STAX SR-009D Reference Earspeakers (with Detachable Cable)

SR-009D Reference Electrostatic Earspeaker, with Detachable Cable, by STAX Audio.

The SR-009 is the origin of STAX's current high-end models. Equipped with a large circular sound unit featuring innovative fixed electrodes, this model led the high-end headphone culture for a long time.

Production had ceased with the arrival of the new flagship model, but now, in response to numerous requests from fans worldwide, it is making a comeback. With changes to the body colour, cable material, and unit case, it is now available at a more accessible price than at its original launch.

MLER (Multi-Layer Electrode)

Released in 2011, the original SR-009 was the catalyst for the current high-end models SR-X9000 and SR-009S. The key technology for high-end models, MLER (Multi-Layer Electrode), originated with this model.

Using thermal diffusion bonding technology, which unifies photo-etched metal plates at the atomic level under vacuum conditions, this new fixed electrode achieves exceptional planarity, low resonance, and high sound wave transmission.

The new SR-009D remains the most affordable option for experiencing the sound of current STAX high-end models.

Replaceable Cable Design

SR-009D adopts the replaceable cable structure, which is now standard across the current lineup. This enhances the usability of the earspeakers by enabling future compatibility with high-quality cables, and easy maintenance in case of unexpected cable breakage.

Electrostatic Technology

Electrostatic transducers consist of two parallel-arranged fixed electrodes with a very thin high-polymer film diaphragm sandwiched and suspended in the middle of the electrodes. The diaphragm is supplied with the biasing voltage from the energizing adaptors or from the driver unit.

When the fluctuating voltage of the audio signal is applied to the electrodes, the diaphragm is pulled by one electrode (which has the opposite charge of the diaphragm) and simultaneously pushed by the other electrode (which has the like charge of the diaphragm).

This continuous flow of alternating voltage causes the diaphragm to vibrate in faithful compliance with the amplifier output without lag, assuring undistorted sound waves. This is why the STAX electrostatic earspeakers sound so good.

Electrostatic driver required

Electrostatic reproduction has many quality advantages, however such units cannot be used directly with a conventional headphone jack, and require a special electrostatic amplifier (driver) unit.

The vibrating diaphragm requires Bias voltage of 580 V (almost no current). Relatively high signal voltage to the fixed pole (up to 300-600 V) must be supplied as push-pull, a rather special electrical signal. The STAX series of driver units are dedicated amplifiers strictly for STAX headphones.

Features

• NEW Detachable cable
• NEW Injection-moulded unit case
• Next-generation MLER Multi-Layer Electrode design
• High-precision enclosure
• Hybrid leather ear pads
• 10-step adjustable headband mechanism

Specifications

• Type: Push - pull electrostatic sound element, open-air type enclosure
• Sound Element Shape: Large round shape
• Frequency Response: 5 - 42,000 Hz
• Electrostatic Capacitance: 110 pF
• Impedance: 145 kOhms
• Sound Pressure Sensitivity: 101 dB
• Bias voltage: 580 V DC
• Cable Design: Parallel 6-strand, low-capacity wide cable
• Cable Conductor: OFC
• Cable Length: 2.50 metre
• Ear Pads: genuine sheep leather (skin touching portion), artificial leather (surrounding portion)
• Weight: 452 g (earspeaker only)

Included

• SR-009D Earspeakers
• Detachable Cable, 2.50 m
• Documentation

More Information

• SR-009D Reference Earspeaker, by STAX Audio