Industry-first DAP with MIL-Spec Vintage Vacuum Tube Raytheon JAN6418 in Quad Configuration
Industry-first DAP with Triple Tube Mode (Triode, Ultra Linear, Pentode)
T Series Signature feature: Triple AMP System
Adjustable Tube Current with Three Levels
High Driving Mode, ESA, and Advanced DAR for superior sound quality
Full Open Android
Enhanced Octa-Core CPU
 
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.
 
The SP4000T is the industry's first DAP to feature Triple Tube Mode. Combined with the T Series Signature Triple AMP Mode and the Tube Current level adjustment first found on the SP3000T, it offers up to 54 possible combinations tailored to any genre or preference — a true Analog Sound Palette.

Because how you operate the same tube fundamentally changes its tonal character, Triple Tube Mode encompasses the full expressive range of a tube amplifier. The delicacy of Triode, the balance of Ultra Linear, the dynamics of Pentode — the extraordinary analog sound experience once exclusive to high-end tube amplifiers is now yours in the SP4000T.
 
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.
 
Specifications
General Specifications
Model:
SP4000T (PPF52)
Body Color:
Silver, Copper
Body Material:
Stainless Steel, 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)
AK Cradle Compatibility:
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 5hours (PD3.0 Charging)
Playback Time:
about 10hours (Standard : FLAC, 16bit, 44.1kHz, Vol.80, LCD Off, Low Gain)
 
Supported OS
Windows 10,11(32/64bit) MAC OS X 10.7