I just wondered how the video guy had done the same thing ,invert the output of comparator.without doing any grounds to the unused pins of hex inverter.Any solutions ?In the beginning you are talking about bridge amplifier ,Did you mean to say that I need to build full H bridge amplifier circuit using two comparators Lm 393 ,1st will be Non inverted output and second will be inverted output and then I need to use two MOSFETs drivers ir2113 for drive full h bridge using 4 MOSFETs? Is this you are asking?