Astell & Kern A&ultima SP4000T Copper Limited Edition Portable High-Resolution Digital Audio Player

SP4000T Copper Edition

The A&ultima SP4000T Copper Edition goes beyond a simple high-end portable audio player, it serves as the ultimate culmination of years spent by Astell&Kern to understand different types of metals for body materials, precision machining expertise, and vacuum tube-based analog sound philosophy. It is a model where every process, from material selection to sound tuning, is organically connected to ideally realize the sound targeted by the SP4000T, rather than a simple change in material used.

The SP4000T Copper Edition captures the unique emotion of vacuum tubes even more deeply using copper. Copper suppresses subtle signal loss with its excellent electrical conductivity, and protects sound from external noise with its superior electromagnetic shielding properties. Added to this is copper's unique rich resonance, adding natural depth to the warm analog harmonics produced by the four vacuum tubes. The analog emotion of vacuum tubes meets copper to maximize each other's strengths, completing the unique sound of the SP4000T Copper Edition.

Copper is theoretically one of the most ideal materials for audio use, but it is an extremely tricky metal to apply to actual products. It oxidizes quickly upon contact with air and has low surface stability, making it a bigger challenge in portable devices exposed to various environments. Based on a deep understanding of material processing developed over the years, Astell&Kern applied a special multi-layer coating process to raw, high-purity (99.98% or more) copper materials. This process suppresses oxidation and discoloration, allowing a deep color tone and subtle luster that is maintained for a long time without additional maintenance.

The appearance does not stop at simple material application. High-purity copper is extremely difficult to machine without subtle deformation. Drawing on years of precision-engineering expertise, Astell&Kern has mastered the exacting tolerances required to create the SP4000T Copper Edition, a product whose beauty deepens with time and whose enduring value extends far beyond its performance.

The A&ultima SP4000T Copper Edition was born for those who understand the essence of pure original sound and the warmth of analog. We hope you experience firsthand the deep emotion that extends beyond music presented by the SP4000T Copper Edition.

RAYTHEON JAN6418 Quad — A New Standard in Tube Configuration

The SP4000T is the industry's first DAP to feature the MIL-Spec vintage vacuum tube RAYTHEON JAN6418 in a Quad configuration.

With independent dual-tube structures dedicated to the left and right channels respectively, the channel-separated design — once exclusive to home audio high-end tube amplifiers — has finally been brought to the world of DAPs.

But the essence is not the number of tubes. Managing multiple highly sensitive vacuum tubes is far more than a simple matter of addition. It demands answers to countless questions: How do you pair tubes with subtly different noise characteristics and gain rates? How do you overcome microphonic noise? How do you minimize output variation between left and right channels?

The four tubes in the SP4000T do not operate independently — they work in a differential configuration, with each pair facing the other in mirror symmetry. In this precise balance, music signals are amplified with twice the clarity, while common-mode noise is mutually cancelled and eliminated.

Each of the four tubes is precisely measured for its noise and gain characteristics before being paired, then fully isolated from noise through independent modular flexible PCBs and a multi-layered architecture — a design that only Astell&Kern, with its long experience in analog circuits and vacuum tubes, could bring to life.

When four hearts beat as one in perfect balance, the tube's signature rich harmonics resonate with the deepest, most resonant sound ever heard in the SP4000T.

DESIGN

“Burst”

The Astell&Kern SP4000T is a model within the flagship lineup that focuses on the very essence of analog sound. To realize the highest level of analog sensibility, Real Vacuum Tubes are applied in Quad configuration for the first time in a DAP, completing a deeply immersive analog sound that transcends the boundaries of digital players.

The SP4000T is the successor flagship to the SP4000, and its design concept keyword is "Burst." Interpreting through formal language the moment when concentrated energy explodes outward from the center, the design gives visual form to the source of power from which sound erupts.

The structure tightly centered around the Volume Wheel expresses a sense of focused, tensioned energy, while the sculptural surface composition and contrast of light clearly convey the presence and physical weight of interaction. A design where mechanical precision and sculptural beauty coexist intuitively communicates a sense of 'power' through the fingertips. The Volume Wheel on the side is a defining element that symbolizes Astell&Kern's heritage — and the deep groove carved into its center symbolically represents the rich density of analog sound and the powerful driving energy of the device.

Specification

General Specifications

• Model: SP4000T (PPF52)
• Body Color: Copper
• Body Material: Copper
• Display: 6inch 2K (2160 x 1080) touch screen
• Supported Audio Formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF
• Sample Rate: PCM: 8kHz ~ 768kHz (8/16/24/32bits per Sample)
  DSD Native: DSD64 (1bit 2.8MHz), Stereo / DSD128 (1bit 5.6MHz), Stereo
  DSD256 (1bit 11.2MHz), Stereo / DSD512 (1bit 22.4MHz), Stereo
• Output Level: Unbalanced 4.2Vrms │ Balanced 8Vrms (Condition No Load)
• CPU: OCTA-Core
• DAC: AKM4191EQ x2 + AKM4499EX x2
• Vacuum Tube: RAYTHEON JAN6418 x4 (Quad Tube)
• Decoding: Support up to 32bit / 768kHz Bit to Bit playback
• Input: USB Type-C input (for charging & PC & MAC)
• Outputs: Unbalanced Out (3.5mm), Optical Out (3.5mm)
  Balanced Out (4.4m, only 5-pole supported)
• Wi-Fi: 802.11 a/b/g/n/ac/ax (2.4/5GHz)
• Bluetooth: V5.2 (A2DP, AVRCP, Qualcomm® aptX™ HD, LDAC, LHDC, SBC, AAC)
• Dimensions: 3.37” (85.7mm) [W] x 5.9” (150mm) [H] x 0.76” (19.5mm) [D]
• Weight: About 19.9oz (565g)
• Feature Enhancements: Firmware upgrade supported (OTA)
• Operating Temperature: 0℃ ~ +40℃ (32℉ ~ 104℉)

Audio Specifications

• Frequency Response: ±0.006dB (Condition: 20Hz ~ 20kHz) Unbalanced │ ±0.006dB (Condition: 20Hz ~ 20kHz) Balanced
  ±0.06dB (Condition: 20Hz ~ 70kHz) Unbalanced │ ±0.06dB (Condition: 20Hz ~ 70kHz) Balanced
• S/N: 124dB @ 1kHz, Unbalanced │ 125dB @ 1kHz, Balanced
• Crosstalk: -136dB @ 1kHz, Unbalanced │ -145dB @ 1kHz, Balanced
• THD+N: 0.0006% @ 1kHz, Unbalanced │ 0.0004% @ 1kHz, Balanced
• IMD SMPTE: 0.0004% 800Hz 10kHz (4:1) Unbalanced │ Balanced
• Output Impedance: Unbalanced Out 3.5mm (0.7ohm) │ Balanced Out 4.4mm (1.7ohm)

Clock Source

• Clock Jitter: 25pS (Typ)
• Reference Clock Jitter: 200 Femto Seconds

Storage Capacity

• Built-in Memory: 256GB [NAND]
• External Memory: microSD x1 (Max. 1.5TB)

Battery

• Capacity: 7,450mAh 3.8V Li-Polymer
• Charge Time: About 5 hours (PD3.0 Charging)
• Playback Time: About 10 hours (Standard: FLAC, 16bit, 44.1kHz, Vol.80, LCD Off, Low Gain)

Supported OS

• Windows 10, 11 (32/64bit), MAC OS X 10.7