Technical highlights of the Stax SR-009
• Diaphragm: The SR-009 features a diaphragm less than 2 microns thick that is made from what Stax calls a “High Polymer Ultra-Thin Film” material called “Super Engineering Plastics”). According to Stax, this is a “much thinner material than conventional engineered plastics.” Stax promises the new diaphragm results, “in a vast dynamic range, excellent tone quality and frequency characteristics from low to super-high (frequencies)!”
• Electrodes: The SR-009 features all-new MLER electrodes (the acronym stands for Multi-Layer ElectRodes,” that are made through a new process that uses both “ultra-precision photo etch” and “high tech heat diffusion” techniques to join three layers of material to form the thin, flat electrode panels. Specifically, Stax sought to balance three performance variables—the thinness of the electrode, the stiffness of the electrode, and the non-resonant qualities of the electrode—with an eye toward maximizing all three at once. At least one authorized Stax dealer claims that the manufacturing process for SR-009 electrodes is three times more difficult to implement, and takes six times longer to execute, than comparable processes for other Stax electrostatic headphones.
• Enclosures: The SR-009 is as open-back design, and features extremely rigid driver housings “precision machined from lightweight aluminum” (giving new meaning to the term, “carved from billet.”).
• Cables: The distinctive signal/bias voltage cable for the SR-009 is made from “silver plated, high purity copper wire 99.9999%.”
• Headband: The SR-009 headband uses a, “newly designed 10-click slider mechanism for optimal wear and comfort.” The same mechanism is also used on the STAX SR-507 Lambda Open-Back Headphones.
• Ear pads: The SR-009 features thick, comfortable, asymmetrical (as in, thicker toward the rear and thinner toward the front) ear pads covered in “hand crafted Lamb leather.”
• The Box: Even the box the SR-009 comes in is special; it’s a padded case made of paulownia wood, whose properties are said to be optimal for “long-term preservations of the product.” Stax includes a special insert in the SR-009 shipping carton to explain that that pawlonia wood is lightweight, heat resistant, insect proof, and offers “moderate cushioning properties.” Moreover, the wood also helps regulate humidity to help keep the ‘phones from becoming overly damp while in storage.
Let me come right out and say it: the Stax SR-009 is the most accurate, neutrally balanced, responsive, nuanced, and detailed audio transducer I’ve heard. It is also—unlike some electrostatic headphones I’ve tried—capable of very robust dynamics and powerful (though ultra-clean) low bass (areas where some electrostats seem to run out of steam earlier than would be desirable). In short, the SR-009 is the best headphone I’ve yet heard.
With this said, however, let’s also note that today’s best dynamic driver-equipped and planar magnetic headphones offer performance that, while not entirely on a par with the SR-009, falls not terribly far behind, while selling for about 60% – 80% less that the Stax ‘phones do. My point is the there is true greatness in the SR-009 design, but greatness that comes at quite a dear price. Still, there are (at least) two ways to look at the issue of pricing. One might be to say, “$5250 is just too much to spend for any headphone; I can get close enough to the sonic mountaintop for a fraction of the SR-009’s price,” which is true. However, another way to look at the situation might be to ask, “In what other class of luxury goods—be it wristwatches, cameras, or high-end audio gear—can you get the very best there is for as little as the SR-009’s cost?” Depending on your frame of reference, then, the SR-009 could be considered an unattainable luxury, or (dare I say it?) a bit of a bargain as best-you-can-get material objects go.
What is the “sonic character” of the SR-009? Well, that’s a tough question to answer because these ‘phones are so neutral and so faithful to the sources that drive them, that they really don’t seem to have a signature sound of their own, though certain sonic common denominators do always seem to be present. For instance, no matter what ancillary components you use, you can count on the SR-009s to sound very accurately balanced, extended on both ends of the audio spectrum, consistently fast, extraordinarily transparent, and capable of delivering lavish amounts of detail (provided the rest of your system is up to the task). But the tricky part is that the underlying sonic “persona” of the SR-009 can and does shift in both subtle and profound ways as you connect these headphones to different amplifiers and source components.