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Balance amplifier

Ah, that's much better. But what's that horrible distortion at ground level? When vIN = 0V, VB1 = VB2 = 0V (assumed R1 = R2). Since VRL is also 0V, VBE1 = VBE2 = 0V. This means that when VIN is between -0.6 and 0.6V, T1 and T2 both remain open. This usually happens when vIN crosses the 0V line. That's why it is called 'cross-over distortion'. To get rid of this, we must make sure that the quiescent voltages VBE1 = 0.6V and VBE2 = -0.6V. This can be simply accomplished by adding two diodes: