Is is OK if the notes in the bass line don't match the chord progression?

This Saturday I'll be leading a group of experienced players in an all-day structured jam session. The goal is not to learn a bunch of new tunes. The goal is to practice a bunch of cool back up ideas.

We'll be focusing on chord progressions and experimenting with different rhythms.  Single notes, root arpeggios, open chords, compact patterns, drones, boom-chucks, down beats, off beats, snippets of harmony ... we intend to try it all! But right now I've got bass lines on my mind.

There are four basic ways for a bass line and a melody line to interrelate:

• contrary motion - movement in opposite directions
• parallel motion - movement in same direction and at same interval, e.g. parallel thirds or sixths
• similar motion - movement in same direction but at different intervals
• oblique motion - one line (usually the bass) sits on the same note while the other (the melody) moves up or down. Think 'drone'.

Bass lines are fun to play and add pizazz to a piece of music. They suggest movement, giving direction to a tune. There are a variety of ways to go about establishing a bass line, but the idea often intimidates players who are new to arranging and playing backup. Here's an easy way to get started:

• Know the key of the tune
• Play a descending scale that starts and ends on the root of the key.
• Believe it ... this works in a lot of tunes!

For example, consider the standard fiddle tune, "Whiskey Before Breakfast". It's typically played in the key of D. Try this in the last four measures of the B part. Go to the lowest D scale on your instrument. While someone else is playing the melody line, you play the D scale backwards ... | D - C# - | B - A - | G - F# | E - D - | ...single notes on beats 1 and 3. Notice the notes of the bass line are exactly the same as the notes of the melody line on beats 1 and 3. (You should be playing the bass line an octave below the melody.) This is a type of parallel motion. Two lines moving together on a unison note creates a powerful sound ... most effective in small doses.

This idea often works throughout an entire A or B part of a fiddle tune. In fact, it will work throughout the entire B part of Whiskey Before Breakfast. Go ahead. Give it a try! (Hint: You'll be playing that backwards D scale twice.)

Now, I know somebody out there will be paying attention and will notice that when you apply this idea to a larger portion of a tune the notes in the bassline do not always jibe with the notes suggested by the chord progression. Yes, it's true. Sometimes a bass line will contain notes that don’t actually belong in the chord progression. It's an accepted exception. The bass line takes precedence. Those odd notes will have some relation to the chords!

So, the answer to the question is 'yes' ... it's ok if the bass line doesn't exactly 'fit' the chord progression. Go ahead ... experiment. Know the key. Start somewhere and MOVE, even for a few notes. Trust your ear. Have fun!