For the a one amplifier circuit is very suitable for use in applications subwoofer speaker, which allows for higher spending enough bass. Although output was spent not high, but for bass sounds do not undoubtedly. Indeed, the output is only 20W mono amplifier with 8 ohm impedance. With a maximum supply 44Volt DC. Part list R1 = 47R R2 = 100K R3 = 1R 2W C1 = 2.2uF C2 = 220uF C3 = 100uF C4 = 47uF C5 = 68uF C6 = 100uF C7 = 1000uF C8 = 0.1uF U1 = STK024 , STK031 ,STK035