Astell&Kern STELLA

Three recognized names from the audio world come together around this project: Astell&Kern for engineering, VOLK Audio (led by Jack Vang) for acoustic design, and Michael Graves, a five-time Grammy Award-winning mastering engineer, for the final sound tuning, carried out at Osiris Studio in Los Angeles. This new high-end in-ear monitor combines twelve drivers per ear divided across four technologies, with a six-way crossover.

A three-way collaboration

Astell&Kern, a Korean brand from the Dreamus group, is known for its high-resolution digital audio players. VOLK Audio, a California-based company founded by Jack Vang, has specialized in the design of multi-driver in-ear monitors. Michael Graves brings a studio perspective, with a career marked by five Grammy Awards and more than fifteen nominations in the restoration and remastering category. The joint work focused on acoustic structures, driver assemblies, and tonal balance, with a target oriented toward precision and phase coherence.

Twelve drivers per ear

The chosen configuration is described as quadbrid: it combines four driver families within the same earpiece. Each ear incorporates one dynamic driver, five Sonion balanced armatures, two VOLK planar magnetic drivers, and four Sonion electrostatic tweeters. Each family handles a dedicated frequency band, under the control of a six-way crossover. The distribution is designed to let each type of driver operate in its most linear working range, without supplementary electronic correction.

Low frequencies in a hybrid system

The LF-H (Low Frequency Hybrid) module handles the 20 – 600 Hz band. It pairs a 9 mm VOLK M9-R dynamic driver, which delivers energy and extension in the bass, with two Sonion balanced armatures responsible for the definition and texture of the upper bass. The whole assembly is integrated into a two-stage chamber whose geometry regulates phase and internal pressure. The bass benefits from the mass and air displacement of a dynamic driver, while the armatures tighten the time-domain signature in the transition toward the lower midrange.

The midrange zone in triple armature

The midrange block relies on three Sonion balanced armatures. Two of them cover the 600 Hz – 7 kHz range, with energy concentrated on the 1 – 5 kHz band, where vocal warmth and instrument articulation are located. A third armature handles the 6 – 15 kHz zone, which reintroduces upper harmonics and attack details, and ensures continuity with the treble module. The distribution seeks a linear transition with the neighboring bands, without any pronounced dip or peak in the vocal range.

Extreme highs in planar and electrostatic

The HF-H module covers 9 kHz – 45 kHz. It combines two VOLK MP-2 planar magnetic drivers and four Sonion electrostatic tweeters. The planars provide fast attack and transient control in the upper part of the audible spectrum. The electrostatic tweeters extend the response into the ultrasonic range, up to 45 kHz, and operate with very low moving mass to preserve the finesse of microdetails. The combination of the two technologies aims to maintain spatial stability and tonal precision beyond 10 kHz.

Six-way crossover and pressure management

The proprietary crossover network splits the signal into six ways, with time alignment and phase correction applied to each group of drivers. Five precision acoustic tubes connect the chambers to the ear canals. A multi-stage damping system reduces internal resonances. Calibrated vents are machined into the aluminum shell and the stainless steel frame, with geometry carefully developed in depth, diameter, and damping profile. This venting balances internal pressure, stabilizes diaphragm movement, and limits standing waves as well as bass bloom in a closed chamber.

Aluminum shell, solid sapphire faceplate

The shell is machined from aerospace-grade 6061-T6 aluminum, microbead-blasted and then satin black anodized. The central plate, also made of 6061-T6 aluminum, features a diamond-cut mirror finish on its visible face. It bears the VOLK and Astell&Kern insignias positioned opposite each other, surrounded by engraved constellation motifs (hence the name STELLA). The faceplate is completed by an optically graded sapphire crystal panel, 9H hardness, cut from a single block and then diamond polished. A mirror-finished 316 stainless steel frame machined to the micron ensures the junction between the sapphire and the shell, and integrates the vent outlets.

A balanced cable included as standard

The supplied cable is part of the acoustic tuning. It combines three conductors (5N purity LCOFC copper, 4N silver, and 24-carat gold) in a 12-strand type 4S Litz geometry, 23.7 AWG gauge in four conductors. A 500D macromolecular fiber core reinforces mechanical strength. The insulation uses soft PVC, covered with a midnight black braided nylon outer sleeve. The metal parts are made of black anodized 6061-T6 aluminum, with polished mirror-finish 316 stainless steel accents. Connection to the earphones is made via 0.78 mm 2-pin connectors, a standard format on high-end in-ear monitors, which opens the way to compatible replacement cables. The termination is a 4.4 mm balanced plug, in AEC format.

Measured acoustic characteristics

The stated frequency response extends from 10 Hz to 45 kHz, well beyond the limits of the audible spectrum. Sensitivity is measured at 103.8 dB at 1 kHz and impedance at 7.17 Ω at 1 kHz. These values indicate high efficiency and a modest load, which makes STELLA undemanding in terms of power: a recent digital audio player or portable DAC is sufficient to drive it comfortably, provided it has a 4.4 mm balanced output to use the supplied cable.

Accessories included in the box

The package includes the left and right earpieces, the 4.4 mm balanced cable described above, three pairs of silicone tips (sizes S, M, L) and three pairs of foam tips (S, M, L) to adapt fit and passive isolation to the shape of the ear, a soft pouch for everyday transport, a cable organizer, and a leather carrying case.

Technical specifications

General information

• Type: in-ear earphones
• Color: silver
• Developed in collaboration with VOLK Audio

Driver architecture

• 12-driver quadbrid configuration
• Hybrid low-frequency system (LF-H)
  • 1 × 9 mm VOLK M9-R dynamic driver (subwoofer)
  • 2 × Sonion balanced armature drivers
  • Operating range: 20 Hz – 600 Hz
• Tri-armature midrange section
  • 2 × Sonion balanced armature drivers (600 Hz – 7 kHz, optimized for the 1 – 5 kHz band)
  • 1 × Sonion armature (6 kHz – 15 kHz)
• Hybrid high-frequency system (HF-H)
  • 2 × VOLK MP-2 planar magnetic drivers
  • 4 × Sonion electrostatic tweeters
  • Operating range: 9 kHz – 45 kHz

Acoustic specifications

• Frequency response: 10 Hz – 45 kHz
• Sensitivity: 103.8 dB @ 1 kHz
• Impedance: 7.17 Ω @ 1 kHz

Crossover and internal architecture

• Proprietary six-way crossover network
• Crossover and time alignment for each acoustic path
• Multi-stage internal damping
• Calibrated chassis venting
• 5 precision acoustic tubes
• Components: to be confirmed

Venting architecture

• Vent system machined into the aluminum shell and stainless steel frame
• Geometry calibrated for depth, diameter, and damping profile
• Internal pressure balancing and diaphragm motion stabilization
• Suppression of standing waves and low-frequency bloom

Materials and finishes

• Shell: aerospace-grade 6061-T6 aluminum, microbead-blasted and satin black anodized
• Center plate: 6061-T6 aluminum, satin black anodized with a diamond-cut mirror-polished face
  • VOLK and Astell&Kern insignias positioned opposite each other
  • Engraved constellation patterns
• Sapphire crystal glass panel, optical-grade 9H, cut from a single block and diamond-polished
• Faceplate frame: 316 stainless steel, machined to the micron and mirror-polished

Cable

• 23.7 AWG gauge, 4-conductor configuration
• Hybrid conductors: 5N LCOFC copper, 4N silver, and 24-karat gold
• 12-strand type 4S Litz geometry
• 500D macromolecular fiber reinforcement core
• SoftFlex PVC insulation
• Midnight black braided nylon outer jacket
• 0.78 mm 2-pin connector
• 4.4 AEC balanced termination
• Metal parts in black anodized 6061-T6 aluminum, mirror-polished 316 stainless steel accents