There is a lot of confusion on baffle step compensation and why it is necessary. But the basic premise, is that just by putting a speaker in a box, you lose 6db of bass. The cutoff frequency is dependent on the size of the box. Now this may seem very complex, but once you get the basic theory down, it is quite simple to implement. Here is a great article that goes into detail about Baffle Step, how to calculate it and what is going on. Enjoy the read!