XH-M802 Preamplifier Passive Tuning Board

XH-M802 Preamplifier Passive Tuning Board is an audiophile-grade tone control module designed to shape and optimize the sound quality of your audio system without requiring any external power supply. Unlike active preamplifiers that rely on transistors or operational amplifiers, this board uses purely passive components—resistors, capacitors, and potentiometers—to achieve its tuning capabilities. By placing the XH-M802 between your audio source and your power amplifier, you can precisely adjust the bass, treble, and overall volume, giving you superior control over the final sound profile. Its passive design ensures zero noise introduction and minimal distortion, which makes it an ideal choice for enthusiasts who demand the purest possible audio signal before amplification.

Key Features:

• Passive Design: Requires absolutely no power supply, eliminating any potential hum or noise introduced by active electronics.
• Pure Tone Control: Features dedicated rotary potentiometers for adjusting Volume, Bass, and Treble, allowing precise acoustic shaping.
• Zero Noise Injection: Since it does not use active components, it maintains the integrity and purity of the original audio signal.
• Two-Channel Stereo: The board supports dual-channel audio, making it perfect for standard stereo amplifier setups.
• High-Quality Potentiometers: Uses durable, high-precision variable resistors to ensure smooth, reliable, and noise-free adjustment over the product’s lifespan.

Technical Specifications:

• Type: Passive Preamplifier / Tone Control Board
• Channels: Dual Channel Stereo
• Power Requirement: None (Passive operation)
• Adjustment Range (Treble): ±10 dB (Typical)
• Adjustment Range (Bass): ±10 dB (Typical)
• Input Impedance: Determined by external components and volume setting (typically high)
• Output Impedance: Determined by external components and volume setting (typically low for minimal impact on the next stage)

Mechanical Specifications:

• Controls: Three Rotary Potentiometers (Volume, Bass, Treble)
• Connectors: Screw terminals for audio input and output wiring.
• Material: Durable FR4 PCB.

Dimensions:

• Board Length: ~60 mm
• Board Width: ~35 mm
• Height (with components): ~20 mm

Pinout and Wiring:

• Input (L/R/GND): Connect the audio source (e.g., DAC, phone, player) output terminals to the corresponding Left, Right, and Ground terminals.
• Output (L/R/GND): Connect these terminals to the input of your main power amplifier board.
• Wiring Note: Always connect the audio source to the Input terminals and the power amplifier to the Output terminals. Since this board is passive, signal levels remain high, making correct grounding essential to prevent hum.

Datasheet Reference:

• Download Generic Passive Tone Control Schematic

Commonly Used in:

• High-Fidelity Audio Builds: Integrated into custom stereo systems where sound purity is the primary goal.
• Vintage Audio Restoration: Used to replace noisy or failing tone control circuits in older receivers and amplifiers.
• Desktop Audio Systems: Provides simple, accessible tone control between a computer’s audio interface and a desktop amplifier.

Applications:

• Custom Amplifier Projects: Add bass and treble adjustments to a power amplifier module that lacks built-in tone control.
• Acoustic Compensation: Adjust sound output to match the unique acoustic characteristics of a listening room or speaker placement.
• Signal Conditioning: Fine-tune the frequency response of music or podcasts before final amplification.

Equivalent Models:

• NE5532 Preamplifier Boards: Active preamp boards that offer higher gain but require a power supply and may introduce minimal noise.
• PT2399-based Tone Controls: Digital tone control chips used in cheaper, mass-market audio equipment.

Package Includes:

• 1 x XH-M802 Preamplifier Passive Tuning Board