The transistor on the left is a common emmiter amplifier with a current source as collector load. The top transistor on the right is an emitter follower and the bottom transistor on the right is a current source, but which is modulated by the input signal ( this increases the output swing of the amplifier )
I built this using BC550 for the CE amplifier, a J111 and 680ohm resistor as current source and the two output transistors are TIP41 ( better to use small heatsink on these )
