Headphone Amplifier

High Quality unit

No need for a preamplifier

Circuit diagram:

Headphone Amplifier

Amplifier parts:

P1_____________22K   Log.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______________1µF   63V Polyester Capacitor
C2,C3,C4______100µF   25V Electrolytic Capacitors
C5_____________22pF   63V Polystyrene or Ceramic Capacitor
C6_____________22µF   25V Electrolytic Capacitor

IC1___________LM833 or NE5532 Low noise Dual Op-amp 

Q1,Q3_________BC337   45V 800mA NPN Transistors
Q2,Q4_________BC327   45V 800mA PNP Transistors

J1______________RCA  audio input socket

Power supply parts:

R8______________2K2  1/4W Resistor

C7,C8________2200µF   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


Technical data:

Output voltage: Well above 5V RMS into all loads

Sensitivity: 250mV input for 5V RMS output

Frequency response: Flat from 30Hz to 20KHz

Total harmonic distortion @ 1KHz & 10KHz:
Below 0.005% into 32 Ohm loads and up to 4V RMS output (typical 0.003%)
Total harmonic distortion @ 1KHz & 10KHz:
Below 0.005% into 100 to 2000 Ohm loads and up to 5V RMS output (typical 0.003%)
Unconditionally stable on capacitive loads