B-I

This extraordinary all-FET control amp with advanced tone control, made with music in mind, was the starting point for the Yamaha hi-fi amp design philosophy of simply preparing a meal from carefully selected ingredients.
Achieves an effective output of 150 W + 150 W with audio-usage vertical power FET and single push pull OCL circuit. That overwhelmingly high sound quality served to further Yamaha's reputation as a premium audio manufacturer.