Martin Logan CLS Speakers

Description

Few loudspeakers have achieved the legendary status of the MartinLogan CLS (Curvilinear Line Source). Introduced in 1986, the CLS represented a revolutionary breakthrough in electrostatic loudspeaker design by becoming the world’s first commercially successful full-range curvilinear electrostatic loudspeaker. Rather than combining an electrostatic panel with conventional cone woofers, the CLS employed a single, full-range electrostatic transducer to reproduce virtually the entire audible spectrum. The result was a level of coherence, transparency, and imaging that forever changed expectations for high-end loudspeakers and established MartinLogan as one of audio’s most respected manufacturers.

The defining innovation behind the CLS was MartinLogan’s patented Curvilinear Line Source (CLS™) panel. Earlier electrostatic speakers often suffered from extremely narrow listening windows due to their flat panels. By gently curving the electrostatic diaphragm, MartinLogan dramatically improved horizontal dispersion while preserving the speed and phase accuracy that make electrostatic transducers so unique. The 48-inch line-source radiator produces an exceptionally focused soundstage with minimal floor and ceiling reflections, allowing instruments and voices to appear startlingly lifelike within the listening room.

Unlike conventional dynamic loudspeakers with multiple drivers and crossover networks, the CLS operates as a single radiating surface over nearly its entire frequency range. Eliminating crossover transitions through the critical midrange gives the speaker a seamless presentation that few loudspeakers—regardless of price—have ever matched. Vocals possess uncanny realism, string instruments shimmer with natural harmonic complexity, and percussion exhibits lightning-fast transient response. Many listeners describe the CLS as sounding less like a loudspeaker and more like an open window into the original performance.

The speaker’s strengths lie in its extraordinary transparency and resolution. Fine details emerge effortlessly from a silent background, while the absence of cabinet coloration allows recordings to breathe with remarkable openness. Imaging is holographic, with performers occupying stable, three-dimensional positions across an expansive soundstage. Properly positioned well into the room, the CLS virtually disappears, leaving only the illusion of live musicians performing between—and often beyond—the speakers.

Like most full-range electrostatic designs, the CLS demands careful system matching. Its impedance falls significantly at high frequencies, making it happiest with stable, high-current amplifiers capable of driving difficult loads. Quality solid-state amplifiers from Krell, Bryston, Mark Levinson, Classe, and Pass Laboratories have long been popular partners, while certain powerful tube amplifiers can also produce exceptional results. Owners willing to optimize placement and amplification are rewarded with a level of midrange realism that has become the benchmark against which many loudspeakers are judged.

The CLS has received widespread praise from both reviewers and owners throughout its production life. MartinLogan itself described the design as delivering “perfectly etched imaging and focus” with “optimum natural reproduction of sound.”

Long-time owners have echoed those sentiments. One experienced user wrote:

“Very transparent, rich, musical, natural, detail and surround sound. Midrange quality not available for normal dynamic speakers.”

Another owner summarized the experience simply:

“Fantastic sound. Not much more to say but FANTASTIC!!”

Although later MartinLogan models incorporated hybrid designs with dynamic woofers for greater bass extension and output, many enthusiasts still regard the original CLS as the purest expression of the company’s electrostatic philosophy. More than three decades after its introduction, it remains one of high-end audio’s most iconic loudspeakers—a reference for transparency, coherence, and musical realism that continues to captivate listeners around the world.

Highlights

• Landmark full-range electrostatic loudspeaker introduced in 1986
• Patented Curvilinear Line Source (CLS™) electrostatic panel
• Single full-range electrostatic transducer with no conventional woofer
• Seamless crossover-free midrange reproduction
• Exceptional transparency and transient response
• Holographic imaging with outstanding soundstage depth
• Minimal cabinet coloration
• Optimized horizontal dispersion compared with flat electrostatic panels
• Compatible with high-quality tube and solid-state amplifiers
• One of the most influential electrostatic loudspeakers ever produced

Specifications

• Type: Full-range electrostatic dipole loudspeaker
• Transducer: 48-inch CLS™ Curvilinear Line Source electrostatic panel
• Frequency Response: 45 Hz – 19 kHz (+2 dB / –3 dB)
• Sensitivity: 85 dB (1 W/1 m)
• Nominal Impedance: 6 ohms
• Minimum Impedance: 2 ohms
• Recommended Amplifier Power: 20–320 watts per channel
• Horizontal Dispersion: 30°
• Vertical Dispersion: 48-inch line source
• Inputs: Single-wire binding posts
• Dimensions (H × W × D): 60 × 28 × 36 in. (152.4 × 71.1 × 91.4 cm)
• Weight: 55 lbs. (25 kg) each
• Original Introduction: 1986

The Bottom Line

The MartinLogan CLS remains one of the most significant loudspeakers ever created. Its innovative curvilinear electrostatic panel solved many of the dispersion limitations that had challenged earlier electrostatic designs while delivering extraordinary transparency, coherence, and imaging. Demanding of placement and amplification yet immensely rewarding when properly matched, the CLS continues to serve as a benchmark for natural musical reproduction. For many audiophiles, it is not merely a classic loudspeaker—it is one of the finest expressions of electrostatic technology ever brought to market.