Description:
A single channel headphone amplifier module suitable for driving headphones of 32 ohms or greater impedance. The amplifier is essentially a TL071 operational amplifier with an additional output buffer stage built from a complementary transistor pair.
Table 1: Component function
| R1,2 |
These set the gain of the amplifier. The voltage gain is given by R1/R2. |
| R3,4 |
Biasing resistors. These allow a small bias current to flow into the bases of T1 and T2, so that both transistors are in a conducting state. |
| R5,6 |
Loading resistors. These prevent excessive current from flowing to the output, or between the supply rails. |
| C1 |
Reduces the gain at very high frequencies. Sometimes required for stability. |
| C2,3 |
AC bypass for D1 and D2. |
| C4,5 |
Low frequency supply decoupling capacitors. |
| C6,7 |
High frequency supply decoupling capacitors. |
| D1,2 |
Biasing diodes. The forward voltage drop of these diodes keep the base-emitter junctions of T1 and T2 forward biased so that they are conducting with zero input signal. This reduces the crossover distortion of the amplifier. |
| T1,T2 |
Discreet transistor buffer for IC1. |
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