Astell&Kern ZERO 1

The AK ZERO 1 represents Astell&Kern’s first foray into the world of in-ear monitors designed under their own brand. This high-end hybrid in-ear monitor (IEM) embodies the brand’s philosophy: to offer a musical experience as close as possible to the original sound. Handcrafted in Japan, the ZERO 1 stands out with its innovative technical design that combines three different driver technologies to create a balanced, detailed, and natural sound signature.

A Revolutionary Sound Architecture

The ZERO 1 is distinguished by its three-way hybrid configuration that integrates technologies rarely combined. At the heart of this sound architecture is a micro-rectangular planar driver, a technology usually reserved for high-end headphones, delivering exceptionally precise highs. This technical feat allows the integration of a planar driver, typically difficult to miniaturize, into an in-ear format.

For midrange frequencies, Astell&Kern has chosen two specially paired balanced armature (BA) drivers to reduce distortion and maximize the naturalness of vocals. The bass is handled by a 5.6 mm dynamic driver, ensuring deep, rich, and perfectly controlled low frequencies.

This unique combination enables the ZERO 1 to achieve an extended frequency response from 25 Hz to 30 kHz, covering the entire audible spectrum and beyond, for faithful reproduction of high-resolution recordings.

Meticulous Acoustic Design

The exceptional performance of the ZERO 1 also relies on advanced crossover network management. Astell&Kern developed this system based on a deep understanding of each driver’s parameters, allowing their respective sound characteristics to be perfectly harmonized.

Each driver is carefully positioned in an optimal location within a specifically designed acoustic chamber. This chamber is manufactured using high-precision 3D printing technology, eliminating unwanted movements and resonances, ensuring stable and consistent performance.

The CNC-machined aluminum external casing features facets that not only contribute to the ZERO 1’s distinctive aesthetics but also play an acoustic role by suppressing unwanted resonances and vibrations. This attention to acoustic detail results in exceptional sound clarity and a total harmonic distortion of less than 0.7%.

Listening Comfort Designed for Long Sessions

Despite its technical complexity, the ZERO 1 remains remarkably comfortable for extended use. The ergonomic shape of the aluminum shells has been specifically designed to naturally fit the ear’s morphology, allowing for hours of listening without fatigue.

To ensure a perfect fit for all ear shapes, Astell&Kern provides five pairs of silicone ear tips in different sizes, as well as one pair of memory foam tips. The latter enhances sound isolation for better bass extension and effective reduction of ambient noise, making the ZERO 1 perfectly suited for on-the-go use.

The relatively long nozzles allow for deeper insertion into the ear canal, which may require some adjustments to find the ideal balance between comfort, stability, and isolation quality. Once the right tip is selected, the listening experience becomes truly captivating.

Detachable Audiophile Connectivity

The ZERO 1 is equipped with a detachable audiophile-grade cable that significantly contributes to its sound performance. This four-conductor cable is made of high-purity oxygen-free copper (OFC) plated with silver. This combination of materials optimizes the transfer of high-resolution audio signals: silver enhances high-frequency transmission, while copper maximizes bass richness.

The MMCX (Micro Miniature Coaxial) connectors on the earphones ensure a reliable and durable connection while allowing the earphones to rotate for a perfect fit. At the other end, a 3.5 mm mini-jack plug ensures universal compatibility with most audio sources, from audiophile players to smartphones.

For demanding audiophiles, Astell&Kern also offers an optional cable with a 4.4 mm balanced connector, allowing users to fully exploit the potential of high-end audio sources equipped with this output.

A Balanced and Refined Sound Signature

The ZERO 1 delivers a sound signature that reflects Astell&Kern’s expertise in high-fidelity audio. The sound reproduction is characterized by a remarkable balance between analytical precision and engaging musicality.

In the low frequencies, the 5.6 mm dynamic driver provides a solid foundation with deep, articulated, and perfectly controlled bass that never encroaches on the midrange. The midrange, handled by the balanced armature drivers, stands out for its transparency and naturalness, particularly noticeable in vocals and acoustic instruments.

The highs, the domain of excellence for the planar driver, are remarkably smooth and precise. They offer extension and airiness that contribute to creating a wide and three-dimensional soundstage, without ever becoming aggressive or causing listening fatigue.

This coherence across the different ranges allows the ZERO 1 to adapt effortlessly to all musical genres, revealing subtle details in recordings that less sophisticated earphones might miss.

Japanese Handcrafted Manufacturing

The ZERO 1 benefits from entirely handcrafted manufacturing in Japan, ensuring impeccable build quality. This artisanal approach allows for rigorous quality control at every stage of production, ensuring exemplary reliability and longevity.

This meticulous craftsmanship is reflected in the flawless finishes of the aluminum shells, whose facets elegantly capture and reflect light. Beyond their aesthetic appeal, these facets also help reduce unwanted resonances, demonstrating the perfect fusion of form and function that characterizes the ZERO 1’s design.

Technical Specifications

Transducer Technology

• Three-way hybrid configuration
  • 1 dynamic 5.6 mm transducer for deep and rich bass
  • 2 custom balanced armature (BA) transducers for clear and detailed vocals
  • 1 micro-rectangular planar magnetic transducer for dynamic and precise highs
• Optimal sound tuning through an advanced filtering network
• Reduction of unwanted resonances and vibrations via an optimized 3D internal structure
• Impedance: 16 ohms

Design and Materials

• 3D-printed acoustic chamber for optimal sound management
• CNC-machined metal housing for increased rigidity
• Advanced ergonomics adapted to the morphology of the inner ear
• Premium finish with cut surfaces that enhance light reflection

Cable and Connectivity

• Asymmetrical 4-conductor cable
• Material: oxygen-free copper (OFC) plated with pure silver
• Connectors:
  • MMCX connector for a stable and durable connection
  • Standard 3.5 mm jack (4.4 mm cable available as an option)
• Aluminum finish for enhanced durability

Manufacturing and Quality

• Hand-assembled in Japan
• Rigorous manufacturing standards
• Strict quality controls ensuring maximum precision and reliability

Included Accessories

• AK ZERO1 earphones (left / right)
• MMCX 3.5 mm cable
• 5 pairs of silicone ear tips
• 1 pair of foam ear tips
• Carrying case