Stax: Japan's top electrostatic headphone monument
In the world of high-end headphones, few brands pursue a single and steadfast technological path like Stax. By persevering with the principle of electrostatic headphone manufacturing for more than eight decades, this Japanese brand has created its own concept called "Earspeaker" - miniature speakers placed close to the ear, reproducing music with detail and sound space that dynamic driver technology can hardly reach.
From the Showa Ko-On recording studio comes the iconic Earspeaker
Stax's story doesn't start with headphones. In 1938, sound engineer Naotake Hayashi founded the Showa Ko-On studio, initially specializing in recording, mastering and producing metal masters for film and music. It was this background in deep recording techniques that led Hayashi to electrostatic technology: in 1950, he introduced the first high-frequency condenser microphone; By 1952, the CP-20 electrostatic vinyl record was needed. Nearly a decade of accumulated experience then brought the company to a decisive milestone - in 1959, Stax successfully developed the world's first electrostatic headphones, and in 1960 officially commercialized them under the name SR-1. From that moment on, the term "Earspeaker" was born as a declaration: this is not a regular "headphone", but a miniature speaker placed against the ear, capable of reproducing a linear sound field like a hi-end speaker system placed in a standard listening room. In 1964, Stax expanded this technology to electrostatic loudspeakers, affirming its comprehensive pioneering position in the field of electrostatic audio technology.
Principle of electrostatics: Why a film thinner than a hair makes a difference
Unlike dynamic or planar drivers, Stax's electrostatic technology operates based on uniform attraction/repulsion across the film surface. The speaker membrane is only a few micrometers thin, has almost zero mass, is fixed between two electrodes and maintained at a fixed bias voltage — most commonly the Pro Bias 580V DC standard on high-end models. When a variable audio signal is applied to the two electrodes, the entire speaker membrane surface vibrates simultaneously, almost instantaneously, without any mechanical resistance.
Stax's electrode technology also evolves with each generation and does not stand still. The first MLER (Multi-Layer Electrode) generation appeared with the legendary SR-009 in 2011; By 2018, SR-009S upgraded to MLER2 with gold plating to help reduce resistance and unwanted resonance. And MLER-3 - a four-layer electrode version, linked by heat diffusion technology at the atomic level - is only equipped with the latest flagship, crystallized from the problem left over from last year's SR-Ω model.
STAX product series arrives in Vietnam
Earphone
The SR-X9000 is the current flagship, considered the spiritual successor of the legendary SR-Ω. The speaker membrane is 20% larger than the SR-009S, the frequency range is 5Hz - 42,000Hz, the sound tube is made of monolithic machined aluminum to help eliminate unwanted vibrations, and comes with 6N pure copper core conductors combined with silver-plated coating.
The SR-009D is an interesting story: this is the revived version of the SR-009 - the headphone model that gave birth to MLER technology and led the high-end headphone culture for a long time before stopping production to make room for the new flagship. Facing a wave of requests from users around the world, Stax brought back the SR-009D with a more convenient detachable cord design and a more accessible price than the original, becoming the most reasonable gateway to access the current high-end sound quality of Stax standards.
Headamp
Because of technical characteristics, Stax's Earspeaker cannot be plugged directly into a regular 3.5mm or 6.35mm port but must be through a specialized headamp.
At the top of the list, the SRM-T8000 is a hybrid amplifier that combines two 6922 electronic tubes in the input stage with a pure Class-A semiconductor power stage, a large capacity toroidal transformer and carefully selected components, giving a maximum output voltage of up to 470V r.m.s - enough to pull all of the company's most demanding headphones.
The SRM-D10 II is aimed at flexibility: integrated DAC using AKM4493 decoder chip, supports DSD256 and PCM 384kHz/32bit, USB-C port both charges the battery and transmits digital signals, suitable for mobile or desk listening needs while still maintaining the 580V Bias standard.
