Ah, that's much better. But what's that horrible distortion at ground level? When v_IN = 0V, V_B1 = V_B2 = 0V (assumed R1 = R2). Since V_RL is also 0V, V_BE1 = V_BE2 = 0V. This means that when V_IN is between -0.6 and 0.6V, T1 and T2 both remain open. This usually happens when v_IN 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 V_BE1 = 0.6V and V_BE2 = -0.6V. This can be simply accomplished by adding two diodes: