Two kick drums and two bass lines at once is the single commonest reason a mix sounds like mud. The bass swap is the fix, and it is the first transition technique worth drilling properly.

By the end of this course you will be able to

Swap the bass from one track to the other without a gap or a lump
Use the mid and top to bring a track in before its bass arrives
Keep the overall level steady while you are moving EQ around
Hear when two bass lines are fighting

Lessons

Using bass, mid and top in the mix

Duration: 8:55
The EQ in a transition

Duration: 7:29
What the mid and top are for

Duration: 9:27
Using the bass in a transition

Duration: 15:25
One bass line into another, smoothly

Duration: 12:21

The stages are the way through

Below this line is the back catalogue, newest first. Useful for browsing, but it is not a course - the videos are in the order they were filmed, not the order to learn them in. Work the stages instead: each one assumes the one before it.