Amplifier circuit here is all based on the ic in the gains. Three IC TA7230P, TA7236P, TA7237AP is intregated circuit (IC) which was applied to the power amplifier. Each IC has a different output, different input voltage, all IC TA7230P, TA7236P, TA7237AP is manufactured by Toshiba.
You can see maximum minimum voltage , power output , and other here
|TA7230P, TA7236P, TA7237AP amplifier schematic|