• JD90

    Current-Mode Tube Power Amplifier

  • Introduction to the Characteristics of Products

    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.

  • Amplifier Technical Specifications

    Stereo Output Power: 25W

    Frequency Response: 6Hz–60kHz ±1dB @ 1W/8Ω, 1kHz Ref

    Frequency Range: 8Hz to 35kHz (-3db); 25W at 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

    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: 4-6 Ω / 8-16 Ω

    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 Weight: Net: 73 lbs (33 kg) | Gross: 86 lbs (39 kg)

    Fuse Rating: T6.3A/250V (100–120V AC, 60Hz); T3.15A/250V (200–240V AC, 50Hz)

    Maximum Power: ≤300VA

  • FRE-1W

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    FRE-15W

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    FRE-30W

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    THD-1W

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    THD-15W

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    THD-30W

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    SNR

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    Sensitivity

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    R-Channel Separation

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    L-Channel Separation

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    Channel Isolation

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  • Compatible Replacement Tubes

    Factory Installed Tube

    6922EH

    SVKT90

    Compatible Tube Types

    ECC88、E88CC、7803、6DJ8

    6550