Both of those circuits are for driving tiny ultrasonic transmitters and the first circuit in particular is very inefficient, the second isn't much better.
You need to give us some specification for the transducer, is it voltage driven like the one in the circuit, in which case it is probably a ceramic piezo unit or is it current driven like a loudspeaker? The amplifier design can't be decided without knowing what it drives. Piezo might need several hundred volts at low current, dynamic might need low voltage but several Amps.
Brian.