I have been reading the following article about Class-A and Class-B amplifers. http://www.antonine-education.co.uk/Pages/Electronics_2/Amplifiers/Power_amps/further_page_12.htm#Question 1.
I am not sure I understand the point of having an Op-AMP in the class-B amplifier ! Why do we use a set up pull-push in the Op-AMP's feeback loop? Why don't we just use OP-AMP by itself? And, how does OP-AMP helps to improve cross-over distrotion?
Also, in the same article, right above question 3, it states the following:
"The op-amp holds the base-emitter voltage of the npn transistor at 0.7 V. When there is a negative signal, the op-amp changes over, dropping 1.4 V, so that it turns on the pnp transistor. The voltage gain is 1, but the power gain is almost infinity."
Could someone please explain the above in relatively easier way?