A switching regulator for regulating an ac signal, and method of supplying power thereto wherein the regulator includes a positive half cycle part and a negative half-cycle part arranged to regulate the respective parts of an input ac signal. Each half-cycle part includes a modulating transistor, having an associated modulator diode, and a clamping diode arranged to protect the modulating transistor from reverse-bias voltages and having an associated clamp switch. The regulator further has a first switching controller operable to cause the modulating transistors to switch and a second, separate switching controller operable to cause the clamp switches to switch.