Product Description
JD90
CURRENT-MODE Tube Power Amplifier
Introduction to the Characteristics of Products
The current-mode circuit architecture eliminates the intermodulation distortion inherent in traditional long-tail phase-split driving circuits, which is the primary factor degrading sound quality.
The current-mode circuit features a wide frequency bandwidth, high slew rate, and unlimited voltage swing, offering a large dynamic range.
The minimal use of vacuum tubes in the amplification path significantly reduces phase distortion.
The adaptive constant-current and constant-voltage hybrid biasing of the JD90 power tubes ensures push-pull arm current balance, minimizing DC magnetization of the output transformer.
The independent balanced feedback structure guarantees stability across the entire frequency spectrum and dynamic range.
The low-noise DC-regulated power supply for the driver stage achieves high power supply noise rejection and stable driving capability for the power tubes, overcoming the influence of Miller capacitance on the slew rate and delivering sharp dynamic performance.
The application of power tube temperature equalization and high-efficiency flat heat pipes significantly reduces the operating temperature of the vacuum tubes. The temperature of the power tube glass envelope decreases by over 100°C, greatly improving the lifespan and reliability of the vacuum tubes while achieving ultra-low background noise. The overall system achieves a signal-to-noise ratio (SNR) of 95dB or higher.
Amplifier technical specification
Stereo Output Power: 25W
Frequency Range:
6Hz - 60kHz -1dB;0dB =1W 1kHz,8Ω
8Hz - 35kHz -3db; 0dB=25W 1kHz, 8Ω
THD+N:
≤0.3% 1W 20Hz - 30kHz,8Ω,typically 0.25% at 1kHz
≤ 1% 15W 20Hz - 30kHz,8Ω
Circuit Mode: Current-Mode,Class A
Bias Adjustment: Auto Biased
The amount of negative feedback: 6dB
Input Impedance: RCA 100kΩ , XLR 55kΩ
Input Sensitivity: Max.1.4Vrms at 1kHz for 25W
SNR: 100dB （A - Weighted）
Rated Output Impedance: 4-6Ω/8-16Ω
Input Channel Isolation: 10~100kHz>70dB, 1kHz>85dB
Channel Separation: 10~20kHz>70dB, 1kHz>85dB
Tubes Used: 4 x KT90；2 x 6922
Machine size: 17 (W) x 14 (D) x 10 (H) inches
44 (W) x 37 (D) x 25 (H) cm
Machine size: Net: 73 lbs (33 kg) | Gross: 86 lbs (39 kg)
Fuse: T6.3A (100–120V, 60Hz); T3.15A (200–240V, 50Hz)
Maximum Power: ≤300W