Advantages of closed power amplifier

The biggest advantages of closed-loop power amplifier are small magnetic leakage, high efficiency and relatively low cost. Widely used in household power amplifier. Ring transformer and EI transformer are commonly used in audio power amplifier, but switching power supply is rare. In fact, the research and development of power amplifier started from switching power supply, because of its high cost and poor low frequency characteristics. It was difficult to solve the electromagnetic interference problem of switching power supply, and then they all gave up.