Efficient, unity power-factor, low cost audio power amp supplies

This article deals with audio power amplifier power supplies with sine wave current absorption, showing all the benefits these offer for audio systems, these benefits being inherently good power factor providing low RMS current, low harmonic pollution, low transformer over-dimensioning and good form-factor of the output current allowing smaller capacitor values and lower output impedance. Although this is not the purpose of the article, these supplies have obvious ecological benefits as well.