Low-cost Headphone Amp
Music to your ears
Materials
Gerber file
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Extra info / Update
Specifications (output load: 33 ?, supply voltage: ±9 V)
• Input impedance (without P1) 10 k?
• Bandwidth 3.4 Hz – 2.4 MHz
• THD + Noise (1 kHz, 1 mW/33 ?) 0.005 % (B = 22 kHz)
• THD + Noise (20 Hz - 20 kHz, 1 mW/33 ?) 0.01 % (B = 80 kHz)
• Signal to noise ratio (ref. 1 mW/33 ?) 89 dB (B = 22 kHz) 92 dBA
• Max. voltage (into 33 ?) 3.3 V (THD+N = 0.1 %)
• Max. input voltage 0.57 V (with P1 set to maximum volume)
• Current consumption 19 mA
Component list
R1,R6 = 10kOhm
R2,R3 = 1kOhm
R4 = 270Ohm
R5 = 1.5kOhm
R7 = 4.7kOhm
R8,R9 = 150Ohm
R10,R11,R12 = 10Ohm
P1 = 10kOhm
P2 = 100Ohm trimpot
Capacitors
C1 = 4.7µF, lead pitch 5mm or 7.5mm
C2 = 6.8pF, lead pitch 5mm
C3 = 10pF, lead pitch 5mm
C4,C5,C6 = 100µF 16V radial
Semiconductors
D1,D2,D3,D4 = 1N4148
T1,T2,T3,T5 = BC550C
T4 = BC560C
T6 = BD139
T7 = BD140
Miscellaneous
Connection for P1 = 3-pin pinheader, lead pitch 0.1 in.
Connection for P1 = 3-way socket strip, lead pitch 0.1 in.
7 pcs 1.3mm diam. solder pin
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