniform surface resistivity characteristics, an optically transparent surface, and a nearly massless diaphragm. This uniform surface resistivity controls the electrostatic charge on the diaphragm surface and regulates its movement.
  • MicroPerf Stator: 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 the XStat CLS panel to be made much smaller without sacrificing performance and lets you enjoy a substantial leap in bandwidth and dynamics.
  • Vacuum Bonding + ClearSpar Spacers: To achieve the power, precision, and strength of the XStat transducer, two insulated high-purity carbon steel stators along with a proprietary plasma bonded diaphragm and ClearSpar spacers are fused into a curved geometry with an aerospace adhesive whose strength exceeds that of welding. MartinLogan's proprietary Vacuum Bonding process guarantees uniform diaphragm tensioning and extremely precise construction tolerances, resulting in precision, linearity and efficiency.
  • AirFrame Technology: The XStat CLS panel is secured to speaker cabinet using MartinLogan's AirFrame technology. The AirFrame, manufactured from aerospace-grade billet and extruded aluminum alloy, make the panel extremely rigid while maximizing playable surface area and dipole sound radiation. At the same time, it provides electrical and acoustical isolation, minimizing intermodulation distortion caused by vibration and resonance. Overall, AirFrame technology enhances imaging, low-level sonic detail, accuracy, and efficiency.

Controlled Dispersion Sound Radiation: A key attribute of the MartinLogan Theos is its naturally dipolar radiation pattern. A true dipole, the Theos radiates sound with equal intensity from the front and back of its diaphragm, but the outputs are in opposite phase. As a result, sound waves rippling out toward the sides meet at the speaker's edge and cancel. That and the relatively large size of the Theos' electrostatic panel cause output at the sides to be very low relative to that of a conventional loudspeaker, which in turn minimizes side-wall reflections that tend to muddle sonic detail and stereo imaging. While the reduction in output to the sides contributes to the astonishing clarity, the energy reflected off the wall behind the speaker opens up and deepens the sound.

Full-Range Operation: Another significant advantage of MartinLogan's exclusive electrostatic transducer technology is that no crossover networks are used above 425Hz, because they are not needed. The Theos consists of a single, seamless electrostatic membrane reproducing all frequencies above 425 Hz simultaneously. This eliminates the crossover phase aberrations that are associated with traditional tweeter, midrange, and woofer systems. The result is a dramatic improvement in imaging and staging performance.

Passive 8" Woofer w/ Ported Cabinet: The MartinLogan Theos employs a passive 8" high-excursion aluminum woofer w/ butyl rubber surround, a 425Hz low-pass crossover, a non-resonant composite/real-wood veneer cabinet, and an ultra-low turbulence down-firing bass port to generate unyielding, detailed bass down to 43Hz. The MartinLogan Theos is available in a black ash or gloss back finish.

Note: When you first begin to play the Theos speaker, it will sound a bit bass shy. This is due to the high-quality, long-life components used in the passive woofer. The custom-made woofer requires approximately 72 hours of break-in at 90 dB (moderate listening levels) before any critical listening. The break-in requirements of the crossover components (and, to a lesser degree, the stator) are equivalent.

Advanced Vojtko Filtering: Proprietary Vojtko filtering technology is utilized to transition between the Theos' electrostatic transducer and passive 8" woofer. This audiophile quality network is carefully hand-built using precision point-to-point wiring, polypropylene capacitors, massive air-core coils, and a custom wound E-I core transformer; flawlessly preserving micro-acoustic subtleties while effortlessly handling the broadest range of dynamics contained within even the most demanding sonic sources.

Bi-Wirable Binding Post: The Theos features bi-wirable binding posts and provide the ultimate level of flexibility for connection and setup. MartinLogan's proprietary tool-less binding posts simplify cable connection and management. Two sets are supplied; one connected to the electrostatic panel and the other feeding the woofer. You can choose to bi-amp the Theos, or use jumper clips between the binding post sets for a single wire-connection. The binding posts will accept bare wire (16- to 8-gauge), pin-connectors, spade-connectors, and banana plugs (single only).

Low-Voltage DC Power Supply: The Theos speaker uses an external low-voltage power supply to energize its electrostatic panel. The included power supply firmly inserts into the "DC Power In" receptacle on the rear-panel of the speaker and then to an AC wall outlet. The Theos speaker features a signal sensing circuit which will switch the Theos off after a few minutes of no music signal, and requires less than two seconds to recharge the panels when a music signal is present.

  • Input: AC 100-240V~50/60Hz, 0.2A
  • Output: DC 15V, 0.4A

Applications: The MartinLogan Theos floor-standing speakers can be used as stereo speakers or home theater front/surround speakers. The Theos speakers are ideal for medium and small rooms.

Placement: The Theos speaker should be placed approximately 2' to 3' from the front wall (the wall in front of the listening position) and about 2' from the side walls. Your sitting distance should be further than the distance between the Theos speakers themselves. This will allow you to attain good center imaging and stage width. Generally, it is found that the ideal listening position is with the speakers slightly toed-in so that you are listening to the inner third of the curved transducer section. 

Note: The front wall surface ideally should be one long wall without any doors, windows, or other openings. If you have openings, the reflection and bass characteristics from each channel can be different.

Interchangeable Feet: The MartinLogan Theos floor-standing loudspeaker includes four pre-installed rubber feet for tile and hardwood floors. You can replace the pre-installed rubber feet with four metal spiked feet for carpeted flooring. Both the rubber and spiked feet are threaded so they can be adjusted to non-level floors.

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MartinLogan Theos Reviews

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5 out of 5

Dream Speakers

Written By CalvinG, Boynton Beach, Fl on Wednesday, June 18, 2014
Crutchfield Customer Review (What's this?)
Better than I expected. Speakers are about 40 hours into break-in. The sound is warming and the bass tighting. I'm still experimenting with positions. I started with the ESL's, the sound was so clear and detailed that I returned the ESL's and ordered the Theos.
Hearing details in my music never heard before.
None so far.
6 out of 7 people found this helpful
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For a more in-depth review and enhanced detailed information on the MartinLogan Theos, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_839THGBLD/MartinLogan-Theos-High-gloss-Piano-Black.html ).

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