MartinLogan didn’t invent electrostatic transducer technology. But by eliminating the perceived deficiencies of electrostatic technology, such as poor power handling, lack of bass response and narrow soundstage (beaming), MartinLogan has reinforced the benefit of electrostatic technology: uncanny audio accuracy.
Parts of an Electrostatic Transducer
An electrostatic transducer has three components—stators, a diaphragm, and spars (non-conductive spacers that keep the tall assembly stationary)—assembled as a sandwich. The diaphragm is an ultra-light film impregnated with an electrically conductive material and stretched taut between two stators, which are perforated steel sheets coated with an insulator.
Electrostatic Forces at Work
When the speaker is operating, the diaphragm is charged with an electrostatic field of fixed positive voltage. The two stators, between which the diaphragm is stretched, are charged with voltages of equal strength but opposite polarity. These charges occur in instantaneously alternating pulses according the signal received from your audio equipment. When the charge on one stator is positive, the charge on the other is negative. Because like charges repel and opposite charges attract, the diaphragm’s constantly positive charge will force it to move forward or backward depending on the stator charges. With this movement, an electrostatic transducer translates an electrical audio signal into the diaphragm motion that produces sound waves in your room.
Because traditional cone loudspeakers produce sound in response to the separate movements of many small parts (voice coil, former, diaphragm), they can’t help but suffer distortion-inducing time lag as the signal travels through these parts and across the cone. But an electrostatic transducer has only one moving part: the diaphragm. Its movement is instantaneous, with no time lag, enabling the diaphragm to trace even the most delicate sonic details with absolute precision. The diaphragm’s surface area is much larger than any cone driver, giving the electrostatic transducer the ability to perform over an exceptionally wide frequency range without having to cross over to another driver.
MartinLogan engineers have improved these basic electrostatic technologies with their unique innovations.
The components of each MartinLogan electrostatic panel are fused in our proprietary Vacuum Bonding process using an aerospace adhesive whose hold-strength exceeds that of welding. Vacuum Bonding ensures uniform diaphragm tensioning, and facilitates the extremely tight tolerances necessary for the construction of such a precision transducer.
The stators that “sandwich” the diaphragm must be rigid enough to remain absolutely stationary despite the strong electrostatic forces pushing and pulling them during operation. They must also be perforated to allow sound to pass through. MartinLogan’s MicroPerf design optimizes this tradeoff by reducing the size of the individual stator holes, increasing the effective radiating area of the diaphragm without compromising the structural integrity of the panel. MartinLogan’s ClearSpar spacers strengthen the assembly across its width, ensuring the consistent tension of the Vacuum Bonded diaphragm between the stators with absolutely no visual or auditory obstructions.