Simple CapM PSU
This is very basic capacitance multiplier PSU for audio amplifier. Differential amplifier senses and filters input voltage through RC network, that filtered voltage is used as a reference for output voltage regulation. Inverting output drives MOSFET gates and regulates output voltage. During PSU startup reference voltage is rising slowly (as the output voltage) - soft start feature. Simple circuit but works very efficient. Before current will pass through speaker coil it must pass through PSU, so that fact can not be ignored. PSU is only a beginning a good start for good amplifier project.