Large circular e-stat drivers with multi-layer electrodes

The STAX SR-009D brings back the large circular electrostatic driver and Multi-Layer Electrode technology introduced with the original SR-009. Updated body color, a revised sound unit case, and a detachable OFC cable accompany its return at a more accessible price than the original model’s launch price.

The return of a STAX reference

Released in 2011, the SR-009 introduced electrode technology that helped shape the SR-009S and SR-X9000. Following the end of its original production run, requests from listeners worldwide prompted its return as the SR-009D. This edition makes that foundational design available again, with changes to the body, cable material, and sound unit case.

Multi-layer electrodes built for precision

The SR-009D uses MLER, short for Multi-Layer Electrode, technology in its fixed electrodes. Photo-etched metal plates undergo thermal diffusion bonding under vacuum conditions, joining them at the atomic level. This process produces flat electrodes with low resonance and high sound wave transmission, allowing sound to pass through the electrode structure with minimal obstruction.

Large circular electrostatic drivers

Each ear cup houses a large circular push-pull electrostatic sound element within an open-back enclosure. The SR-009D has a specified frequency response of 5Hz to 42kHz and operates with a 580V DC bias. It brings the original SR-009’s driver architecture to listeners seeking an entry into STAX’s current high-end range.

A replaceable cable for easier maintenance

The detachable cable structure makes replacement straightforward if the cable becomes damaged. It also allows you to fit compatible alternative cables. The supplied 8.2-foot (2.5m) cable uses oxygen-free copper conductors in a parallel six-strand, low-capacitance wide configuration.

Sheepskin leather ear pads

The ear pads use genuine sheepskin leather on the surfaces that touch your skin, with artificial leather around the surrounding portions. The earspeakers weigh approximately 15.9 ounces (452g).

Product highlights

• Large circular push-pull electrostatic sound elements
  
• MLER fixed electrodes derived from the original SR-009
  
• Thermal diffusion bonding for electrode flatness, low resonance, and sound wave transmission
  
• Open-back enclosure
  
• Detachable OFC cable for replacement and maintenance
  
• Genuine sheepskin leather on ear pad contact surfaces
  
• 580V DC bias operation

Specs

• Type: Push-pull electrostatic sound element
  
• Enclosure: Open-air
  
• Sound element shape: Large circular
  
• Frequency response: 5Hz–42,000Hz
  
• Electrostatic capacitance: 110pF
  
• Impedance: 145kΩ
  
• Sound pressure sensitivity: 101dB
  
• Bias voltage: 580V DC
  
• Cable conductor: Oxygen-free copper (OFC)
  
• Cable construction: Parallel six-strand, low-capacitance wide cable
  
• Cable connection: Detachable
  
• Cable length: 8.2 feet (2.5m)
  
• Ear pad contact surface: Genuine sheepskin leather
  
• Ear pad surrounding surface: Artificial leather
  
• Earspeaker weight: 15.9 ounces (452g)

What’s included

• STAX SR-009D electrostatic headphones
  
• Detachable 8.2-foot (2.5m) OFC cable