Advanced Thin Film (ATF) Theory and MartinLogan Speakers

Parts of a MartinLogan ATF Transducer

MartinLogan ATF transducer.

A) Aluminum Etched Kaladex Diaphragm
B) Neodymium Super Magnets
C) Rigid Steel Housing

ATF Transducer at Work

MartinLogan ATF transducer.

Opposite charges attract. Like charges repel. The neodymium magnets hold constant, opposite charges. The diaphragm charge is constantly reversed, causing the diaphragm to move.

ATF™ (Advanced Thin Film) Theory

MartinLogan Preface floor standing hybrid Advanced Thin Film speaker.

Based on RADIA planar technology, high-resolution ATF drivers approach the clarity and detail of our electrostatic panels while permitting the use of a compact cabinet. Each MartinLogan ATF transducer has a micro-thin, low-mass diaphragm with an ultra-light, etched aluminum conductive surface, suspended between two opposite-polarity, high-field-strength neodymium magnet arrays. When the electrical audio signal from an amplifier passes through the diaphragm's surface, it creates an alternating electromagnetic field that interacts with the fields of the fixed magnet arrays, forcing it back and forth to produce sound waves in the air. The strength and polarity of the diaphragm's field varies according to the audio signal.

Opposite charges attract. Like charges repel. The neodymium magnets hold constant, opposite charges. The diaphragm charge is constantly reversed, causing the diaphragm to move.

The diaphragm substrate is Dupont Kaladex® PEN (polyethylene napthalate). This material is chemically akin to the PET (polyethylene terathylate) film used for the diaphragms of our CLS Generation 2 electrostatic panels, but capable of handling the heat generated by the current passing through an ATF diaphragm's thin aluminum skin.

High Magnetic Field Strength for Superb Control and Efficiency

Our ATF drivers incorporate neodymium iron boron (NIB) rare-earth magnets, which can maintain field strengths almost 20 times those of same-size conventional magnets. Combining such a powerful magnetic motor system with an extremely lightweight Kaladex® diaphragm yields an outstanding force-to-mass ratio. Like a sports car's high power-to-weight ratio, this characteristic allows extraordinary acceleration. Fast in the straight-aways, quick and nimble in the curves, ATF drivers are very efficient and always under perfect control. The sound that results is pure MartinLogan, with super-low distortion, astonishing clarity, and absolute precision.

Ultra-Linear Push-Pull Operation

Like our electrostatic panels, ATF drivers are push-pull transducers: When the diaphragm's field polarity is the same as that of the magnet array on one side, pushing them apart, it is the reverse of the polarity on the other side, pulling it toward that opposing array with exactly the same force. This inherently linear mode of operation maintains uniform diaphragm control regardless of its instantaneous position and is a major contributor to the vanishingly low distortion and amazing transparency of MartinLogan loudspeakers.

Direct Full-Surface Drive

Unlike the cones and domes of conventional drivers, ATF diaphragms are directly and uniformly driven over their entire surface. This full-surface drive system (similar to that of our electrostatic speakers) produces superior transient response with no diaphragm breakup. The difference is readily apparent in the delicacy, nuance, and clarity that distinguish MartinLogan speakers from all others.

Hybrid Design

MartinLogan ATF transducer.

Although our ATF technologies enable them to operate to lower frequencies, they cannot reproduce deep bass as effectively as a conventional speaker of similar size. Our solution is to reproduce the lowest frequencies with a very high-quality dynamic woofer. Other companies who have made such hybrids have often exhibited something of a Napoleon complex, overemphasizing the output from the woofer in an apparent effort to prove their loudspeaker manhood. The result of that misguided strategy is invariably thick, turgid bass that obscures midrange detail, thereby obliterating one of the main reasons for building an thin-film speaker to begin with. We don't do that. Instead, our speakers incorporate extremely high-performance woofers, crossed over the ATF transducers via carefully tailored, precisely calculated networks made with top-quality components. Low crossover frequencies, phase- and amplitude-optimized crossovers, and critically damped woofers ensure a seamless transition between the two types of drivers, yielding speakers that really do offer the best of both worlds.

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