The Tsar bomb was in the ballpark of a 50 megaton explosion, whereas estimates that I've seen for Krakatoa put it at up to 200 megatons. That said, there would be differences due to the fact that h-bombs are exploded at a height to maximize the damage from the blast wave, and that a significant fraction of Krakatoa's energy would have been spent on throwing earth around. It's always hard to compare different explosions because it's difficult to know what fraction of the energy output goes into acoustic energy, but I think it's reasonable to assume that Krakatoa was louder (at least in that the sound was heard further).
