STAX SR-X9000

The Stax SR-X9000 is an open-back electrostatic earspeaker designed to represent the highest level of technology achieved by Stax in the development of electrostatic headphones. It incorporates numerous innovations developed through more than twenty years of research, with the aim of improving transparency, reproduction accuracy, and the naturalness of sound while preserving the core principles that have made the brand's electrostatic technology renowned.

One of its defining features is the new MLER-3 (Multi-Layer Electrodes) structure, a four-layer electrode system that combines metal mesh electrodes with chemically etched electrodes joined through a thermal diffusion bonding process. This design creates a highly rigid structure that is less susceptible to resonance while improving sound wave transmission compared to conventional multilayer electrodes. The use of metal mesh revives a concept first explored in early Stax models, where increased air permeability helped reduce acoustic reflections and air resistance, although manufacturing limitations had previously prevented its widespread implementation due to structural stability challenges.

The diaphragm is made from an ultra-thin high-performance polymer film and offers a surface area 20% larger than that of the previous flagship SR-009S. Its extremely low mass provides exceptionally fast transient response and extended high-frequency performance while improving linearity across the entire audible spectrum and contributing to a wider, more uniform soundstage.

The sound unit is housed within a precision-machined solid aluminum enclosure. This construction increases the rigidity of the transducer assembly, eliminates unwanted vibrations, and optimizes the flow of sound waves inside the acoustic chamber, reducing internal reflections that could otherwise affect playback clarity.

Special attention has also been given to the protective mesh positioned in front of the electrostatic element. In conventional designs, a parallel guard mesh can generate direct reflections that negatively affect sound quality. In the SR-X9000, this issue is minimized through a design featuring supports of different lengths between the front and rear sections, altering the angle of the guard mesh relative to the sound element. This configuration controls sound reflections more effectively and promotes a smoother propagation of acoustic waves.

The headband assembly features a stainless steel structure that provides increased resistance to torsion while ensuring a stable fit. A nine-position click adjustment system allows precise adaptation to different head sizes. The head pad is covered in genuine leather, while the ear pads are made from genuine sheepskin leather, selected for its softness and breathability. This combination provides a comfortable, secure fit and maintains comfort during extended listening sessions.

The detachable cable uses a construction with ultra-pure 6N annealed OFC copper conductors at its core and silver-plated annealed copper conductors around them, a configuration designed to optimize signal transmission across the entire frequency range. Two cables are supplied, measuring 2.5 meters and 1.5 meters respectively, allowing the earspeaker to be adapted to different listening environments and system configurations.

The package includes a paulownia wood storage case. Thanks to its low thermal conductivity and natural humidity-regulating properties, this material provides effective protection for the earspeaker during storage and transport.

Technical Specifications:

• Type: Push-pull electrostatic earspeaker; open-back design
• Sound Element Shape: Large circular diaphragm
• Fixed Electrodes: MLER-3 (Multi-Layer Electrodes)
• Frequency Response: 5 Hz – 42,000 Hz
• Electrostatic Capacitance: 110 pF
• Impedance: 145 kΩ
• Sensitivity: 100 dB
• Bias Voltage: 580 V DC
• Cable Conductors: 6N (99.9999%) ultra-pure OFC copper; silver-plated annealed copper
• Cable: Parallel 6-conductor; low-capacitance design
• Cable Lengths: 2.5 m; 1.5 m
• Ear Pads: Genuine sheepskin leather (skin-contact surface); synthetic leather (outer section)
• Weight: 432 g (earspeaker only)