Remix if you want to learn more about how to make a dubstep bass drop.
I usually use Growl, Yahy or Yoy, Blips, and Modern Talking. Most of the time, the BPM would be at 140.
For the growl, I would mess around the master tuning and the velocity or frequency to make wobbles.
Yahy is making wobbles with the frequency, but adding a bitcrusher and playing with the downsampling.