True Diamond Diaphragm DU

Diamond has excellent sound speed and hardness, making it the most ideal material for diaphragms. In particular, its excellent bending rigidity greatly contributed to the realisation of the ultra-low distortion DU (driver unit) that we aimed for this time.
When observed with a laser displacement meter, even a hard metal diaphragm deforms in various directions, causing distortion, but due to diamond’s bending rigidity, the displacement is extremely small, making it possible to reproduce the input signal faithfully. Furthermore, diamond has contradictory properties: it has high rigidity and excellent internal loss (internal damping).
This enables accurate transient response without causing so-called “ringing,” which is unnecessary vibration that continues even after the sound has stopped.
For this product, the diamond diaphragm is manufactured using the CVD method (chemical vapour deposition method, a manufacturing method in which gaseous raw materials undergo a chemical reaction to crystallise a thin film), which involves crystallising diamond on silicon and then melting the silicon.
We have not only used diamonds, but have also developed some new designs and manufacturing techniques to maximise the performance of diamonds as acoustic components.

The shape of the diaphragm adopted for this product is the optimal solution for achieving both strength and lightness in a diamond diaphragm. This is derived from our own research.
In addition to the steep dome shape that is unprecedented in conventional headphone diaphragms, a new structure with cylindrical ribs on the outer periphery of the diaphragm allows us to overcome the problem of the trade-off between rigidity and mass in diaphragm development to a high level.
By realising the ideal shape of the diamond diaphragm, we have achieved high rigidity and light weight, leading to high response performance.

Although diamond has ideal performance, it has a specific gravity of 3.5, about twice that of beryllium, and has the problem of rolling on film-based edges when loaded with weight.
Additionally, common edge materials inevitably suffer from the problem of resonance at certain frequencies.
To solve these problems, we adopted a special polyurethane.
Conventional polyurethane had the disadvantage of being easily degraded, but this model uses a material that overcomes this weakness.
It is lightweight and has high elasticity and stretchability, solving the contradictory problems of mobility and resonance suppression.

Revised design of the voice coil

To guide the diaphragm, which is supported by highly flexible edges, to smooth piston motion, we have revised the design of the voice coil, which is normally hardened with adhesive, and adopted a lightweight, high-strength polyimide bobbin coil.
By giving the coil high rigidity, the bobbin transmits power accurately without being affected by the movement of the vibration system, increasing the accuracy of the piston motion of the diaphragm.
It also prevents weight variations and imbalances due to the amount of adhesive applied.
However, accurate driving force is meaningless if the mechanical symmetry of the moving parts is not maintained.
Traditional designs bond the voice coil lead directly to the back of the edge, creating an asymmetry in weight distribution and physically restricting the natural expansion and contraction of the edge.
At large amplitudes, this imbalance causes the diamond dome to tilt or roll, causing mechanical distortion.
To solve this problem, we adopted an aerial wiring structure in which the voice coil lead wire is suspended in the air and wired directly to the terminal.
By completely separating the lead wire from the edge, conditions are created for the diaphragm to be driven by pure piston motion.
A long-standing issue in aerial wiring is durability. Lead wires floating in the air tend to break due to repeated vibrations, which has been considered a design drawback.
To overcome this, we have newly developed and adopted a high-strength special aluminium alloy wire with significantly improved tensile strength and bending fatigue resistance for the lead wire.

The final stage of DU design is completed by a design philosophy that eliminates any invisible factors that impair sound quality.

In order to bring out the performance of a diamond diaphragm, it was necessary to precisely control many variables related to the magnetic circuit and internal acoustics.
The final stage of DU design is completed by a design philosophy that eliminates any invisible factors that impair sound quality.

■ N55 neodymium magnet
In order to maintain high control power, we use the highest grade N55 neodymium magnet. The ultra-high density magnetic flux instantly activates the diamond dome to achieve good transient response, and at the same time, the high braking force allows for a quick fall in sound.

■ Aluminium short ring
The DU’s magnetic circuit incorporates a short ring that is also used in high-end speakers. The opposing eddy currents generated by this ring cancel the voice coil’s inductive inductance and stabilise the magnetic field. As a result, distortion is significantly reduced even in low-frequency reproduction with large amplitude.

■ DU internal damping system
In the acoustic space behind the driver, the sound waves emitted from the back reflect and affect the sound quality of the driver. In order to reduce the effects of this resonance, we have constructed a dedicated damping system that places precision-moulded, high-performance sound-absorbing material directly below the diamond dome. This greatly suppresses the resonance that occurs inside the DU.

Housing with both rigidity and airtightness

It is common knowledge that high-end speakers are designed to thoroughly increase the rigidity of their enclosures (speaker casings) to eliminate unnecessary vibrations and resonances.
High rigidity is also the foundation that supports airtightness, which is another important element. If the casing bends even slightly, gaps will appear at the joints, disrupting the carefully designed internal air behaviour.

This philosophy applies only to closed-back headphones.
The sound quality of closed headphones is largely determined by whether the airtightness inside the housing (the part that houses the diaphragm and driver unit) can be completely controlled, and even the slightest air leak during assembly can have a major impact on sound quality.

In such a situation, by incorporating the design philosophy of high-end speakers into headphones, we have achieved a housing design that is both rigid and airtight.

A housing that is both rigid and lightweight requires steeply angled surfaces and complex geometric shapes, which cannot be achieved using conventional 3-axis CNC machining (a machining method in which the housing is machined from three directions using computer control).
Therefore, we precisely cut the aluminium-magnesium alloy using 5-axis CNC, which has a higher degree of processing freedom, to ensure the dimensional accuracy and rigidity required for acoustic design.
The interior has also been machined to reduce weight while maintaining rigidity.
Since unnecessary resonance occurs due to the effect of the space created at this time, by filling the cut parts with acoustic adjustment material, we simultaneously achieved weight reduction and control of internal reverberation.

The completely sealed structure

The completely sealed structure that seals the ear pads, which is often used in closed-back headphones, increases the low-frequency range excessively, so it is necessary to raise the high-frequency range to maintain sound balance.
To achieve the detailed sound that we were aiming for with this product, the sound pressure frequency response needed to be balanced with a smooth curve.
Ultrasuede® (a man-made suede material made of densely woven ultra-fine fibres) is a material that allows a small amount of air to escape while maintaining an acoustic seal due to the fine air permeability of its fibre structure.
This characteristic is what made the sound pressure frequency characteristics required by this product possible. We manufacture exclusive ear pads by combining this Ultrasuede® with a foam material that guarantees the volume inside the pad and the fit.

The case is fastened using a unique design

The case is fastened using a unique design in which 12 screws pass through the outer housing to the front plate that secures the ear pads.
This design, which does not use any adhesive, applies a uniform and strong tightening force to the entire housing, achieving both high rigidity and airtightness

Repairable construction for long-term use

This product uses a screw fastening structure that does not use adhesive, so the casing can be disassembled and reassembled. This structure, which was designed for airtightness and manufacturing quality, is directly linked to repairability during long-term use. Being able to replace consumable parts and provide service in the event of an emergency is the basis for continued use of our products for a long time.

Final: Two original “silver-coated cables”

This is a jointly developed product with Junkosha, which is famous for developing and manufacturing cables for the K supercomputer. For the wire material, we use silver-coated OFC wire (oxygen-free copper, a copper wire that has increased purity and removed oxygen, which causes sound quality deterioration), which brings together the know-how that Junkosha has cultivated over many years as part of the Junflon brand. The combination of the high conductivity of the silver-coated conductor and the insulation material with optimised dielectric properties maintains a high level of audio signal purity while minimising signal loss.

The 4.4mm/1.5m cable uses ePTFE (expanded fluoropolymer), which has a lower dielectric constant (the lower the value, the less the effect on the signal) than conventional PFA (a type of fluororesin), for the insulation coating. The 4XLR/3m cable uses conductors with a large cross-sectional area to achieve low resistance even when long. The coating uses PFA, which has high strength and can withstand long handling.

Includes two types of conversion adapters

4XLR to 6.3mm and 4.4mm to 6.3mm conversion adapters are included.

Comes with a special protective case that can also store various cables.

The product and accessories are stored in a special protective case that is convenient to carry. It can be locked using the included special key.