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Build Your Own High-Quality Headphone Amplifier Circuit
High-quality unit. Preamplifier is not required.
Circuit Diagram
Amplifier Components:
- P1 22K Logarithmic Potentiometer (Dual-gang for stereo)
- R1 560R 1/4W Resistor
- R2, R3 10K 1/4W Resistors
- R4 12K 1/4W Resistor
- R5, R6 2R2 1/4W Resistor
- R7 22R 1/2W Resistor
- C1 1uF 63V Polyester Capacitor
- C2, C3, C4 100uF 25V Electrolytic Capacitors
- C5 22pF 63V Polystyrene or Ceramic Capacitor
- C6 22uF 25V Electrolytic Capacitor
- IC1 LM833 or NE5532 Low-noise Dual Operational Amplifier
- Q1, Q3 BC337 45V 800mA NPN Transistors
- Q2, Q4 BC327 45V 800mA PNP Transistors
Power Supply Components:
- R8 2.2K 1/4W Resistor
- C9, C10 2200uF 25V Electrolytic Capacitors
- D1 100V 1A Diode Bridge
- D2 5mm or 3mm Red LED
- IC2 7815 15V 1A Positive Voltage Regulator IC
- IC3 7915 15V 1A Negative Voltage Regulator IC
- T1 220V Primary, 15 + 15V Secondary 5VA Mains Transformer
- PL1 Male Mains Plug
- SW1 SPST Mains Switch
Notes:
- Can be directly connected to CD players, tuners, and tape recorders.
- Tested with multiple headphone models of various impedances: 32, 100, 245, 300, 600, and 2000 Ohms.
- Capable of driving older 8 Ohm impedance headphones; however, these obsolete devices are not recommended for operation.
- The schematic represents the left channel and the power supply.
- The numbers in parentheses indicate the pin connections for IC1 on the right channel.
- Proper grounding is crucial for eliminating hum and ground loops. Connect the ground sides of J1, P1, C2, C3, and C4 together. Then, establish separate grounds at the power supply ground for the input and output.
Technical Specifications:
- Output Voltage: Significantly above 5V RMS across all loads.
- Sensitivity: 250mV input for a 5V RMS output.
- Frequency Response: Flat from 30Hz to 20KHz.
- Total Harmonic Distortion @ 1KHz & 10KHz: Below 0.005% on a 32 Ohm load and up to 4V RMS output (typical 0.003%).
- Total Harmonic Distortion @ 1KHz & 10KHz: Below 0.005% on a 100 to 2000 Ohm load and up to 5V RMS output (typical 0.003%).
The design exhibits unconditional stability on capacitive loads.
author: RED Free Circuit Designs
circuit from http://www.redcircuits.com/
circuit from http://www.redcircuits.com/