The Power of Bone Conduction

Bone conduction redefines audio with cutting-edge technology. No in-ear insertion—sound transmits directly through skull bones, keeping you aware of surroundings for safety. Lightweight and secure, it stays stable during workouts without discomfort. Clear sound, ergonomic design, perfect for commuting, sports, and the office. A smart blend of innovation and comfort, unlocking a freer way to listen.

Acoustic Architecture

True excellent sound quality never comes from the solitary efforts of a single driver, but rather the harmonious coexistence of different drivers such as dynamic, moving iron, and electrostatic drivers, which collide to create an auditory feast beyond imagination. The dynamic driver brings a warm and mellow sound, carrying the fullness and atmosphere of low frequencies. Every dive of the low frequencies is steady and powerful, restoring the most authentic warmth of the sound. The moving iron driver is precise and delicate, unlocking the clarity and resolution of mid-to-high frequencies. The breath of vocals and the overtones of instruments are clearly distinguishable, bidding farewell to blurriness and turbidity. The electrostatic driver brings out every detail, fully extending the high frequencies, creating an ethereal and transparent sound that is not harsh, allowing every sound detail to be gently captured.

Ultimate sound quality and craftsmanship

The Mest Jet Black is a high-end in-ear monitor (IEM) from the UM MEST series, featuring a revolutionary Hybrid Bone Conduction System and Bone Conduction Crossover Technology. It combines dynamic, balanced armature, electrostatic, and bone conduction drivers for an immersive and natural sound experience.

Crafted with a black ceramic shell, it offers enhanced acoustics, durability, noise isolation, and comfort. The earphones use a hybrid driver setup, delivering deep bass, clear mids, and refined highs. Accompanied by premium custom cables and a luxury leather case, the Mest Jet Black is designed for audiophiles seeking ultimate sound quality and craftsmanship.

The beginning…

Since its launch in 2019, the MEST series has been widely praised for its outstanding sound quality and bone-conduction technology. After analysing the strengths and weaknesses of the MEST series, we developed the all-new MEST Jet Black. Mest Jet Black is not just about a change in shell material-it represents a revolutionary advancement in technology. We have refined the sound, particularly the bone-conduction component, to achieve a more open, intuitive bone-conduction experience. These improvements are evident and have been thoroughly tested by audiophiles in the U.S., Japan, Korea, China, and beyond.
Following the philosophy of ultimate pursuit and meticulous craftsmanship, we chose a black ceramic shell for the Mest Jet Black. The ceramic shell is delicate, with a smooth, jade-like texture, earning it the name “Black Jade”.

Innovative Material Selection

The manufacturing process for the ceramic shell and faceplate is extremely complex. It begins with zirconia powder processing, followed by sintering at 1600°C and multiple intricate procedures. The final product undergoes precise manual refinement and high-precision machining to achieve its stunningly refined texture. During the sintering process, the earphone size shrinks by approximately one-third, requiring rigorous verification and testing of design tolerances and final dimensions. Due to the high hardness of ceramic, diamond-tipped tools are necessary for milling, making the final processing stage highly challenging.

Reasons for Choosing a Ceramic Shell

• Enhanced Acoustic Performance – The high density of ceramic provides Mest Jet Black with superior acoustic properties, ensuring more stable sound transmission while reducing distortion and unwanted noise.
• Excellent Sound Isolation – The ceramic shell effectively blocks external noise, allowing for a pure and immersive listening experience.

• Exceptional Durability and Scratch Resistance: The material maintains its pristine appearance even after prolonged use.
• Strong Antibacterial Properties Compared to traditional materials, ceramic is environmentally friendly, recyclable, and hygienic.
• Smooth, Comfortable Texture – The warm and refined feel of ceramic enhances wearing comfort.

In summary, the ceramic shell of the Mest Jet Black not only elevates its overall aesthetics and texture but also offers significant advantages in acoustics, noise isolation, durability, hygiene, and comfort, delivering an unparalleled experience for users.

Hybrid Bone Conduction System | Bone Conduction Crossover Technology

After six years of research and testing, UM has developed the revolutionary Hybrid Bone Conduction System and Bone Conduction Crossover Technology.
By refining the characteristics of composite balanced armature bone conduction drivers and piezoelectric bone conduction drivers, UM has seamlessly integrated both into a new hybrid bone conduction system. Through crossover technology, each frequency band is handled by dedicated drivers, reducing distortion and enhancing the detail of bone conduction compensation.
Composite balanced armature bone conduction drivers focus on low and mid-frequency signals
Piezoelectric bone conduction drivers handle high-frequency signals

Similar to air conduction, Bone Conduction Crossover Technology reduces the burden on a single driver to process the full frequency range, minimising nonlinear distortion and resulting in a more natural sound.
This advancement provides an unparalleled auditory experience.
With the strategic combination of two composite balanced armature bone conduction drivers and one piezoelectric bone conduction driver, UM has successfully pioneered a new Hybrid Bone Conduction System and Bone Conduction Crossover Technology.
Conduction Method: Vibration
Conduction Medium: Composite Balanced Armature Bone Conduction Driver + Piezoelectric Bone Conduction Driver Human Ear
Key Features:

1. Enhanced response speed and impact of low frequencies
2. Smoother transition in mid-to-high frequencies
3. Jet Black preserves its core strengths while further improving tonal integrity and layering

Driver Configuration

Mest Jet Black continues the MEST series’ hybrid driver design, integrating dynamic, balanced armature, electrostatic, and bone conduction drivers. By combining bone conduction technology with traditional air conduction, it delivers a more comprehensive auditory experience.
Below are the two transmission systems formed by Mest Jet Black’s different driver types:

1. Air Conduction System and reaches the cochlea. Traditional drivers generate sound waves that travel through the ear canal
   Air conduction driver setup: 1 dynamic driver + 4 balanced armatures + 2 electrostatic drivers.
2. Bone Conduction System Sound is transmitted directly to the inner ear via skull vibrations.
   Bone conduction driver setup: 2 composite balanced armature bone conduction drivers for low and mid frequencies + 1 piezoelectric bone conduction driver for high frequencies.
3. In this configuration, the dynamic driver is responsible for low frequencies, balanced armatures handle mid and high frequencies, electrostatic drivers cover the ultra-high frequencies, and the combination of composite balanced armature bone conduction for low and mid frequencies with piezo-electric bone conduction for high frequencies ensures full-frequency compensation.

UM Dreamy Custom IEM Cable

Dreamy utilises single-crystal copper that has undergone nearly a year of natural annealing and features a seven-fold pipe structure, providing a more natural sound experience for IEMs.

Sleeve Material: PVC
Conductor Material: OCC Copper with Seven-Fold Pipe
Conductor Gauge:24AWG
Number of Conductors: 4

UM Jet Link Custom IEM Cable

The UM Jet Link custom cable is specially developed and designed for the Mest Jet Black. Its black cable jacket and metal components complement the black ceramic shell of the earphones. Made with OCC copper, featuring a seven-core twisted structure and 26AWG four-wire custom wiring, it delivers clear and profound sound.

Sleeve Material: PVC
Conductor Material: OCC Copper
Conductor Gauge: 26AWG
Number of Conductors: 4

Carrying Case

UM has upgraded the leather case for the MEST series, making adjustments in both design and materials. 80% of the case is made from high-end Italian cowhide leather, continuing UM’s signature blue as the primary colour. The leather thickness ranges from 1.3mm to 1.5mm, offering high durability, excellent tension, and a vibrant sheen.
The centre of the lid features Teal SUEDE Indian goatskin, which has a velvety, soft texture. The interior lining is made of natural navy blue cowhide from Korea, providing great elasticity and durability. For functionality, the case incorporates a circular Velcro structure, ensuring both convenience and security. Additionally, a built-in pocket allows for easy storage of warranty cards, ear tips, and other accessories.