STAX SR-007S

The culmination of over six decades of Japanese expertise in electrostatic technology, the STAX SR-007S represents the latest evolution of the legendary Omega II series—a lineage that has shaped the history of audiophile headphones since 1998. This model combines meticulous technical innovations with a timeless sound philosophy, offering a unique approach to musical reproduction where precision and naturalness converge in remarkable balance.

Electrostatic Technology: A Radically Different Approach

The SR-007S continues the electrostatic tradition that STAX began in 1960 with the world’s very first headphone of this type, the SR-1. Unlike conventional dynamic headphones that use coils and magnets, the electrostatic system is based on a fundamentally different principle. An ultra-thin polymer diaphragm, less than 2 microns thick, is suspended between two fixed perforated electrodes. This diaphragm, held under a constant 580V charge, vibrates in response to variations in the audio signal applied to the electrodes in a push-pull configuration.

This architecture offers decisive intrinsic advantages. The diaphragm’s virtually negligible mass allows for exceptionally fast transient response, while the complete absence of magnets eliminates any magnetic distortion. The new circular electrodes of the SR-007S feature a 20% reduction in perforation diameter compared to previous generations, the result of a high-precision etching process that optimizes the overall acoustic profile.

A Mechanical Design Rethought for Comfort and Rigidity

The physical architecture of the SR-007S reflects particular attention to structural details. The headband, made from a seamless stainless steel plate, now incorporates the anti-resonance structure (ARS) directly inspired by the flagship SR-X9000 model. This innovation significantly reduces unwanted vibrations while improving overall rigidity.

The newly designed movable hinge system allows for natural adaptation to all head shapes, while the rubberized material on the headband preserves the automatic adjustment characteristic of the SR-007 series. Genuine lambskin ear pads, equipped with a free-rotation mechanism, perfectly contour to the face. The redesigned inner cushion improves acoustic absorption and contributes to more precise and expansive sound staging.

The signature brown finish, a visual heritage of the SR-007 lineage, demonstrates a commitment to aesthetic continuity. Weighing 430 grams without the cable, the SR-007S maintains an optimal balance between structural robustness and long-term wearing comfort.

Technical Evolution: What Sets the SR-007S Apart from Its Predecessors

The history of the SR-007 series reveals a technical progression marked by subtle yet significant changes. The original SR-007 MK1, lacking a bass port, offered remarkably linear bass extension down to about 10 Hz. The MK2 introduced a port in the ear cups—a controversial modification that created a slight mid-bass hump while reducing extension in the lowest bass. This feature led many users to adopt the famous “BluTak mod,” which involved sealing the port to restore the MK1’s characteristics.

The SR-007S marks a return to the roots by permanently eliminating this controversial port. The diaphragms have been completely redesigned, as have the fixed electrodes, which benefit from the aforementioned high-precision etching process. This approach achieves a frequency response extending from 6 Hz to 41 kHz with a sensitivity of 101 dB for 100V RMS, parameters that reflect an exceptionally wide reproduction capability.

Detachable Cable for Easier Maintenance

A major practical innovation, the SR-007S adopts the detachable cable system now standard on new STAX models. The 2.5-meter cable uses a parallel 6-strand construction in very low-capacitance OFC (Oxygen-Free Copper), ensuring unaltered signal transmission. This modularity greatly simplifies maintenance and extends the product’s lifespan, while also allowing for potential future cable upgrades.

The Essential Electrostatic Amplification

A feature inherent to electrostatic technology, the SR-007S absolutely requires a dedicated amplifier, known as an “energizer” in STAX terminology. These specialized devices not only provide the constant 580V bias voltage essential for diaphragm operation, but also generate the high-voltage audio signals in a balanced configuration.

STAX offers a complete range of amplifiers, from transistor models like the SRM-400S to hybrid tube versions such as the SRM-700T or SRM-007tII. High-end models like the SRM-T8000 represent the pinnacle of STAX electrostatic amplification. Other specialized manufacturers also offer compatible amplifiers, notably HeadAmp with its legendary Blue Hawaii SE, Mjolnir Audio with its KGSSHV models, and Woo Audio with the WES.

Technical Specifications

Acoustic Performance

• Type: Open-back push-pull electrostatic headphones
• Transducers: Large-format diaphragms, optimized fixed electrodes
• Frequency response: 6 Hz – 41,000 Hz
• Sensitivity: 101 dB / 100 V RMS

Electrical Specifications

• Electrostatic capacitance: 110 pF
• Impedance: 145 kΩ
• Bias voltage: 580 V DC

Cable and Connectivity

• Detachable cable
• Construction: 6 parallel OFC (oxygen-free copper) strands
• Features: low capacitance, high fidelity
• Length: 2.5 m

Design and Comfort

• Seamless rigid stainless steel headband
• Movable hinge for optimized fit
• Free-rotating genuine sheepskin earpads
• Redesigned inner cushion for improved soundstage
• Anti-resonance structure (ARS) inspired by the SR-X9000

General Information

• Weight: 430 g (without cable)
• Finish: STAX signature brown
• Manufacturing: made in Japan