Encompassing the blessings of nature and the culmination of human knowledge, it presents the myriad of expressions within sound. In traditional Japanese culture, "NARUKAMI" refers to the god of thunder, and thunder is seen as a manifestation of the power of nature. The frequent occurrence of thunderstorms in the lunar month of June is also referred to as the "Month of NARUKAMI." The image of NARUKAMI often appears in festivals and traditional dramas, symbolizing people's reverence for nature.
In traditional cultural performances, the presence of NARUKAMI is often depicted as striking drums to produce lightning and thunder. Hence, it is common to find many music-related elements named after NARUKAMI, symbolizing the power and vitality of sound, while also reflecting people's passion and pursuit of music.
Named after "NARUKAMI", this headphone amplifier/pre-amplifier, "HPA-KG NARU" also strives for high-quality performance and sound. It incorporates the audio technology accumulated by Audio-Technica over the past sixty years and meticulously selected custom-made components. It allows people to experience the intricate details and emotional depth of sound, providing a refined and natural listening experience that brings joy; the delight of music.
A Rare and Precious Presence
In order to highlight Audio-Technica as a Japanese brand, we pondered over the choice of materials for crafting the product bearing the name "NARUKAMI". Ultimately, we believe that KUROGAKI best embodies the "wonders of nature" and the "craftsmanship of Japan," making it the perfect choice for this rare and precious wood.
The Mysterious KUROGAKI
KUROGAKI means "black persimmon" in Japanese. It is not the name of a specific tree species. It refers to the persimmon wood that exhibits black patterns internally. The reason behind the appearance of these black patterns remains elusive to this day, as they can only be found in ancient trees that are over a hundred years old. Furthermore, even intentionally cultivating them yields a very low probability of encountering KUROGAKI, making it an incredibly rare and mysterious wood to obtain. Additionally, the drying process of KUROGAKI is quite challenging and requires extensive knowledge and expertise accumulated over years. These factors contribute to its revered status across Japan.
KUROGAKI in History and Culture
Due to its mystique and Zen-like patterns, KUROGAKI has been cherished by nobles and literati throughout history. The Tōdai-ji Shōsōin in Nara City houses numerous ancient treasures, including a significant collection of KUROGAKI crafts, serving as a testament to the important role of KUROGAKI in Japanese culture.
Design and Appearance
Traditional garden landscaping emphasizes harmony with space and nature, encapsulating it within the confines of a garden. The concept of the NARUKAMI amplifier draws inspiration from this idea, fusing elements of dry landscape gardens (karesansui) and traditional Japanese tatami rooms. It aims to embody the diverse expressions of nature that Audio-Technica seek to present through this amplifier.
KARESANSUI, or dry landscape gardens, is a traditional garden style characterized by its simplicity and abstract design. It utilizes fine sand and gravel to represent water flows, mountains, and a minimal amount of vegetation to depict natural scenery, while incorporating Zen Buddhist concepts. The top orifices correspond to the positions of the vacuum tubes; the horizontal flow of water creates ripples upon encountering these orifices, forming the symbol of infinity (∞) and eventually cascading down on both sides, creating a flowing motion around the KUROGAKI panels. In Asian cultural, the number 8 is also considered auspicious.
The metal mesh cover used to protect the vacuum tubes and output transformers features an Ayasugi pattern. Ayasugi is a native Japanese species of tree that is widely used in garden and landscape design. It has deep green, flat needles that are densely arranged on the branches, creating a lush and beautiful crown. The beauty of these needles has been cherished since ancient times and is incorporated into many traditional pattern designs.
Carefully Selected Audio Components and Circuit Design
Reflecting on 60 Years of Audio Excellence
To convey Audio-Technica's enduring commitment to analog audio, we began contemplating what breakthroughs could be achieved as we approached our 60th anniversary, in 2022. Ultimately, we decided to create a headphone amplifier / pre-amplifier that embodies the culmination of our existing technologies, showcasing Audio-Technica's drive to innovate, even after six decades.
Over the course of ten years, our development team went through eleven prototype iterations before reaching the final specifications. Throughout the process, they relied solely on their auditory senses to assess the differences in sound quality caused by circuitry, components, and structural variations. Adjusting parameters that couldn't be measured by existing instruments presented a significant technical challenge. It required an understanding of the sound tendencies of each individual component, building upon layers of accumulated knowledge to progress further. Through this meticulous design, we aim to deliver a lifelike sound experience that evokes a new level of emotional connection for the listener.
Compliance with New Safety Standards
To ensure a safe product, the NARUKAMI amplifier complies with the new safety standard IEC 62368. This new standard not only sets higher requirements for the electrical characteristics of devices but also emphasizes the practical resolution of safety issues. In other words, it can handle risks in a more preventive manner based on the conventional standards. Moreover, care has been taken to adopt various safety measures without compromising the sound quality.
The voltage amplification stage utilizes the SRPP circuit with ECC83S tubes, while the current amplification stage employs TA-300B tubes to drive the LL2765AgAM output transformer. The circuit design incorporates the use of the high-quality components available.
These include the input transformer LL1532 and the output transformer LL2765AgAM made with special Amorphous Core and silver wire from Lundahl Transformers. TA-300B vacuum tubes were carefully selected by Takatsuki Electric Industry specifically for headphone amplifiers, premium audio resistors with exceptional heat dissipation properties from Amtrans Corporation, and specially designed power transformer for this unit by Someya Denshi, as well as selected vacuum tubes such as ECC83S-gold and GZ34S from JJ ELECTRONIC. Each component has been carefully selected for its superior performance.
All input switching and output transformer switching are achieved through sealed relays, ensuring durability and stability. The use of relays also enables the optimization of signal flow for enhanced performance.
Luxurious Full-Balanced Circuit Design
The Narukami Headphone Amplifier employs a fully balanced drive design. The four ECC83S tubes in the front stage amplify the signal using a "Shunt Regulated Push-Pull" circuit design known as SRPP, providing strong drive to the four TA-300B tubes in the rear stage. This design achieves a refined amplifier circuitry.
When using balanced inputs, the signal is directly sent to the left and right balanced circuits. When using line inputs, the signal is converted to a balanced signal through the LL1532 input transformer before being sent to the left and right balanced circuits. This balanced conversion circuit exhibits rich harmonics and dynamic range, further enhancing the distinctive sound characteristics of vacuum tubes and delivering clear and high-quality audio reproduction.
Independent Signal Circuit and Power Supply for L/R Channels
The circuit design of the NARUKAMI Amplifier features a luxurious configuration with four circuits, each consisting of a balanced arrangement of HOT and COLD sides for the left and right channels.
The current supplied to the left and right audio signal circuits is sourced from dedicated power transformers, ensuring stable and pure current delivery. This design achieves high separation and low noise, resulting in transparent and rich sound quality. With such a design, the NARUKAMI Headphone Amplifier achieves exceptional music playback capabilities, aiming to satisfy even the most discerning audio enthusiasts.
Amorphous Core Silver Wire Output Transformer from Lundahl
Among the factors influencing audio equipment, the output transformer plays a crucial role. Therefore, we have chosen output transformers manufactured by Lundahl. These transformers are constructed with amorphous alloy cores, which are different from conventional cores, offering extremely low magnetic hysteresis loss, high saturation magnetic flux density, and excellent frequency response. The cores are meticulously wound with high-purity silver wire, providing very low resistance and outstanding conductivity.
This design is used to match the impedance between the output transformers of the vacuum tube amplifier and the headphones, offering optimal impedance matching. This allows the amplifier to deliver greater power to the headphones, adding richness to the sound and maintaining excellent frequency response. In addition, the output transformer features a headphone matching circuit with three impedance positions, allowing users to choose the impedance that suits their headphones' characteristics and desired sound quality.
Furthermore, this unit also features a preamp output function, allowing the signal from the output transformers driven by TA-300B vacuum tubes to be outputted and drive a power amplifier.
Carefully Selected Vacuum Tubes
The vacuum tubes used in this amplifier are individually tested and matched to ensure optimal performance. The signal amplification stage employs paired JJ ECC83S tubes, known for their rich and resonant sound characteristics. In the power stage, two pairs of Takatsuki TA-300B tubes are utilized, delivering powerful driving force and dynamic high-quality sound.
The TA-300B vacuum tube is meticulously handcrafted in Japan and known for its exceptional performance and sound quality. It features plates that are pressed with dedicated molds, filaments designed and manufactured using special techniques, and highly precise grids. It offers a rich midrange and natural high frequencies without being overly bright or harsh on the ears. The low frequencies are compact, clear, and exhibit excellent extension and rich details.
To prevent hum and other noise from entering the signal, the TA-300B employs a complex DC filament biasing method and undergoes multiple filtering stages to purify the filament power supply, resulting in low noise performance.
The NARUKAMI amplifier is not just a headphone amplifier; it also serves as a pre-amplifier with preamp output functionality. It can drive power amplifiers using the signal from the output transformer driven by TA-300B vacuum tubes, making it suitable for use as a pre-amplifier for speakers.
The NARUKAMI Headphone Amplifier provides a 4.4mm XLR 4-pin balanced headphone socket, as well as a 6.3mm single-ended headphone socket, ensuring true versatility. You can use most of headphones to fully experience the pure and exquisite sound delivered by the full-balanced designed circuit.
Selectable Headphone Output Impedance
The headphone matching circuit of the Lundahl output transformer offers three native impedance positions, allowing users to choose the appropriate impedance based on the characteristics of their headphones and the desired sound quality. This feature enables optimal compatibility with various headphone designs, ensuring the best listening experience.
L/R Channel Volume Balance
The NARUKAMI amplifier features a convenient volume balance control knob, allowing users to adjust the volume balance between the left and right channels according to their individual preferences and requirements.
Specially Tuned Headphones AW-KG NARU
The limited edition NARUKAMI headphones, "AW-KG NARU", are crafted with housings also made from KUROGAKI. They have been specially tuned to deliver exceptional sound quality and come equipped with a dedicated headphone cable, allowing you to fully maximize their potential when paired with the NARUKAMI Headphone Amplifier.