It is all in the design of the sub and how all the parts interact. You can have a big driver that reacts just as quick as a small one but the tone it has will be different as the bigger driver will tend to produce the lower frequencies better so that is what you hear. If you were able to play excatly the same singular frquency through the bigger sub and smaller sub then you would hear the same sound but as the sub is reproducing many different frequencies all at the same time, the bigger subs generally emphasize the lower ranges while the smaller ones work better in the midrange of bass and of course all this is room depend etc. I think this is why so many people say that smaller subs are more musical. It is just that they tend to play all but the lowest of musical notes very well as that is where they are deisgned to play due to the laws of physics but my PB13 Ultra is very musical yet can still reach down to 15hz for HT
