1. Right Circuit (Auto-Bias Power Stage)
Active Bias Feedback: It uses a dedicated auto-biasing (dynamic bias) control loop.
Current Sensing: The 220\text{ m}\Omega emitter resistors continuously sense the current flowing through the output stage.
Feedback Diodes & Control Transistors: Diodes connected from the output node back to the driver stage, along with the auxiliary driver transistors, form a dynamic feedback loop. This automatically senses quiescent/operating current and adjusts base voltages to maintain proper Class-AB bias without needing a manual V_{BE} multiplier or bias potentiometer.
2. Left Circuit (Op-Amp Driven Push-Pull Stage)
Global Feedback Correction: This circuit uses an operational amplifier (100\text{ kV/V} open-loop gain) driving compound (Sziklai) transistor pairs.
No Active Output Bias Network: There is no dedicated V_{BE} multiplier or active bias-sensing loop in the output stage itself. Instead, it relies on the op-amp's high gain and global negative feedback loop (10\text{ k}\Omega / 1\text{ k}\Omega) to rapidly slew through the dead-band region and correct crossover distortion at the output.
