Watch the Using Melodicism online guitar lesson by Andrew Ford from Focus On: Reggae Bass
Here I will demonstrate 3 typical reggae style grooves. They will all be played over a 1-4 chord progression in the key of C. These patterns all share a melodic quality typical of reggae bass. The organ bubble rhythm is essential in creating the bed for the bass line to lie in. Like I mentioned before, it's like the bass and guitar have switched roles in this context, the guitar being more simple and supportive where the bass has liberties to create melodies within the groove.
Example 1 establishes beat one using the root even though there is a one drop type pattern(no accent on one) played by the drums. It follows with a 16th rhythm using the root, 6 and 5 in C. The second half of the bar establishes the root again over the F chord and does a similar 16th note motif with the octave, major 7, and 6. In this 2 bar phrase we start the second bar by playing 8th notes on the root for some contrast and following that with the same exact rhythms from the previous bar. A lot of repetition but somehow not boring especially if you are focusing on the depth of the groove and note placement.
In Example 2 we use the same 1-4 progression in C but this time we begin the line with a short root-5 rhythm followed by space, the space is critical, don't let the notes ring over. The length of notes is critical to the feel as it is in any style bass line. Next we have a slurred note from E, the major 3rd to F, the root of the next chord. We continue with a 4 sixteenth note rhythm using F and finish out the chord by walking down playing the major 7th and 6. This leads us smoothly back to C, the root of bar 2, but this time we use space to set up a different slurred rhythm that goes from the 5, G, to the major 3rd of our new chord F. We finish off that F chord with a rhythm using the 5, C, major 3rd, A, and G which is the 2 but also the 5 of C so it works as a great transitional note.
Example 3 is our busiest line. We use almost the same line in both bars only ending each phrase differently. In bar 1 we play octave rhythm using the root over the C chord. Then we have a 16th pattern that uses the 6, 5, 3, and root which are A, G, E, and C. We end the phrase with a 1, 3, 5 rhythm that is 16th based, over the F chord. In bar two we begin with that same motif over the C chord and finish it off with a 1, 3, 2 rhythm that is 8th note based.