Based on UK NAD 3020 Tone Control Circuit Finished HiFi Class A Preamplifier Board with All-Discrete Gold-Sealed Transistor

Finished Class A All-Discrete Preamplifier Board with Tone Control, Based on the Classic British NAD 3020 Circuit

This is a meticulously crafted, all-discrete component preamplifier board with tone controls, based on the legendary tone section of the famous British NAD 3020 integrated amplifier. The circuit operates in a single-ended Class A mode, providing an exceptionally warm, alluring, and high-fidelity sound. It's the perfect choice for audiophiles looking to add musicality and high-quality tone adjustment to their home audio system.

Key Features at a Glance:

 ▶ Based on the Classic NAD 3020 Circuit: The design is a tribute to the tone control section of the classic NAD 3020, renowned for its uniquely musical and effective equalization.

 ▶ Pure Class A, All-Discrete Design: Utilizes "gold-sealed" transistors in a true discrete circuit (no op-amps in the signal path), providing a warm, clear, transparent, and non-fatiguing sound.

 ▶ Premium Audiophile Components: Built with carefully selected components for
superiorperformance, including military-spec 718 factory copper pin resistors, Nichicon and ELNA filter capacitors, German WIMA non-polar capacitors, and high-quality Taiwan SONG potentiometers.

 ▶ High-Precision Regulation: The power supply section uses high-precision, low-noise LM317/337 voltage regulator ICs to ensure a clean and stable power foundation for the audio circuit.

 ▶ Unique Tone Control Philosophy: Its greatest feature is that when adjusting the Bass (±15dB) and Treble (±10dB) controls, the critical Midrange remains almost entirely unaffected, preserving the core musicality while allowing for fine-tuning.

Technical Specifications:

 Circuit Design: Based on NAD 3020 Tone Section
 Circuit Type: Single-Ended Class A, All-Discrete
 Gain: 8dB
 Tone Control Range: Bass ±15dB, Treble ±10dB
 Power Supply Requirement: Dual AC 22V to Dual AC 24V (3-wire transformer)
 PCB Dimensions: 138mm x 81mm x 1.6mm

Important Wiring Note:
When testing the bare board, it is essential to connect the metal outer casings of all potentiometers together with a single wire, and then connect that wire to the main "GND" (Ground) point on the PCB. This will eliminate any potential hum or noise. Input signals must be delivered via shielded cables.