- Recommended for people like this
- Overview of Astell&Kern AK ZERO1
- Features of Astell&Kern AK ZERO1
- Build quality
- Sound quality
- Sound quality features
- General comment
- Purchase link
- This review is based on "private purchases" or "items rented for a consideration".
- No remuneration or compensation, such as a manuscript fee, has been received for publishing this, and it is an honest evaluation based on measurement data from personal testing and personal opinion.
Recommended for people like this
- People who like studio tuning
- People who value separation
- Appearance oriented people
- Astell&Kern fans
Overview of Astell&Kern AK ZERO1
- Total Score: 8.0 / 10.0
- Package: 8.0 / 10.0
- Build quality: 9.0 / 10.0
- Fitment: 8.5 / 10.0
- High range: 9.0 / 10.0
- Mid range: 9.5 / 10.0
- Low range: 9.0 / 10.0
- Less distortion: 7.0 / 10.0
- Want to see the score ranking? Click here!
- Frequency response: 25Hz to 30kHz
- Impedance: 16Ω
- Sensitivity: 96dB
- Connector: mmcx
Features of Astell&Kern AK ZERO1
Astell&Kern AK ZERO1
The New Standard for Hybrid Sound
Triple Hybrid Driver with 3 Different Drivers
Astell&Kern's first original IEM (In-Ear Monitor)
Astell&Kern's first original IEM
The AK ZERO1 is Astell&Kern's first original IEM that delivers the unique Astell&Kern sound. The AK ZERO1 is a new start for Astell&Kern, a new standard for in-ear monitors. The project was started to bring the joy of music to as many users as possible, with analog faithful sound as intended by Astell&Kern. The project has been launched.
Triple hybrid driver configuration with three different drivers
In order to achieve the high-precision acoustics Astell&Kern is aiming for, the AK ZERO1 combines the sound of three different driver technologies into one: one special planar driver, two BA drivers (dual type), and one 5.6mm dynamic driver. We have arrived at a triple hybrid driver configuration.
- Driver 1: Micro Rectangular Planar Driver
The Micro Rectangular Planar Driver is an advanced driver developed specifically for application to IEMs using a planar driver design that is difficult to scale down for headphones. It uses a sturdy yet lightweight planar diaphragm to minimize frequency loss, and a composite diaphragm that combines a polymer membrane with a thin metal film to create a sound that has the crystal clarity of a BA-type, but is driven by a coil shaped on a plane to achieve both a dynamic-like presence and a dynamic-like character.
- Driver 2: Dual Custom Balanced Armature Drivers
Dual BA drivers with custom-designed armatures and coils provide ultra-low distortion and crystal-clear vocals.
- Driver 3: Single ø5.6mm dynamic driver
Equipped with a φ5.6mm dynamic driver made by a fully automated and error-free process. Compared to dynamic drivers assembled by hand using conventional manufacturing methods, these drivers deliver low distortion and rich, deep low frequencies.
Micro Rectangular Planar Driver Features
This driver is called rectangular because it uses a rectangular-shaped planar drive diaphragm. It has a highly rigid composite diaphragm that combines a polymer membrane and thin metal film, and features a sound character that combines the crystalline clarity of a BA type with the presence of a dynamic type by being driven by a coil shaped on a planar surface. In addition, although it is a planar type, it is enclosed in a metal body case similar to that of the BA type, enabling a degree of freedom in acoustic design that has been difficult to achieve with conventional planar types. By combining this high degree of freedom in acoustic design with multi-networking, we have realized a design that brings out the potential of the planar type even more. In terms of the magnetic circuit, enclosing the diaphragm in this metal body case reduces magnetic flux leakage from the powerful magnets that drive the diaphragm, further enhancing the potential of the diaphragm. The micro rectangular planar driver is "a rectangular diaphragm enclosed in a metal body case similar to that of the BA type.
- Sound Characteristics that Cross BA Type and Dynamic Type
While the diaphragm is extremely rigid like the BA type, it is driven by a coil shaped on a flat surface like the dynamic type. This method is characterized as a method that combines the best aspects of both BA and dynamic types of sound.
- Metal body case that seals out magnetic flux through antimagnetic treatment
Micro Rectangular Planar uses extremely strong magnets, and the assembly is highly sophisticated and precise. By encapsulating these powerful magnets in a metal body, leakage of magnetic flux is reduced, flux density is increased, and efficiency is improved. In addition, sealing the magnetic flux reduces the adverse effects of flux leakage on other drivers, contributing to high sound quality.
- Miniaturized and Precise Unit Design
Micro Rectangular Planar can be designed with the same architecture as the BA type. This means that the use of matured development methods, multi-driver, and combinations of sound tube length, thickness, and acoustic resistance are available, allowing sound quality to be adjusted in a variety of ways. While these methods were difficult to achieve with conventional models due to their large size, the miniaturization of the driver unit makes conventional development methods possible and enables the potential of the driver unit to be brought out to a great extent. In addition, while it is difficult to place planar magnetic units close to the ear in a multi-way system because they are often large, the AK ZERO1's rectangular planar design enables placement as close to the ear as possible by reducing the size of the planar magnetic units.
Optimal Crossover Network
The hybrid driver IEM "AK ZERO1" focuses on combining the sound of three proprietary driver technologies into one. In order to achieve a new sound with ideal frequency response, the crossover network was designed based on a thorough understanding of each driver's parameters to achieve the ideal frequency response required by Astell&Kern. At the same time, each driver was carefully positioned in its optimal location and housed in a specially manufactured acoustic chamber using 3D printing technology precisely controlled to the μm level. This precision enclosure cleverly eliminates unwanted driver movement and resonance to ensure consistent performance. And the main housing, precision CNC-machined using Astell&Kern's proprietary advanced aluminum refining technology, reduces internal and external vibrations for focused, accurate sound.
Hi-Fi grade 4-core sterling silver coated OFC cable
To further enhance the audio performance of the AK ZERO1, a 4-conductor pure silver-coated OFC cable is used, which is flexible and easy to handle. The cable is designed to transmit audio signals loss-free, using high-purity silver plating, copper, and aluminum plugs. In addition, the high-precision MMCX connector improves the quality of the connection between the ear housing and the cable, ensuring stable performance.
Astell&Kern's signature design
AK ZERO1's premium sound opens up a new world of sound never before experienced. This is symbolized by the thick diagonal line across the product, reflecting the identity of the AK ZERO1. The cut surfaces created by the AK ZERO1's character lines sparkle in the light, emphasizing the premium nature of the product. The shape is carefully designed to follow the inner ear canal for a perfect fit in the ear. Light bounces off each surface, making the earpiece sparkle like a piece of jewelry. The uniquely shaped nozzle is narrow to fit snugly in the ear and provides enough space for the AK ZERO1's three drivers to work in harmony. This allows the high quality sound of the hybrid driver configuration to be delivered accurately and efficiently to the ear.
Handcrafted in Japan
AK ZERO1 is handmade in Japan by experienced technicians, using superior equipment and rigorous processes to ensure the highest quality.
Full lineup of accessories
Five types of silicone earpieces in different sizes (XS/S/M/L/XL) and one type of urethane foam earpiece (Free Size) are included. A carrying case is also included for easy transportation.
The quality of the packaging meets the price standard. Gorgeous for the price.
- Astell&Kern AK ZERO1
- Carrying pouch
Build quality meets the price standard.
Design is very sophisticated.
The fit is good.
REW Frequency Response
Sound quality description
In this review, I use the standard eartips size L and drive it with the FiiO M15.
The Astell&Kern AK ZERO1 has a near-neutral, U-shaped sound signature with an emphasis on mid-high frequencies.
Please see here for detailed reviews on sound quality.
Lows / Bass
The Astell&Kern AK ZERO1's low frequencies are fairly linear and deep. It is almost balanced with the midrange in terms of presence.
Drum kicks feel reasonably weighted and not too deep, but the rumble is a bit short on the level. It sounds a bit tap-like light to me.
The electric bass is also a bit bright and has a good perspective, but it sounds a little shallow.
The bass is rather monitor-like, and while the rhythm is easy to understand, it tends to lack a bit in volume and depth for bass lovers.
The midrange of the Astell&Kern AK ZERO1 is tuned almost to neutral, and the texture is fairly accurate.
It is almost orthodox studio tuning, but only the edges are quite excessive. Sound contours are crisp, acoustic guitars and cymbals are quite detailed, and overall separation is high, while pianos tend to sound tinny, electric guitars and brass sounds like it was emphasized by the loudspeaker, and vocals are a bit shouty.
The distortion rate is quite high due to the hybrid, the separation from the background tends to be poor, and there are many incidental sounds and transparency is not excellent.
In my previous review of the Astell & Kern x Campfire Audio Pathfinder, I mentioned that the midrange could have been better if Astell & Kern had been proactively involved in the tuning, but despite having more types of drivers than the Pathfinder Astell & Kern has achieved a much more linearity and a much more accurate sound balance in texture with this debut.
The midrange performance is still lacking for the price, but Astell & Kern has done a good job for a debutant challenging the rather difficult task of tribrid. At this rate, I think we can expect more of the same in their next work.
Highs / Treble
The highs on the Astell&Kern AK ZERO1 are a little more aggressively tuned overall, with an emphasis in the mids and highs, a slight noticeable peakiness, and a little too much sibilance. It may be a bit harsh for those who are sensitive to high frequencies.
The sense of detail is adequate, but lacks a bit of subtlety, and as mentioned above, the edges and the sibilance are a little too strong, so it is easy to get a bit of a stinging feeling.
Extensibility is lacking considering the price.
Sound quality general comment
Forgetting the price once and talking about it, the Astell&Kern AK ZERO1 is a little too edgy and aggressive for its own good, but it almost takes the royal road of studio tuning and is well put together for a debutant.
As is typical of Astell&Kern, which makes digital audio players, the damping characteristics are relatively excellent despite being tribrid, and the design is also as expected to minimize differences in sound quality depending on the amplifier.
However, the price is too high for the sound quality because of the lack of skill in challenging the tribrid design, when it would have been better to start with single dynamic or at most 1DD+1BA or 3BA. If I were to price it based on sound quality, it would be reasonable to sell it for $300 at most, even taking into account its good appearance.
Even so, the sound quality is much better than that of the Astell & Kern x Campfire Audio Pathfinder, which costs $2000, and Astell & Kern's insight is still excellent. At least, the direction of tuning is much more decent than Campfire Audio, as this model proves.
Sound quality features
- Excellent texture
- Excellent separation
- Bright midrange
- Good original fidelity
- Monitor-like bass
- Good detail
- Edge sound
- Good focus on midrange
- Good sound balance
- Speaker-like forward localization
- Lacks in depth of low frequency range
- A little aggressive sound for those sensitive to high frequencies
- Prone to shoutiness
- Tends to sound a little noisy, with a tinny or raspy sound
- Lacks clarity due to high distortion
- Excessively high price for the overall sound quality
The Astell&Kern AK ZERO1 is the brand's debut, and it is a labor of love that overcomes the considerable challenge of being a tribrid to successfully put together a studio monitor. Unfortunately, the sound quality is not quite worth the price, but the build quality is excellent, and it is a decent product among the generally incoherent tuning of the high end of the market.