Product Description
JD90
CURRENT-MODE Tube Power Amplifier
1. Circuit Innovation The JD90 current-mode circuit architecture eliminates the intermodulation distortion inherently present in traditional long-tail phase-splitter driver circuits. This type of distortion is one of the primary factors responsible for sound quality degradation.
2. Breaking Through Traditional Sonic Limitations The JD90 current-mode circuit features wide bandwidth, high slew rate, and unrestricted voltage swing capability, providing an exceptionally large dynamic range.
3. Cost Reduction with Improved Reliability The JD90 uses the minimum practical number of vacuum tubes in the amplification path, significantly reducing phase distortion while improving overall reliability.
4. Optimized AUTO-BIAS System The JD90 output stage utilizes an adaptive hybrid constant-current and constant-voltage bias system to ensure balanced current flow in the push-pull output stage while minimizing DC magnetization of the output transformer.
5. True Fully Balanced Amplification Circuit The JD90 employs an independent balanced feedback structure to ensure balance and stability throughout the entire frequency range and dynamic range.
6. High-Performance Power Supply Design The low-noise regulated DC power supply for the driver stage provides excellent power-supply noise rejection and stable drive capability for the output tubes. It overcomes the influence of Miller capacitance on slew rate, resulting in sharp and dynamic transient performance.
7. World’s First Actively Cooled Tube Amplifier Structure The JD90 incorporates patented high-efficiency flat heat-pipe technology and temperature-equalization technology for its output tubes. This design significantly reduces tube operating temperature. The glass envelope temperature of the output tubes is reduced by more than 100°C, greatly improving tube life and reliability while achieving an ultra-low noise floor. The entire system achieves a signal-to-noise ratio exceeding 100 dB.
Technical Specifications
Stereo Output Power: 25 W per channel into 8 Ω
Frequency Response: 6 Hz – 60 kHz ±1 dB (1 W into 8 Ω)
Power Bandwidth: 8 Hz – 62 kHz (-3 dB)
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
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
Tube Complement: 4 x KT90；2 x 6922
Machine size: 17 (W) x 14 (D) x 10 (H) in
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