The Astell&Kern SP4000T is a model from the flagship lineup that focuses on the essence of analog sound. To achieve the highest level of perception of analog signals, real vacuum tubes are used in a quad configuration for the first time in a DAP, providing a deep immersion into analog sound that goes beyond digital players.
A&ultima SP4000T - a reinterpretation of analog sound
A&ultima SP4000T is the culmination of almost two years of work, starting with the planning and development of the SP3000T. While high-quality audio elements such as DACs and tube amplifiers could be available to any user, what ultimately comes out of them, using the same elements, is completely different. Using the SP4000 technology, embodying the essence of digital sound, Astell&Kern has been asking one important question for the past two years: "How can we convey deeper emotions through analog sound?"
The answer was found with sincerity and endless passion, stroke by stroke. Every detail of this journey is embodied in the SP4000T. Astell&Kern's in-house analog sound - listening to it is pleasant, but the longer you listen to it, the more its depth and character are revealed. Discover it all with A&ultima SP4000T.
RAYTHEON JAN6418 Quad - a new standard in tube configuration
The SP4000T is the industry's first DAP equipped with the vintage RAYTHEON JAN6418 MIL-spec quad vacuum tube. Thanks to independent tube structures designed for the left and right channels respectively, which were once exclusive to high-end home audio tube amplifiers, this setup finally makes its appearance in the world of DAPs. But it's not just about the number of tubes. Managing multiple high-sensitivity vacuum tubes is much more than mere addition. It requires answers to countless questions: How to connect tubes with slightly different noise characteristics and gain ratios? How to overcome microphonic noise? How to minimize output differences between left and right channels?
The four tubes in the SP4000T do not work independently - they work in a differential configuration, where each pair faces each other in mirror symmetry. Thanks to this precise balance, musical signals are amplified with doubled clarity, and common-mode noises are mutually neutralized. Before connecting to each of the four tubes, their noise characteristics and gain characteristics are precisely measured, then they are completely isolated from interference using independent modular flexible printed circuit boards and multilayer architecture - a design that only Astell&Kern, with years of experience in analog circuitry and vacuum tubes, could bring to life. When four hearts beat as one in perfect balance, the signature rich tube harmonics create the deepest and most sonorous sound ever heard in the SP4000T.
SP4000T is the industry's first DAP with Triple "Tube" mode. Combined with the signature T-series triple amplifier mode and tube bias, first introduced in the SP3000T, it offers up to 54 possible combinations adapted to any genre or preference - a true analog sound palette. Since how you handle the same tube drastically changes its timbre, the "Triple Tube" mode provides a full range of tube amplifier sound. The elegance of triode, the balance of Ultra Linear, the dynamics of pentode - extraordinary analog sound that was once only found in high-end tube amplifiers is now available in the SP4000T.
Triode mode - Purest tube timbre
This mode reproduces the richest harmonic texture inherent in vacuum tubes, allowing the breath of the vocalist and the tremor of the strings to smoothly dissolve into a juicy, reverberating reverb.
Ultra Linear mode - Aesthetic balance
A design combining the tonality of Triode and the power output of Pentode. The sound gently decays at the edges but has a solid foundation - a well-balanced mode capable of faithfully rendering sound in any genre.
Pentode mode - The most powerful tube sound
By increasing the power of the tube amplifier and dynamic range, this mode retains the characteristic warmth of the tube amplifier while eliminating reverberation, providing a clean, powerful sound that speaks directly and forcefully.
Perfect harmony of real vacuum tubes and operational amplifier
The A&ultima SP4000T, based on Astell&Kern's exclusive Teraton Alpha technology, provides the perfect combination of truly analog sound from Real Vacuum quad-channel tubes and dynamic sound from the operational amplifier. The SP4000T offers a tube amplifier mode for authentic analog sound, an operational amplifier mode for signature clarity and an expansive soundstage, and a hybrid amplifier mode that combines the best of analog warmth and high-resolution output signal. Experience a distinctly discernible sound thanks to the signature T-series amplifier technology.
High-resolution and dynamics in operational amplifier mode
High resolution reproducing the original sound without distortion, unparalleled sense of space, and the highest clarity and dynamics - the operational amplifier mode provides the highest quality sound that Astell&Kern applies for the first time in each of its products. Ultra-low noise levels and high resolution achieved through Astell&Kern TERATON ALPHA technology will open up new facets of music you have never encountered before in all genres.
True analog sound in tube amplifier mode
The warm texture and unique soundstage of a tube amplifier cannot be replicated by any modern digital amplifier. Beloved since the advent of tube amplifiers, they remain unmatched in conveying the emotional depth of music. The tube amplifier mode in the SP4000T combines deep, rich analog sound unique to Real Vacuum quad-channel tubes with stunningly low noise levels achieved through advanced technologies and craftsmanship, allowing you to fully immerse yourself in the music.
Enhanced hybrid amplification mode
In addition to two modes - tube and operational amplifier - the new generation hybrid amplification mode allows you to manually select the desired timbre. Combining analog sensitivity with the benefits of high-resolution output, the five-stage HYBRID amplifier mode allows you to freely adjust the sound to your taste and according to your music.
Generation 2 microphonic noise protection architecture
The most significant technical challenge when using vacuum tubes in a compact portable device is achieving low noise levels even at high resolution and high performance. In the SP4000T, there are twice as many tubes as its predecessor, and a redesigned 5-stage Generation 2 architecture (compared to the previous 4-stage design) is used to suppress microphonic noise (interference generated in vacuum tubes even with slight external vibrations). Through patented know-how and years of experience, exhaustive design, testing, and verification, an optimal solution was found to overcome the structural limitations associated with microphonic noise.
- Separate modular flexible printed circuit board, isolated from the main printed circuit board
- Silicone base cushion for primary tube damping
- Specially selected silicone sleeve around tube tips absorbs shocks transmitted along the wires
- Silicone damper encircling the tube and suspending it in the air at the end of the damper
- Copper shield covering the entire tube suppresses even the weakest micro-noises
The most delicate analog sound
Engineers have checked the safe operating range of vacuum tubes and developed a system that regulates the voltage on the internal plate at 3 levels, each of which changes the gain of the tube amplifier, along with the tonal structure of the sound. Feel the subtle but striking changes in density and soundstage - the finest nuances that headphones can reveal thanks to the tube current adjustment.
Vacuum tube LED indicator
When operating in tube or hybrid mode, the vacuum tube on the back panel of the SP4000T emits a soft, warm light, enhancing the refined, stylish aesthetics of the analog device.
HEXA audio circuit architecture with full digital and analog signal separation
The SP4000T is equipped with two AK4499EX DACs - the latest flagship from AKM, which has established itself in Astell&Kern devices. These chips, combined with specialized AK4191EQ processors for each left and right channel, form a fully discrete audio circuit architecture. Unlike conventional DACs that process both digital and analog signals inside the DAC, the SP4000T audio circuit uses a special digital delta-sigma modulator (AK4191EQ) to reduce noise in the digital signal before transmitting it to the fully isolated DAC (AK4499EX) for independent analog signal decoding. With such a physically complete separation of channels for transmitting digital and analog signals, Astell&Kern's signature analog sound in the SP4000T has more depth than ever before.
High Driving mode for unparalleled sound
The SP4000T inherits the beloved High Driving mode from the SP4000, cherished by audiophiles worldwide. With twice as many operational amplifiers laid horizontally, it provides an even denser sound. Similar to a four-wheel-drive vehicle traversing rugged terrain, the High Driving mode delivers excellent engine power to achieve a stronger and more stable sound, accurately conveying even the subtlest sound details and providing a deeper and brighter perception.
Enhanced Signal Alignment (ESA) technology to minimize group delay
The SP4000T significantly improves group delay - one of the most challenging issues in audio recording. Thanks to the Enhanced Signal Alignment (ESA) proprietary technology. ESA aligns frequency signals to arrive more evenly, minimizing frequency distortions and providing greater clarity and purity of sound.
Advanced Digital Audio Reconstruction (DAR) support for improved sound
Advanced DAR is a 2nd generation DAR technology that provides even more natural and refined sound. Instead of sending the sound directly to the DAR engine, it first routes the signal through the VSE (Virtual Sound Extender) to practically restore lost harmonics and improve sound quality, then applies DAR technology to the second stage to achieve a more complete frequency upsampling result. This enables listeners to enjoy a deeper and more immersive sound that more closely resembles the original recording.
TERATON ALPHA technology
To create an unprecedented DAP unlike anything that existed before, Astell&Kern went beyond simply implementing the latest DACs and specifications. Engineers continued development and applied TERATON ALPHA, Astell&Kern's perfect sound solution, incorporating advanced and innovative audio technologies. Enhanced through constant research, TERATON ALPHA represents Astell&Kern's comprehensive expertise in audio technology. With effective noise cancellation, energy-efficient stable amplification, and precisely designed sound output interface, it delivers sound closest to the original source.
Bit-Perfect
Astell&Kern Direct Path (ADP) - a proprietary Astell&Kern customization technology - allows bypassing the sample rate conversion (SRC) limitation inherent in the Android operating system, ensuring lossless Bit-Perfect playback even in streaming environments with maximum sound quality. Aligned with the shift towards streaming-oriented listening, the SP4000T runs on the latest Android 15 version, providing the highest quality analog sound alongside exceptional convenience.
High-precision sound with multi-layer HDI PCB
The SP4000T uses the same high-density multi-layer HDI PCB as the SP4000 to ensure high performance. This high-density PCB, commonly used in smartphones and high-end electronics, allows for precise design of complex schemes in smaller dimensions, minimizing signal loss and providing higher-quality sound.
99.9% pure copper shielding
The SP4000T uses a fully shielded Can design that blocks noise and electromagnetic interference that can affect sound quality. With a copper case containing 99.9% copper, it goes beyond standard shielding and provides an even cleaner and brighter sound.
Enhanced battery protection mode
The battery protection mode, previously set at 85%, now offers a wider range of options. Choose the option that best suits your music style.
Real-time information display with LED backlight
The LED backlight around the power button displays information about the bit depth of the currently playing song, adding a visual effect that makes it bright and stand out.
Crossfeed function
Crossfeed mixes part of the signal from the opposite channel with a slight time delay and sends it to each channel, creating an effect of sound positioning closer to the center, similar to listening through speakers. This provides a more natural listening experience and helps reduce listening fatigue. With detailed settings such as playback time limit, playback time gain, and mixing level, you can precisely tailor the sound to your personal preferences.
Support for DSD512, PCM 32-bit / 768 kHz
Thanks to support for built-in DSD512 format and high-resolution PCM up to 32 bit / 768 kHz, you can enjoy your favorite music with outstanding quality. High-quality sound thanks to Astell&Kern's exclusive technology.
Support for fast USB PD 3.0 charging
With support for fast USB PD 3.0 charging, the SP4000T can be fully charged in approximately 5 hours.
First Astell&Kern model with dual Wi-Fi antennas
With the first-ever dual Wi-Fi antenna Astell&Kern model, data loading has become faster and more stable. According to internal testing results, the download speed on the 5 GHz frequency is approximately twice as high compared to the previous model.
Hi-Fi wireless sound playback with BT Sink
With BT Sink, you can connect the SP4000T to an external device via Bluetooth, similar to how a smartphone connects to a Bluetooth speaker. Music played on the external device can be transmitted to the SP4000T via BT Sink.
ReplayGain function for automatic volume leveling
The ReplayGain function has been applied to automatically adjust tracks with different volume levels to a consistent volume. With ReplayGain, it will be more convenient to play your playlists. ReplayGain supports audio files up to 24-bit / 192 kHz.
Large 6-inch Full HD display
With a large 6-inch Full HD display providing excellent image quality, you can enjoy the SP4000T with even greater comfort.
Premium-class leather case
The leather case for the SP4000T, included in the package, is made of "MINERVA" leather in the well-known "BADALASSI CARLO" leather workshop located in the San Miniato area of Florence, Italy. Badalassi Carlo is a tannery that has been producing leather for over 40 years, combining traditional Tuscan vegetable tanning methods with theories and techniques from "BADALASSI CARLO," a former professor at a leather school in the Santa Croce region.
Vegetable tanning is an eco-friendly process of making leather, slow and labor-intensive, in which hides are tanned using only vegetable tannins. In the production of Badalassi Carlo leather, Tuscan vachetta technology is used - after removing the wool from the hide during tanning with vegetable oils, a fat obtained from powdered bovine bones is added. Striving for small-batch production of high-quality products rather than mass production, the workshop has a high reputation among leather workshops of well-known brands that place great emphasis on material quality.
The case is available in the color "Cognac" and snugly envelops the entire device, providing a perfect fit, while the cutout with the pattern on the back is designed to showcase the glowing tube LED.
Explosive Design
The SP4000T is the flagship successor to the SP4000, and the key concept of its design is "Explosion." Interpreting the moment when concentrated energy bursts out from the center using formal language, the design gives visual form to the source of energy from which the sound bursts out. The structure, tightly focused around the volumetric wheel, creates a sense of concentrated, tense energy, while the sculptural surface composition and the contrast of light clearly convey the presence and physical significance of interaction.
A design where mechanical precision and sculptural beauty harmoniously blend, intuitively conveying a sense of "power" at the fingertips. The volume control wheel on the side is a defining element, symbolizing Astell&Kern's heritage, while the deep groove cut in its center symbolically reflects the saturation of analog sound and the powerful energy of the device.
Package includes:
- Player
- USB-C cable
- Premium leather case
- Manual
